Efficacy of periodic intraoral repolishing on the structural and mechanical properties of resin materials for CAD/CAM after different cycles of simulated brushing combined with mechanical fatigue.

• Grant number: 24/13572-7
• Support Opportunities: Scholarships in Brazil - Master
• Start date: May 01, 2025
• End date: February 28, 2026
• Field of knowledge: Health Sciences - Dentistry - Dental Materials
• Principal Investigator: Aldiéris Alves Pesqueira
• Grantee: Gabriel Nunes Sampaio
• Host Institution: Faculdade de Odontologia (FOA). Universidade Estadual Paulista (UNESP). Campus de Araçatuba. Araçatuba , SP, Brazil

Abstract

Resin-based materials for CAD/CAM are affected by in vitro aging processes, which can degrade their structural and mechanical properties. During clinical use, restorations are exposed to complex intraoral forces and repeated subcritical masticatory loads in the presence of saliva, resulting in a significant reduction in the mechanical properties of the restorations. Furthermore tooth brushing can alter the morphology and surface roughness of ceramics and composites. Therefore, the purpose of this in vitro study will be to evaluate the structural and mechanical properties of two resin-based materials for CAD/CAM with surface treatment (OptraGloss - IVOCLAR) - zirconia and silica ceramics in an interpenetrating resin matrix - Shofu HC (SHOFU DENTAL) and the nanohybrid resin block - Tetric CAD (IVOCLAR), subjected to different cycles of mechanical fatigue (MC) combined with simulated brushing (SB) with and without periodic repolishing. They will be evaluated through surface roughness (Ra), scanning electron microscopy (SEM), atomic force microscopy (AFM), Knoop microhardness (KH), flexural strength (Ã), and modulus of elasticity (ME). The analyses will occur at three levels: T0, representing baseline after storage in distilled water at 37°C for 24 hours; T1, after MC+SB (3 years) with specimens subjected to 7.2 x 105 cycles of MC combined with 30,000 cycles of SB; and T2, after MC+SB (5 years), with specimens subjected to 12 x 105 cycles of MC combined with 50,000 cycles of SB. All statiscal analysis will be performed with appropriate test with a signicance level of 5%. The SEM and AFM tests aim to perform a qualitative analysis of the specimen surfaces.