Desempenho biomecânico de cimentos dual/core - validação de produto nacional

Abstract

The resin-based cements and light activation protocol can influence the mechanical properties of post cementation and core reconstruction in endodontically treated teeth. This study analyzed how the mechanical properties are affected by immediate or 5-minute photoactivation of different resin materials used in cementation of glass fiber posts (dualcure resin cements or dual-cure resin-core) and to build the core (bulk-fill resins or dualcure resin-core). Nine resin-based materials were tested, including 4 core cements: Allcem Core, FGM; LuxaCore Z, DMG; Rebilda DC, VOCO; Clearfil DC Core Plus, Kuraray; 3 dual cements: RelyX Universal, 3M Oral Care; RelyX U200, 3M Oral Care; Allcem Dual, FGM; and 2 bulk-fill composite resins: Opus Bulk Fill APS, FGM; and Filtek One Bulk Fill, 3M Oral Care. The dual cements and core composites were photocured immediately and after 5 minutes. The measured properties included post-gel shrinkage (%), flexural strength (MPa), elastic modulus (MPa), diametrical tensile strength (MPa), compressive strength (MPa), Knoop hardness (N/mm²), degree of conversion (%), depth of cure (mm), thermogravimetric analysis (% filler content), and radiodensity. Scanning electron microscopy and energy-dispersive X-ray spectroscopy were used to examine the morphology and filler content. The residue of the dual cements and core cements that remained in the self-mixing tip was weighed. Post-gel shrinkage, thermogravimetric analysis, flexural strength, elastic modulus, diametrical tensile strength, compressive strength, depth of cure, and radiopacity data were analyzed using 2-way ANOVA and 2- way repeated-measures ANOVA for Knoop hardness and degree of conversion, followed by Tukey's test to identify differences between groups (α = 0.05). Light activation performed 5 minutes after application resulted in a significant reduction in post-gel shrinkage in all dual cements and core cements (p < 0.001). Increasing the depth of cure caused a significant decrease in Knoop hardness values for all materials tested (p < 0.001). Bulk-fill resins and core composite resins presented higher Knoop hardness values than dual cements (p < 0.001). The light activation after 5 minutes significantly reduced post-gel shrinkage values without having a negative or improving effect on the mechanical properties tested. Dual-cure resin-based materials showed greater depth of cure than bulk-fill resins. Resin-core materials showed higher Knoop hardness values than dual cements and similar mechanical properties to bulk-fill resins.