The Journal of Adhesive Dentistry, 05/2016

Purpose: To perform a systematic review of the clinical performance of a low polymerization shrinkage, siloranebased composite (SBC) compared with a methacrylate-based composite (MBC) in posterior restorations. Materials and Methods: Electronic databases were searched: PubMed, Scopus, Bireme, Science Direct, Web of Science, ClinicalTrials.gov and OpenGrey. The search strategy included MeSH terms, synonyms and keywords with no language or date restrictions. Reference lists of eligible studies were cross checked in an attempt to identify additional studies. Based on the PICOS strategy, only randomized clinical trials (RCTs) were included. The risk of bias in the included studies was assessed and classified through the Cochrane Collaboration common scheme for bias. Two meta-analyses were performed using RevMan software, one with all 11 studies and another that included only studies with over 24 months of follow-up, for the main parameters analyzed. Results: A total of 544 studies were identified. After removing duplicates and examinating titles and abstracts, 17 texts were selected and read in full. Six of them were excluded, so the final sample of this systematic review included 11 studies. Six of the 11 studies were classified as having a "low risk of bias" and five were "unclear". The heterogeneity (I²) in all parameters was not significant. The exclusion of studies with less than 24 months of follow- up did not change the final result of the meta-analysis: both SBC and MBC have satisfactory and statistically similar clinical performances. Conclusion: Low polymerization shrinkage is not the principal factor that determines the superiority of a resin. Keywords: silorane resins, composite resins, permanent dental restorations, randomized clinical trial

Purpose: To assess the influence of surface treatment on the microtensile bond strength (μTBS) of resin cements to monolithic zirconia materials. Materials and Methods: Two types of monolithic zirconia (Zenostar T [ZT] and Prettau Anterior [PA]) were evaluated. The specimens were assigned to three groups based on the surface treatment applied: group 1: control, assintered; group 2: sandblasted with 50-μm Al₂O₃; group 3: tribochemically silica sandblasted. Two types of resin cements (Multilink Speed [MS] and Multilink N [MN]) were applied to each group for evaluating the bond strength using the μTBS test. The fractured specimens were observed with a stereomicroscope and SEM. Surface roughness and topography of monolithic zirconia were examined after treatment. Data were analyzed using ANOVA and Tukey's test. A Weibull analysis was performed on the bond strength data. Results: The bond strength was significantly affected by the surface treatment and the type of resin cement (p 0.001), but not by the type of monolithic zirconia (p = 0.387). Surface treatment with tribochemical silica sandblasting revealed significantly higher bond strength (p 0.05) compared with sandblasting with 50-μm Al₂O₃ and control groups. SEM and surface roughness evaluations revealed that the surface morphology and topography of monolithic zirconia was changed due to surface treatments. Conclusion: The surface treatment of monolithic zirconia with tribochemical silica sandblasting enhanced the bond strength between zirconia and resin cements. Resins cements containing adhesive phosphate monomer (APM, MS) provided higher bond strength to monolithic zirconia than non-APM (MN). Keywords: bond strength, microtensile, monolithic zirconia, resin cement, surface roughness, surface treatments

Purpose: This study investigated the influence of several methodological details on the shear bond strength (SBS) testing of pit and fissure sealants. The following variables were considered: type of enamel surfaces, prismatic vs aprismatic enamel, etching time, and aging and shearing procedures. Materials and Methods: The surfaces of 180 healthy human third molars were divided into 4 different sections (mesial, distal, buccal, and oral). After tooth separation, the specimens were randomly allocated to the following groups: 1) enamel preparation: prismatic vs aprismatic; 2) etching: 30 s vs 60 s; 3) aging: 1 day or 3 months vs 5000 thermocycles; 4) shearing: notched-edge method (ISO 29022:2013) vs knife-edge method. After following each protocol, SBS was determined using a universal testing machine, followed by failure mode analysis. Data were analysed using Mann-Whitney U-tests and regression analyses. Results: In the aprismatic enamel group, the longer etching time resulted in slightly, not statistically significantly higher SBS. When aging sealants on aprismatic enamel with different procedures, significantly lower SBS was found for 5000 thermocycles. In the case of aprismatic enamel etched for 60 s and sheared with the notched-edge blade, there was no significant difference between the aging procedures. Failure mode analysis showed adhesive failures to be predominant. Simple linear regression revealed that all of the included factors significantly influenced SBS. In a multiple linear regression model, the variables "aprismatic enamel" and "distal surface" were associated with a higher SBS; "5000 thermocycles" reduced SBS significantly. Conclusion: Enamel grinding, aging method, and type of enamel surface significantly influenced the SBS. Keywords: pit and fissure sealants, shear bond strength, mechanical testing, methodology

Purpose: To evaluate the effect of dentin treatment using HEMA phosphate (HEMA-P) on the microtensile bond strength (μTBS) and nanoleakage of an etch-and-rinse adhesive system. Materials and Methods: The occlusal surfaces of human molars were wet ground until superficial dentin was exposed. The specimens were then assigned to two groups according to dentin treatment: PA: 37% H₃PO₄ for 15 s; or HP: HEMA-P for 15 s. Adper Single Bond 2 was applied to the treated dentin surfaces and resin composite buildups were incrementally constructed over them. After 24-h storage in artificial saliva at 37°C, the bonded teeth were cut into resin-dentin sticks with a cross-sectional area of 1 mm², which were submitted to μTBS testing immediately or after 3 months of storage in artificial saliva at 37°C. Nanoleakage was assessed using SEM/EDS, and the interaction between dentin and H₃PO₄ or HEMA-P was evaluated by combining micro-Raman and FT-IR spectroscopy. The data were analyzed using two-way ANOVA and Tukey's HSD post-hoc test (α = 0.05). Results: HP presented significantly higher μTBS than PA at both times (p 0.05). Both treatments maintained μTBS stability after 3 months of artificial saliva storage (p > 0.005). At both times, PA presented higher nanoleakage than HP (p 0.05). Conclusions: Both dentin treatments maintained μTBS stability after 3 months of artificial saliva storage. The use of HEMA-P was associated with less nanoleakage than was traditional phosphoric-acid etching. Keywords: dentin bonding, dentin treatment, HEMA phosphate, microtensile bond strength, nanoleakage

Purpose: To investigate the effects of a novel tribochemical silica coating technique with powders made from feldspathic ceramic and leucite-based ceramic on the bond strength of zirconia to resin cement before and after aging. Materials and Methods: Zirconia blocks were divided into 3 groups according to the material used for airborne-particle abrasion: 1) SP (control): silica-coated alumina particles; 2) FP: feldspathic ceramic powder; 3) LP: leucite glass-ceramic powder. After silanization, composite resin cylinders were cemented on the zirconia surface using a dual-curing resin cement. Prior to the shear bond strength (SBS) test, half of the samples (n = 15) were stored in distilled water for 24 h; the other half (n = 15) were submitted to aging (10,000 thermocycles of 5°C to 55°C; 150 days of water storage). The bond strength data were analyzed using two-way ANOVA and Tukey's test (α = 0.05). Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and x-ray diffraction analysis were performed. Results: The initial bond strengths did not differ significantly between the groups (p = 0.053). However, after aging procedures, airborne-particle abrasion with feldspathic ceramic powder (FP) resulted in higher values of bond strength (p = 0.0001). SEM and EDS indicated that all the treatments promoted silica deposition on the Y-TZP surface ceramic. Airborne-particle abrasion with FP and LP induced a lower percentage of the monoclinic phase. Conclusion: Airborne abrasion with fine feldspathic ceramic particles is a novel tribochemical technique and appears to be suitable for improving the bond strength between zirconia and resin cements. Keywords: tribochemical silica coating, zirconia surface treatment, silica deposition, glass ceramic, topography alteration

Purpose: To evaluate whether the etch-and-rinse or self-etching mode of a universal adhesive is the best protocol to optimize bond strength to primary and permanent artificially-induced caries-affected dentin. Materials and Methods: Flat midcoronal dentin surfaces were exposed in 24 primary and 24 permanent molars and submitted to pH cycling for 14 days to induce artificial caries-affected dentin. For each tooth type (primary and permanent), the teeth were randomly assigned to 4 different groups according to the adhesive systems and bonding strategy: a universal adhesive, Scotchbond Universal Adhesive, in self-etching and etch-and-rinse modes; a twostep etch-and-rinse adhesive, Adper Single Bond 2 (control); and two-step self-etching system, Clearfil SE Bond (control). After bonding and restorative procedures, specimens were sectioned to obtain rectangular sticks (0.8 mm2) that were submitted to microtensile tests (crosshead speed: 1 mm/min). The data were analyzed using two-way ANOVA (α = 0.05). Results: The universal adhesive showed bond strengths similar to those of the control groups, irrespective of the bonding strategy. Likewise, statistically similar bonding performance was observed for all adhesives to either artificially- induced caries-affected primary or permanent dentin. Conclusion: The new universal adhesive, Scotchbond Universal Adhesive, can be used in both application modes in artificially-induced caries-affected primary and permanent dentin, as the bond strength was not influenced by the different substrates or application mode. Keywords: caries-affected dentin, artificial caries, microtensile, bond strength, universal adhesives

Purpose: To examine the influence of different adhesive restoration protocols on the survival of composite resin restorations in primary teeth. Materials and Methods: This study included 601 patients at risk of caries (319 males and 282 females), with a mean age of 6.6 years (range: 1 to 13 years) and an average need for 3.6 restorations per patient (range: 1 to 20). The mean observation period was 1.3 years (± 1.4), with a maximum of 7 years. Six different adhesive restoration protocols with respect to etching, adhesives, and composite materials were analyzed. The statistical analyses included descriptive analyses and a Cox regression model from which hazard ratios (HR with 95% CI) for protocols and possible predictors were calculated. Results: The mean dmft was 6.6 (± 4.0), which indicates a high risk population. Secondary caries was the most frequent reason for loss of restoration in this study (52.2%). Out of 2146 restorations, 368 failed; the mean annual failure rate was 13.2%. Adhesive restoration protocols that employed a self-etching system performed significantly better (HR range: 1.0 to 1.8) than did the etch-and-rinse system (HR range: 1.8 to 2.8). Protocols using only flowable materials had a moderately increased probability of failure. Conclusion: With respect to the practice-based study design, young age, and high risk of caries in this population, comparatively high failure rates were observed for direct composite restorations in primary dentition, but adhesive restoration protocols using self-etching adhesives in combination with universal composites yielded a higher probability of survival. Keywords: retrospective, composite resin, adhesive restoration protocol, restoration, longevity, deciduous dentition