Effect ceramic type and mode of polymerization on degree conversion of resin cements used to lute full ceramic crowns by Raman spectroscopy

Abstract

There is a growing application of resin based cements in ceramic prostheses for exhibit superior aesthetic and biomechanical properties to conventional cements. This study aims to assess the degree conversion (DC) of four resin cements, one with photoactivated curing mode (ChoiceTM 2/Bisco Inc), with two dual-cure mode (DuolinkTM/Bisco Inc; VariolinkII®/Ivoclar-Vivadent) and a chemical polymerization mode cement (C & BTM / Bisco Inc), used for cementation of crowns made of ceramic. Will be used 42 humans premolars to be prepared to receive crowns made with two ceramic systems: Lithium Dissilicate ceramic (IPSeMaxPress/Ivoclar-Vivadent) and oxide Yttrium stabilized Zirconium ceramic (IPSeMaxZirCAD/Ivoclar-Vivadent) for the fabrication of copings, and a ceramic-based coverage as fluorapatite (IPS e.maxZirPresss / Ivoclar-Vivadent). For cementation, the teeth / crowns / cement will be divided randomly and the photo-activation of the dual-cure and physical cure cements will be made with two different protocols: photo-activation in the buccal, occlusal and lingual, with an exposure time of 40 seconds on each side and photo-activation only by occlusal for 60 seconds. The chemical cement will remain undisturbed for 15 minutes. After cementation, the specimens will be stored in deionized water in a greenhouse with temperature of 370C and sectioned after 7 days in three regions: cervical, in the center of the buccal and 2 mm below the occlusal surface. The degree of conversion will be determined by the technique of Micro-Raman spectroscopy along the cement line. (AU)