Finite element analysis (FEA) has been used extensively to predict the biomechanical performance of various dental implant designs as well as the effect of clinical factors on implant success. By understanding the basic theory, method, application, and limitations of FEA in implant dentistry, the clinician will be better equipped to interpret results of FEA studies and extrapolate these results to clinical situations. This article reviews the current status of FEA applications in implant dentistry and discusses findings from FEA studies in relation to the bone-implant interface, the implant-prosthesis connection, and multiple-implant prostheses.

/pdf/application-of-finite-element-analysis-in-implant-dentistry-52b1nibbjh.pdf

Application of finite element analysis in implant dentistry: A review of the literature

Purpose: This overview presents a description of organofunctional trialkoxysilane coupling agents (silanes), their chemistry, properties, use, and some of the main clinical experiences in dentistry. Materials and Methods: The main emphasis was on major dental journals that have been reviewed from 1958 up to the latest research news from 2002. A MEDLINE search with the key words “dental silanes” was used. Special silane literature and journals outside dentistry were also cited. Results: The main emphasis is on the use of silanes in prosthetic and restorative dentistry. Clinical relevance was based mainly on either short- or long-term tests. The interpretation of various results is not given, mainly because of controversial observations that may be very difficult to explain. Nevertheless, the majority of the clinical results pointed to silanes playing a significant role in the adhesion process. Silane reaction mechanisms were not entirely understood, and there exist several theories for bonding mechanisms for silanes and substrates. Conclusion: Dental materials offer a continuously challenging forum for silanes, and silanes will play an essential role in material development. Publ. in: Int J Prosthodont 2004;17:155–164.

An Introduction to Silanes and Their Clinical Applications in Dentistry

Statement of problem Discoloration of resin-based composites by colored solutions is a common problem. The use of bleaching agents for discolored natural teeth is becoming increasingly popular. It is not clear if bleaching agents can remove the stain from composite resins. Purpose The purpose of this study was to investigate the effects of 2 staining solutions and 3 bleaching systems on the color changes of 2 dental composite resins. Material and methods Forty-five disk-shaped specimens (9 × 2.5 mm) of each of 2 composite resins, Filtek Supreme (FS) and Esthet X (EX), were prepared. The specimens were then divided into 3 groups of 15 specimens each and immersed in 2 staining solutions (coffee or red wine) or distilled water (control) for 3 hours daily over a 40-day test period. The 3 groups were then divided into 3 subgroups (n=5), and 3 bleaching agents (Crest Night Effects, Colgate Simply White Night, or Opalescence Quick) were applied to the surface of the specimens over a 14-day period. Color of the specimens was measured with a spectrophotometer using CIELAB color space relative to CIE standard illuminant D55 at baseline, after staining, and after bleaching. The color differences (ΔE ab ∗ ) between the 3 measurements were calculated. The value ΔE ab ∗ =3.3 was used as an acceptable value in subjective visual evaluations. Analysis of variance and nonparametric analysis (Kruskal-Wallis test and Mann-Whitney test) were used to analyze the data. Results After staining, FS had more color change than EX and was more affected by the wine solution. After bleaching, the color of both EX and FS specimens returned to the baseline. The color differences between bleaching and baseline were less than value ΔE ab ∗ =3.3 for all groups. Conclusion The nanocomposite (FS) changed color more than the microhybrid composite (EX) as a result of staining in coffee or red wine solutions. After bleaching, discoloration was removed completely from the composite resins tested.

Effects of staining and bleaching on color change of dental composite resins

Background: Platform switching for maintaining peri-implant bone levels has gained popularity among implant manufacturers over the last few years. However, the assumption that the inward shifting of the implant-abutment junction may preserve crestal bone was primarily based on serendipitous finding rather than scientific evidence. The objectives of the present study were to systematically review radiographic marginal bone-level changes and the survival of platform-switched implants compared to conventional platform-matched implants. Methods: A literature search of electronic databases (MEDLINE, EMBASE, The Cochrane Oral Health Group’s Trials Register, The Cochrane Central Register of Controlled Trials, the U.K. National Research Register, the Australian New Zealand Clinical Trials Registry, the Database of Abstracts of Reviews of Effectiveness, and Conference Proceedings Citation Index) was performed up to March 15, 2010. Hand searches included several dental journals, and authors were contacted for missing information. Controlled trials that compared marginal bone-level changes around platform-switched dental implants with those restored with platformmatched prostheses were selected. The review and meta-analysis were done according to the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. Data were analyzed using two meta-analytic statistical packages. Mean differences (MDs) were calculated for analyzing continuous data, and risk ratios (RRs) were used for dichotomous data with 95% confidence intervals (CIs). Results: Ten studies with 1,239 implants were included. The marginal bone loss around platform-switched implants was significantly less than around platform-matched implants (MD: -0.37; 95% CI: -0.55 to -0.20; P <0.0001). No statistically significant difference was detected for implant failures between the two groups (RR: 0.93; 95% CI: 0.34 to 2.95; P = 0.89). Subgroup analyses showed that an implant-abutment diameter difference ‡0.4 was associated with a more favorable bone response. Conclusions: The review and meta-analysis show that platform switching may preserve interimplant bone height and soft tissue levels. The degree of marginal bone resorption is inversely related to the extent of the implant-abutment mismatch. Further long-term, well-conducted, randomized controlled studies are needed to confirm the validity of this concept. J Periodontol 2010;81:1350-1366.

Platform Switching for Marginal Bone Preservation Around Dental Implants: A Systematic Review and Meta-Analysis

Effect of bleaching on restorative materials and restorations—a systematic review

Statement of problem Bleaching agents may affect the color of existing composite restorations. Purpose The purpose of this study was to compare the effect of 10% carbamide peroxide and 10% hydrogen peroxide on the color of light-polymerized hybrid, macrofilled, and polyacid-modified composites. Material and methods Two light-polymerized hybrid composites (3M Valux and Spectrum TPH), 1 macrofilled condensable composite (Solitaire), and 2 polyacid-modified composites (Dyract AP and Compoglass) were used. The hybrid composites served as controls. The color of 8 specimens of each material was analyzed by use of a spectrophotometer before bleaching. The specimens were then divided randomly into 2 subgroups (n=4). One group was immersed in 10% carbamide peroxide solution and the other in 10% hydrogen peroxide, for 8 hours each for 14 consecutive days. After bleaching, color changes (Δ E) were determined for each material and compared by use of the Kruskal-Wallis test, followed by the Mann-Whitney U test ( P Results After bleaching with carbamide peroxide, the color changes (ΔE) for Dyract AP (2.18; SD=1.41), Compoglass (1.14; SD=0.26) and Solitaire (1.56; SD=0.89) were higher than the color changes recorded for 3M Valux (0.63; SD=3.60), and Spectrum TPH (0.66; SD=1.24). The differences between materials bleached with carbamide peroxide were not statistically significant. After bleaching with hydrogen peroxide, the color changes for Dyract AP (9.39; SD=0.53) and Compoglass (5.15; SD=0.52) were higher than the changes recorded for Spectrum TPH (4.53; SD=1.53) and 3M Valux (3.41; SD=4.40), whereas the color change of Solitaire (3.69; SD=0.57) was significantly higher than that of 3M Valux ( P =.01). The color changes for all restorative materials tested were clinically detectable after the application of 10% hydrogen peroxide. However, clinically noticeable discoloration was observed only for Dyract AP treated with 10% carbamide peroxide. Conclusion In comparison to 10% carbamide peroxide, 10% hydrogen peroxide caused more color changes in the composites tested.

The effect of current bleaching agents on the color of light-polymerized composites in vitro.

Surface roughness and bond strengths of glass-infiltrated alumina-ceramics prepared using various surface treatments

The distribution of stress around implants placed in the first molar region of the mandible was biomechanically analyzed in a two-dimensional mathematical model. Two types of implants, vertical and angled, were subjected to a vertical load of 100 N and a horizontal load of 50 N in turn. The magnitudes and contours of compressive and tensile stress within the surrounding bone were determined. For the sake of comparison, maximal compressive stress and maximal tensile stress at the surrounding bone were calculated. There were no measurable differences in stress values and contours when a horizontal load was applied to the vertical and angled implants. However, with the vertical loading, the compressive stress values were five times higher around the cervical region of the angled implant than around the same area in the vertical implant.

Senay Canay

Papers

The effect of current bleaching agents on the color of light-polymerized composites in vitro.

Surface roughness and bond strengths of glass-infiltrated alumina-ceramics prepared using various surface treatments

Comparison of stress distribution around vertical and angled implants with finite-element analysis.

Tensile bond strength of ceramic orthodontic brackets bonded to porcelain surfaces

The effect of enamel air abrasion on the retention of bonded metallic orthodontic brackets.