The influence of three different Erbium:YAG pulse energies on the microleakage of Class V compomer restorations

Summary. Objectives. To investigate the influence of three Erbium:YAG pulse energies (200 mJ, 240 mJ, and 300 mJ with a 100 mJ dentine finish) on the microleakage of Class V compomer restorations (Compoglass). Design. In vitro study Sample and methods. Sixty-one extracted human premolar teeth were randomly allocated to three groups (according to pulse energy). Each tooth hosted one test cavity prepared with one of the three Er:YAG pulse energies using a pulse repetition rate of 5 Hz and a pulse duration of 250 s, and one control cavity prepared with a conventional diamond bur in a high-speed hand piece. Both cavities were placed at the cervical margin of the tooth and were restored and finished according to the manufacturer’s instructions. Each tooth was then stored in 0·12% thymol solution at 37 °C for three months, before being thermocycled through water baths between 5 °C and 55 °C for 240 cycles. Microleakage was assessed using a methylene blue dye penetration technique and was quantified using a score 0 (none) to 4 (to and into the axial wall). The data was analysed using the Kruskal–Wallis and Mann–Whitney U-tests. Results. Leakage was seen in all groups at both the dentine and enamel margins. There were no statistically significant differences in leakage (P < 0·05) at either the enamel or dentine margins, except for the 240 mJ lased enamel margins. This group performed significantly better than the enamel margins prepared with 200 mJ (P = 0·03) and the 300/100 mJ (P = 0·01) laser energies as well as the conventionally prepared enamel margins (P < 0·001). Conclusion. Cavity preparation with this Erbium:YAG laser did not influence the microleakage of Compoglass restorations adversely. Different pulse energies were required for optimum cavity sealing at the enamel and dentine margins and for different materials