Nd:YAG激光照射治疗牙本质敏感症的能量密度范围的离体牙研究

Energy Density Range in the Treatment of Dentin Hypersensitivity Using a Pulsed Nd:YAG Laser:in Vitro Study

目的：探索Nd：YAG激光照射牙本质后,既能显著降低其通透性,又不引起表面形态破坏的能量密度范围。方法：10个离体磨牙均切成6个2mm×3mm×4mm的牙本质块,随机分为：空白对照组、Gluma组、50、100、200、450J/cm2激光组。37%磷酸处理,每组随机取8个标本浸入2%亚甲蓝溶液5h,体视显微镜下测量染液渗透深度,另2个标本观察表面形态变化。结果：1）染液渗透深度,空白对照组、Gluma组、50J/cm2,100J/cm2,200J/cm2,450J/cm2激光组分别为（3.211±0.345）、（1.714±0.475）、（3.058±0.193）、（2.603±0.389）、（1.979±0.380）、（1.156±0.397）mm。50J/cm2激光组牙本质通透性与对照组无差异,其余各组与对照组相比均明显下降,且随着激光能量升高,通透性降低。其中200J/cm2激光组的牙本质通透性与Gluma组相当。2）牙本质表面观察,450J/cm2激光组牙本质表面有显著改变,可见大小不一,形态不规则的凹坑。结论：Nd：YAG激光用于治疗牙本质敏感症时,考虑到有效性和安全性,建议能量密度为200~450J/cm2。

Objective：To explore the best energy density range which can significantly reduce the dentin permeability,but also does not cause obvious damage of the dentin surface after Nd：YAG laser irradiation.Methods：10extracted mandibular first molars were collected.Each molar was sectioned yielding six dentin blocks of 2mm×3mm× 4mm,which were randomly divided into six groups：control group,Gluma group,50J/cm2 laser group,100J/cm2 laser group,200J/cm2 laser group and 450J/cm2 laser group.The experimental side of dentin blocks was treated with 37% phosphoric acid.Then 8specimens of each group were randomly chosen and immersed in 2% methylene blue solution 5h,the penetration depth was measured under stero-microscope.The other 2specimens were observed under a stero-microscope about dentin surface morphological changes.Results：1）Penetration depth,the control group（3.211± 0.345）mm;Gluma group（1.714 ± 0.475）mm;50J/cm2,100J/cm2,200J/cm2,450J/cm2 laser group were（3.058±0.193）mm,（2.603±0.389）mm,（1.979±0.380）mm,（1.156±0.397）mm respectively.Data analysis shows that there was no difference in dentin permeability in the 50J/cm2 laser group versus the control group,the rest groups were decreased significantly（P0.05）,and with the increase of laser energy density, dentin permeability decrease.Dentin permeability of the 200J/cm2 laser group was as the same as Gluma group.2） Dentin surface observation,450J/cm2 laser group had significant morphological change,pits of different size and shape were observed.Conclusion：Considering the effectiveness and safety of laser desensitization,the recommended energy density range is 200~450J/cm2 in the treatment of dentin hypersensitivity.