RESUMEN
Introduction: When repairs are needed in restorations made with methacrylate-based resin composites, the clinician still has doubts whether it is possible to use a silorane-based material and which is the best procedure. Objective: To evaluate the shear bond strength between a methacrylate-based resin composite and a silorane-based material using different surface treatments. Material and methods: Eighty flat bases made with methacrylate resin composite (Filtek Z350 XT) were prepared (n = 8). The bases were stored into water at 37°C for one week. Ten groups were evaluated: G1 (control - no repair); G2 (surface grinding, washing, drying, adhesive and repair with Filtek Z350 XT); G3 (surface grinding, washing, drying, adhesive and repair with silorane - Filtek P90); G4 (surface grinding, washing, drying, adhesive, silane and repair with Filtek Z350 XT); G5 (surface grinding, washing, drying, application of silane, adhesive and repair with silorane - Filtek P90). All groups were kept at 37°C for 24 h in either water (G1 to G5) or ethanol (G6 to G10). The results were analyzed with one-way ANOVA and Tukey test (α = 0.05). Results: There were significant differences between groups (p < 0.001). Only repairs made with silane and Z350 XT (G4 = 46.2 ± 12.9; G9 = 48.1 ± 16.3) resulted in values similar to controls (G1 = 59.2 ± 15.8; G6 = 62.3 ± 15.9) (p = 0.33). The smallest value occured when the repair was performed with silane and silorane-based based and stored into ethanol (G10 = 29.9 ± 12.4). The storage media had little influence on the results. Conclusion: The silorane-based resin composite was not effective for repair of the methacrylate-based material.
RESUMEN
O estudo avaliou, in vitro, as variáveis relacionadas à alteração de cor e à rugosidade superficial das resinas compostas micro-híbridas: Charisma (Heraeus-Kulzer), Filtek Z-250 (3M - Espe), Herculite XRV (Kerr), Opallis (FGM), TPH Spectrum (Dentsply) e W3D (Wilcos), antes e após o envelhecimento artificial acelerado, tendo como fatores de variação duas fontes de luz, lâmpada halógena e LED, com densidades de potência de 300 mW/cm2 ou 600 mW/cm2. Foram confeccionados 240 corpos-de-prova distribuídos em grupos de 10 unidades para cada condição de estudo totalizando 24 grupos constituídos por 4 protocolos de fotoativação para cada marca de resina composta. Estes corpos-de-prova foram armazenados em água deionizada, ao abrigo de luz e a temperatura de 37ºC por 1 semana quando então receberam polimento superficial com discos Diamondpro (FGM). Sequencialmente, os mesmos foram submetidos às análises iniciais de rugosidade superficial (rugosímetro Hommle Tester T1000 basic) e de cor (Espectrofotômetro EasyShade). Decorridas 24 horas, os espécimes foram submetidos ao Sistema de Envelhecimento Acelerado para materiais não metálicos C-UV por 384 horas quando então foram novamente realizadas as leituras de rugosidade e cor. Os valores de rugosidade superficial e alteração de cor das resinas compostas, após o processo de envelhecimento acelerado, demonstraram alterações significativas, sendo os valores de E muito superiores ao considerado clinicamente aceitável (∆E≤3,3). De forma geral, o efeito exercido pelos protocolos de fotoativação não permitiu distinguir a influência direta das irradiâncias das fontes de luz no comportamento das diferentes resinas compostas, observando-se uma correlação positiva média entre rugosidade superficial e a alteração de cor.
This study aimed to evaluate changes in color and surface roughness, before and after artificial accelerated aging of six micro hybrids composites resins (comparable to Vita shade A2) cured by quartz tungsten halogen (H) or a light emitting diode (L) polymerization unit with 300 mW/cm2 or 600 mW/cm2. Forty disc specimens (7 x 2 mm) were prepared for each composite (Charisma®, Filtek Z-250®, Herculite XRV®, Opallis®, TPH Spectrum®, W3D®), being 10 specimens for each condition (Q 300/600 mW/cm2 or L 300/600 mW/cm2). After cured, each specimen was evaluated by color (Easy Shade® spectrophotometer) according to CIE L*a*b* color scale and by surface roughness (Hommelwerke GmbH ) Ra values before and after submitting to artificial accelerated aging (4 h UV-B/4 h condensing vapor) for 384 hours total. The surface roughness and color change values of composite resins, after the process of accelerated aging, showed significant changes. Also, the values of E after accelerated aging were much higher than the values considered clinically acceptable (∆E≤3.3). In general, the protocols curing effects showed varied influence over different composite resins and a positive correlation between average change in surface roughness and color change after accelerated aging process.