Mousavinasab Sayed Mostafa, Taromi Zahra, Zajkani Elham
Dental Materials Research Center, Department of Restorative Dentistry, Dental Research Institute, Isfahan University of Medical Sciences, Isfahan, Iran.
Department of Restorative Dentistry, School of Dentistry, Zanjan University of Medical Sciences, Zanjan, Iran.
Dent Res J (Isfahan). 2020 Aug 14;17(4):293-299. eCollection 2020 Jul-Aug.
Light curing of resin composite is associated with a thermal rise that may have harmful effect on the health of the vital pulp. In addition, desirable polymerization is important to achieve mechanical properties and clinical function. The purpose of this in-vitro study was to compare the thermal rise under normal dentin during photopolymerization and degree of conversion (DC) of bulk fill and conventional resin composite using continuous high- and soft-start mode.
In this in-vitro study, Cl I cavities with a dimension of 4 mm × 4 mm × 4 mm and remaining dentin thickness of 1 mm were prepared on 56 extracted human molars. The temperature rise during the light curing of conventional resin composite (Tetric N Ceram, Ivoclar Vivadent) by incremental filling technique and bulk-fill resin composite (Tetric N Ceram Bulk Fill, Ivoclar Vivadent) by bulk-filling technique were measured with a K-type thermocouple wire. DC of both resin composites was measured using Fourier-transform infrared spectroscopy. Data were analyzed using one-way ANOVA, Tamhane and Duncan post hoc, two-way ANOVA at the significance level of α = 0.05.
Photopolymerization temperature rise due to soft start mode and the first layer of conventional composite was higher than continuous high mode and bulk-filling technique, respectively ( < 0.001). DC of conventional resin composite was higher than bulk-fill composite ( < 0.001).
Soft-start mode produced higher thermal rise than continuous high mode and conventional resin composite showed higher DC than bulk-fill composite.
树脂复合材料的光固化会伴随温度升高，这可能对活髓健康产生有害影响。此外，理想的聚合反应对于获得机械性能和临床功能很重要。本体外研究的目的是比较在连续高功率模式和软启动模式下，光聚合过程中正常牙本质下的温度升高以及大块充填树脂复合材料和传统树脂复合材料的转化率（DC）。
在本体外研究中，在56颗拔除的人类磨牙上制备尺寸为4mm×4mm×4mm且剩余牙本质厚度为1mm的Cl I类洞。采用K型热电偶丝测量通过分层充填技术光固化传统树脂复合材料（Tetric N Ceram，义获嘉伟瓦登特公司）和通过大块充填技术光固化大块充填树脂复合材料（Tetric N Ceram Bulk Fill，义获嘉伟瓦登特公司）过程中的温度升高。使用傅里叶变换红外光谱法测量两种树脂复合材料的DC。数据采用单因素方差分析、Tamhane和Duncan事后检验、在α = 0.05显著性水平下的双因素方差分析进行分析。
软启动模式和传统复合材料第一层引起的光聚合温度升高分别高于连续高功率模式和大块充填技术（<0.001）。传统树脂复合材料的DC高于大块充填复合材料（<0.001）。
软启动模式产生的温度升高高于连续高功率模式，且传统树脂复合材料的DC高于大块充填复合材料。
