A review of CAD/CAM use in dentistry (part II): Comparison of intraoral digital scanners used in restorative dentistry

Introduction: Intraoral imaging technology has become one of the most exciting new fields in dentistry. Three-dimensional scanning of the oral cavity is used in many dental procedures such as restorative dentistry and orthodontics. To date, a number of intraoral scanners have been developed for restorative dentistry throughout the world, and many researchers and manufacturers seek the design and development of new digital devices. Only some of these devices are currently available on the market and some others are being clinically tested. All existing intraoral scanners try to overcome the drawbacks of traditional impression processes. The aim of the present article is to provide an extensive evaluation of intraoral scanners in restorative dentistry, with special attention to their assessment principles, characteristics and performance. Review report: This review article was prepared by scientific searching in electronic sources of Pubmed and ISI Web of Science in connection with articles published in English until 2014, and with these key words: intraoral scanners and digital impression. Conclusion: Over the years there have been major advances in digital scanning systems, and a variety of digital systems have been introduced that enable the dentist to select different intraoral reconstruction methods in the extraoral environment. The ultimate goal of dentists is to provide accurate and efficient dental restorations for the patient, while maintaining patient comfort during the impression process. High-resolution dental optical scanners will enable the operator to provide high-quality restorations. With digital impression techniques, the number of operators and material variables will decrease, making restoration fabrication processes more predictable and easier

Marginal integrity of low-shrinkage and methacrylate-based composite resins: Effect of three different hemostatic agents

Background: Moisture control is very important in restorative procedures in dentistry. Use of hemostatic agents helps control moisture; however, they might result in changes on enamel and dentin surfaces, affecting composite resin bond quality. The aim of this in vitro study was to evaluate the marginal microleakage of two different composite resins with the use of three different hemostatic agents. Material and Methods: Standardized Class V cavities were prepared on the buccal and lingual surfaces of 48 premolars with cervical margins 1 mm apical to the cementoenamel junction (CEJ). The samples were randomly divided into 8 groups. In groups 1 to 4, an etch-and-rinse adhesive (Adper Single Bond) was applied as the bonding system, followed by exposure to different hemostatic agent: group 1: no hemostatic agent (control); group 2: ViscoStat; group 3: ViscoStat Clear; and group 4: trichloracetic acid, as hemostatic agents. The cavities were restored with Z-250 composite resin. In group 5 to 8 Silorane System Adhesive (Filtek P90 Adhesive) was applied as a bonding agent, followed by exposure to different hemostatic agents in a manner similar to that in groups 1to 4. The cavities were restored with Filtek P90, a low-shrinkage composite resin. The samples in each group were evaluated for dye penetration under a stereomicroscope at ×36 after 24 hours and a 500-round thermocycling procedure at enamel and dentin margins. Statistical analysis was carried out using Kruskal-Wallis and Mann-Whitney tests (α=0.05). Results: Z-250 composite resin exhibited significantly higher dentin microleakage scores compared to Filtek P90 (P = 0.004). Trichloracetic acid increased dentin microleakage with Filtek P90 (P=0.033). Conclusions: Under the limitations of this in vitro study, application of hemostatic agents did not affect microleakage of the two tested composite resins except for trichloracetic acid that increased marginal microleakage when used with Filtek P90. © Medicina Oral

Comparison of microleakage in Class II cavities restored with silorane-based and methacrylate-based composite resins using different restorative techniques over time.

BACKGROUND Despite the growing tendency toward tooth-colored restorations in dentistry, polymerization shrinkage and subsequent marginal microleakage remains a problem. The aim of this in vitro study was to compare microleakage between silorane-based and methacrylate-based composite resins at different time intervals and with different restorative techniques. MATERIALS AND METHODS In this in vitro study, 108 sound extracted human molar teeth were used. Mesial and distal proximal class II boxes with dimensions of 1.5 mm depth and 4 mm width were prepared. The gingival margins of all cavities were 1 mm below the cement enamel junction. The teeth were randomly divided into three groups based on test materials. In the first group, the teeth were restored by a nanocomposite (Filtek Z350XT, 3MESPE) and SE Bond adhesive (Kuraray, Japan), in the second group, the teeth were restored with a silorane-based (Filtek P90, 3MESPE) and Filtek P90 Adhesive (3M ESPE, USA) and in the third group, the teeth were restored with a microhybrid posterior composite resin (Filtek P60, 3MESPE) and SE Bond adhesive (Kuraray, Japan). Half of the proximal cavities in each of these three groups were restored in two horizontal layers and the other half in four horizontal layers. After a period of aging (24-h, 3-month and 6-month) in water and then application of 500 thermal cycles, the teeth were immersed for 24-h in 0.5% fuchsin and evaluated under a stereomicroscope at ×36 magnification to evaluate leakage in gingival margin. Data was statistically analyzed using Kruskal-Wallis and Mann-Whitney U-tests. P ≤ 0.05 was considered as significant. RESULTS In Z350XT statistically significant differences were observed in microleakage in comparison of 24-h and 6-month intervals (P = 0.01) that was higher in 6-month. Comparison of microleakage in P90 and P60 composite resins was also statistically significant and was less in P90. Microleakage was not significantly different between P90 and Z350XT at 24-h. However, this difference was significant at 3-month and 6-month intervals. Differences in microleakage of P60 and Z-350XT composite resins were not statistically significant in all intervals (P = 0.38). P90 showed the lowest microleakage during storage in water. Z350XT had microleakage similar to P90 within 24-h, but after 6-month of storage in water, it showed the highest microleakage among all the groups. The number of layers (2 layers vs. 4 layers) did not result in any differences in microleakage scores of the composite resins (P = 0.42). CONCLUSION Water storage times did not result in any significant effect on microleakage of P90 and P60

An overview of application of CAD/CAM in dentistry (Part I)

Introduction: Today, new developments in the field of computer hardware and software have led to the production of advanced equipment and devices in industry, including the dental field. One of these devices is computer-aided design (CAD) and computer-aided manufacture (CAM) system. CAD/CAM systems are able to collect data and design and manufacture a wide range of dental restorations such as inlays, onlays, veneers, crowns, fixed partial dentures, orthodontic appliances and dental implant abutments. The aim of this article is to review the history of CAD/CAM, types of available CAD/CAM systems, how they function and application concepts in digital dentistry. Article description: This article was collected by scientific search in electronic resources, books, Pubmed and ISI Web of Science websites, in articles published in English until 2013, and with the following key words: history, advantages and disadvantages, an overview of the components and the performance of CAD/CAM systems in dentistry. Conclusions: In recent years, digital technology is advancing rapidly in dentistry and now it can be applied to almost any restorative situation, including full-mouth rehabilitation. Computer technology has made fabrication of restorations easier, faster, cheaper and more predictable than before. While there are many benefits for dental digital systems, it is necessary for the dental team to master their function in order to maximize their advantages for creating well-fitting restorations

An overview of aesthetic prostheses for gingival replacement

An increasing patient and clinician awareness of the importance of gingival and smile aesthet¬ics has resulted in the development of both surgical and prosthetic techniques aimed at improving or maintaining these aes¬thetic characteristics.surgical gingival procedures,trauma,ridge resorption or traumatic tooth extraction,periodontal disease, and congenital defects can result in both soft tissue and hard tissue defects that can present with aesthetic problems. gingival replacement prostheses have historically been used to replace lost tissue when other methods (surgery or regenerative procedures)were considered unpredictable or impossible. Aim:This paper describes problems associated with soft tissue defects; introduce both traditional and contemporary)either removable and fixed) gingival prostheses available in the prosthetic management of soft tissue aesthetics on single teeth, on multiple teeth,on implants,in edentulous spans and in the denture patients ;discusses their advantages,disadvantages and alternatives; and also describes several clinical situations in which gingival prostheses were used effectively. Conclusion:Where recession is localised to a single tooth and root coverage surgery is not indicated, the use of adhesive direct or indirect materials can be considered. Where multiple recession defects are present in stabilised periodontal patients, the use of a gingival prosthesis can be provided relatively easily with a predictable result. In patients requiring fixed restoration in the aesthetic zone, the use of gingivally coloured porcelain can help in recreat¬ing natural tooth proportions. As the prosthetic techniques described in this paper are minimally invasive with low morbidity, they may provide alter¬natives to surgery for patients concerned about soft tissue aesthetics