微型CT检测随机负荷疲劳试验后不同根管充填材料对牙根抗折性的影响

Effects of different root canal filing materals on root flexure resistance after random load fatigue test detected by Micro-CT

目的:采用微型CT检测体外疲劳试验后牙根的裂纹,探讨2种不同根管充填材料对牙根抗折性的影响。方法:60颗新鲜拔除的人单根管前牙随机分为对照组、OrthoMTA组和Gutta-Percha+AH-plus组,每组20颗。全部样本去除牙冠后使用BLX镍钛系统预备根管,对照组不进行根管充填,OrthoMTA组采用OrthoMTA根管充填,Gutta-Percha+AH-plus组采用Gutta-Percha和AH-plus封闭剂充填。将所有样品置于机械循环机(500~1500 N,2 Hz正弦交替,循环7200次)进行体外疲劳试验。采用微型CT检测各组牙根内部裂纹并进行裂纹严重程度评分。结果:微型CT扫描,受力后对照组、OrthoMTA组和Gutta-Percha+AH-plus组大部分牙根出现了不同程度裂纹,包括不完全裂纹、完全裂纹以及2种裂纹并存,且绝大多数裂纹方向为近远中方向。OrthoMTA组牙根裂纹评分低于对照组,但组间比较差异无统计学意义(P>0.05);Gutta-Percha+AH-plus组牙根的裂纹评分高于对照组,但组间比较差异无统计学意义(P>0.05);OrthoMTA组牙根裂纹评分低于Gutta-Percha+AH-plus组,但组间比较差异无统计学意义(P>0.05)。结论:随机负荷疲劳试验证实体外牙体阻力模型制备成功。OrthoMTA完全根管充填和Gutta-Percha+AH-plus根管充填对牙根抗折性的影响无明显差异。

Objective:To detect the root crack after in vitro fatigue test with Micro-computed tomography(Micro-CT),and to explore the effects of two different root canal filling materials on the root flexure resistance.Methods:A total of 60 freshly extracted human single canal anterior teeth were randomly divided into control group(n=20),OrthoMTA group(n=20),and Gutta-Percha+AH-plus group(n=20).After removing the crowns of all samples,the root canals were prepared using the BLX nickel titanium system.The root canals in control group were not filled,the root canals in OrthoMTA group were filled with OrthoMTA root canal,and the root canals Gutta-Percha+AH-plus group were filled with Gutta-Percha and AH-plus sealant.All samples were placed in a mechanical cycler(500-1500 N,2 Hz,with sinusoidal alternation and cycle 7200 times),and the in vitro fatigue test was performed.Micro-CT was used to detect the internal cracks in the roots of each group and the crack severity scores were evaluated.Results:The results of Micro-CT scanning showed that after stress,most of the roots in control group,OrthoMTA group and Gutta-Percha+AH-plus group appeared the cracks of varying degrees,including incomplete cracks,complete cracks,and two types of cracks.Most of the cracks were in the near,far,and middle directions.The crack score of the root in OrthoMTA group was lower than that in control group,but the difference was not statistically significant(P>0.05).The crack score of the root in Gutta-Percha+AH-plus group was higher than that in control group,but the difference was not statistically significant(P>0.05);the crack score of the root in OrthoMTA group was lower than that in Gutta-Percha+AH-plus group,and the difference was not statistically significant(P>0.05).Conclusion:The random load fatigue test confirms that the in vitro resistance model is constructed successfully.Based on this study,OrthoMTA complete root canal filling and Gutta-Percha+AH-plus filling have no significant difference in influence in the root flexure resistance.