Is Conventional Resin Cement Adhesive Performance to Dentin Better Than Self-adhesive? A Systematic Review and Meta-Analysis of Laboratory Studies.

CLINICAL RELEVANCE: Conventional multistep resin cements presented higher adhesive performance to dentin than simplified self-adhesive cements, which is an important criterion for indirect restoration prognosis. SUMMARY: This study aimed to conduct a systematic review of the literature on laboratory studies assessing bonding performance to dentin of conventional and self-adhesive resin cements, in cementing indirect restorations. This review was reported according to the PRISMA Statement. Of a total of 518 studies, 36 were screened full text and reviewed according to exclusion criteria. Nineteen papers were included in the systematic review and meta-analyses, according to the following inclusion criteria: studies that evaluated the bond strength to dentin of indirect restorations cemented with dual conventional or self-adhesive resin cements and those that presented bond strength data in MPa as an outcome. Statistical analyses were conducted using Rev-Man 5.1. Comparisons were performed with random effects models at 5% significance level. A global analysis comparing conventional and self-adhesive cements and three subgroup analyses comparing immediate and long-term results were performed. Global analysis showed a difference between groups, with conventional resin cements presenting higher bond strength results than self-adhesive resin cements, in immediate and long-term time periods (both p=0.03). Immediate and longterm bond strength results were different for self-adhesive cements, favoring immediate bond strength (p=0.03), but immediate and long-term bond strength results for conventional resin cements were not different (p=0.06). Medium or high risk of bias was found in all studies. Conventional multistep resin cements showed superior overall adhesive performance compared with simplified self-adhesive resin cements when used to cement indirect restorations to dentin.

The Use of Composite Layering Technique to Mask a Discolored Background: Color Analysis of Masking Ability After Aging-Part II.

The aim of this study was to evaluate the effectiveness of the layering technique to mask a discolored background (C4) after one year of water aging. The technique was used with three resin composite restorative systems (IPS Empress Direct, Charisma Diamond, and Filtek Z350XT). Ninety 1.5-mm-thick specimens were divided into groups and subgroups according to the restorative system and resin composite shade combination used in the layering technique (enamel, body, and dentin). The color measurements were made by reflection spectrophotometer (SP60, EX-Rite) over the C4 substrate at two time points: after 24-hour water immersion (T0) and after one-year water aging (T1). The masking ability was evaluated by calculating the ΔE between an inherent color background and a C4 background at T0 and T1. CIELAB and CIEDE2000 formulas were used for comparative analysis between T0 and T1 color measurements. Analysis of variance and Turkey's post hoc test (a=0.05) were performed to analyze ΔEab and ΔE00 mean values. The Z350XT restorative system presented adequate masking ability in the combinations of 0.5 mm body + 1.0 mm dentin, 0.5 mm enamel + 1.0 mm dentin, and 1.5 mm dentin after 24-hour water immersion. The masking ability was affected negatively by water aging in most of the combinations. The IPS Empress Direct was the only system that remained stable after aging in the combinations of 0.5 mm enamel + 1.0 mm dentin and + 1.5 mm dentin (p=0.05 and p=0.47 for CIELAB; p=0.15 and p=0.51 for CIEDE2000), although it did not present adequate masking ability in both time points. None of the combinations of any system presented adequate masking ability after prolonged water aging.

Degradation of Multimode Adhesive System Bond Strength to Artificial Caries-Affected Dentin Due to Water Storage.

The purpose of this study was to evaluate the influence of water storage on bond strength of multimode adhesive systems to artificially induced caries-affected dentin. One hundred twelve sound bovine incisors were randomly assigned to 16 groups (n=7) according to the dentin condition (sound; SND, artificially induced caries-affected dentin; CAD, cariogenic challenge by pH cycling for 14 days); the adhesive system (SU, Scotchbond Universal Adhesive; AB, All-Bond Universal; PB, Prime & Bond Elect; SB, Adper Single Bond 2; and CS, Clearfil SE Bond), and the etching strategy (etch-and-rinse and self-etch). All adhesive systems were applied under manufacturer's instructions to flat dentin surfaces, and a composite block was built up on each dentin surface. After 24 hours of water storage, the specimens were sectioned into stick-shaped specimens (0.8 mm2) and submitted to a microtensile test immediately (24 hours) or after six months of water storage. Bond strength data (MPa) were analyzed using three-way repeated-measures analysis of variance and post hoc Tukey test (α=5%), considering each substrate separately (SND and CAD). The etching strategy did not influence the bond strength of multimode adhesives, irrespective of the dentin condition. Water storage only reduced significantly the bond strength to CAD. The degradation of bond strength due to water storage was more pronounced in CAD, regardless of the etching strategy.

The Use of Resin Composite Layering Technique to Mask Discolored Background: A CIELAB/CIEDE2000 Analysis.

The purpose of this study was to evaluate the ability of three resin composite systems to mask a severely discolored background by the application of a layering technique through CIELAB and CIEDE2000 analysis. Ninety 1.5-mm-thick disc specimens were produced from three different resin composite restoration systems: IPS Empress Direct (Ivoclar Vivadent), Charisma Diamond (Heraeus Kulzer), and Filtek Z350 XT (3M-ESPE). The specimens were divided into groups according to the restoration system and the resin composite shade combination used for the layering technique (enamel, body, and dentin shades). Color measurements were performed by a reflectance spectrophotometer (SP60, EX-Rite) against a C4 shade background and an inherent color background, which simulates a severely discolored background and a tooth surface with no discoloration, respectively. The total color difference between both color measurements was calculated by CIELAB (ΔE*ab) and CIEDE2000 (ΔE00) formulas. The mean ΔEab* and ΔE00 values were analyzed by analysis of variance (general linear models) and Tukey's post hoc tests (α=0.05). Three groups presented clinically acceptable color difference values (ΔE*≦3.46 and ΔE00≦2.25): 1.5 mm dentin, 1.0 mm dentin/0.5 mm body, and 1.0 mm dentin/0.5 mm enamel; ie, all the groups from the Z350 XT restoration system. The resin composite layering technique is an effective way to mask severely discolored backgrounds. The Filtek Z350 XT system was the only restoration system capable of masking the C4 background.

Color stability of a resin composite: Effect of the immersion method and surface treatments.

BACKGROUND: In vitro staining methods expose the entire specimen to staining solutions. In a real clinical situation, this is not observed, since one should consider that the bonded surface is not exposed to the oral environment. Theoretically, the clinical condition would be the best simulated if the specimens were exposed to staining solutions by partial immersion. AIMS: To evaluate if different immersion methods and surface treatments influence the color stability of resin-based specimens. METHODOLOGY: A stainless steel matrix was used to prepare 30 disc-shaped specimens that were randomly allocated in three groups: Without polishing, polishing with abrasive discs, and surface sealant. Half of the specimens were isolated to maintain only the upper surface exposed to staining (partial immersion) and the other half was totally immersed in coffee solution for 48 h (total immersion). The coordinates ΔE*, ΔL*, Δa*, Δb* were assessed by spectrophotometer. STATISTICAL ANALYSIS: Two-way ANOVA and Tukey's post hoc tests (α =0.05). RESULTS: Specimens submitted to partial immersion showed lower values of ΔE*, ΔL*, Δa*, Δb*, in comparison to total immersion (P = 0.000). Specimens covered by a surface sealant presented lower ΔE* values regardless of the immersion method. CONCLUSIONS: Specimens totally immersed in staining solutions could in somehow overestimate the color change, once that in most clinical conditions not all of the restoration surfaces are exposed to the oral environment. Moreover, as the surface sealant application produces color change values that are clinically acceptable, it might be used in esthetic restorations as an adjunct treatment.