Lohbauer Ulrich, Zinelis Spiros, Rahiotis Christos, Petschelt Anselm, Eliades George
Dental Clinic 1 - Operative Dentistry and Periodontology, University of Erlangen-Nuremberg, Glueckstr. 11, D-91054 Erlangen, Germany.
Dent Mater. 2009 Apr;25(4):514-9. doi: 10.1016/j.dental.2008.10.006. Epub 2008 Dec 10.
To determine monomer conversion and polymerization shrinkage of a resin composite after different pre-heating procedures and storage intervals.
For a commercial resin-based composite the immediate (5 min) and final (24h) degree of conversion was measured on top and bottom surfaces utilizing FTIR spectroscopy. Composite pre-heating temperatures were selected between 10 and 68 degrees C. Polymerization shrinkage was measured according to Archimedes' principles of buoyancy after 5 min at respective pre-heating temperatures and after 24h dark and wet storage at 37 degrees C. Intra-cavity temperature development was monitored using a K-type thermocouple.
No significant increase in immediate as well as in final degree of conversion were measured from composite pre-heating at 68 degrees C compared to 54 and 39 degrees C. Linear correlations were detected immediately after photo-polymerization and on the top surface after 24h storage. Polymerization shrinkage as a function of pre-heating temperatures exhibited a linear correlation after 5 min, but no statistically different behavior after 24h.
Pre-heating of resin composites does not increase degree of conversion over time. It can be clinically beneficial, due to a superior marginal adaptation. This advantageous effect of reduced material paste viscosity has to be clinically addressed, since temperature rapidly drops to the physiological level upon removal from the pre-heating device.
确定不同预热程序和储存时间间隔后树脂复合材料的单体转化率和聚合收缩率。
对于一种市售的树脂基复合材料，利用傅里叶变换红外光谱法测量其顶面和底面的即时（5分钟）和最终（24小时）转化率。复合材料的预热温度在10至68摄氏度之间选择。根据阿基米德浮力原理，在各自的预热温度下5分钟后以及在37摄氏度黑暗潮湿储存24小时后测量聚合收缩率。使用K型热电偶监测腔内温度变化。
与54摄氏度和39摄氏度相比，68摄氏度预热的复合材料在即时和最终转化率方面均未显著增加。光聚合后立即以及储存24小时后在顶面上检测到线性相关性。聚合收缩率作为预热温度的函数在5分钟后呈现线性相关性，但在24小时后没有统计学上的不同行为。
树脂复合材料的预热不会随时间增加转化率。由于边缘适应性更好，这在临床上可能是有益的。由于从预热装置取出后温度会迅速降至生理水平，因此必须在临床上解决降低材料糊剂粘度的这种有利效果。
