Optical characteristics of lithium disilicate ceramics to CAD / CAM submitted to different clinical polishing protocols and after cycles of thermal fatigue without and with repolishing

• Grant number: 17/25840-2
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): February 01, 2018
• Effective date (End): January 31, 2019
• Field of knowledge: Health Sciences - Dentistry - Dental Materials
• Principal Investigator: Aldiéris Alves Pesqueira
• Grantee: Júlia Nakazoni Rinaldi
• Host Institution: Faculdade de Odontologia (FOA). Universidade Estadual Paulista (UNESP). Campus de Araçatuba. Araçatuba , SP, Brazil

Abstract

The best method to achieve a smooth surface of dental ceramics is a controversy, due to the lack of a protocol established in the literature. Nowadays, the question is whether office polishing kits result in superior finishing and polishing or similar to that obtained with glaze, being this issue of utmost importance, especially for restorations performed through the CAD / CAM system in the dental office, where the dentist is in charge of the final finishing and polishing of the ceramics, which can be performed before and after cementation. In this way, the present study will aim to evaluate the color stability (”E), translucency (TP) and degree of contrast (CR) of lithium disilicate ceramics for the CAD / CAM system, submitted to different clinical polishing protocols and after cycles of thermal fatigue with and without repolishing. 170 specimens with 14 × 4 × 1.2 mm will be prepared, divided into 07 groups according to their polymeric surfaces and thermal fatigue cycles (FT). Three polishing systems will be evaluated: (Glaze, Ceramisté Polishing Kit (Shofu) and OptraFine Polishing Kit (Ivoclar)); aged by different tests: T0 - storage in distilled water for 24 hours (Control); T1 - after 21,900 cycles of 5 and 55oC for 30 seconds of FT; T2 - after 43.800 cycles of FT and T3 - after 21.900 cycles of FT + repolishing of the specimens + 21.900 cycles of FT. The readings of the optical characteristics of the specimens will be realized by visible ultraviolet reflection spectrophotometry, model UV-2450 in two backgrounds (black and white) in the periods (T0, T1 T2 and T3). The obtained data will be submitted to analysis of variance (ANOVA) single factor for ”E and ANOVA with repeated measures two factors for TP and CR. The Tukey test will be applied for all analyzes, with a significance of 5%. (AU)