Er:YAG Laser in QSP Modality for Treatment of Indirect Adhesive Restoration Build-Up: Surface Roughness Analysis and Morphology Assessment by Environmental Scanning Electron Microscopy (ESEM).

Abstract

Background/Objectives: Sandblasting build-ups before applying the acid and adhesive significantly improves the bond strength. The aim of this study is to evaluate, for the first time, the effectiveness of an Er:YAG laser used in QSP mode to treat the surface of build-ups before the adhesive cementation sequence. Methods: This ex vivo study was conducted on 12 intact, undecayed extracted teeth kept hydrated in NaCl 0.9% solution. A cavity was created in the center and reconstructed with composite resin (build-up). Then, samples were prepared with burs and divided into three groups: control group G1, prepared only with burs; group G2, in which surfaces were treated with a sandblaster (2.5 bar, 10 mm from composite surface, aluminum oxide, 10 s); and group G3, treated using an Er:YAG laser (QSP modality, 1 W, 10 Hz, 100 mJ). The surface roughness of the build-ups was measured using a CCI MP-L digital optical profiler (Taylor Hobson, Leicester, UK), and surface morphology was studied using the Quanta™ 250 FEG (FEI, Hillsboro, OR, USA) ESEM instrument. Results: Regarding enamel, mean surface roughness in G1 vs. G2 was not statistically significant (p = 0.968); meanwhile, differences between the Er:YAG laser group (G3) and G1 or G2 were significant (G3 vs. G1 p < 0.001; G3 vs. G2 p < 0.001). Regarding dentin, G1 vs. G2 was significant (p = 0.021); differences between G3 and G1 or G2 were extremely significant (G3 vs. G1 p < 0.001; G3 vs. G2 p < 0.001). The same trend was detected for resin. Conclusions: An Er:YAG laser in QSP mode used on the build-up surface for indirect adhesive restorations is innovative and should be investigated with further studies. However, it seems extremely effective with increased roughness, the absence of a smear layer and characteristics potentially favorable for good adhesion for all substrates (enamel, dentin, resin).