Nd:YAG laser influence on tensile bond strength of self-etching adhesive systems.

OBJECTIVE: We evaluated the tensile bond strength of composite resin on enamel and dentine, treated with Nd:YAG laser before and after bonding procedures. BACKGROUND DATA: The use of laser radiation in dentistry is being developed day by day. One of the possible applications of dental lasers includes increasing the quality of self-etching bonding systems. METHODS: Forty-eight human teeth were used and separated into six groups: Group 1 (enamel control), Clearfil Liner Bond 2V (CLB 2V); group 2 (enamel), Nd:YAG + CLB 2V; group 3 (enamel), CLB 2V + Nd:YAG; group 4 (dentine control), CLB 2V; group 5 (dentine), Nd:YAG + CLB 2V; group 6 (dentine), CLB 2V + Nd:YAG. Tensile bond strength was performed. RESULTS: Enamel means (15,54) were lower than dentine means (20,38). Bond strength of laser before (15,73) was lower than laser after (20,65). Interaction results G1 x G3; G2 x G3; G4 x G1; G2 x G5 were statistically significant. CONCLUSIONS: Tensile bond strength of composites reached with self-etching adhesive systems were greater in dentine than in enamel. The best moment for application of Nd:YAG laser is after the use of adhesive system. Self-etching adhesive systems tested in this study can be used together with Nd:YAG laser without compromising to adhesion to dentine.

Nd:YAG laser effects on the microleakage of composite resin restorations.

OBJECTIVE: This study evaluated microleakage of composite restorations submitted to marginal treatment with Nd:YAG laser and surface sealant. BACKGROUND DATA: Previous studies have demonstrated that Nd:YAG-lased enamel melted and became recrystallized with a morphologic appearance similar to lava, and has been used clinically in the sealing of enamel pits and fissures. METHODS: Class V cavities in enamel of human premolars were restored with composite resin (Z100, 3M) and randomly divided in six groups: G1, control; G2, surface sealant marginal treatment; G3 to G6, were treated with pulsed Nd:YAG laser (1.064 microm) marginal treatment, contact fiberoptic (300 microm), air cooling, for 30 seconds, powers of 1.2-2 W, repetition rates of 20-30 Hz, energies of 40-100 mJ. Teeth were impermeabilized, immersed in a rhodamine dye, sectioned, and evaluated under stereomicroscope microscopy with scores. RESULTS: There were significant differences between marginal treatments; there were no differences between groups 1, 2, and 4, and 3,5, and 6; lower values of microleakage were at groups 3, 5, and 6 (Kruskal-Wallis,p = 0.05). CONCLUSION: Nd:YAG laser showed improved marginal sealing and decreased microleakage of composite resins restorations.