J Oral Laser Applications 8 (2008), No. 3 (28.10.2008)
Assessment of the Ability of Er:YAG Laser to Remove Composite Resin Restorations
Correa-Afonso, Alessandra M. / Delfino, Carina Silncler / da Silva, Reginaldo S. / Palma-Dibb, Regina G. / Pécora, Jesus Djalma
Purpose: The purpose of this study was to assess in vitro Er:YAG laser efficacy for composite resin removal, as well as the thermal alterations occurring during laser irradiation.
Materials and Methods: Cavity preparations (1.0 mm deep) in bovine teeth were restored with resin and divided into 2 groups: the control group, in which restorations were removed with a high-speed bur, and the experimental group, in which restorations were removed with Er:YAG laser at 250 mJ output energy, 80 J/cm2 energy density, and 6 Hz pulse repetition rate. The removal time was measured and the temperature alteration was checked. After the removal, the specimens were split in the middle, and the surrounding and deep walls were analyzed to check for the presence of restorative material.
Results: The results revealed that the temperature rise during composite resin removal in both groups occurred on the substrate underneath the restoration. Although the temperature rose during composite filling removal, none of the groups presented a temperature increase higher than 5.6°C, which is considered the critical temperature increase above which there may be irreversible thermal damage to the pulp. Regarding the time for composite filling removal, it was observed that the laser group required more time than the control group for complete elimination of the material from the cavity walls.
Conclusion: Although there was a greater temperature increase during composite resin removal with Er:YAG, it did not reach the critical temperature value above which there may be irreversible thermal damage to the pulp.
Keywords: ablation, Er:YAG laser, composite resins, temperature, time, efficacy