News

There are some problem we usually may have during the dental restorations cement, which due to the cement materials, the structures of the abutment after preparation, the dental restorations. 1), The pontic and abutment cement surface cause jackknifing: first of all, we need to check the reason and the jackknifing surface. Technically, we need to remove the pontic and remake it if we find it that the pontic rocks on the abutment. 2), The abutment is too sensitive to the hot and cold: this situation normally happens to those patients who have gingival atrophy, or revealing of the root. When dentist doing the acid etching on the abutment, few acid liquid might permeate the root. When this happens, dentist can make a layer of enamel or bonding material around the root, or give patient desensitization collutory to make patient feel better. If we ignore this, this sensitive symptom will take about one to two weeks at least or one to two months for the sever patient to disappear by itself. 3), Gingivitis: There are two mainly reasons for gingivitis: the cement covers the gingiva or gets into the groove of the gingiva; the unreasonable design of the pontic or the unfitting pontic might cause gingivitis. For the former, we should check seriously and remove the extra composite material and use some medicine. It will need a remake for the unfitting pontic. 4), Abutment Secondary Caries: Most causes of the secondary caries is that the adhesive dental bridge is partially broken but does not fall off, especially existing in the the abutment gingival undercut where the composite remains or which depends on the retention of wire clasp. Patient needs another treatment as long as there is a secondary caries. 5), Pontic Labial abrasion or defectiveness: The pontic labial abrasion is usually caused by patient using hard brush. The good way to against the abrasion is to choose a soft fur tooth brush. If there is an abrasion, we can repair it in Veneer restoration way. As for the defectiveness, it`s because of the shortness of the metal surface of the Maryland bride pontic labial contact. The bite force will be on the incisal of the composite occlusion. 6), Metal Wing Adhesive is off: There are three reasons: 1. the metal wing design has no retention shape; 2. the cement material is not good enough; 3. the abutment which to be adhesive is not dealt with well enough as inquired. As long as the metal wing is off, we need to remake the Maryland in most cases.

Mega Dental Lab wishes all friends in China, and who are abroad a happy DuanWu Jie(i.e. Dragon Boat Festival)! Dragon Boat Festival 2017 falls on May 30 (Tuesday). The holiday in China starts from May 28 to 30, 2017. Dragon Boat Festival, also called Duanwu or Tuen Ng Festival, is a traditional holiday observed annually over 2,000 years in China to commemorate Qu Yuan (340-278 BC), an ancient Chinese patriotic poet. Originated from south China, Dragon Boat Festival enjoys higher popularity in southern areas, such as Jiangsu, Zhejiang, Guangdong and Fujian Provinces. Dragon Boat Festival Facts Chinese: [duān wǔ jié] Date: 5th day of 5th lunar month History: more than 2,000 years Traditions: eating Zongzi (sticky rice dumplings), dragon boat race Dates Defined by Chinese lunar calendar, the date of Dragon Boat Festival falls on the 5th day of the 5th lunar month according to lunar calendar, so the Gregorian date varies every year, and hereunder is the holiday schedule from 2016 to 2021. Year Date Holiday 2016 June 9 June 9 - 11 2017 May 30 May 28 - 30 2018 June 18 June 16 - 18 2019 June 7 June 7 - 9 2020 June 25 June 25 - 27 2021 June 14 June 12 - 14 Origin & History Why is the Dragon Boat Festival celebrated? With a history over 2,000 years, it used to be a hygiene day when people would use herbs to dispel diseases and viruses. However, the most popular origin is closely related to the great poet Qu Yuan in the Warring States Period (475 – 221BC). To engrave his death on the fifth day on the fifth lunar month, people celebrate the festival in various ways. Great people like Wu Zixu and Cao E also died on the same day, so in certain areas, people also commemorate them during the festival. Legend of Qu Yuan As a minister in the State of Chu - one of the seven Warring States, Qu Yuan was a patriotic poet who wrote a lot of works to show his care and devotion to his country. Composing masterpieces like Li Sao (The Lament), he was regarded as one of the greatest poets in Chinese history. After he was exiled by the king, he chose to drown himself in the river rather than seeing his country invaded and conquered by the State of Qin. He died on the fifth day of the fifth lunar month, thus people decided to commemorate him on that day every year. Traditions & Customs Many traditional customs and activities are held on the specified day by people in China and even by people in neighboring Asian countries. Dragon boat racing and eating Zongzi are the central customs of the festival. In some regions in China, people also wear a perfume pouch, tie five-color silk thread and hang mugwort leaves or calamus on their doors. Eating Zongzi Most Chinese festivals are observed by eating a particular food as a custom, and the Dragon Boat Festival is no exception. Zongzi, a pyramid-shaped glutinous rice dumpling wrapped in reed leaves, is the special food eaten on the day. It has various fillings. In north China, people favor the jujubes as the filling, while the south sweetened bean paste, fresh meat, or egg yolk. Nowadays, Zongzi already becomes a common food, which can be easily found in supermarkets. However, some families still retain the tradition to make Zongzi on the festival day. Dragon Boat Racing Dragon boats are thus named because the fore and stern of the boat is in a shape of traditional Chinese dragon. A team of people works the oars in a bid to reach the destination before other teams. One team member sits at the front of the boat beating a drum in order to maintain morale and ensure that the rowers keep in time with one another. Legend holds that the race originates from the idea of the people who rowed their boats to save Qu Yuan after he drowned himself. Now it has turned to be a sport event not only held in China, but also observed in Japan, Vietnam, and Britain. The best places to experience the dragon boat races during the festival are: a. Yueyang International Dragon Boat Race: Miluo River Dragon Boat Race Center, Yueyang, Hunan b. Zigui Dragon Boat Racing: Xujiachong Bay, Zuigui County, Yichang, Hubei c. Miao People`s International Canoe Festival: Qingshui River, Guizhou d. Hangzhou Xixi Dragon Boat Race: Xixi Wetland Park

Dear Friends, Customers and Colleagues, A new month is coming soon. May 1st is the official holiday for celebrating the Labor Day which happens to Monday. Therefore, we Mega Dental Lab will be closed from Sunday to Monday. All dental jobs will be finished and sent out by Saturday, except for those problem pending jobs. Please kindly be noted. More details or other questions, please feel free to contact our customer services in time. We---Mega Dental Lab wish you a nice Holiday! Happy Labor Day ! Mega Dental Lab

by Michael Tischler, DDS We believe that there are still lots of patients are in need of Implant Overdentures. For those senior citizens, Implant over denture will be a good efficient option. Let's check why. Here is what Dr. Michael told us as below: While I still believe overdentures are a valid option for a patient for full-arch tooth replacement, I now treatment plan overdentures either as a transitional option toward a zirconia implant bridge or as a final option for patients who just can`t afford anything else. This month`s Implants Today topic is implant overdentures. Overdentures are one of a few different and important prosthetic options to replace a patient`s entire arch of teeth. Why would a clinician choose this removable option for their patient over other fixed-implant prosthetic alternatives? The answer to this question could be based on the financial cost to the patient, the clinician`s experience, the operator comfort level in providing this option, the choice for the patient with respect to manual dexterity related to hygiene issues, the use of an overdenture as a transition to a fixed prosthetic alternative, or a combination of all of these concepts. It is important to keep in mind that overdentures are a full-arch implant prosthetic solution, and from that context, other full-arch implant prosthetic solutions have to be evaluated as part of the patient`s treatment plan. Ten years ago in my practice, 50% of my full-arch cases were bar overdentures as a full-arch tooth replacement solution. I appreciated the fact that implants were splinted with a bar, and the overdenture was mostly supported by the implants instead of soft tissue-a patient could have second molar occlusion, and a bar overdenture would fulfill the parameters of lip support, aesthetics, occlusion, and other prosthetic solutions. In 2009, I was fortunate to be featured on the cover of Dentistry Today with a model of a bar overdenture in my hand for an article entitled [The Future of Implant Dentistry for General Dentists." The future of implant dentistry in my practice has evolved to doing more screw-retained, full-arch zirconia implant bridges instead of overdentures as a final prosthetic option. I have found that the success rate is much higher with this option than with acrylic hybrid bridges, by a large margin. There is also less maintenance with regard to the prosthesis with a screw-retained zirconia implant bridge. Overdentures, due to their inherent removable nature, create wear and tear on retentive parts. The time needed by a clinician to replace overdenture parts should be taken into consideration from a treatment planning and practice management standpoint. Discussion of the time and costs to maintain overdenture parts is important when treatment planning with a patient. There are advantages and disadvantages with each prosthetic option. While I still believe overdentures are a valid option for a patient for full-arch tooth replacement, I now treatment plan overdentures either as a transitional option toward a zirconia implant bridge or as a final option for patients who just can`t afford anything else. As with every prosthetic option in implant dentistry, treatment planning is the most important starting point. Treatment planning is about explaining the available options to a patient while considering the individual`s lifestyle, age, economic situation, health, career, and more. As clinicians, we are looking for the right prosthetic fit for each patient. From a clinician`s standpoint, the prosthetic steps to create an implant overdenture parallels the steps for a Misch classification fixed prosthetic 3 (FP3) option on many levels. The FP3 classification indicates that a prosthetic pink gingival area is being utilized to address bone loss from either alveoloplasty or natural causes. Patient records, impressions, verification jigs, try-ins, and other steps all have to be done. From a surgical standpoint, there are also many similarities, including similar implant positions and performing adequate alveoloplasty, to allow for prosthetic thickness. These similar prosthetic and surgical steps allow for an easy transition between overdentures and FP3 zirconia, porcelain, or acrylic options. These parallel steps between overdentures and a FP3 prosthesis become important with respect to treatment plans and how clinicians transition implant cases. Another advantage of utilizing overdentures for treatment is the choice of utilizing a bar for overdenture support or just using overdenture attachments. This allows for much flexibility in treatment planning with a large difference in costs to the patient. Misch classifies these 2 removable restoration choices as RP4 and RP5; the RP4 overdenture is primarily supported by a bar and the RP5 is partially supported by soft tissue. Even more flexibility for the clinician exists with attachment choices for either RP4 or RP5 overdentures. Different attachments are available with regard to retention, height, and angulations. This flexibility that overdentures offer allows for ideal transitioning options as a step toward a fixed-implant prosthetic option. Often, patients can`t afford a more expensive fixed option, and an overdenture allows for transitional support of a denture that can later be converted to a fixed implant-supported prosthesis. The fixed prosthesis following an overdenture would have to be a FP3 screw- or cement-retained implant bridge, though. The only exception for overdentures being a transitional step toward a fixed implant-supported prosthesis is when the overdenture is supported by mini dental implants or implants with a fixed ball or retentive attachment. Once mini implants or fixed attachment implants are placed, the patient is then committed to a removable prosthesis. This is a very important treatment planning decision for a patient, as the future prosthesis for an arch is basically permanently decided. This issue`s Implants Today has 2 great articles that represent many of the concepts and other information that I have alluded to in this introduction. One of our distinguished Implants Today advisory board members, Dr. Tim Kosinski, presents the article entitled, [A Sequential Approach to Implant-Supported Overdentures." This clinical case report article exemplifies the concept of transitioning a patient to a nonsplinted RP5 overdenture from a dentate starting point. The treatment planning concepts of utilizing a CBCT scan for planning and placing implants in ideal positions with regard to the anterior-posterior spread are discussed. Dr. Paresh Patel`s article entitled, [Maximizing Stability and Prosthetic Durability," outlines the surgical and prosthetic steps to create a screw-retained full-arch zirconia implant bridge. The implant positions, impressions, verification jigs, and try-in steps are very similar to the steps to create an overdenture. The overdenture options available to our dental patients allow for very powerful choices for a clinician pertaining to either transitional or the final full-arch replacement. The commonality between the surgical and prosthetic steps for an FP3 prosthesis and an overdenture allows for a seamless interchangeability for treatment planning choices. An important strength of every overdenture option is the value in transitioning our patients toward a less affordable but more successful FP3 option. While every prosthetic full-arch option has advantages and disadvantages, the overdenture option has a firm hold in treatment plans for full-arch, implant-supported tooth replacement.

Dentsply Sirona`s Lucitone High Impact Pour Acrylic (HIPA) is the first pourable acrylic denture base on the market to exceed both of the required International Organization for Standardization standards for improved impact resistance, according to the company. The self-curing material is designed for use in the fabrication, repair, rebasing, or relining of full and partial dentures, including implant overdentures or other dental appliances. It also features excellent color stability and accurate fit-to-model, Dentsply Sirona reports. [Lucitone HIPA truly provides solutions to dental labs. Labs who use the traditional heat-cured technique can now work faster while still providing a high-impact denture," said Catherine Bonser, Dentsply Sirona`s director of prosthetics, global removable products. [Increased durability reduces the potential for fractures in the dental lab, resulting in time and cost savings due to less remakes. And, increased durability reduces the risk of breakage from the patient during normal use."

by Gideon Balloch The buzz is back. Excitement about 3-D printing in the dental industry seems to grow every day. With a history of 3-D printing technology generating high expectations but delivering poor reliability and limited applications at a high cost, many dentists are rightfully wondering what the fuss is about this time, and whether to take it seriously. Well, this time is different. Adoption of 3-D printing in dentistry is growing at a quickening pace, and the signs indicate that 2017 will see that growth intensify. To understand why, let`s take a look at the trends that have led us to this point, how both additive manufacturing technology and the dental industry have evolved, and what these indicators reveal about the future. Dentistry: The Perfect Environment for 3-D Printing With unique anatomies and clinical needs for every patient, dentistry has always been a profession in need of not only custom manufacturing, but also highly specialized, high performance devices like crowns, bridges, retainers, splints, surgical guides, and dentures. The list seems almost endless, and it's all about mass customization. Enter 3-D printing. The ability to cost-effectively produce high volumes of customized parts at scale makes 3-D printing the perfect solution for dental production needs. It makes sense, then, that dentistry was one of the first spaces where this technology began to take hold as a digital manufacturing solution in the 1990s. Even clinicians to whom 3-D printing seems radically new have likely interacted with either a 3-D printed part or a part indirectly made using a 3-D printer. Surgical guides and clear aligners were 2 of the earliest applications for direct and indirect 3-D printed parts in dentistry. In fact, Invisalign is probably the largest single manufacturer of 3-D printed models in the world. In the coming years, we expect to see 3-D printing expand across even more applications as more affordable solutions take hold. But it wasn't always this way. Recent Advances in 3-D Printing Driving Adoption Even with a seemingly perfect market fit, for a long time 3-D printing failed to take off from its initial foothold in dentistry, hamstrung by costly machines, spotty reliability, limited materials, and barriers to usability. Just as hype about consumer 3-D printing failed to deliver 3-D printers in use in every household, dental 3-D printing seemed poised to remain a niche. But massive technological advancements in recent years are completely changing the game. Professional-grade 3-D printers have been plummeting in cost while simultaneously improving in quality and reliability. Affordable desktop 3-D printers are pushing barriers to adoption down even further. Some systems have been shown to perform at clinically acceptable levels of accuracy and even to compete with expensive, large-format systems. Desktop machines, designed with simplified user experiences and out-of-the-box precision, are making 3-D printing more intuitive and easier to use than ever before. These advances have effectively diminished the high barriers to the adoption of 3-D printing technology to the point where it has not only become accessible to dental labs of any size, but chairside 3-D printing also is now a viable reality. A Digital World in Search of Manufacturing Endpoints Two other trends in the market are essential to understanding the upcoming possibilities of 3-D printing in dental: the growing adoption of intraoral and desktop optical scanning, and the growth of dental treatment and computer-aided design (CAD) software. For example, 15% to 20% of dental practices have intraoral scanners, with 40% to 50% considering adoption in the next 5 years. Adoption of desktop optical scanners in dental labs has also grown significantly. In addition, an established set of dental software companies such as 3Shape now offer a wide range of treatment design and CAD software for a huge range of applications. This is creating a large market of dental professionals in need of manufacturing endpoints for their digital workflows. What`s Next for 3-D Printing and Dentistry? With a market swinging so heavily into digital workflows, whether dental 3-D printing will take off will depend on its ability to prove itself as the most cost effective, high quality, easiest to adopt manufacturing option for a wide range of dental products. At the end of the day, what matters to any dental professional isn't whether something is handmade, milled, or 3-D printed. What matters is the quality of that final part, the ease with which it can be made, and the cost of making it. Ironically, if 3-D printer manufacturers do their job well, 3-D printing itself will never be a selling point, and the process should fall into the background. (Even though, let's admit it, machines with lasers are pretty cool.) With prices for desktop dental 3-D printers already less than $5,000, cost doesn't appear to be the barrier it once was. The key things to look for in the growth of adoption are applications and materials, reliability, and ease of use. Dental offices and labs have already adopted 3-D printing for applications like surgical guides and models, bringing prices for individual surgical guides down from hundreds of dollars to $3 to $5 per printed guide. But this only represents a small portion of the dental market. We expect to see adoption explode across new 3-D printing applications such as splints, dentures, temporaries, and, one day, permanent restorations, as 3-D printing materials improve in mechanical properties, biocompatibility, and printability. All signs point to a coming of age for 3-D printing technology in an industry that`s ripe for change. With several industry players sensing the opportunity and positioning themselves to drive the future of digital dentistry toward additive manufacturing, it's going to be an exciting year!

Formlabs has announced a pair of dental 3-D printing materials and biocompatible materials designed for 3-D printed dentures, all of which will be showcased and demonstrated at IDS 2017 in Koelnmesse, Germany, March 21 to March 26. The new materials include the following: Dental Model: a high-accuracy resin for crown and bridge models with removable dies; Dental LT Clear: a long-term biocompatible resin for direct-printing orthodontic appliances such as splints and retainers; A pair of Class IIa biocompatible materials for the direct 3-D printing of dentures. Also, Formlabs will partner with 3Shape to introduce software integration solutions for seamless dental 3-D printing workflows to market. This collaboration follows Formlabs` recent distribution agreement with Zahn Dental. Formlabs` Form 2 3-D printer targets dental applications. [To date, Formlabs dental users have completed more than 150,000 prints, and Form 2 printed guides have been used in more than 10,000 implant surgeries," said Gideon Balloch, dental product lead at Formlabs. You may check more real jobs from Mega Dental Lab:

by Michael Tischler, DDS The angle and platform height at which an implant is surgically placed can be corrected through various implant manufacturers` components as well as by using custom abutments. Some implant companies have angle corrections built right into the implant fixture itself; however, these require more exacting placement positions. This month`s Implants Today topic is implant fixtures and abutment considerations. The choice of how a final prosthetic solution attaches to the dental implant(s) involves various factors and is a fundamental concept in implant treatment. The 2 main considerations for an abutment choice are (1) the angulations or platform height of the implant(s) and (2) the soft-tissue height around the implant(s). The final prosthetic option, as determined by a properly prepared treatment plan, should dictate the positions and numbers of dental implants to support that prosthetic decision. This is called prosthetically driven implant dentistry. The abutment that connects the prosthesis with an implant can address the variability of a patient`s hard- and soft-tissue anatomy and is the buffer between a prosthetic goal and the patient`s hard- and soft-tissue anatomy. The angle and platform height at which a im-plant is surgically placed can be corrected through various implant manufacturers` components as well as by using custom abutments. Some implant companies have angle corrections built right into the implant fixture itself; however, these require more exacting placement positions. Multi-unit abutments are a way to correct the angle of an implant, allowing the screw hole to be redirected. Multi-unit abutments come in various angles and heights. The disadvantages of using a multi-unit abutment include the following: an additional microgap, increased costs, and a connection with the potential to loosen. Ultimately, ideal surgical placement should be performed to create optimal implant platform heights and angles based upon the desired prosthetic outcome. The tissue height around an implant is also the result of the surgical technique used and correct treatment planning. If the ideal tissue height cannot be achieved after hard- and soft-tissue grafting and manipulation, then abutments can be used to bring an implant platform to a more coronal position. Ideally, an implant platform should be 1.0 to 3.0 mm below firm keratinized tissue. When an implant platform is more than 3.0 mm below the keratinized tissue, there is an increased propensity for soft-tissue problems and more pain with prosthetic try-ins. Ideally, it is better to achieve the correct platform height by employing correct surgical procedures than to gain that height through prosthetic parts (such as a tall multi-unit abutment). In this month`s issue of Dentistry Today, we have a cover-featured article by Implants Today Advisory Board member, Dr. Jack Piermatti. Dr. Piermatti expertly discusses the details of different abutment choices in implant dentistry. Dr. Daniel Drake has contributed an article on the latest technologies in implant dentistry. Lastly, our editor-in-chief Dr. Damon Adams and I would like to announce the addition of Drs. Charles Babbush, Paul Fugazzotto, and David Little to our distinguished list of Implants Today Advisory Board members.

Tom and Janne came to visit us in March, 2017. We are glad to meet them and communicate and the dental future technology. We both sides are happy to get agreement on cooperation on 3D dental technology. And if any one needs 3D printed model and dental service, please don't hesitate to contact us. Our 3 Shape receiving account is digital@megadentallab.com which for EU and USA area, megadental@live.com for Asia area. More products interested in? Please welcome to our website www.megadentallab.com

Dental Implant Market to Top $4.4 Billion by 2020 The global dental implants market will surpass $4.4 billion by 2020, according to analysts at Technavio, driven by 4 factors: the rise in the population of edentulous individuals and incidence of oral diseases, the increased use of CAD/CAM technology, the growing adoption of evidence-based dentistry, and greater demand for oral care. Approximately 24% of the global population age 65 years and older were edentulous in 2012, Technavio reports, due to age, dental caries, and periodontal and other gum diseases, with injuries only accounting for a small percentage of cases. Additionally, between 60% and 90% of children and nearly 100% of adults had cavities in 2012. [Advances in technology have led to the introduction of new procedures that offer efficient oral care, minimally invasive procedures, early detection of caries using laser equipment, and treatment of periodontal diseases," said Barath Palada, a lead analyst at Technavio. [This will increase the number of patients and dental visits, which, in turn, will drive the growth of the dental implants market." Additionally, advances in CAD/CAM technology have enabled vendors to produce improved dental implants. CAD/CAM technology allows the customization of implants according to the patient`s oral anatomy and supports their correct placement for less invasive procedures and shorter recovery periods. As a result, implant adoption will increase. Dentists, meanwhile, are adopting stringent controls and performance standards to evaluate new products and technologies while generating robust data in clinical studies to standardize dental implant protocols. Also, dental associations are relying on evidence-based dentistry to set up policies that follow a defined process of systematically collecting and analyzing scientific evidence to answer specific clinical questions. These analyses help dentists in their routine clinical practice, Technavio says. They also help in the development of protocols that can make dental implants more affordable. This increases the safety, efficacy, and affordability of dental implants, the company reports. Finally, the Centers for Disease Control and Prevention (CDC) report that about 47% of adults age 30 years and older have some form of periodontal disease and nearly 30% of people between the ages of 65 and 75 years are devoid of natural teeth. Due to the connections between oral health and systemic health, private organizations and governments alike are creating initiatives to promote awareness of the importance of oral health. For example, the CDC is collaborating with the American Academy of Periodontology and the ADA to improve and sustain surveillance of periodontal diseases in adults in the United States. Also, the World Health Organization (WHO) is forming oral health policies to effectively control oral health risks and implement community-based projects to prevent oral disease. Currently, the WHO is working with national health authorities to implement efficient fluoridation programs worldwide to prevent dental caries and provide technical support to various countries to integrate oral health programs into their public health systems. [These initiatives will create awareness and generate demand for oral care and implants, thereby driving the growth of the global dental implants market," said Palada.

Guided Implant Surgical Applications By Michael Tischler, DDS We would like to focus on the various CBCT-generated implant guides that are available and look at their advantages and disadvantages. A CBCT-based implant guide is a state-of-the-art concept that represents the highest aspects of implant technological advancements. (picture from Mega Dental Lab) This month`s section revisits guided implant surgical applications, a topic that will appear in each December issue. We will focus on the various CBCT-generated implant guides that are available and look at their advantages and disadvantages. A CBCT-based implant guide is a state-of-the-art concept that represents the highest aspects of implant technological advancements. (picture from Mega Dental Lab) Of the 3 categories of guides available, tooth-supported guides for quadrant implant dentistry is the most predictable and simple of the guided implant scenarios. A tooth-supported guide has little room for error, as it is a hard-tissue-supported guide that is supported by teeth that are visible and accessible. This is different than a bone-supported guide, which is more complex surgically and more involved to create. (picture from Mega Dental Lab) Soft-tissue-supported guides for full-arch implant dentistry are appropriate when the final full-arch implant-supported prosthesis does not required alveoloplasty. If alveoloplasty is required for prosthetic thickness or to hide the prosthetic smile interface, then a bone-supported guide is needed. A soft-tissue-supported guide can be used when extractions are being done concurrently at the time of surgery, but extractions can create complexities with a soft-tissue-supported guide. An example of extractions causing a complexity with a soft-tissue-supported guide is if extractions cause the ridge shape to change during the process, rendering an inaccurate fit of the preplanned guide on the ridge. Bone-supported guides for full-arch implant placement are by far the most technically advanced guide in both the presurgical planning and during the procedure itself. Bone-supported guides in full-arch treatment require that aggressive flaps be done in order for the guide to fit. When extractions are being performed, in addition to alveoloplasty, the complexities are furthered. In the situation of extractions and alveoloplasty, these full-arch guides are either stackable guides or multiple guides. These advanced guides are, in general, associated with higher costs for the doctor and require more time to plan and have delivered to an office. Another scenario that has become more popular as technology has improved, are the dynamic navigation systems based on motion tracking technology. There are a few systems available now for this that are FDA approved. The concept is to take a prosthetically driven plan from a CBCT scan, and then place the implants in the correct position freehand with the assistance of an on-screen program guiding with precise feedback. While there is a learning curve with this technique, the concept certainly offers some exciting potential. Implants Today advisory board member Dr. Randolph Resnik offers an excellent article that exemplifies many of the points I presented here. Randy`s dual-scan technique shows an accurate way to represent the prosthetic end result on a CBCT scan. As time goes on, guided-implant surgery and its related technologies will become even more innovative. Also featured this month, Dr. L. Stephen Buchanan addresses today`s need for general practitioners to learn how to start placing and restoring dental implants in their own office.

Dental Implants in the Aesthetic Zone by Michael Tischler, DDS The aesthetic zone represents the center stage for implant placement. This is true in a patient with a high lip-line when smiling as all aspects of implant treatment are immediately visible to the patient and all others who may interact with the patient. Treatment in the aesthetic zone is even more scrutinized than other areas of the mouth. This month`s Implants Today focuses on dental implants in the aesthetic zone. The aesthetic zone represents the center stage for implant placement. This is true in a patient with a high lip-line when smiling as all aspects of implant treatment are immediately visible to the patient and all others who may interact with the patient. Treatment in the aesthetic zone is even more scrutinized when compared to treatment in other areas of the mouth. For example, the steps for provisionalization are a crucial aspect of treatment since the type of provisional and shape of the provisional can help set up the emergence profile of an implant site. Implant Site Development (March 2012, Wiley-Blackwell) by Drs. Michael Sonick (an Implants Today advisory board member) and Debby Hwang covers the concept of setting up sites for implant placement in depth. It also includes chapters by other prominent experts, such as Drs. Craig Misch and Scott Ganz (also advisory board members). I recommend this textbook because site development is so important; just like constructing a building, each foundational step sets up for the success desired in the final result. The multidisciplinary topics that must be taken into account with implant treatment in the aesthetic zone include but are not limited to: soft-tissue site development, vertical and horizontal bone augmentation concepts, socket preservation materials, immediate versus delayed placement, the role of a CBCT scan, growth factors, provisionalization options, emergence profile and abutment considerations, soft-tissue biotype assessment, and implant spacing and depth. This is a true merging of surgical and prosthetic principles, as treating a patient for tooth replacement in the aesthetic zone requires a sound understanding of many principles that must come together for success. This is why I personally enjoy implant dentistry so much-there is so much to know and implement clinically. When you approach treatment with this kind of respect, treatment becomes a true passion as a clinician. Our patients` lives are being changed and everyone benefits. This is certainly an endeavor worth pursuing! While the principles for implant treatment success in the aesthetic zone are used in other areas of the mouth, the anterior region mandates that almost every principle be used. As Dr. Carl Misch said, [Don`t place your first implant on a central incisor in a patient with a high lip-line!" Learn dental implant principles in less demanding areas of the mouth while building expertise and clinical skills. Lastly, don`t just read and watch; step in and do it! The best way to learn is to do and to experience. This issue presents an outstanding article by Dr. Michael Sonick et al that sums up the many aspects of success mentioned here. Also, Drs. Todd Schoenbaum and Chandur Wadhwani contribute excellent content that focuses on the screw-retained versus cement-retained restorative options in the aesthetic zone, and Dr. Dino Javaheri presents a simplified chairside technique for both temporary fabrication and impression taking.

The next International Dental Show (IDS) opens its doors in Cologne from 21 to 25 March 2017. Around 2,300 exhibitors from 60 countries will present the latest products, developments and trends of the dental industry over the five days of the fair. More than 140,000 international trade visitors are expected to attend. Visitors will experience more innovation and a wider product range than ever before on an exhibition surface of over 160,000 m² in total. A visit to IDS is a must for dental professionals, dental laboratories, as well as representatives of the dental specialised trade and the dental industry. Dear friends, you are welcome to meet us during the IDS show, and you may contact us in advance. Contact: Mr. Arthur Cel or whatsapp: +0086 181 2631 1613

Understanding Impression Materials and Techniques There is no single procedure that a dentist can do, or any single procedure that a lab can do for the dentist, that will improve the final result of indirect restorations more than improving the quality of the impression. The impression is the basic starting point for all laboratory procedures, as well as the basis for quality and cost-effective dentistry for the clinician. Unfortunately, there are a great many choices regarding the best tray to use (full-arch, quadrant, or dual-arch [triple" trays, stock or custom, plastic or metal trays) and regarding which technique is best (1- or 2-step putty/wash, heavy-body tray/wash, or monophase), and an even greater number of choices regarding which impression material to use to take the impression. At least 43 different brands of polyvinyl siloxane impression materials are offered by at least 29 different companies. Confusion abounds and is further complicated by the omission from marketing literature of some information about PVS materials that is instrumental in using them and understanding how to get the best results from them. This article will attempt to clarify some of the areas of confusion regarding impression materials and techniques. TRAY SELECTION Consider first the type of case that is being done. Laboratories estimate that about 85% of units are single crowns, and most of those are done with a dual-arch quadrant or triple tray. Because of their ease of use, conservation of material, and elimination of the need for an opposing impression and bite registration, dual-arch quadrant impressions have become the overwhelming choice for most dentists. When employed properly they can be used satisfactorily; however, the overuse and abuse observed in commercial laboratories have frustrated both technicians and clinicians. This is further complicated by the fact that many commercial laboratories employ plastic, disposable articulators to use in the fabrication process, adding to the inaccuracies that can occur. Evaluation of the 6 most popular plastic, disposable articulator systems used with dual-arch impressions found that with all systems, it was virtually impossible to maintain and repeat a centric occlusal position stop. The conclusion was that they should only be used for single units, not when the terminal unit in the arch is being prepared.1 Another study evaluated the effect of the viscosity of the impression materials in plastic and metal dual-arch trays.2 There were statistically significant differences noted in the accuracy of the dies. Rigid materials in metal trays were the most accurate, while monophase materials in plastic trays produced dies that were dramatically shorter. Figure 1. Dual-arch impression that was correctly taken in maximum intercuspation shows tooth-to-tooth contact anterior and posterior to the prepared tooth. Figure 2. Soft-tissue contact with the plastic tray leading to distortion of the final impression. Figure 3. Tooth contact with the plastic tray leading to distortion of the final impression. Figure 4. Even soft-tissue contact with a plastic tray can cause the tray to distort. Figure 5. CLINICIAN`S CHOICE metal Quad-Tray. Figure 6. Photograph illustrating the difficulty in stabilizing a quadrant tray. The 2 most common problems observed in commercial labs with dual-arch trays are tissue or tooth contact with the tray and failure to record maximum intercuspation. Recent visits to 3 commercial labs in 3 different states in 3 different regions of the country showed that only about 40% of the 100 randomly selected dual-arch quadrant impressions were in maximum intercuspation. Maximum intercuspation can be visually verified by observing tooth-to-tooth contact anterior and posterior to the prepared tooth (Figure 1). Few metal trays were observed, even though the preceding evidence, as well as the anecdotal advice of many prominent clinicians, suggest they are more accurate. Soft-tissue contact was frequently observed in plastic trays, with an occasional tooth contact to the tray (Figures 2 and 3). Any contact between soft or hard tissue and a plastic tray applies an occlusal force to the tray that is likely to cause it to distort. When the patient opens-removing the occlusal force that distorted the tray-the tray returns to its original dimension because of the memory of the plastic, and the final impression is distorted, causing inaccuracies in dies as well as occlusal and contact discrepancies (Figure 4). A properly designed metal dual-arch tray assists in tray placement and increases the ease of reaching maximum intercuspation, as well as provides the proper rigidity to decrease the chance of 3-D distortion (Figure 5). For more involved cases where a full-arch impression is indicated, research utilizing an optical laser scanner showed that dies from a stock impression tray were as accurate as those produced from a custom tray.3 Custom trays do save money in impression material because they generally use less material. That savings is more than offset, though, by the additional cost of tray material and labor to fabricate a custom tray. Custom trays should be employed when the patient`s anatomy dictates their necessity, most commonly in cases of mandibular tori or a particularly large or small arch form. Quadrant single-arch trays are the most difficult tray to use without introducing distortion because of the difficulty in stabilizing the tray while the material sets. It is virtually impossible to keep the tray steady-particularly on the mandibular arch-if the patient makes any kind of movement with his or her lips or tongue while swallowing. Because the clinician is unable to obtain cross-arch stabilization during setting of the impression material, movement permits a slight rocking of the tray that causes distortion (Figure 6). TECHNIQUE CHOICES Dentists can use a number of different techniques that employ a variety of different materials and viscosities to take impressions. Traditionally, a heavy-body tray material is utilized with a lighter body wash material that is syringed around the tooth just before the tray is seated. Since the 1980s, with the introduction of vinyl putties, several putty/wash techniques have been advocated. Various innovations of these techniques have emerged, further confusing the clinician. Although it is possible to get many different techniques to work, the final choice as to technique should center on which is least problematic and most likely to produce consistent results. The putty/wash techniques fall into 2 basic categories: (1) a single-step procedure where the putty is loaded into the tray and inserted immediately after syringing a wash material around the prepared tooth or teeth, or (2) a 2-step procedure where the putty is used to take an impression before starting the preparation, allowed to set, and removed from the mouth. After tooth preparation is complete, the tooth has a wash material syringed over it, and the initial tray and putty impression are reinserted over the wash. Variations of this include routing out part of the putty impression around the prepared tooth to produce space for the wash, and relining the entire impression with wash material. Statistically, laboratories see more problems with 2-step impressions than any other technique. This is a result of the difficulty in repositioning the impression in the exact same position without creating a [step" between the original putty impression and the detailed wash impression. It is much more difficult to reseat the tray than it appears, and the result is more chairside occlusal adjustments in the completed restoration. There appears to be little difference in reducing the creation of [steps" by routing out some of the material around the prepared tooth or washing the entire arch. The single-step putty/wash technique can also be equally difficult to produce a consistent result with because the viscosity of the putty material is most often considerably lower than heavy-body tray material produced from a mixing machine or by hand- held gun extrusion mixing cartridges. The extremely stiff putty material, when seated in the mouth, forces the much thinner wash material away from the prepared tooth, and the resultant impression is captured in more putty than wash. ADA/ANSI specifications require that a wash material capture details to 20 µm, while tray materials are required to capture only 70 µm of detail.4 For this reason, most if not all of the prepared tooth should be captured in the fine detail of the wash material. Recently, variations of these putty/wash techniques suggest that they can be successfully utilized to obtain impressions without the use of retraction cords. The concept is that the wash material can hydrostatically be forced into the gingival sulcus when the set putty impression is reseated in the mouth, thereby capturing the impression of the margins without having to place retraction cords or remove gingival tissue with a laser or electrosurgically. Some techniques further suggest that this technique can hydrostatically displace crevicular fluids as well as tissue. Again, with these techniques the commercial laboratories report inconsistent results with their clients regardless of the brand of material used. The degree of preparation taper plays an integral role in the amount of hydrostatic pressure that is placed at the margin of the preparation during this impression technique. The greater the preparation taper, the greater the dimensional accuracy.5 Too much hydrostatic pressure at the margin causes a [pull-back" or rebound effect when the impression is removed from the mouth after setting. This is why all full-arch impressions should be held passively while setting. Any active force while the impression is setting causes an increase in elastic recoil when the impression is removed from the mouth and creates a reduction in the size of the casting. The greater the preparation taper, the less the hydrostatic pressure at the margin, creating (in theory) enough hydrostatic pressure to displace fluids and tissue, but not enough to create 3-D distortion. Unfortunately, an increase in the degree of preparation taper to fulfill the requirements to make this technique work adds to the clinician`s problems by ultimately increasing retention difficulties because of excessive taper. Finally, the reason for using retraction cords, laser, or electrosurgical techniques is not limited to taking the impression. Precise viewing of the margin of the preparation is imperative, unless placed completely supragingival, for final preparation of the margin. Most clinicians advocate the use of a dual-cord impression technique, where the first cord is placed to fill about one half of the sulcus as soon as the contact is broken. This process expands the sulcus to allow for better visualization of the preparation margins for final preparation, and greatly benefits the procedure because the first cord is placed prior to any gingival bleeding. It is much easier to do this and prevent gingival hemorrhage than it is to arrest hemorrhage after it begins. A correctly chosen diameter of cord can be placed quickly and atraumatically. After the preparation is completed, the second cord is placed to expand the sulcus further so that the margin is visible for impression taking. The second cord is left in position for 3 to 5 minutes and removed for the impression, while the first cord is left in place to ensure hemostasis until completion of the impression, when it is removed. If the gingival sulcus is very shallow (1 to 2 mm), particularly on anterior teeth, veneer preparations, and when the gingival margin is being placed just at or just below the height of the sulcus, it is frequently better to use only one cord. In these situations the preparation is completed supragingival, and then the retraction cord is placed, again filling about one half of the depth of the sulcus. The preparation can then be refined to the height of the sulcus or slightly below without trauma to the gingival tissues. The impression can be taken after careful removal of the retraction cord, or the cord can be left in place, as there should be adequate access to the supragingival margin to take the impression. A colleague recently pointed out that it is appropriate to change terminology from gingival retraction to the more correct sulcus expansion. Gingival retraction, which may have been a more viable term in years past when a patient`s tissue health might have been less than ideal, is no longer descriptive of the procedure that is actually performed. When a patient has good gingival health-and there should be no reason to begin an indirect restoration until that has been achieved-the procedure that is accomplished is a temporary expansion of the sulcus to permit access for final preparation of the margin and then taking the impression. Removing the cords after completing the impression then permits the tissue to return to its normal biological position without a change in the occlusal-apical height of the tissue. Changing the terminology helps the dentist, chairside assistant, and patient more accurately visualize and then achieve the ideal result. MATERIAL CHOICES Figure 7. Two-dimensional representation of polymerization shrinkage that occurs toward a rigid wall and to the center of its mass when no rigid wall is present. With the elimination of the putty viscosity as a recommended choice, the remaining choices are heavy-body, light-body, and monophase materials. To logically choose the best to use, it is important to consider how all materials react during setting and the impact that has on the previous discussion of trays and techniques. All impression materials-polyvinyls, polyethers, polysulfides, and hydrocolloids-polymerize toward the rigid wall of the tray that has adhesive and/or perforations to retain the material. Unfortunately, the interproximal material has no tray, so it polymerizes toward its center (Figure 7). This explains why an impression of a perfectly round machined steel die produces an elliptical casting, which is observed regardless of the type or brand of material used.6 Polymerization shrinkage accounts for the 3-dimensional differences in dies made from impressions taken with the same material, but with different techniques-trays, dual-arch trays with sides, and sideless dual-arch trays. There is one material that is marketed specifically for use in the dual-arch quadrant metal tray (Inflex [CLINICIAN`S CHOICE]). Monophase materials are limited in their clinical application. An ideal material must be resilient enough to be withdrawn from the mouth easily, particularly when mobile teeth or prepared teeth are thin. The material must also be flexible enough to be removed from the model without breaking off a thin preparation. This has led to the development of the [soft" formulas of polyethers. However, any material when used in a sideless, dual-arch tray must be firm enough to support the weight of the gypsum when the model is poured, without sagging under the weight of the stone. It appears that one viscosity of material would not be able to ideally fulfill all of these parameters simultaneously. CONCLUSION When the clinical procedure is limited to 1 or 2 units, the clinician may choose a dual-arch tray. A metal tray would be preferred over a plastic tray because of its rigidity and resultant dimensional stability. A tray material that is very inflexible should be used for its rigidity and ability to support gypsum when the model is poured. When the clinical procedure calls for a full-arch impression, a stock tray coated with a compatible adhesive can be utilized with a slightly less rigid tray material to aid in removal from the mouth. In all cases it is imperative to be able to see the preparation for final margination, and then take the impression. The dual-cord technique accomplishes both, and when done properly in the preparation sequence can lead to minimal hemorrhage or gingival trauma.

Zirconium CAD/CAM and Bioesthetic Layering of Porcelain: Color From Within Today`s aesthetic dentistry can involve the selection of methods and materials that can be very overwhelming to the clinician. The dental profession is experiencing a large addition to the services it provides for patients. This change follows the introduction of root form endosseous implants that were introduced in the 1980s, and the aesthetic enhancements provided by the porcelain laminate veneers introduced in the 1990s. The use of CAD/CAM machines to fabricate high-strength ceramic cores for crowns and bridges promises to surpass the effects of the prior two revolutions.1 The switch to all-ceramic restorations and the use of CAD/CAM machines are being driven by a number of factors. The increasing demand for cosmetic procedures by today`s population will cause the demand for all-ceramic crowns and bridges to grow. This in turn will increase the demand for ceramic cores as a substitute for the metal frames used in traditional metal-ceramic crowns and bridges.2 Layering porcelain to nonmetallic cores is not new to dentistry, although certain materials lend themselves to this application better than others when attempting to adhere to sound dental principles and provide strength and exceptional aesthetics. The challenge that the clinician and laboratory technician face with the advent of CAD/CAM-fabricated ceramic cores is finding a porcelain material that can reproduce the aesthetics found in the all-ceramic restorations without ceramic cores. Ceramic restorations from CAD/CAM machines tend to be very bright, white, high-value, opaque materials. The traditional method of layering porcelain tends to produce high-value and low-translucency restorations, which when placed adjacent to human dentition have a less-than-desirable outcome; the lack of translucency serves as the most important challenge of these new ceramic frameworks. The search for a porcelain substrate that will generate sound porcelain adherance and aesthetics has been the great quest of dental manufacturers. This article will discuss a ceramic material manufactured for use with CAD/CAM frameworks. A case report using this material is included. ALL-CERAMIC MATERIALS Over the years several materials have been used for all-ceramic restorations; however, today only 2 types of ceramics are recommended for use with both anterior and posterior crowns and anterior bridges. These categories include the interpenetrating phase composites or glass-infiltrated ceramics, and the polycrystalline ceramics.3,4 Glass-infiltrated ceramics consist of a product formed by infiltrating molten glass into a partially sintered oxide material (aluminous oxide or alumina-zirconia oxide). Examples of this are InCeram Alumina and InCeram Zirconia (Vident). Polycrystalline ceramics are materials with densely packed particles containing no glassy components. They cannot be processed to shapes without the use of computer-assisted machinery. Examples of this material include densely sintered, high-purity aluminum oxide, Procera AllCeram (Nobel Biocare), and the yttria tetragonal zirconia polycrystal (Y-TZP) systems. The majority of these systems use CAM of partially sintered Y-TZP blocks, followed by complete sintering of the shaped product for an additional 5 to 8 hours. These systems include Lava (3M ESPE), Cercon (DENTSPLY Ceramco), CEREC InLab (Sirona), and Procera All-Zirkon (Nobel Biocare). The partially sintered or [green state" material is milled to a size that is 20% to 25% larger than the final sintered core to compensate for the shrinkage that occurs during final sintering. As the fit of each final core is deemed to be acceptable, there is no standardization in fit and strength among different manufactured blocks of material because of the differences in the handling of the material by the various laboratories once it has been milled.5 A different system, DCS-Zirconium (DCS Popp Dental Laboratory) uses fully sintered Y-TZP blocks to mill fully sintered frames. No shrinkage is involved in the process when the fully sintered material is used, and the core made from totally industrially prepared material is structurally more reliable than the post-sintered green state material. There are questions that the CAD/CAM procedures may induce surface and subsurface flaws that may affects its physical properties.6 The use of ultrasonic machining promises to revolutionize the treatment of ceramic material in dentistry, as well as all phases of the industry. This technology greatly minimizes contact of the cutting tool with the material, which significantly reduces friction, heat, and the creation of surface flaws. Furthermore, the process increases the accuracy of the final milled product.7 The exceptional physical properties of these CAD/CAM ceramic cores have been described extensively in the literature and are not the focus of this article. This article focuses on the porcelain ceramic that will generate good to excellent aesthetics layered over the CAD/CAM alumina zirconia oxide (AL/ZR) core. The basic fundamental use and qualities for a particular type of porcelain, Initial Zr (GC America), is described. Initial Zr is one of 6 Initial ceramics in an integrated product line (manufactured by GC Europe) with one color system, which can create metal-ceramic restorations as well as full-ceramic restorations. Each GC Initial ceramic is adapted to meet the needs of its particular fabrication process and frame-work, such as its coefficient of thermal expansion, therefore avoiding stress and fractures. This article focuses on GC Initial Zr, which is designed for layering over CAD/CAM frameworks. GC Initial Zr has an array of unique shades that have been developed for internal layering and external staining, high fluorescence, opalescence, and/or high translucency that allows for very favorable color matching with natural tooth structures. For simple and promising handling of these high-strength ceramics, it is important for clinicians and lab technicians to consider a few fundamental points. With zirconium oxide there are 2 variations: • A white, more or less opaque, milled or sintered zirconium oxide. • A dyed (in the corresponding shade) sintered zirconium oxide. Figure 1. Internal aspect of DCS Precifit Zirconium (DCS Popp Dental Laboratory) core with final layers of porcelain. Note the [white" opaque color of the fully sintered core as discussed in the article. Figure 2. DCS Precifit Zirconium oxide frame or copings ready for porcelain layering. The former lends itself better to higher-value restorations that are the norm of most patients requesting anterior restorations (Figure 1). The latter definitely offers a more compatible color base for the standard tooth shade buildup, especially for standard layering.8 When using the white zirconium oxide, Initial Zr porcelain lends itself very well to generating the desired aesthetic outcome. The white neutral base of the zirconium oxide allows the applied colors to appear very pure and genuine. The fluorescence missing from zirconium oxide cores or frames must be replaced with a thin coating of liner or frame modifiers to provide the natural fluorescence from inside the restoration. The liners/modifiers can also be individually tinted with the fluorescing Initial stains.9 When the clinician prescribes the shade A2, as was done in the case report described later in this article, the laboratory needs to adapt the base chroma in a different fashion than conventional porcelain layering. When making A2 shades, the base chroma should be at least the color effect of A3. With zirconium oxide frames it should be even a warmer tone because the dentin-colored frame material becomes lighter with each firing. The result is that layered restorations without intensified chroma appear too light in the patient`s mouth.9 A similar appearance is seen with the white, non-chroma-intensified zirconium oxide restorations. The missing chroma and fluorescence on the frame causes a light, too white/gray appearance. The Initial Zr layering system compensates for this unwelcome addition and standardizes the layering procedure for the laboratory technician.10 It is not as simple to evaluate the optimal firing of AL/ZR ceramic. Improper firing causes the incorrect shade seen frequently in AL/ZR restorations. Most furnaces fire 20° to 30°C lower, especially in the temperature firing range of zirconium ceramics. All such ceramics, but particularly AL/ZR, react to low firing temperatures with slightly limited transparency and color effects. On the other hand, somewhat higher firing cycles cause no problems and actually support the color and transparency effects. The ceramic firing stability is unusually good, so that in most furnaces raising the end temperature by 10° to 30°C is recommended in order to achieve the best outcome.10 Incorrectly constructed or layered frames are another reason for aesthetic failures when using white zirconium oxide restorations. In general, the frames should be the same size as the circumference of all the frames and built with light material zirconium oxide. If the frames are of different sizes, then the circumferences of the smaller frames will differ in color, and will appear either gray or too dark and intense in color11 (Figure 2). When using these AL/ZR frames one must be aware of the aesthetic limits of the material. This material is very difficult to control aesthetically for inlay, onlay, and veneer restorations due to the very white-colored margins. This restorative method lends itself to full-coverage restorations due to the preparation of the tooth structure with circumferential shoulder preparations. The aesthetic effect necessary in veneer, inlay, or onlay restorations is not generally achieved due to the opacious zirconium oxide material blocking light in the enamel of natural teeth, resulting in a color impact along the margin. Therefore, any preparation of the teeth should have a 0.8-mm to 1.0-mm reduction at the margin to prevent this [light-blocking" effect onto the enamel. A shoulder preparation allowing for 0.8-mm to 1.0-mm ceramic material must be provided12 (Figures 3 and 4). As a side note, the author has noticed that often in the use of inlay, onlay, crown, or veneer restorations with less than 0.8 to 1.0 mm of marginal reduction, a cut-back of the core is needed and traditional shoulder porcelain is necessary for the optimal aesthetic result. The only problem with this is that this shoulder material is often radiolucent and can show up as open margins or defective restorations to the uninformed clinician when doing follow-up radiographic examination.13 Due to this and the aesthetic reasons previously described, the author recommends from experience that another conventional method be utilized if the required amount of preparation cannot be obtained. PORCELAIN LAYERING Figure 3. Left maxillary restorations on model demonstrate good aesthetics and light translucency. Figure 4. Left maxillary restorations cemented demonstrate the disappearance of the restorative gingival margin with the natural enamel of the tooth. (Note fit of zirconium frame and the disappearance of the white gingival line often seen with ZR cores.) Figure 5. Application of FD-91 for internal copying of dentinal structure. Figure 6. Bioesthetic layering with modifiers and transparent porcelains. Figure 7. Restorations after first firing ready for the transparent and translucent porcelains. Figure 8. Lingual depiction of [color from within" of Initial porcelain. Note the transparency and translucency achieved by the Bioesthetic Layering Method. Figure 9. Facial aesthetics of restorations with refracted and reflected light demonstrating the [halo effect" desired for optimal aesthetics. Figure 10. Maxillary premolar demonstrating [color within" without the use of external stains or modifiers. The color mimics natural tooth aesthetics. With many restorative porcelain layering techniques, technicians learned to build porcelain in the following way: apply opaque, build dentin, layer enamel, and add translucent material. Unfortun-ately, this method has little correlation with a natural tooth. Transparency is found primarily from the inside of all natural teeth, in the transparent dentin. In anterior teeth, abrasion and wear over time cause this transparent layer covering the dentin to appear at the incisal edge. This changes the transparency of natural teeth considerably depending on the angle of light or the angle of incidence. The teeth appear at times lighter, grayer, darker, or even deeper in chroma. The amount of light reflecting through the transparent dentin also changes the perception of depth. The internal transparent layer of dentin from tooth morphology comes to the surface at the junction of the root and cervical margin, completely covering the root and influencing the value of the gingiva. Therefore, it makes no sense to use opaque marginal materials in this area where nature shows us differently. The use of GC Initial porcelain, due to its highly chromatic and fluorescent INside powders (GC America), imitates the primary dentin and fluorescence that lie imbedded within the teeth. Layering dentin material over the INside material achieves a perfect balance of chroma and value. When one pairs fluorescent, crystal clear transparency with real opalescent enamel, it makes it possible to copy the effect of natural tooth structure. The layering of Initial porcelain has been described as the Bioesthetic Layering Method. This method is oriented toward copying the light dynamics and transmission of natural teeth. The method begins with the clinician taking the shade. This can be a very complex challenge, as one needs to make allowances for color in natural teeth under different light situations. These variances in color under different light situations are very difficult or almost impossible to achieve utilizing conventional ceramic materials. Even the most talented technicians depend on materials to produce these natural light effects. When the GC Initial materials are layered analogously to the structure of natural teeth, they automatically produce a complete and logical layering process. The natural chroma and fluorescence seen within natural teeth can be transferred to the restoration with the Bioesthetic Layering Method. This is a method of layering porcelain through incremental layering of porcelains in a systematic manner, unlike the traditional manner described previously. The first step is the use of a fluorescent Fired Frame Modifier, since zirconium frames lack fluorescence. The next step is the application of INside materials to the cervical and proximal areas. Next, the light-reflecting edges are covered with highly fluorescent white dentin (FD-91), and the body is covered with INside material (Figure 5). Next, the dentin body is built, and the enamel table is built over the dentin body with translucent dentin. Next, modifier stains and INside material continue the layering process. The buildup is now covered with a layer of fluorescent transparent material (CLF[GC America]). Next, a cut-back in the incisal area down to the highly fluorescent dentin is accomplished, and FD-91 is again applied. Another layer of INside on the desired internal structure is placed. Next, opalescent enamel is layered (Figure 6). Now the restorations have their first bake in a porcelain oven. Any corrections to shades or colors can now be accomplished with translucent materials and opalescent enamels (Figure 7). The restorations are baked a second time and finished. Anterior teeth pose a great aesthetic challenge. Incisals of teeth are very sensitive, since all optical light phenomena converge at this small space. Layering porcelain in the incisal table is very critical because the most light is transmitted here. This area will exacerbate the optical differences between felds-patic porcelains and synthetic ceramic frames. A totally different optical appearance can result when dissimilar frame sizes or materials are used side by side. This difference in optical appearance can be neutralized with the high fluorescent dentins and the INside powders (Figure 8). To achieve the desired natural effect at the incisal angle, Initial porcelain`s different white fluorescent, fluorescent transparent material, and transparent dentin can be utilized to provide the optical phenomenon known as the [mammelon structure" or the [Incisal halo effect" (Figure 9). If there is too much transparency at the incisal edge in the mouth, then this results as an unappealing, unnatural gray and flat effect. The use of the white fluorescent, fluorescent transparent material, and transparent dentin along with the opalescent enamels of Initial porcelain copies natural tooth structure very well (Figure 10). When compared to conventional enamels, the difference aesthetically can be enormous. The use of conventional enamels, dentins, and opaques correlates well with the Vita Lumin shade guide system, but not with the dynamics of light in natural teeth. The opalescent effect on the surface, with fluorescence coming from the inside, creates a highly natural appearance. One needs to utilize the ready-made shade guides as a general reference, but not rely on the shade guide to reproduce the desired outcome. Communication with the laboratory technician needs to be addressed more explicitly with the design of [shade-mapping." The clinician must communicate to the technician how and where the porcelain and modifiers are to be utilized so that the maximum aesthetic and optical effects are generated. This can pose a big challenge to the clinician when describing the colors seen to the technician. A thorough understanding of tooth morphology and natural opacious dentins, translucent dentins, and enamels in teeth must be utilized if one is to achieve the optimal effect desired. Initial has simplified this with the Bioesthetic Layering Method described earlier.9 CASE REPORT Figure 11. Preoperative smile view of patient. Figure 12. Preoperative retracted view of patient`s dentition depicting failing restorations and poor aesthetics. Figure 13. Dentition evidencing compromised gingival heights, crowding, failing restorations, wear, and overall poor aesthetics. Figure 14. Preoperative right lateral view. This patient was very unsatisfied with the anterior aesthetics of his maxillary dentition. He wanted a result that would dramatically change the anterior aesthetics. He was concerned with severe crowding of the anterior incisors as well as the failing restorations that had been present for many years. The patient was presented with a treatment plan involving a complete restoration of his dentition in both the maxillary and mandibular arches. Prior to the restorative dentistry phase he was advised to undergo orthodontic therapy as a method to improve his interdental and intradental relationship. In discussion with the author the patient elected to avoid orthodontic treatment because full-coverage restorations would be necessary to restore his dentition. Gingival concerns were discussed, as the patient was very unhappy with the differing gingival heights in the maxillary anterior segment (Figures 11 to 14). The treatment the patient wanted to undergo at the operative session was to restore the maxillary anterior segment, periodontally recontour the maxillary anterior gingiva, and recontour the incisal edges of the opposing dentition to aid in incisal guidance. The lower arch was to be restored at a later time. The shade requested as the final shade would be considerably lighter than the patient`s intial shade. Figure 15. Right lateral view of provisional restorations at corrected vertical and incisal lengths. Figure 16. GC Fuji Plus single-use dispensing capsule in action demonstrating precise delivery of glass ionomer adhesive material. The patient was appointed for the initial operative session. The first operative session included a laser-assisted Smile Lift Procedure to accomplish recontouring the gingival architecture to more harmonious and even gingival heights.14 The teeth were prepared for full-coverage restorations with a 0.8-mm to 1.0-mm circumferential marginal reduction. Tissue retraction, impressions, bite records, and provisional restorations were all accomplished at this session (Figure 15). Upon completion of the restorations, the second operative session was to be the try-in phase to determine restoration fit, marginal integrity, occlusion, aesthetics, and patient satisfaction. With all these accomplished, the restorations were to be placed with final cement. Zirconium restorations can be easily cemented in the conventional manner with glass ionomer cements or conventional ce-ments. The cement chosen for this case was GC Fuji Plus (GC America). The author utilizes this product due to high fluoride release and high bond strengths.15-17 This cement is very versatile due to its ability to cement indirect restorations. The material is supplied in a capsule (Figure 16). It is also available as a Paste-Pak system (FujiCEM). This ensures the proper mixing ratio every time to achieve the highest compressive, tensile, and bond strengths with the lowest film thickness, and maximum fluoride release.18 Figure 17. Fully retracted view of final restorations in maxillary arch. (The higher value restorations that the patient requested will be matched during the mandibular reconstruction phase.) Figure 18. Final restorations showing translucency and transparency of the zircon frame/Initial porcelain technique. Figure 19. Preoperative smile view of patient. Figure 20. Postoperative smile view of patient. The final results were very aesthetic, and the patient was highly pleased with the results. A third and final operative session was utilized for occlusal accuracy and postoperative evaluation. There was little to no sensitivity during the entire procedure as well as during the provisional and postoperative phase (Figures 17 to 20).

Use a Laser to Replace a Fractured Solid Zirconia Crown by Jeffrey P. Cranska, DDS Dentists can use lasers like the Fotona PowerLase AT Erbium: YAG to replace fractured solid Zirconia crowns. Figure 1: A 50-year-old male patient presented with a fractured CAD/CAM Zirconia crown. Figure 2: The laser removed the crown No. 31 fragment in one piece. Figure 3: The laser crown removal had no effect on the composite buildup or tooth structure. I am a dentist beginning my seventeenth year of using dental laser technology, which works by utilizing a beam of amplified light energy. The energy is produced in the laser`s resonator and directed into a fiber-optic system before moving to the tip of the laser handpiece and precisely onto the biologic tissue-all at the speed of light. Different lasers operate at specific wavelengths of light with different effects on soft tissue, tooth enamel, dentin, and caries, as well as on restorations, cement, and ceramics. This contact creates a thermal interaction that has changed my everyday general dentistry operations. A Representative Case One of my 50-year-old male patients presented with a fractured CAD/CAM solid Zirconia crown (Figure 1). The BruxZir all-ceramic crown was placed 30 months before the fracture on tooth No. 31, and treatment was needed to replace it. The crown broke because of improper adjusting and finishing techniques and because of occlusal forces. Tooth preparation was determined to allow more than 1.5 mm of occlusal clearance, with round line angles and no undercuts. My best option was to have this laboratory-made restoration remade under warranty. The lab that made the original crown had all of its information on file and saved, so it could make an exact copy. I temporized the exposed dentin. I had the equipment and technique to remove ceramic crowns, but I decided to remove the rest of the crown and cement the replacement crown after the case came in. I can use my Erbium laser crown removal technique to remove the Zirconium restoration without damaging or altering the composite core buildup or tooth structure. When it was time to remove the crown, I used the Fotona PowerLase AT Erbium: YAG (2940 nm). A cylindrical quartz tip (8 mm length/1 mm end diameter) in contact in the R14 handpiece or the non-contact R02 handpiece also can be used. I used the narrowest pulse width (50 µsec) with a 2/1 water-to-air mix. Settings were 3.0 W and 200 mJ at 15 Hz SSP. I traced the complete external aspect of the crown in contact while firing the laser. Using only the laser, I started on the occlusal surface, slowly painting back and forth over all surfaces. Next I treated the buccal surface, back and forth and top to bottom, and then the lingual surface. In less than a minute, the crown popped off (Figure 2). There was cement in the crown, and some remained bonded to the prepared tooth and core material (Figure 3). I cleaned the remaining resin cement off tooth No. 31 with a 12-fluted finishing bur. The replacement crown was adjusted utilizing a high-speed diamond with copious water spray, and then I polished it. It`s easier to polish Zirconia in the lab than in the mouth. I lightly micro-abraded the internal surface of the crown with 50 µm aluminum oxide, and then I cemented it with 3M ESPE Rely X Unicem (A2) resin cement. The permanent replacement was seen at 6 months with no problems present. This technique for removing ceramic restorations utilizing an Erbium without damaging the a crown or the underlying tooth structure is very predictable. Conclusion An Erbium laser can be used to remove ceramic and Zirconium restorations without damaging the restorations or the underlying tooth structure. I have placed hundreds more Lava, IPS e.max Press, IPS Empress Esthetic, Prismatik CZ, and BruxZir veneers, crowns, and bridges than I have had to remove. Now I have a tool to use in those infrequent circumstances. Dr. Jeffrey P. Cranska practices full-time laser and family dentistry in Severna Park, Md. He has an Advanced Proficiency Laser Certification from the Academy of Laser Dentistry and a Standard Proficiency and Training Certification from the Institute for Advanced Laser Dentistry (IALD). He can be reached at 410-975-9331 or familylaserdentistry@outlook.com. Dr. Cranska has no financial interest in any laser company but is compensated as a clinical consultant for presenting, lecturing, and training from the IALD, Millennium Dental Technologies, and Fotona LLC.

Orthodontics: What is Orthodontics? Written by Christian Nordqvist Orthodontics is a branch of dentistry that specializes in treating patients with improper positioning of teeth when the mouth is closed (malocclusion), which results in an improper bite. Orthodontics also includes treating and controlling various aspects of facial growth (dentofacial orthopedics) and the shape and development of the jaw. An orthodontics specialist is called an orthodontist. Orthodontics used to be called orthodontia - the word comes from the Greek orthos, meaning "straight, perfect or proper", and dontos, which means "teeth". Orthodontics also includes cosmetic dentistry; when the patient's aim is to improve his/her appearance. An orthodontist uses a range of medical dental devices, including headgears, plates, braces, etc. to help in: Closing wide gaps between the teeth Making sure the tips of the teeth are aligned Straightening crooked teeth To improve speech or eating (oral function) To improve the long-term health of gums and teeth To prevent long-term excessive wear or trauma (of the teeth) Treating an improper bite What is malocclusion? Malocclusion literally means bad bite. Some children's jaws and teeth do not develop properly. Malocclusion refers to crooked, misaligned teeth and a fault in the relation between the bottom and top set of teeth (the two dental arches). This may develop because of injury to the teeth or facial bones, frequent thumb sucking, or for reasons unknown. Thumb sucking (or finger sucking) can result in localized deformation of the teeth and supporting bone. In order to restore a natural improvement, the thumb sucking habit has to be stopped. Generally, malocclusions do not affect physical health, malocclusion is not a disease, it is a variation in the normal position of teeth. However, it may impact on the shape of the person's face and the appearance of their teeth, which can lead to embarrassment, a lack of self-confidence, and even depression. Severe malocclusion may affect eating, speech and keeping the teeth clean. UK health authorities say that approximately one third of all 12 year-olds in the country probably need orthodontic treatment. People may require orthodontic treatment for different problems: The front teeth protrude - treatment not only improves the patient's appearance, but also protects the teeth from damage; people with protruding front teeth are more likely to injure them in sports, falling down, etc. Crowding - if the patient's jaw is narrow, there may not be enough space for all the teeth. In such cases the orthodontist may have to remove one or more teeth to make room for the others. Impacted teeth - an adult tooth does not emerge from the gum, or only emerges partially Asymmetrical teeth - the upper and lower teeth do not match, especially when the mouth is closed but the teeth are showing. Deep bite (overbite) - when the teeth are clenched, the upper ones come down over the lower ones too much Reverse bite - when the teeth are clenched, the upper teeth bite inside the lower ones Open bite - when the teeth are clenched, there is an opening between the upper and lower teeth. Underbite - the upper teeth are too far back, or the lower teeth a too far forward ("bulldog" appearance) Crossbite - at least one of the upper teeth does not come down slightly in from of the lower teeth when the teeth are clenched; they are too near the cheek or the tongue Spacing - there are gaps or spaces between the teeth, either because a tooth is missing, or the teeth simply do not fill-up the mouth (opposite of crowding) When can orthodontic treatment start? Treatment will not usually commence until the child is about 12 or 13 years old; when the adult teeth have come through and developed fully. In some cases treatment may start a couple of years later if teeth problems had not become noticeable beforehand. Children with a cleft lip and palate may require orthodontic treatment before their adult teeth have developed completely. Good oral hygiene is essential before any orthodontic work can begin. When devices are placed on the teeth, bits of food are much more likely to become stuck; the patient will need to brush much more carefully and more often to prevent tooth decay while treatment is ongoing. Patients who have not reached good oral hygiene standards beforehand are much more likely to suffer from tooth decay after treatment begins. Diagnosing dental problems and recommending treatment options Assessment - the orthodontist will assess the state of the patient's teeth and make a prediction on how they are likely to develop without treatment. The following diagnostic procedures will be performed: A full medical and dental health history A clinical examination X-rays of the teeth and jaw Plaster models of the teeth After the assessment is done, the orthodontist will decide on a treatment plan. On the next page we look at examples of orthodontic appliances, including both fixed and removable braces. Examples of orthodontic appliances There are two types of orthodontic appliances: fixed and removable ones. Fixed orthodontic appliances The most common devices used in orthodontics. They are used when precision is important. Although the patient can eat normally with fixed appliances, some foods and drinks need to be avoided, such as carbonated drinks, hard sweets, or toffee. People who participate in contact sports need to tell their orthodontist, so that special gum shields can be made. Examples of fixed orthodontic appliances include: 1) Braces Consisting of brackets and/or wires and bands. Bands are fixed firmly around the teeth and serve as anchors for the appliance, while brackets are usually connected to the front of the teeth. Wires in the shape of an arch pass through the brackets and are fixed to the bands. As the arch wire is tightened, tension is applied to the teeth, which over time moves them into proper position. A patient sees the orthodontist once a month so that the braces can be adjusted. The treatment course may last from several months to a number of years. Children tend to prefer the colored braces, while adults usually go for the clear styles. 2) Fixed space maintainers If the child loses a milk tooth, a space maintainer will stop the two teeth at either side of the spaces from moving into it until the adult tooth comes through. A band is fixed to one of the teeth next to the space, and a wire goes from the band to the other tooth. 3) Special fixed appliances These may be recommended to control tongue thrusting or thumb sucking. Patients may find them uncomfortable, especially when they are eating. Experts say they should only be used if they are really necessary. Removable orthodontic appliances These are typically used for treating minor problems, such as preventing thumb sucking or correcting slightly crooked teeth. They should only be taken out when cleaning, eating or flossing. Sometimes, the orthodontist may advice the patient to remove them during certain activities, such as playing a wind instrument or cycling. Examples of removable appliances include: 1) Aligners - an option instead of traditional braces for adult patients. They are virtually unnoticeable by other people and can be taken out when patients brush their teeth, floss, or eat. 2) Headgear - there is a strap around the back of the head, which is attached to a metal wire in the front, or face bow. The aim is to slow down upper jaw growth, and keeping the back teeth in position while the front ones are pulled back. 3) Lip and cheek bumpers - specially made to relieve the pressure of cheeks or lips on the teeth. 4) Palatal expander - an appliance designed to make the arch of the upper jaw wider. The device consists of a plastic plate that is placed in the palate (the roof of the mouth). The plate has screws which exert pressure on the joints in the bones, forcing them outward, thus expanding the size of the palatal area (roof of mouth area). 5) Removable retainers - these are placed on the roof of the mouth. They are designed to stop the teeth from moving back to their original positions. If modified, they may also be used to stop children from sucking their thumbs. 6) Removable space maintainers - an alternative to fixed space maintainers. 7) Splints (jaw repositioning appliances) - they are placed either in the top or lower jaw and help the jaw close properly. Splints are commonly used for TMJ (temporomandibular joint disorder) syndrome. Written by Christian Nordqvist

Dental implant with slow-release drug reservoir reduces infection risk Written by Catharine Paddock PhD Scientists have developed a dental implant containing a reservoir for the slow release of drugs. Laboratory tests in which the reservoir slowly released a strong antimicrobial agent showed that the new implant can prevent and eliminate bacterial biofilms - a major cause of infection associated with dental implants. Researchers have developed a dental implant with a built-in reservoir for the slow release of drugs. This schematic shows it integrated into the jawbone and with a crown on the tooth. Image credit: Kaat De Cremer, KU Leuven The researchers, from various departments at KU Leuven in Belgium, describe how they designed and tested the implant in a paper published in the journal European Cells & Materials. Lead author Dr. Kaat De Cremer, from the Centre of Microbial and Plant Genetics at KU Leuven, explains that the reservoir in the implant can be filled by removing the cover screw. She adds that: "The implant is made of a porous composite material, so that the drugs gradually diffuse from the reservoir to the outside of the implant, which is in direct contact with the bone cells. As a result, the bacteria can no longer form a biofilm." In general, bacteria have two life-forms. In one, the planktonic state, they exist as single, independent cells, and in the other, they aggregate in a slime-enclosed mass called a biofilm. Biofilms are notoriously stubborn and hard to treat, and when they become chronic, they are extremely resistant to antibiotics. Mouth infections are often cited as the main reason why dental implants fail. This has led to research looking for ways to protect against infection - by developing an antimicrobial coating for the implant, for example. Implant prevents and eliminates biofilms In their study paper, the researchers note that implant developers are increasingly using materials with rough surfaces because they enlarge the contact area - thus improving anchorage with bone cells and integration into the bone. However, greater surface area also raises the risk of biofilm development. The new implant is a composite of a silicon-based "diffusion barrier" integrated into a porous, load-bearing titanium structure. The researchers subjected the implant to various laboratory tests, during which they filled the reservoir with chlorhexidine, a powerful antimicrobial commonly used as an oral rinse or mouthwash. Tests showed that the chlorhexidine-filled implant stopped Streptococcus mutans - a common mouth bacterium that attacks teeth - from forming biofilms. It also eliminated biofilms that were grown on the implant before loading the reservoir. Researchers say that the results prove that the implant is effective at both preventing and eliminating biofilms, and it may potentially be able to prevent and cure infections in patients. Implant design suits personalized treatment In a discussion with reviewers that accompanies the study paper, the authors point out that their work is a "proof of principle" based on tests done in the laboratory. Further research should now be done to show that the implants are effective in patients. This needs to address several issues, including whether the new material fulfils the mechanical requirements of dental implants, and whether there is a risk of protein and calcification clogging up the pores. The team also notes that the design of the titanium silicon composite implant suits personalized treatment; different drugs can be loaded into the internal reservoir, depending on the patient's individual need. The authors conclude that: "This study focuses on dental implant applications, but the concept could, in principle, be translated to any percutaneous implant that can incorporate an internal reservoir, such as percutaneous fixation devices, as long as this does not compromise the mechanical strength of such load-bearing devices." Written by Catharine Paddock PhD

2017 is the Year of the Rooster according to Chinese zodiac. The Year of the Rooster will start from Jan. 28, 2017 (Chinese New Year) and last to Feb. 15, 2018. To Celebrate the Spring Festival, we will close for a week from 25th Jan. to 31st. Jan. Lab will open again on 1st., Feb. We wish you all a Happy New Year! Happy Rooster Year! Mega Dental Lab Jan., 22,2017

FDA CONCLUDES MERCURY IN DENTAL FILLINGS NOT RISKY WASHINGTON - The government declared Tuesday that silver dental fillings contain too little mercury to harm the millions who've had cavities filled with them - including young children - and that only people allergic to mercury need to avoid them. It was something of an about-face for the Food and Drug Administration, which last year settled a lawsuit with anti-mercury activists by posting on its Web site a precaution saying questions remained about whether the small amount of mercury vapor the fillings can release were enough to harm the developing brains of fetuses or the very young. On Tuesday, the FDA said its final scientific review ended that concern. Still, the agency did slightly strengthen how it regulates the fillings, urging dentists to provide their patients with a government-written statement detailing the mercury controversy and what science shows. "The best available scientific evidence supports the conclusion that patients with dental amalgam fillings are not at risk for mercury-associated adverse health effects," said Dr. Susan Runner, FDA's dental products director. Anti-mercury activists accused the agency of bowing to the dental industry and said they'd go back to court to try to force a change."FDA broke its contract and broke its word that it would put warnings for children and unborn children," said Charles Brown of Consumers for Dental Choice. "This contemptuous attitude toward children and the unborn will not go unanswered." Too much mercury can harm the brain. It has made headlines in recent years as scientists have warned that some types of seafood contain enough to harm a fetus or young child. Used since the 1800s, amalgam fillings are a mix of a different kind of mercury - a kind the body absorbs differently - with silver, copper and tin to harden it. Tuesday, the FDA took the regulatory step of formally classifying amalgam fillings as a Class II or "moderate risk" medical device to ensure that dentists handle the mercury properly - using adequate ventilation - but to allow the allergy warning. Until now, the FDA had classified the fillings' ingredients separately. The practical effect of that technical change? The FDA released its review of 200 scientific studies that found no risk to adults or children over 6 from the fillings. What about pregnant women or younger children? Tuesday's ruling supersedes the precaution from last year's lawsuit settlement, Runner said.The FDA found that while there have been only a handful of rigorous studies comparing young children given either amalgam fillings or mercury-free tooth-colored resin composite ones, those studies haven't detected any brain problems. Runner cited additional evidence concluding that babies and young children would be exposed to amounts well below safety limits. But the statement dentists are urged to share with patients does raise the issue so that people who are concerned about the mercury can discuss an alternative. Removing the fillings actually releases more mercury vapor, FDA said. People who think they're allergic to a filling ingredient should discuss that with a dentist. Amalgams now account for about 30 percent of U.S. fillings, their popularity dropping in favor of tooth-colored alternatives. But they remain the cheapest filling and dentists say there are some conditions that demand amalgams, such as spots on back teeth that won't stay dry long enough for composite fillings to bond. By: AP Medical Writer Lauran Neergaard, July 28, 2009.