Clinical performance and wear resistance of milled resin composite material versus direct nanohybrid bulk-fill resin composite in the restoration of endodontically treated posterior teeth over 1 year: Randomized clinical trial.

Context: The restorative complexities associated with endodontically treated teeth surpass those encountered with vital ones. The field of adhesive dentistry experienced a significant advancement that led to a shift in treatment approach toward bonded restorations. Aim: The aim of the study was to assess the clinical performance of using indirect Milled composite or direct bulk-fill resin composite restorations for endo-treated teeth, as well as to measure the amount of wear on the occlusal tables of both restorations using a digital scanner. Subjects and Methods: Participants were divided into two groups, where R1 represents the endodontically treated teeth restored with Milled composite, R2 represents the endodontically treated teeth restored with direct bulk-fill composite where 13 patients in each group were treated with a total number of 26 restorations in all patients. Where each restoration was assessed immediately at baseline (T0), 6 months (T6), and 12 months (T12) using the modified United States Public Health Service criteria. Moreover, wear was measured immediately at (T0) and (T12) intraorally and extraorally using intraoral scanners and three-dimensional surface-based superimposition software. Statistical Analysis Used: Chi-squared test, Mann-Whitney U-test, Friedman's test, Nemenyi post hoc test, Shapiro-Wilk test, paired t-tests, intraclass correlation coefficient. Results: At all intervals, the majority of the cases in both groups had an alpha score. Some cases exhibited bravo scores in both groups at T6 and T12 regarding the color match, marginal adaptation, marginal discoloration, and marginal integrity without statistically significant difference (P > 0.05). Direct nanohybrid bulk-fill resin composite showed a greater amount of wear without a statistically significant difference (P > 0.05). Extraoral measurement was significantly higher than intraoral measurement (P < 0.001). There was no significant reliability/agreement between both methods. Conclusions: Both milled composite and direct bulk-fill resin composite restorations in endodontically treated teeth demonstrated appropriate clinical performance and minimal wear over an 1-year follow-up period.

Bond efficacy and interface morphology of self-etching adhesives to ground enamel.

PURPOSE: This study compared the microshear bond strengths to ground enamel of three one-step self-etching adhesive systems, a self-etching primer system and an etch-and-rinse adhesive system. MATERIALS AND METHODS: Three self-etching adhesives, Futurabond DC (Voco), Clearfil S Tri Bond (Kuraray) and Hybrid bond (Sun-Medical), a self-etching primer, Clearfil SE Bond (Kuraray), and an etch-and-rinse system, Admira Bond (Voco), were selected. Thirty human molars were used. The root of each tooth was removed and the crown was sectioned into halves. The convex enamel surfaces were reduced by polishing on silicone paper to prepare a flat surface. The bonding systems were applied on this surface. Prior to adhesive curing, a hollow cylinder (2.0 mm height/0.75 mm internal diameter) was placed on the treated surfaces. A resin composite was then inserted into the tube and cured. After water storage for 24 h, the tube was removed and shear bond strength was determined in a universal testing machine at a crosshead speed of 0.5 mm/min. The results were analyzed with ANOVA and the Tukey.-Kramer test at a 59 degrees confidence level. The enamel of five additional teeth was ground, and the etching component of each adhesive was applied and removed with absolute ethanol instead of being light cured. These teeth and selected fractured surfaces were examined by SEM. RESULTS: Adhesion to ground enamel of the Futurabond DC (25 +/- 3.5 MPa) and Clearfil SE Bond (23 +/- 2.9 MPa) self-etching systems was not significantly different from the etch-and-rinse system Admira Bond (27 +/- 2.3 MPa). The two self-etching adhesives Clearfil S Tri bond and Hybrid Bond demonstrated significantly lower bond strengths (14 +/- 1.4 MPa; 11 +/- 1.9 MPa) with no significant differences between them (p < 0.05). CONCLUSION: Bond strengths to ground enamel of self-etching adhesive systems are dependent on the type of adhesive system. Some of the new adhesive systems showed bond strength values comparable to that of etch-and-rinse systems. There was no correlation between bond strength and morphological changes in enamel.

Effect of conditioning time of self-etching primers on dentin bond strength of three adhesive resin cements.

OBJECTIVES: To evaluate the effect of increasing the dentin conditioning time with self-etching primers of different aggressiveness (pH) on the microtensile bond strength (muTBS) of three resin cements. MATERIALS AND METHODS: Pre-cured composite blocks were cemented with M-Bond, Bistite II DC, or Panavia F to flat occlusal dentin surfaces of human third molars, which were conditioned with M-Bond or Bistite II-primer for 30, 60 or 180 s or with Panavia-primer for 60 or 180 s. Each dentin-composite block assembly (four in each group) was longitudinally sectioned to obtain 1x1 mm microbars and tested for the muTBS. The morphology of the conditioned dentin surface and the hybrid layer was examined with SEM. RESULTS: Extending the primer conditioning time for Bistite II DC from 30 to 60 s significantly increased the muTBS (p<0.001) but did not further increase from 60 s to 180 s. For M-Bond there was only a significant increase from 30 to 180 s (p<0.05). For Panavia F the primer-conditioning time had no influence on the muTBS. SEM observations of conditioned dentin showed that the Bistite II DC and M-Bond self-etching primers with the lowest pH completely dissolved the dentin smear layer and plugs and formed well-defined hybrid layers. This was not found for Panavia F. SIGNIFICANCE: Dentin bond strength of resin cements using more aggressive self-etching primers is improved by increasing the conditioning time. To enable resin infiltration of highly filled resin cements, sufficient smear layer dissolution is necessary.

Microtensile bond strength testing of luting cements to prefabricated CAD/CAM ceramic and composite blocks.

OBJECTIVES: To investigate the Microtensile bond strength (microTBS) and failure mode of resin cements bonded to composite and ceramic CAD/CAM blocks following various surface treatments. METHODS: Paradigm composite blocks and Cerec Vitablocs received three surface treatments following the control treatment of surface grinding with 600 SiC grit. (1) Application of adhesive resin (Adh), (2) etching with hydrofluoric acid and silanization (HF+S) or (3) combination of the previous two treatments (HF+S+Adh). Three resin cements (Tetric Flow, Nexus 2, RelyX ARC) were applied to these surfaces and built-up in layers. After 24 h water storage at 37 degrees C, the non-trimming version of microTBS test was used to produce 1 mm(2) microbars. The Microbars were subjected to a tensile load using a modified testing device. The broken specimens were examined with a stereomicroscope and SEM to determine the failure mode. RESULTS: All control and adhesive treated groups of the ceramic substrate showed premature debonding during cutting. The overall mean microTBS for the three resin cements bonded to ceramic following HF+S and HF+S+Adh surface treatment, was 27 and 29.2 MPa and for the resin cements bonded to composite substrate was 42.3 and 54.2 MPa, respectively. The mode of failure was 98% adhesive with composite as a substrate and 68% mixed failures with ceramic as a substrate. CLINICAL SIGNIFICANCE: CAD/CAM restorations fabricated from processed composite blocks may have advantage over the ceramic blocks with regard to the higher bond strength with resin cements.