Evaluate of Knoop microhardness and surface roughness of ceramics for the CAD / CAM system after of different polishing and repolishing protocols

• Grant number: 19/01392-6
• Support type: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): May 01, 2019
• Effective date (End): December 31, 2019
• Field of knowledge: Health Sciences - Dentistry - Dental Materials
• Principal researcher: Aldiéris Alves Pesqueira
• Grantee: Júlia Nakazoni Rinaldi
• Home 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 of Knoop microhardness (KM), surface roughness (Ra), surface energy (SE) and scanning electron microscopy (SEM) associated with energy dispersive spectroscopy (EDS) of lithium disilicate ceramics for the CAD/CAM system, submitted to different clinical polishing protocols and after thermal cycling cycles fatigue with and without repolishing. 187 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.Four response variables will be considerate: (1) Knoop microhardness (KM), (2) surface roughness (Ra), (3) surface energy (SE) and (4) scanning electron microscopy (SEM) associated with energy dispersive spectroscopy (EDS). The data will be analyzed in the adherence testing curve, applying the appropriate statistical test to compare the specimens' average values.