Long-term degradation of resin-based cements in substances present in the oral environment: influence of activation mode

Abstract

Indirect restorations in contact with free gingival margins or principally within the gingival sulcus, where the presence of organic acids produced by oral biofilm is higher, may present faster degradation of the resin-based cement pellicle.Objectives:To investigate the degradation of four resin-based cements: Rely X ARC (R), Variolink II (V), enforce (E) and All Cem (A), after immersion in distilled water (DW), lactic acid (LA) and artificial saliva (AS) and to analyze the influence of the activation mode on this response.Material and Methods:Two activation modes were evaluated: chemical (Ch) and dual (D). In the dual activation, a two-millimeter thick ceramic disk (IPS empress System) was interposed between the specimen and light-curing unit tip. Specimens were desiccated, immersed in distilled water, artificial saliva and lactic acid 0.1 M at 37ºC for 180 days, weighed daily for the first 7 days, and after 14, 21, 28, 90 and 180 days and were desiccated again. Sorption and solubility (µg/mm3) were calculated based on ISO 4049. The data were submitted to multifactor analysis of variance (MANOVA) and Tukey's HSD test for media comparisons (α=0.05).Results:Sorption was higher after immersion in LA (p<0.05) and increased significantly with time (p<0.05). Sorption was influenced by the activation mode: Ch>D (p<0.05). The lowest solubility was presented by R (p<0.05). Conclusions:Lactic acid increased the degradation of resin-based cements. Moreover, the physical component of activation, i.e., light-activation, contributed to a low degradation of resin-based cements.

Evaluation of ISO 4049: water sorption and water solubility of resin cements

“…Weighing and drying of specimens should be continued for at least 3 d after reaching a mass loss of less than 0.1 mg in a 24-h time period, in order to achieve reliable data. The immersion time of 7 d is sufficient; values obtained after an immersion period of 3 months did not differ (40,41).…”

Efeito da intensidade de fontes de luz e barreiras de cerâmica na microdureza de cimento resinoso dual

“…O processo de conversão dos monômeros em polímeros determinará a absorção de água do material, a presença de monômeros residuais, a biocompatibilidade da restauração dentária e a sua dureza 2,16 . A dureza superficial é uma das propriedades físicas mais importantes dos materiais dentários e é definida como a resistência de um material a indentação ou penetração.…”

“…Result: The average hardness and standard deviation in the control group for cement polymerized 1000mW/cm² was 43.9±1. 5 1,2 . Além disso, a escolha das cerâmicas está ainda associada a alta biocompatibilidade com os tecidos dentais, adequada estabilidade de cor, baixa condução térmica e alta resistência à abrasão, e por permitir baixo acúmulo de placa bacteriana 1,2 .…”

“…5 1,2 . Além disso, a escolha das cerâmicas está ainda associada a alta biocompatibilidade com os tecidos dentais, adequada estabilidade de cor, baixa condução térmica e alta resistência à abrasão, e por permitir baixo acúmulo de placa bacteriana 1,2 . Essas características podem ser encontradas em diferentes tipos de cerâmicas, porém em intensidade e dimensões diferentes, de acordo com a composição 3 .…”

“…Os cimentos à base de resina são, geralmente, resinas compostas híbridas, constituídas por uma matriz de BIS-GMA (Bisfenol glicidil metacrilato) 2,6 . Normalmente, a reação de polimerização desses materiais é iniciada de forma química ou pela exposição à luz visível, a um comprimento de onda de 400 a 500 nm 6 .…”