Department of Endodontics and Restorative Dentistry, School of Dental Medicine, University of Zagreb, Gunduliceva 5, Zagreb, Croatia.
Community Health Center, Zagreb, Croatia.
Clin Oral Investig. 2019 Oct;23(10):3777-3788. doi: 10.1007/s00784-019-02807-1. Epub 2019 Jan 28.
To investigate radiant energy, microhardness, and temperature rise in eight resin composites cured with a blue or violet-blue curing unit, using a curing protocol which exceeded manufacturer recommendations.
Cylindrical composite specimens (d = 8 mm, h = 2 or 4 mm, n = 5 per experimental group) were light-cured for 30 s. Light transmittance through specimens was recorded in real time to calculate radiant energy delivered to the specimen bottom. Vickers microhardness was used to evaluate the polymerization effectiveness at depth. Temperature rise at the bottom of the specimens was measured in real time using a T-type thermocouple.
Radiant energy delivered from the blue and violet-blue curing unit amounted to 19.4 and 28.6 J/cm, which was 19 and 13% lower than specified by the manufacturer. Radiant energies at bottom surfaces (0.2-7.5 J/cm) were significantly affected by material, thickness, and curing unit. All of the composites reached 80% of maximum microhardness at clinically relevant layer thicknesses. The benefit of using the higher-irradiance violet-blue curing unit was identified only in composites containing alternative photoinitiators. Temperature rise during curing ranged from 4.4 to 9.3 °C and was significantly reduced by curing with the lower-intensity blue curing unit and by increasing layer thickness.
Curing for 30 s, which can be regarded as extended considering manufacturer specifications, produced radiant energies which are in line with the recommendations from the current scientific literature, leading to adequate curing efficiency and acceptable temperature rise.
Extended curing time should be used to minimize concerns regarding undercuring of composite restorations.
研究在超出制造商建议的固化方案下，使用蓝光或蓝紫光固化器对 8 种树脂复合材料进行固化时的辐射能、显微硬度和温升。
将圆柱形复合试件（d=8mm，h=2 或 4mm，每组实验 n=5）进行 30s 的光固化。实时记录试件的透光率，以计算传递到底部试件的辐射能。采用维氏显微硬度计评估聚合深度的效果。使用 T 型热电偶实时测量试件底部的温升。
蓝光和蓝紫光固化器传递的辐射能分别为 19.4 和 28.6 J/cm，比制造商规定的能量低 19%和 13%。底部表面（0.2-7.5 J/cm）的辐射能受材料、厚度和固化器的显著影响。所有复合材料在临床相关的层厚下都达到了 80%的最大显微硬度。只有在含有替代光引发剂的复合材料中，使用高辐射强度的蓝紫光固化器才具有优势。固化过程中的温升范围为 4.4-9.3°C，使用低强度蓝光固化器和增加层厚可显著降低温升。
考虑到制造商的规范，延长 30s 的固化时间产生的辐射能与当前科学文献的建议相符，可达到足够的固化效率和可接受的温升。
应使用延长的固化时间来最小化对复合材料修复体未充分固化的担忧。
