The Journal of Adhesive Dentistry, 05/2012

Purpose: More than five hundred million direct dental restorations are placed each year worldwide. In about 55% of the cases, resin composites or compomers are used, and in 45% amalgam. The longevity of posterior resin restorations is well documented. However, data on resin composites that are placed without enamel/dentin conditioning and resin composites placed with self-etching adhesive systems are missing. Material and Methods: The database SCOPUS was searched for clinical trials on posterior resin composites without restricting the search to the year of publication. The inclusion criteria were: (1) prospective clinical trial with at least 2 years of observation; (2) minimum number of restorations at last recall = 20; (3) report on dropout rate; (4) report of operative technique and materials used; (5) utilization of Ryge or modified Ryge evaluation criteria. For amalgam, only those studies were included that directly compared composite resin restorations with amalgam. For the statistical analysis, a linear mixed model was used with random effects to account for the heterogeneity between the studies. P-values under 0.05 were considered significant. Results: Of the 373 clinical trials, 59 studies met the inclusion criteria. In 70% of the studies, Class II and Class I restorations had been placed. The overall success rate of composite resin restorations was about 90% after 10 years, which was not different from that of amalgam. Restorations with compomers had a significantly lower longevity. The main reason for replacement were bulk fractures and caries adjacent to restorations. Both of these incidents were infrequent in most studies and accounted only for about 6% of all replaced restorations after 10 years. Restorations with macrofilled composites and compomer suffered significantly more loss of anatomical form than restorations with other types of material. Restorations that were placed without enamel acid etching and a dentin bonding agent showed significantly more marginal staining and detectable margins compared to those restorations placed using the enamel-etch or etch-and-rinse technique; restorations with self-etching systems were between the other groups. Restorations with compomer suffered significantly more chippings (repairable fracture) than restorations with other materials, which did not statistically differ among each other. Restorations that were placed with a rubber-dam showed significantly fewer material fractures that needed replacement, and this also had a significant effect on the overall longevity. Conclusion: Restorations with hybrid and microfilled composites that were placed with the enamel-etching technique and rubber-dam showed the best overall performance; the longevity of these restorations was similar to amalgam restorations. Compomer restorations, restorations placed with macrofilled composites, and resin restorations with no-etching or self-etching adhesives demonstrated significant shortcomings and shorter longevity.

Purpose: The aim of this literature review was to investigate the results from in vitro laboratory studies on the influence of temperature and relative humidity present before polymerization on enamel and dentin bonding systems. Materials and Methods: A systematic search was carried out including articles published in English, in peerreviewed journals, and indexed in MEDLINE/PubMed database. The search was carried out using the terms: relative AND humidity AND dental. In vitro studies were retrieved and divided into laboratory simulation studies and studies on physical properties. Laboratory simulation studies were addressed by subtopic: resin-enamel bond strength, resin-dentin bond strength, and dentin-enamel microleakage. Studies on physical properties tested the influence of humidity and temperature through polymerization contraction, flexural strength, and dentin wettability. Results: Laboratory simulation studies demonstrated a strong influence of humidity and temperature on dentin and enamel bond strength and microleakage with dental adhesives systems. The studies on physical properties failed to demonstrate any influence of humidity on the adhesion performance, except for wettability measurement. Conclusion: The clinical relevance of these in vitro results remains to be demonstrated. A review of in vivo clinical studies will complete the literature data presented here. Keywords: relative humidity, temperature, enamel bonding, dentin bonding, polymerization, review

Purpose: To compare shear bond strengths of three different self-etching adhesive systems of different pH values to enamel bleached with carbamide peroxide, treated with casein phosphopeptide-amorphous calcium phosphate (CPP-ACP), or treated with CPP-ACP subsequent to bleaching with carbamide peroxide. Materials and Methods: Thirty-six human third molars were cut into 4 sections and randomly assigned to 4 groups (n = 36): group I: no treatment; group II: bleaching; group III: CPP-ACP; group IV: bleaching and CPP-ACP. After surface treatments, the samples of each group were further divided into three subgroups (n = 12) based on the adhesive used. The adhesives Clearfil SE Bond (CSE), AdhesE (ADE), and Adper SE Plus (ADP) were applied, and resin composite cylinders with a diameter of 2 mm and a height of 4 mm were bonded to the enamel. Then the specimens were subjected to shear bond strength testing. Two-way ANOVA and a post-hoc Tukey's test were used for statistical analysis (α = 0.05). Results: There were significant differences between the adhesive systems (p 0.001) and surface treatments (p 0.001), but no significant interactions were observed between these variables (p = 0.78). The CSE adhesive system showed the highest bond strength, and the bleaching procedure reduced bond strengths (p = 0.001). Furthermore, there were no significant differences in shear bond strength values between the control and CPP groups. However, the differences between other groups were statistically significant (p 0.05). Conclusion: Bleaching reduced shear bond strength to enamel, but CPP-ACP application did not affect the bond strength to intact and previously bleached enamel. The bond strength of adhesives with different pH values to enamel was material dependant. Keywords: pH, self-etching adhesives, bleaching, casein phosphopeptide-amorphous calcium phosphate, bond strength

Purpose: To evaluate the effect of surface treatments on the shear bond strength (SBS) of a resin cement to commercially pure titanium (CP Ti). Materials and Methods: Two hundred cast CP Ti disks were divided into 5 groups (n = 40), which were treated with one of the following air-abrasion techniques: (1) 50-µm Al2O3 particles; (2) 120-µm Al2O3 particles; (3) 250-µm Al2O3 particles; (4) 30-µm silica-modified Al2O3 particles (Cojet Sand); (5) 50-µm Al2O3 particles followed by 110-µm silica-modified Al2O3 particles (Rocatec Plus). For each air-abrasion technique, the following additional surface treatments were used (n = 10): (1) none; (2) adhesive Adper Single Bond 2; (3) silane RelyX Ceramic Primer; (4) silane plus adhesive. RelyX ARC resin cement was bonded to CP Ti surfaces. All specimens were thermocycled (5,000 cycles) before being tested in shear mode. Data (MPa) were analyzed using two-way ANOVA and Tukey's test (α = 0.05). Failure mode was determined with a stereomicroscope (20X). Results: The results revealed that the air-abrasion technique (p 0.001), additional surface treatment (p 0.001) and their interaction were significant (p 0.001). Except for the 50-µm Al2O3 + adhesive group, 250-µm Al2O3 particles promoted significantly higher SBS than 50-µm Al2O3 particles (p 0.001), while Rocatec Plus provided bond strengths that were similar to or higher than those of Cojet Sand. Of the additional surface treatments, the adhesive provided the best results in combination with the 3 air-abrasion techniques (50-µm, 120-µm, and 250-µm Al2O3), whereas in the groups abraded with silica-modified Al2O3 particles (Cojet Sand and Rocatec Plus), the best results were obtained with additional silane. The two combinations that promoted the highest SBS were 250-µm Al2O3 + adhesive and Rocatec Plus + silane. All groups showed 100% adhesive failure. Conclusion: The selection of the best additional surface treatment varied according to the air-abrasion technique. Particle size was the decisive factor in determining the bond strength when micromechanical retention was the only bonding mechanism. When both mechanisms were present, in addition to particle size, the material applied as the additional surface treatment also contributed to determining the bond strength. Keywords: resin cement, titanium, surface treatment, air abrasion, silica coating

Purpose: To evaluate the effect of applied power on dental ceramic bonding of composite resin using nonthermal atmospheric pressure plasma (APP). Materials and Methods: A pencil-type APP torch was used to modify the surface chemical composition and hydrophilicity of dental ceramic and to improve the adhesion of composite resin to the surface. The effect of the applied power on chemical changes of the plasma polymer on a ceramic surface and the adhesive strength between the composite resin and feldspathic porcelain were examined. Adhesion was evaluated by comparing shear bond strengths (SBS) using the iris method. The chemical composition of the plasma polymer deposited on the ceramic surface was evaluated using x-ray photoelectron spectroscopy (XPS). Hydrophilicity was evaluated by contact angle measurements. The fracture mode at the interface was also evaluated. Results: The APP treatment was effective and the SBS of the experimental groups were significantly higher than those of the negative control group (p 0.05). Moreover, the SBS obtained with the APP treatment at the highest input voltage was statistically similar to the gold standard of HF etching and silane coupling-agent coating. Two-thirds of the fractures observed in the specimens bonded with application of APP were mixed and cohesive fractures. Conclusion: Application of APP enhanced adhesion by producing carboxyl groups on the ceramic surface and as a result by improving surface hydrophilicity. The carboxyl group contents in the plasma polymer on the ceramic surface increased as the applied power increased. Keywords: nonthermal atmospheric pressure plasma (APP), ceramic bonding, applied power, hydrophilicity, chemical composition, polymer deposition

Purpose: To evaluate the effect of mechanical cycling and cementation strategies on the push-out bond strength between fiber posts and root dentin and the polymerization stresses produced using three resin cements. Materials and Methods: Eighty bovine mandibular teeth were sectioned to a length of 16 mm, prepared to 12 mm, and embedded in self-curing acrylic resin. The specimens were then distributed into 8 groups (n = 10): Gr1 - Scotchbond Multi Purpose + RelyX ARC; Gr2 - Scotchbond Multi Purpose + RelyX ARC + mechanical cycling; Gr3 - AdheSE + Multilink Automix; Gr4 - AdheSE + Multilink Automix + mechanical cycling; Gr5 - phosphoric acid + RelyX U100 (self-adhesive cement); Gr6 - phosphoric acid+ RelyX U100 + mechanical cycling; Gr7 - RelyX U100; Gr8 - RelyX U100 + mechanical cycling. The values obtained from the push-out bond strength test were submitted to two-way ANOVA and Tukey's test (p = 0.05), while the values obtained from the polymerization stress test were subjected to one-way ANOVA and Tukey's test (α = 0.05). Results: Mechanical cycling did not affect the bond strength values (p = 0.236), while cementation strategies affected the push-out bond strength (p 0.001). Luting with RelyX U100 and Scotch Bond Multi Purpose + RelyX ARC yielded higher push-out bond strength values. The polymerization stress results were affected by the factor "cement" (p = 0.0104): the self-adhesive cement RelyX U100 exhibited the lowest values, RelyX ARC resulted in the highest values, while Multilink Automix presented values statistically similar to the other two cements. Conclusion: The self-adhesive cement appears to be a good alternative for luting fiber posts due to the high push-out bond strengths and lower polymerization stress values. Keywords: cementation, fiber posts, mechanical cycling

Purpose: This paper describes a clinical, conservative approach and the details of cavity preparation for the replacement of a maxillary first premolar using a minimally invasive preparation combined with the adhesive approach. Material and Methods: A patient with a missing first premolar was treated with a 3-unit indirect fiber-reinforced composite (FRC) fixed dental prosthesis (FDP). The preparation on the canine was a slot combined with modified wing to increase the amount of fiber in the restoration. Glass fiber (Vectris; Ivoclar Vivadent) was used in an anatomical shape for the framework and incrementally veneered with resin composite (Adoro; Ivoclar Vivadent). The cavities were prepared by etching enamel and dentin with orthophosphoric acid, priming the dentin, and applying a three-step adhesive system and dual-cured luting resin (Variolink II, Ivoclar Vivadent). Finally, the indirect FRC FDP was finished and polished with 15-µm diamond burs (Composhape, Intensiv) and a polishing kit. Results: The patient was satisfied with the esthetics and function of the restoration, which has served without repair for 5 years. At the 5-year clinical follow-up, the restoration was found to be clinically successful. Conclusion: The correct cavity-preparation technique in combination with the FRC system could enhance the long-term survival of an inlay FDP. Keywords: fiber reinforced composite, inlay-fixed partial dentures, adhesive system, resin composite

Purpose: To evaluate the 24-month clinical performance of cervical restorations using a nanohybrid and a flowable resin composite with a one-step self-etching adhesive. Materials and Methods: Twenty-one patients with at least one pair of non-carious cervical lesions participated in this study. A total of 134 non-carious cervical lesions were restored (67 with a nanohybrid resin composite, Grandio; 67 with a flowable resin composite, Grandio Flow) using a one-step self-etching adhesive system, Futura Bond NR, by one dentist. The restorations were evaluated for retention, color match, marginal discoloration, marginal adaptation, surface texture, anatomic form, and secondary caries by two calibrated examiners at baseline and after 6, 12, and 24 months using modified USPHS criteria. The survival rates of the restorations were calculated by the Kaplan-Meier estimator. The comparison of resin composites for each category was performed with the Pearson chi-square test, and the performance of restorations at baseline and after each recall time was evaluated using McNemar's test (p 0.05). Results: All patients attended the 24-month recall. The retention rates at 6 months were 66% and 58%, and 61% and 57% at 12 months for Grandio and Grandio Flow, respectively. At the 24-month recall, the retention rate was 60% for Grandio and 54% for Grandio Flow. No statistically significant differences were found in retention rates among the restorative materials in any evaluation period (p > 0.05). For marginal discoloration and anatomical form, three Grandio and three Grandio Flow restorations showed Bravo scores at the end of 24 months. The restorations in both groups had Alfa ratings of 100% for the rest of the criteria evaluated. Conclusion: The nanohybrid and flowable resin composites showed similar clinical performances in the restoration of non-carious cervical lesions over 24 months. Keywords: nanohybrid composite, flowable composite, self-etching adhesive, cervical lesions, clinical trial