Postoperative dental bleaching: effect of microleakage on Class V tooth colored restorative materials

The effect of 3 percent, 11 percent, and 16 percent carbamide peroxide bleaching solutions and 35 percent hydrogen peroxide bleaching gel on microleakage of Class V composite resins, resin modified glass ionomer cements, and compomer restorative materials together with corresponding (if indicated) fourth/fifth generation bonding agents was evaluated using previously extracted human teeth. Five groups of Class V cavity preparations were placed in enamel of the facial surfaces of 200 teeth. Groups A through D included 40 restorations each (4 different restorative materials and their accompanying bonding agent multiplied by 10 teeth) treated with 3 percent, 11 percent, and 16 percent carbamide peroxide bleach and 35 percent hydrogen peroxide bleach. Group E included 40 restorations without treatment of bleach and stood as the control. The restorative materials included were: Fuji II LC resin modified glass ionomer cement, Helioprogress composite resin/-Heliobond adhesive system, Aelitefil composite resin/Allbond 2 adhesive and Dyract compomer material/Prime & Bond adhesive system. Bleaching agents included were Rembrandt 3 percent peroxide gel, Perfecta 16 percent carbamide peroxide gel, White & Brite 11 percent carbamide peroxide solution and Superoxyl 35 percent hydrogen peroxide gel. All teeth were thermally stressed for 100 cycles and microleakage were assessed by dye penetration. The results were tabulated using Analysis of Variance (ANOVA) testing procedures. The Aelitefil composite resin material behaved the least favorably (relative to microleakage) compared to the other materials when exposed to various concentrations of dental bleaching agents.     

Finite element analysis of strength characteristics of various resin based restorative materials in Class V cavities

This study investigated the strength characteristics of various composites (Tetric Ceram, Tetric Flow, Prisma AP.H, Synergy Duo Shade, Synergy Compact, and Z 100) and compomers (Compoglass, Compoglass F, Dyract AP, F 2000) that were applied in a Class V cavity of a maxillary central incisor. The study was conducted by using a 3-dimensional finite element approach and in the study ansys package program was used. The tooth model had 294 elements and 420 nodes. The teeth considered were assumed to be subjected to an incisal load of 200 N acting at an angle of 26 degrees with the longitudinal axis of the tooth but the effects of different loading angles and different loads were also analysed. Hence, the loads of 100 and 400 N and the loading angles of 0 degrees representing bruxism and 90 degrees representing a traumatic load were also taken into consideration. The effects of the cavity preparation size were also studied. It was determined that any increase in the loading angle and/or the amount of the load resulted in a proportional increase in the stresses developed in the tooth. Furthermore it was also verified that, as a cavity weakens the tooth structure by creating a discontinuity in an intact tooth, the larger sized cavity preparations inevitably cause larger stresses to be developed in the tooth. Strictly from the mechanical point of view, the stresses developed in the restored teeth were determined to be inversely proportional with the modulus of elasticity of the restorative materials. Therefore within the scope of the study Z 100 was found to be superior to the other materials concerned.     

Marginal adaptation of Class V restorations using different restorative techniques

This in vitro study compares the marginal adaptation of Class V restorations with margins located half in enamel and half in dentine, which were placed using different restorative techniques. Five operative procedures were evaluated both in saucer-shaped erosion lesions and in box-shaped cavities with bevels in enamel. The five procedures included a composite inlay technique using both the chemically and the light curing versions of a resin based composite cement, a bulk placement technique using a chemically curing composite resin, an incremental technique and an incremental technique combined with a built-up base, using a light curing composite resin. A combination of Gluma/Clearfil served as the dentinal adhesive. The micromorphology of the tooth/restoration interface was analysed before and after thermal cycling; the marginal seal was analysed after thermal cycling only. In the conventional cavities, the restorations showed less leakage, and micromorphologically a better, but statistically insignificant superior marginal adaptation. The inlay technique rendered the best marginal quality in both enamel and dentine before and after thermal cycling. Due to the unique curing characteristics of the chemically cured composite resin and cement resulting in a significantly reduced rigid contraction, the inlays cemented with the chemically curing cement and the restorations placed with the chemically curing composite resin were superior to their light cured counterparts. The built-up base yielding a reduction of the composite mass did not enhance marginal adaptation because of the partial replacement of the strong adhesion to dentine mediated by the Gluma/Clearfil combination by the weaker bond promoted by the etched glass ionomer cement.     

Microleakage of several class V anterior restorative materials: a laboratory study.

The study was designed to evaluate the marginal leakage of abraded gingival areas in extracted teeth using five anterior composite resin acid-etch restorative materials and a glass ionomer cement, ASPA. In using three of the composite resin restorative materials, Simulate, Cervident, and Concise, there was a layer of unfilled resin between the etched tooth surface and the composite resin. Restodent and Enamelite were placed directly on the etched tooth surface. The results of the study indicate that there is a significantly greater degree of marginal leakage at the gingival margin than there is at the occlusal or incisal margin of composite restorations. In addition, greater marginal leakage was observed in those restorations where no layer of unfilled resin was placed between the etched tooth surface and the composite resin. The glass ionomer cement showed no marginal leakage at intervals of one day, three months, and six months; however, a small amount of leakage was observed at the incisal or occlusal and gingival margins at a year on half of the autoradiographs. A study has been initiated to determine leakage patterns around composite resin restorations placed in teeth with naturally occurring cervical erosion or abrasion.     

Comparison of surface finish of new aesthetic restorative materials

This study compared the surface finish of eight different types of aesthetic restorative materials. The materials included resin-modified (Fuji II LC [FL], GC) and highly viscous (Fuji IX GP Fast [FN], GC) glass ionomer cements, a compomer (F2000 [FT], 3M-ESPE), minifilled (Z100 [ZO], 3M-ESPE) and microfilled (A110 [AO], 3M-ESPE) composites and materials based on recently introduced ormocer (Admira [AM], Voco), nanomer (Filtek Supreme Translucent [FST], 3M-ESPE) and nanocluster technology (Filtek Supreme [FS], 3M-ESPE). Sixteen specimens (3-mm long x 3-mm wide x 2-mm deep) of each material were divided into two equal groups. Specimens in Group 1 received no further treatment after polymerization against a matrix strip, while the specimens in Group 2 were roughened with 320 grit grinding paper using a lapping device and were finished/polished with a graded abrasive disk system (Super-Snap, Shofu). The mean roughness (Ra, microm) of materials was determined using a surface profilometry. Data was analyzed by ANOVA/Scheffe's test at significance level 0.05. Mean Ra values ranged from 0.04 to 0.16 microm for Group 1 specimens and 0.15 to 0.68 microm for Group 2 specimens. Results of statistical analysis were as follows: Group 1-FS, FST, FL, FN, AM > FT, AO, ZO; Group 2-FN, FT, FL > AO, FS, ZO, AM, FST (> indicates significantly greater Ra values). For the finished/polished composite materials, Ra values observed for AM and FST were significantly lower than for AO and FS. The surface finish of glass ionomers and compomer was significantly poorer than composites. Composite materials based on ormocer and nanomer technology were significantly smoother than those based on microfillers and nanoclusters.     

Adhesion of direct restorative materials.

The development of adhesive restorative systems has been a major focus in dentistry. Materials that can attach to tooth structure make it possible to take a far more conservative approach to restorative dentistry.     

A calcium aluminate cement as restorative material in Class V cavities

Recently a calcium aluminate cement (Doxa Certex, Uppsala, Sweden) has been developed intended to be used as direct restorative filling material.The aim of this study was to evaluate intra-individually the experimental calcium aluminate cement (CAC) and a resin composite (RC;Tetric Ceram) in Class V restorations. Each of 46 participants received at least one pair of restorations of the same size, one CAC and one RC.The 119 restorations were evaluated clinically, according to slightly modified USPHS criteria, at baseline, after 6 mths, 1, 2 and 3 yrs. None of the patients reported post-operative sensitivity. At 3 yrs, 111 restorations were evaluated. Significantly better clinical durability was shown for RC.Two non-acceptable CAC restorations were observed at 6 months, 3 CAC and 1 RC at 12 months, 5 CAC and 2 RC at 24 months, and 8 CAC at 36 months.This resulted in a cumulative failure frequency of 32% for the CAC material and 5% for the RC material. Main reason for failure for the CAC was total or partial lost restorations, and for the RC lost restorations. It can be concluded that the CAC showed a non-acceptable clinical failure rate for Class V restorations.     

Comparison of the flexural strength of six reinforced restorative materials

This study calculated the flexural strength for six reinforced restorative materials and demonstrated that flexural strength values can be determined simply by using physical parameters (diametral tensile strength and Young's modulus values) that are easily determined experimentally. A one-way ANOVA analysis demonstrated a statistically significant difference between the two reinforced glass ionomers and the four composite resin materials, with the composite resin being stronger than the glass ionomers.     

Clinical evaluation of four Class 5 restorative materials: 3-year recall

PURPOSE: To place four restorative materials, including two resin-based composites (Pertac III and Synergy), an improved resin-modified glass-ionomer (Fuji II LC Improved), and a compomer (Dyract AP), in Class 5 non-carious cervical lesions and to evaluate and compare those restorations for marginal discoloration, anatomic form, surface texture, secondary caries, retention, and marginal adaptation at baseline and annually for 3 years. METHODS: The tested materials were used to restore moderate-size Class 5 non-carious cervical lesions. All materials were used following the manufacturers' directions for etching, bonding, curing, and finishing. Thirty restorations of each material were placed. After rubber-dam isolation, a bevel was placed on the occlusal margin of all preparations except the Fuji II LC Improved, and all preparations were cleaned with pumice. Each restorative material was placed and cured in increments except Fuji II LC Improved. All restorations were evaluated at baseline, 6 months, 1, 2, and 3-year recalls using a modified USPHS scale. RESULTS: Analysis with Chi Square and Logit Analysis revealed that, at 3 years, Pertac III and Fuji II LC Improved were significantly rougher than all other materials. Pertac III had significantly poorer marginal adaptation than all other materials. All other comparisons were not significant. At 3-year recall, most restorations were satisfactory.