“Efficiency of Er, Cr:YSGG laser in laminate veneers debonding on two ceramic materials and resin cement” -An in vitro study-

Abstract

This study was designed to show the proficiency of using Er,Cr:YSGG laser in debonding of laminate veneers of two types of glass ceramics (IPS EMAX and VITA MARK II), which were cemented using resin cements with different curing modes and its effect on the shear bond strength of rebonded ceramic discs. Materials and methods: specimens were divided into two groups according to the glass ceramic material and then were further divided into two subgroups according to the cement-curing mode (light and dual cured resin) then finally each subgroup was finally subdivided into two subdivisions according to applied tests. The specimens were cut with dimension 10×10 mm and thickness 0.7 mm each using electric saw Isomet 4000 then were cemented on bovine teeth after surface preparation of both tooth and ceramic discs following manufacture instructions for bonding protocol, standardization of the tooth preparation was done by customized paralleling device, each bovine tooth was fixed in acrylic resin blocks which were color coded ; Pink acrylic for IPS Emax cemented by light cured resin cement and translucent for IPS Emax cemented by dual cured resin cement and green for VITA MARK II cemented by light cured resin cement and A2 shaded acrylic for VITA MARK II cemented by dual cured resin cement, After the cementation procedure, the specimens were stored in distilled water at 37 °C for 24 h to mimic intraoral situation. Then Laser beam was applied of wavelength 2780 nm using the following settings for each group: Power 4.5 W, repetition rate 20 Hz, Hand piece turbo (MX7), pulse duration (60µs) H mode Non-Contact mode 5 mm away, which has been established by a custom made stopper . Then, the specimens were evaluated with SEM 10,000x and 20,000x after being debonded and the mode of failure as well with SEM 500x.