Influence of pulse duration when performing Er:YAG laser irradiation on dental tissues.

PURPOSE: To evaluate the marginal adaptation of mixed Class V composite restorations in cavities prepared with the Quantum Square Pulse (QSP) mode Er:YAG laser, compared to Super Short Pulse (SSP) and diamond bur. The impact of Er:YAG laser finishing with low pulse energy and two irradiation distances was also evaluated. METHODS: Class V cavities were prepared in enamel and dentin by varying the above parameters, and then restored with Clearfil SE Bond and Clearfil AP-X composite under dentin fluid simulation. The control groups were prepared and finished using conventional diamond burs (80 and 25 microm respectively). Scanning electron microscope (SEM) marginal adaptation analysis at x200 magnification was performed on replicas before and after thermo-mechanical cyclic loading in order to determine the percentage of continuous margins (i.e. from 0 to 100% of gap free margins). The differences between groups were analyzed with one-way ANOVA and Duncan post hoc test. RESULTS: Dentin treated with SSP showed significantly lower percentages of "continuous margin" than the QSP and control groups. QSP was as effective as bur preparation. CLINICAL SIGNIFICANCE: The preparation and finishing protocol may no longer be necessary when using the QSP mode, reducing clinical time without compromising marginal adaptation.