The efficiency of laser application for debonding laminate restorations manufactured of current CAD-CAM materials with different thicknesses.

BACKGROUND: Using lasers for adhesive restoration removal can be practical and atraumatic. AIMS: The purpose of this study was to investigate Er: YAG laser exposure on debonding the adhesive cementation between enamel and feldspar ceramic, lithium disilicate-reinforced and resin nano ceramic composite laminate restorations. MATERIALS AND METHODS: Vita Cerec Blocs, IPS e.max Computer-aided design (CAD). Computer-aided design and manufacturing (CAD-CAM) in full and Lava Ultimate restorative materials were chosen. The 3 × 3 mm2 standardized, 0.5-mm and 1 mm thick specimens were cemented on an enamel surface. After thermocycling, each material group was randomly divided into laser treated and control (non-laser treated) groups. Shear bond strength test was done with a universal testing machine with crosshead speed 0.5 mm/min. Factorial ANOVA Technique and TUKEY HSD multiple comparison test were used for statistical analyses. Moreover, the surface morphology of the debonded samples and the enamel was observed using a scanning electron microscope. RESULTS: The laser application was found to weaken the SBS values significantly (P < 0.05) for all groups; however, the most dramatic SBS decrease was observed for laser treated IPS e.max at both thicknesses. CONCLUSIONS: Laser treatment can serve as a practical and effective method that eliminates the risk the enamel damage and restoration fracture.

Surface Roughness of Ceramic-Resin Composites After Femtosecond Laser Irradiation, Sandblasting or Acid Etching and Their Bond Strength With and Without Silanization to a Resin Cement.

OBJECTIVES:: The aim of this study was to investigate the effects of femtosecond laser irradiation, sandblasting, or acid etching treatments on the surface roughness of ceramic-resin composites and also shear bond strength (SBS) with and without silanization to a resin cement. METHODS:: Samples of Vita Enamic (VE; Vita Zahnfabrik, Bad Säckingen, Germany) and Lava Ultimate (LU; 3M ESPE, Seefeld, Germany) were classified into control (no treatment), sandblasting, hydrofluoric acid, and femtosecond laser groups (n=30). Surface roughness was determined using two-dimensional contact profilometry. Surface topography was evaluated using a three-dimensional contact profilometer and a scanning electron microscope. Then groups were divided into two subgroups with similar surface roughness values, including control (C), control + silane (C-S), sandblasting (SB), sandblasting + silane (SB-S), hydrofluoric acid (HF), hydrofluoric acid + silane (HF-S), femtosecond laser (FS), and femtosecond laser + silane (FS-S) groups (n=15). Panavia F 2.0 resin cement was applied to the sample surfaces using an SDI SBS rig (SDI Limited, Bayswater, Australia). The SBS test was performed after water storage (24 h, 37°C) and thermocycles (2000 cycles, 5°C to 55°C), and failure modes were evaluated. RESULTS:: The highest surface roughness was observed in the FS group, and the highest SBS was observed in the FS-S group for both VE and LU ( p<0.001). Silanization improved the SBS of VE significantly ( p<0.001) in all surface treatments but did not improve that of LU except in the FS group ( p=0.004). There was a significantly moderate negative correlation in the VE/SB group ( p=0.012) and a moderate positive correlation in the VE/HF group ( p=0.049). CONCLUSIONS:: Femtosecond laser irradiation was found to be more effective than sandblasting or acid etching in increasing the surface roughness, and it was also the most effective surface treatment with silanization on the SBS of a resin cement to the ceramic-resin composites.