Objective:The shear bond strength of adhesives applied to dentin was investigated after irradiation with an erbium-doped yttrium aluminum garnet (Er:YAG) laser.Methods:Superficial and deep dentin specimens from human molars were treated either with carbide bur or an Er:YAG laser. Two etch and rinse adhesives (Single Bond and XP Bond) and two self-etch adhesives (Prompt L-Pop and Xeno III) were employed to bond the composite. Shear bond strength (SBS) was determined after storage in water for 24 h using a universal testing machine with a crosshead speed of 0.5 mm/min. Failure patterns and modes were analyzed and evaluated using a stereomicroscope. In addition, samples were processed for Scanning Electron Microscopy SEM evaluation. A linear mixed model was used, and pairwise comparisons were made using the Bonferroni test.Results:Results showed significant differences between the levels of dentin treatment (p=.01) in carbide bur-cut dentin and lased dentin, as well as significant interaction effects due to the depth of dentin and the bonding system used. The etch and rinse adhesives bonded less effectively with lased dentin than with carbide bur-cut dentin, while self-etch adhesives bonded equally well with lased and bur-cut superficial dentin but much less effectively with lased deep dentin than with bur-cut deep dentin. SEM revealed a predominantly adhesive failure mode in laser-ablated fractured specimens, while a mixed failure mode was apparent in the bur-cut fractured specimens.Conclusions:Cavities prepared by laser seem less receptive to adhesive procedures than conventional bur-cut cavities.

Aim: To compare the shear bond strength (SBS) of a solvent free self-etch adhesive with solvent containing adhesives. Methods: Forty-five human teeth were sectioned longitudinally to expose superficial dentin and substrates polished with 600-grit SiC paper. The adhesive area was isolated with a cylindrical Teflon mold 3x4 mm. Fifteen specimens were prepared for each material. Were evaluated a solvent free self-etch adhesive (Bond 1 SF), an ethanol self-etch adhesive (Futurabond M), and a water-acetone-ethanol self-etch adhesive (Optibond All-In-One). All specimens were subjected to an aging procedure by thermo-cycling (5000 cycles). Thirty-six specimens were stressed in shear at a rate of 0.5mm/min. Mean data values were analyzed statistically using the Welch robust analysis of variance and the Games-Howell statistic. Failure patterns were analyzed using stereomicroscope and scanning electron microscopy (SEM). Additional more dentin specimens were prepared for SEM. Results: The Bond 1 SF showed the statistically significant lowest SBS to dentin (Welch statistic p<0.001). Failures for Bond 1 SF were mainly adhesive failures with partial cohesive failures in the adhesive resin, while for Futurabond M and Optibond All-In-One were mainly mixed. SEM findings confirm the results. Conclusions: Eliminating solvents from self-etch adhesive systems may decrease the bonding strength to dentin.

Objective:The objective was to investigate the way that various surface treatments could influence the bond strength of the repair of methacrylate (MC) and silorane (SIL) composites.Materials and Methods:A total of 160 MC and SIL cylindrical specimens were polymerized and aged in artificial saliva solution for 7 days. Depending on the following surface treatment (diamond bur or air abrasion), and the conditioning procedure (orthophosphoric acid or sodium hypochlorite), 16 groups were formed and repaired either with MC, either with SIL composite. Repaired specimens were subjected to an additional aging procedure in artificial saliva for 7 days, followed by thermo-cycling and then stressed in shear at a rate of 0.5 mm/min until failure. Failure patterns were analyzed using stereomicroscope and scanning electron microscopy.Results:MC composite showed statistically significant higher bond strength both as a base or repair material than SIL (P < 0.001). Statistically significant differences were not observed, when grinding and conditioning procedures was compared. Pretest failures were observed when aged MC-based composite was repaired with SIL-based.Conclusions:Type of composite seems to be the main factor influencing the bond strength of the repair. MC-based composite showed better repairability than SIL composite. Optimum repair conditions should include knowledge of the composite's composition.

SUMMARY Aims: To evaluate the effect of two composite restorative techniques (direct bulk fill vs indirect CAD/CAM) on the fracture resistance and mode of fracture of extended mesio-occlusal-distal (MOD) cavity preparations. Methods: Fifty-one sound human mandibular third molars were divided into three groups (n=17). Extended bucco-lingual MOD cavities were prepared. Teeth in group 1 were restored with a bulk-fill resin composite (Filtek Bulk-Fill Posterior Restorative), teeth in group 2 were restored with composite computer-aided design/computer-aided manufacturing (CAD/CAM) inlays (Lava Ultimate), and teeth in group 3 served as control and remained intact. All specimens were submitted to thermocycling, and a fracture resistance test was performed using a Universal testing machine (0.5 mm/min). Mode of fracture was classified into five types. One-way analysis of variance and the Duncan test were used to analyze the fracture load data at a significance level of α = 0.05. A chi-square test was used for the analysis of fracture mode between the restorative groups. Results: Statistical analysis showed significant differences in fracture resistance among the experimental groups. The teeth restored with the bulk-fill composite exhibited lower fracture resistance (1285.3±655.0 N) when compared to the teeth restored with the composite CAD/CAM inlays (1869.8±529.4 N) (p&lt;0.05). Mode of fracture showed the same distribution between the restorative groups. Conclusions: Although both types of restorations failed at loads larger than those found in the oral cavity, the CAD/CAM composite inlays increased the fracture resistance of teeth with large MOD cavities when compared to direct bulk-fill composite restorations. The majority of fracture types were intraorally repairable for both restorative techniques.

Evaluation of photopolymerization efficacy and temperature rise of a composite resin using a blue diode laser (445 nm).