A comparative evaluation of preheat treatment, postcure heat treatment, and combined heat treatment on degree of conversion of a bulk-fill composite: An in vitro study

AIMS: The aim of this study was to evaluate the effect on the degree of conversion of Tetric N-Ceram Bulk Fill Composite subjected to preheat treatment, postcure heat treatment, and combined heat treatment. MATERIALS AND METHODS: A total of 90 samples were prepared from Tetric N-Ceram Bulk Fill using customized stainless steel molds and divided into six groups of 15 samples each based on the heat treatment. Group I (control group): no heat treatment, Group II: preheat treatment at 60°C, Group III: postcure heat treatment at 100°C, Group IV: postcure heat treatment at 200°C, Group V: combined preheat treatment at 60°C and postcure heat treatment at 100°C, and Group VI: combined preheat treatment at 60°C and postcure heat treatment at 200°C. The degree of conversion was analyzed using Raman spectrometer. STATISTICAL ANALYSIS USED: Data were analyzed using analysis of variance followed by the Scheffé test using Statistical Package for the Social Sciences 20.0 version. RESULTS: The order of values of degree of conversion from maximum to minimum for the groups are as follows: Group VI (98.77 ± 0.52) > Group V (97.11 ± 0.78) > Group IV (95.00 ± 0.86) > Group III (93.00 ± 1.22) > Group II (86.88 ± 1.36) > Group I (76.55 ± 1.42). The statistical analysis revealed a statistically significant difference between the groups (P < 0.05). CONCLUSIONS: Combined heat treatment samples showed better values of degree of conversion.