engleski

Long-term degree of conversion of contemporary dual-cure composite cements

Introduction: This study investigated the development of the degree of conversion (DC) over a 30-day period for dual-cure resin composite cements. Materials and methods: Four dual-cure resin cements were investigated. A light-cure resin cement was used as a reference. A thin layer of resin cement (0.1 mm) was cured using the following three curing protocols: (I) 1200 mW/cm2 for 10 s immediately adjacent to the specimen surface, (II) 1200 mW/cm2 for 20 s through a 1-mm layer of disilicate ceramics, and (III) without light illumination. DC was evaluated using attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) after 1, 7, and 30 days. Results: The measured DC values ranged from 44.3–77.8%. A statistically significant DC increase up to 30 days was identified in three materials, with the post-cure DC improvements up to 26.2%. Only one of the investigated materials showed no significant postcure DC increase. The response of the materials to different curing protocols was material- dependent, with self-cure protocol resulting in up to 13.9% lower DC values compared to the light-curing protocol (I). On the other hand, one of the tested materials showed no significant reduction of the DC due to different curing protocols. Conclusions: The behavior of the investigated dual-cure composite cements regarding their long-term polymerization and sensitivity to different curing protocols proved to be highly material-dependent. While for the most of the materials the DC values were dependent on the curing protocol and a long-term DC increase was observed, a different behavior was also possible, including no significant post-cure increase and insensitivity to curing protocols.

degree of conversion ; resin composite cements ; light-curing ; dual-curing ; selfcuring

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