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Pre-heating time and exposure duration: Effects on post-irradiation properties of a thermo-viscous resin-composite.
Dental Materials ( IF 5 ) Pub Date : 2020-05-05 , DOI: 10.1016/j.dental.2020.03.025
Jiawei Yang 1 , Nikolaos Silikas 1 , David C Watts 2
Affiliation  

OBJECTIVE To evaluate the effects of pre-heating time and exposure duration on the degree of conversion (DC), maximum rate of polymerization (RPmax), polymerization shrinkage strain (PS) and surface micro-hardness (VHN) of Viscalor. METHODS Viscalor syringes were pre-heated using a Caps Warmer (VOCO, Germany) in T3 mode (at 68°C) for 30s (T3-30s) and 3min (T3-3min) and then the composite paste was extruded into appropriately sized molds. Light irradiation was applied at zero distance from the upper surface with a LED-LCU of mean irradiance 1200mW/cm2 for either 20 or 40s. The real-time polymerization kinetics and DC at 5min and 24h post-irradiation (DC5min and DC24h) were measured using ATR-FTIR (n=3). PS was obtained with the bonded-disk technique (n=3). Top and bottom Vickers micro-hardness (VHNtop and VHNbottom) were measured at 5min post-irradiation and after 24h dry storage (n=5). Data were analysed using one-way ANOVA, two-way ANOVA, independent t-test and Tukey post hoc tests (p<0.05). RESULTS Polymerization kinetic curves of Viscalor from 0 to 15min were similar for different pre-heating times and exposure durations. Pre-heated Viscalor (T3-30s and T3-3min) with 40s exposure had greater VHNtop and VHNbottom than for Viscalor (no heat) (p<0.05). Exposure duration did not significantly affect DC, RPmax and PS (p>0.05). After 24h storage, DC and VHN increased. Pre-heating did not increase the DC24h, relative to no pre-heating (p>0.05). Two-way ANOVA showed that there was no significant interaction between pre-heating time and exposure duration (p>0.05). SIGNIFICANCE Increasing irradiation time from 20 to 40s did not affect DC, RPmax or PS, but increased VHNtop. Composite pre-heating had no adverse effect through any premature polymerization. For Viscalor, 3min pre-heating and 20s irradiation were sufficient to provide adequate hardness, without increasing PS or compromising polymerization kinetics.

中文翻译:

预加热时间和暴露时间:对热粘树脂复合材料辐照后性能的影响。

目的评估预热时间和暴露时间对Viscalor的转化率(DC),最大聚合速率(RPmax),聚合收缩应变(PS)和表面显微硬度(VHN)的影响。方法使用Caps Warmer(VOCO,德国)以T3模式(在68°C下)将Viscalor注射器预热30s(T3-30s)和3min(T3-3min),然后将复合糊剂挤出到合适尺寸的模具中。以平均辐照度1200mW / cm2的LED-LCU在距上表面零距离处照射20或40s。使用ATR-FTIR(n = 3)测量辐照后5min和24h的实时聚合动力学和DC(DC5min和DC24h)。PS是用粘合盘技术获得的(n = 3)。在照射后5分钟和干燥储存24小时后(n = 5),测量顶部和底部维氏显微硬度(VHNtop和VHNbottom)。使用单向方差分析,双向方差分析,独立t检验和Tukey事后检验分析数据(p <0.05)。结果在不同的预热时间和暴露时间下,Viscalor从0到15min的聚合动力学曲线相似。暴露40s的预热Viscalor(T3-30s和T3-3min)具有比Viscalor(无热量)更大的VHNtop和VHNbottom(p <0.05)。暴露时间对DC,RPmax和PS无明显影响(p> 0.05)。储存24小时后,DC和VHN增加。相对于未预热,预热并没有增加DC24h(p> 0.05)。双向方差分析表明,预热时间和暴露时间之间无显着相互作用(p> 0.05)。重要性将照射时间从20s增加到40s不会影响DC,RPmax或PS,但会增加VHNtop。复合物预热不会因任何过早聚合而产生不利影响。对于Viscalor,3分钟的预热和20s的照射足以提供足够的硬度,而不会增加PS或损害聚合动力学。
更新日期:2020-05-05
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