Repair bond strength and surface topography of resin-ceramic and ceramic restorative blocks treated by laser and conventional surface treatments

Abstract

This study intended to compare the repair bond strength of computer-aided design/computer-aided manufacturing (CAD/CAM) blocks consisting of resin and feldspathic ceramics following different surface treatments using the microtensile bond strength (mu TBS) test. Ten specimens were prepared with 4 mm height for Vita Enamic (VE), Lava Ultimate (LU), Vita Mark II (VM), and thermocycled (10,000 cycle, 5-55 degrees C). Each material was categorized into one of five subgroups according to following surface treatments: (a) bur grinding (BG), (b) hydrofluoric acid etching (HF), (c) neodymium-doped yttrium aluminum garnet (Nd:YAG or NY), (d) erbium-doped yttrium aluminum garnet (Er:YAG or EY), and (e) erbium, chromium-doped yttrium, scandium, gallium, and garnet (Er,Cr:YSGG or ECY) laser conditioning. After surface treatment procedures, specimens were properly restored to 4 mm high with a micro-hybrid composite resin. Bar specimens (1 x 1 x 8 mm) were obtained using a low-speed cutting machine and then thermocycled (10,000 cycle, 5-55 degrees C). The mu TBS was tested at 1 mm/min crosshead speed, and failure modes were evaluated. Data were analyzed with two-way ANOVA and post hoc Tukey tests. LU-BG showed significantly higher mu TBS (32.94 +/- 5.80 MPa) compared to LU-laser groups (p < .05). VE-BG showed significantly higher mu TBS (22.06 +/- 4.26 MPa) compared to other VE groups (p < .05). Among the laser groups, the NY laser produced the lowest (p < .05) mu TBS for LU (13.42 +/- 3.44 MPa) and VE (2.27 +/- 0.85 MPa), while EY showed the highest (p < .05). Laser-treated VM groups were all prefailured. VM-HF produced a higher mu TBS (18.73 +/- 3.75 MPa) than VM-BG (5.05 +/- 1.76 MPa) (p < .05).