Efeito de diferentes estratégias de reparo na resistência de união à resina composta e viabilidade celular de novos materiais cad/cam: estudo in situ

Abstract

Introduction: New CAD/CAM blocks of resin, hybrid and ceramic restorative materials have been recently developed. However, the literature does not yet have a repair protocol for these materials against a cohesive fracture of the restorative material. Purpose: To determine the influence of surface treatment (diamond burs, abrasive jet Al2O3, COJET, and hydrofluoric acid) and in situ aging on CAD/CAM shear bond strength (LU:Lava Ultimate / 3M, VE: Vita Enamic / VITA and VS:VITA Suprinity / VITA) to the composite resin. Methodology: 390 blocks (6 x 5 x 2.5mm) were made, 130 of each restorative material. 300 samples were used for the shear bond strength test, the other samples were used for extra analysis. Fifty samples of each restorative material were embedded in total dentures in use, and after a period of 60 days (aging in situ), the 150 aged and 150 unripe samples were randomly divided (N = 30 / n = 10) according to treatment carried out: 1. Diamond burs + Single Bond Universal (SUB); 2. Diamond burs + silane + conventional adhesive; 3. Hydrofluoric acid 10% + silane + conventional adhesive; 4. COJET + silane + conventional adhesive; 5. abrasive jet aluminum oxide Al2O3 + silane + conventional adhesive. Then, Z350 (3M ESPE) composite resin cylinders (: 2.37mm, height: 2mm) were built on the surface of the blocks. Subsequently, the 300 specimens were then subjected to thermocycling (10,000 cycles, 50 / 550C) and then to the shear test (50kgf, 0.5mm / min). After fracture, the failure analysis was performed in stereomicroscope (20X). Additional samples of each restorative material were used for the Vickers microhardness and Roughness (n = 10) analyzes for the two tests; analysis of fungal cell viability (n = 10); scanning electron microscopy (SEM) analysis of the surface treatments and EDS analysis (n = 10) for characterization of the same materials for the two tests. The shear strength (MPa), cell viability (UFC / mL) and microhardness (HV) data were analyzed statistically by ANOVA and Tukey's test (5%). The other tests were qualitative descriptive analyzes. Results: The bond strength was affected by the in situ aging exposure for the LU and VS materials (p = 0.0001), the highest bond strength for the diamond burs group + Single Bond Universal (SUB) was observed in the LU (14.67MPa), for the VE the aged HF group (17.10MPa) presented higher union strength, and the VS the HF group without aging (14.27MPa) had higher union strength (p = 0.0001). The adhesive failure presented a higher prevalence in all types of CAD/CAM block (LU: 78%, VE: 61%, VS: 98%). The Vita Suprinity (734.31HV) exhibited the highest Vikers hardness and Lava Ultimate (137.34HV) the lowest (p = 0.0001). Cell viability analysis showed no difference between fungal adhesion in the three materials (p = 0.9064). Regarding the analysis of the treated surfaces (SEM) and roughness, it was observed that the blasting and diamond burs asperisation showed a greater change in the surfaces of all the materials; the EDS analysis demonstrated that surface treatments alter the surface chemical composition of the materials. Conclusion: In situ aging changes the bond strength of LU and VS materials. The most effective surface treatment for LU was diamond burs grinding + SBU, for VS and VS the conditioning with HF. The VS presented greater Vickers hardness. The surface treatments promoted surface changes of topography and roughness of all the materials tested, the largest roughness per material were LU: COJET, VE: Al2O3 and VS: Diamond burs, besides altering the superficial chemical composition in the materials.