Composite Resin Restoration Microleakage Following Laser Conditioning and Acid Etching

Objectives: The use of laser for cavity preparation or conditioning of dentin and enamel surfaces as a replacement for acid-etch preparations has been increased in recent years. The aim of this in vitro study was to compare microleakage at enamel/composite and dentin/composite interfaces following Er:YAG laser conditioning or acid-etch preparation surfaces, hybridized with different bonding systems.

Methods:

Class V cavities were prepared on the lingual and buccal surfaces of 50 extracted intact human posterior teeth using diamond drill. The cavities were randomly assigned to five groups: Group 1: Conditioned with laser (Energy=120mJ, Frequency=10Hz, Pulse duration=100ms for enamel and Energy=80mJ, Frequency=10Hz, Pulse duration=100ms for dentin) + Optibond FL; Group 2: Conditioned with laser + etching with 35% phosphoric acid + Optibond FL; Group 3: Conditioned with laser + Clearfil SE Bond; Group 4 (control): Acid etched with 35% phosphoric acid + Optibond FL; Group 5 (control): Only Clearfil SE Bond. All the cavities were restored using Point-4 composite resin. All samples were stored in distilled water at 37°C for 24 h, then were thermal cycled for 500 cycles and immersed in 50% silver nitrate solution for 24 h. The teeth sectioned bucco-lingually and then dye penetration was scored. Kruskal-Wallis & Mann-Whitney tests were used for statistical analyses.

Results: In occlusal margins, the least microleakage was found in groups 2, 4 and 5. The maximum microleakage was observed in group 3 (P = 0.009). In gingival margins, the least microleakage was observedd in group 2, while the most microleakage was found in group 5( P = 0.001). All the differences observed were statistically significant (P < 0.05). The microleakage scores were higher at the gingival margins. 

Conclusions: The use of the Er:YAG laser for conditioning with different dentin adhesive systems influenced the marginal sealing of composite resin restorations.