Er:YAG激光用于比格犬牙髓切断术

Preliminary research of Er: YAG laser used for pulpotomy of Beagle dogs

目的:通过比格犬动物试验,观察铒钇铝石榴石(erbium:yttrium aluminium garnet,Er:YAG)激光去除比格犬冠髓后剩余牙髓的变化及牙本质桥形成情况,探索Er:YAG激光照射与牙髓反应及牙本桥形成的关系。方法:选取2只12月龄雄性比格犬前磨牙为试验牙,共24颗,分别应用200 m J/20 Hz Er:YAG激光、100 m J/20 Hz Er:YAG激光及传统机械方法去除冠髓,三氧化矿物凝聚体(mineral trioxide aggregate,MTA)盖髓后充填。通过临床检查试验牙的动度和牙龈情况评价临床效果,拍摄试验牙平行投照X线根尖片评价影像学效果。试验术后1 d、2周、4周、8周拔牙,苏木精-伊红染色(Hematoxylin-Eosin staining,HE)下观察根髓情况及牙本质桥形成情况。结果:牙髓切断术后1 d、2周、4周、8周后机械去髓组和激光去髓组试验牙均无松动,牙龈无红肿瘘管等异常;X线片发现机械去髓组和激光去髓组试验牙均未见牙周膜增宽、根尖周低密度影、牙根内外吸收等影像学异常表现;HE染色组织学切片检查发现术后1 d、2周、4周、8周机械去髓组和激光去髓组试验牙根髓均未见明显炎症反应,2周时可见激光去髓组牙本质桥完全覆盖牙髓断面,而机械切髓组未见完整牙本质桥。结论:100 m J/20 Hz和200 m J/20Hz Er:YAG激光去髓对剩余根髓未见影响。

Objective ： To investigate the effects of erbium ： yttrium aluminium garnet （ Er ： YAG） laser irradiation on pulp and formation of dentin bridge. The beagle dogs＇ coronal pulp is amputated by Er： YAG laser. Methods： In the study, 24 premolar teeth of two one-year-old Beagle dogs were used. They were divided into 3 groups： bur group, 200 mJ laser group, 100 mJ laser group. The coronal pulp were removed by traditional bur or 200 mJ/20 Hz or 100 mJ/20 Hz Er： YAG laser. Then, they were dressed with mineral trioxide aggregate （MTA） and sealed with resin. Clinical, radiological and histological analyses were performed 1 day, 2 weeks, 4 weeks and 8 weeks after treatment. The mobility and gingiva si- tuation were evaluated for clinical evaluation. Periapical films were used for radiological evaluation. The extracted teeth were preserved in 10% formalin. After decalcification, tissue processing, paraffin embedding, serial sectioning at 5 μm thickness, staining （ Hematoxylin and Eosin, HE） , the samples were assessed by an independent observer for calcified bridge formation and radieular pulp inflammation. The mean thickness of dental bridge was measured if there was complete dental bridge. Results： Clinical evaluation ： there were no signs of fistula or mobility or any abnormal symptoms in Er ： YAG laser groups and bur group during the observation period. Radiological evaluation： there were no signs of widened periodontal ligament or root absorption or periapical radiolueency in Er：YAG laser groups and bur group. Histological evaluation： there was no severe inflammation reaction in 200 mJ/20 Hz, 100 mJ/20 Hz Er： YAG laser groups and bur group 1 day, 2 weeks, 4 weeks, 8 weeks post-operation in Hematoxylin and Eosin staining. A complete dentin bridge could be observed in 200 mJ/20 Hz, 100 mJ/20 Hz Er：YAG laser groups, while no complete dentin bridge in bur group 2 weeks post-operation. Complete dental bridge could be observed in each group 4 and 8 weeks post-operation. The mean thickness of dental bridge 4 weeks post-operation in 200 mJ laser group was 77 μm, 100 mJ laser group 87 μm, and bur group 101 μm, and 8 weeks post-operation in 200 mJ laser group was 222 p.m, 100 mJ laser group 160 μm,and bur group 152 μm. Conclusion： The 200 mJ/20 Hz and 100 mJ/20 Hz Er：YAG laser pulpotomies show no harm to radicular pulp and can promote the formation of dentin bridge.