Based on the results of this study, Er, Cr: YSGG laser was confirmed to be as effective as air-abrasion for laboratory composite repair.

This study compared the effects of two mechanical surface preparation techniques, air abrasion and Nd:YAG laser, with the use of two adhesive systems, self-etch and etch and rinse, on the repair bond strengths of an indirect composite resin. One hundred fifty cylindrical samples of an indirect composite resin were prepared and randomly divided into six groups (n = 25). In groups 1-3, the composite resin surfaces were respectively prepared as follows: no roughening, roughening by air abrasion, and roughening by Nd:YAG laser, followed by application of an etch-and-rinse adhesive. In groups 4-6, the preparation techniques were respectively the same as those in groups 1-3, followed by application of a self-etch adhesive. Subsequently, a direct composite resin was added and repair bond strengths were measured. Data were analyzed with two-way ANOVA and post hoc Tukey's test. Mean bond strength value was significant based on the preparation technique (P < 0.001), i.e., in air abrasion and Nd:YAG laser groups, bond strengths were significantly higher compared to no-preparation groups (P < 0.0005). There were significant differences in bond strength values between air abrasion and Nd:YAG laser groups, with significantly higher values in air abrasion groups (P < 0.0005). However, there were no significant differences in bond strength values between the adhesive systems. Furthermore, the cumulative effects of the adhesive system and the surface preparation technique were not significant. Surface preparation of the indirect composite resin with air abrasion and Nd:YAG laser resulted in a significant increase in the repair bond strength, with air abrasion being more effective. There were no significant differences in bond strength between the two adhesives.

The weak link in the adhesive luting of fiber posts to root canal dentin is at the cement-dentin interface. The aim of the present study was to evaluate the effect of Er,Cr:YSGG laser irradiation on push-out bond strength of fiber posts cemented to root canal dentin using a self-adhesive cement. A total of 30 sound human maxillary central incisors were equally divided into two groups after root canal treatment, decoronation and preparation of the post space. Teeth of group 1 were treated with the Er,Cr:YSGG laser, and teeth of group 2 (control) received no laser treatment. After cementation of fiber posts with Maxcem self-adhesive cement, 3-mm cervical, middle and apical sections were prepared from the roots. Then a push-out test was performed using a universal testing machine at a strain rate of 0.5 mm/min. Data were analyzed using two-way ANOVA and the Bonferroni test. Statistical significance was defined as P < 0.05. There was a significant difference in the mean bond strength values between groups 1 and 2 (P = 0.001), but there were no significant differences between the various root parts (P = 0.14). In addition, the cumulative effects of dentin treatment type and various root parts were not statistically significant (P = 0.41). The mean bond strength in the laser group was significantly higher than in the control group (P = 0.001, post hoc Bonferroni test).The failure mode was evaluated under a stereomicroscope at × 20 magnification.

Success in sandwich technique procedures can be achieved through an acceptable bond between the materials. The aim of this study was to compare the effect of 35% phosphoric acid and Er,Cr:YSGG laser on shear bond strength of conventional glass-ionomer cement (GIC) and resin-modified glass-ionomer cement (RMGIC) to composite resin in sandwich technique. Sixty-six specimens were prepared from each type of glass-ionomer cements and divided into three treatment groups as follows: without pretreatment, acid etching by 35% phosphoric acid for 15 s, and 1-W Er,Cr:YSGG laser treatment for 15 s with a 600-μm-diameter tip aligned perpendicular to the target area at a distance of 1 mm from the surface. Energy density of laser irradiation was 17.7 J/cm(2). Two specimens in each group were prepared for evaluation under a scanning electron microscope (SEM) after surface treatment and the remainder underwent bonding procedure with a bonding agent and composite resin. Then the shear bond strength was measured at a crosshead speed of 0.5 mm/min. Two-factor analysis of variance and post-hoc Tukey test showed that the cement type, surface treatment method, and the interaction of these two factors significantly affect the shear bond strength between glass-ionomer cements and composite resin (p < 0.05). Surface treatment with phosphoric acid or Er,Cr:YSGG laser increased the shear bond strength of GIC to composite resin; however, in RMGIC only laser etching resulted in significantly higher bond strength. These findings were supported by SEM results. The fracture mode was evaluated under a stereomicroscope at ×20.

The bacteria in mature and old biofilms were more resistant to 1% NaOCl than were the bacteria in young biofilms. Overall survival and residual bacteria increase with biofilm aging. PDT and the 2.5% NaOCl solution were equally efficient in completely eliminating E. faecalis biofilms at all three stages.