骨性Ⅲ类下颌第一磨牙近、远中骨量的CBCT研究

CBCT Study of Proximal and Distal Bone Mass in Skeletal ClassⅢMandibular First Molars

目的研究成人轻度骨性Ⅲ类患者下颌第一磨牙近、远中根间距、牙根之间对应颊侧牙槽骨厚度、骨密度及两邻牙之间相应的颊侧面积,为此区域支抗钉植入位点的选择提供参考依据。方法方便选择2016年1月—2021年1月厦门医学院附属口腔医院就诊的成人轻度骨性Ⅲ类患者22例,拍摄CBCT并导入Dolphin软件进行测量。分别选择下颌第一磨牙近、远中釉牙骨质界根方4、5、6、7 mm 4个不同截面作为测量平面,测量左、右侧下颌第一磨牙与近、远中邻牙牙根之间的距离、颊侧骨厚度、骨密度及相应的颊侧面积。结果下颌第一磨牙远中的颊侧骨厚度明显大于近中的骨厚度,差异有统计学意义(P<0.05),在7 mm截面上,两者差异为(-2.92045±1.87723)mm,差异有统计学意义(t=-10.320,P<0.05);下颌第一磨牙远中相对应骨皮质密度在7 mm截面大于近中的骨皮质密度,差异有统计学意义(P<0.05);下颌第一磨牙远中相对应颊侧面积大于近中颊侧面积,差异有统计学意义(P<0.05),在7 mm截面,二者差异为(-31.37045±24.06154)mm2,差异有统计学意义(t=-8.684,P<0.05)。结论对骨性Ⅲ类成人患者,若考虑于下颌后牙区牙根之间植入支抗钉,则下颌第一磨牙近、远中的位置都可选择。若考虑于牙槽嵴外植入,需优先选择第一磨牙远中的区域,且靠近前庭沟底的骨皮质较为致密。

Objective To study the mesial and distal root distances of mandibular first molars,the corresponding buccal alveolar bone thickness between the roots,the bone mineral density and the corresponding buccal area between the two adjacent teeth in adult patients with mild skeletal classⅢ.The selection of anchorage nail implantation sites in this region provides a reference basis.Methods Twenty-two adult patients with mild skeletal typeⅢwho were treated in the Affiliated Stomatological Hospital of Xiamen Medical College from January 2016 to January 2021 were conveniently selected,CBCT was taken and imported into Dolphin software for measurement.Four different sections of 4mm 5 mm 6 mm and 7 mm at the proximal and distal cementoenamel boundary of the mandibular first molar were selected as the measurement planes,and the distance between the left and right mandibular first molars and the proximal and distal adjacent teeth was measured.The distance between the two groups,the thickness of the buccal bone,the bone mineral density and the corresponding buccal area.Results The buccal bone thickness in the distal part of the mandibular first molar was significantly larger than that in the mesial,and the difference was statistically significant(P<0.05).On the 7 mm section,the difference between the two was(-2.92045±1.87723)mm,the difference was statistically significant(t=-10.320,P<0.05);the corresponding bone cortical density in the distal part of the mandibular first molar was greater than the mesial bone density in the 7 mm section,and the difference was statistically significant(P<0.05).The corresponding buccal area of the distal part of the first molar is larger than that of the mesial buccal area,and the difference was statistically significant(P<0.05).In the 7 mm section,the difference between the two was(-31.37045±24.06154)mm~2,and the difference was statistically significant(t=-8.684,P<0.05).Conclusion For adult patients with skeletal classⅢ,if implantation of anchorage screws between the roots of the mandibular posterior teeth is considered,the mesial and distal positions of the mandibular first molars can be selected.If implantation outside the alveolar ridge is considered,the distal region of the first molar should be preferentially selected,and the cortical bone near the bottom of the vestibular groove is relatively dense.