上颌切牙单一斜行复杂冠根折折断形态和位置的锥形束CT研究

Research on the cone-beam CT of the fracture morphology and location of a single oblique complicated crown-root fracture of maxillary incisors

目的通过锥形束CT全面了解单一斜行复杂冠根折的形态学规律及其与牙周硬组织的相对位置关系,为临床提供参考。方法收集2015年1月至2019年1月就诊于首都医科大学口腔医学院急诊综合诊疗中心的56例上颌恒前牙单一斜形复杂冠根折患者初诊锥形束CT影像学资料,对56颗患牙的折断形态、折断角度、折断深度和折断宽度,以及折断线与邻面牙槽嵴顶的相对位置进行回顾性分析。采用独立样本t检验比较折断角度、折断深度和折断宽度在不同性别和牙位之间的差异,比较不同牙位患牙折断前后冠根比;将患牙按患者年龄发育阶段分为少年组(≤18岁)、青年组(19~34岁)及中老年组(≥35岁),用单因素方差分析比较折断角度、折断深度和折断宽度在不同年龄组间的差异,Fisher确切概率法比较患牙折断形态和折断线与邻面牙槽嵴顶相对位置的差异。结果56例患者中男性35例,女性21例,年龄(28.2±13.2)岁。少年组19例,青年组14例,中老年组23例。56颗患牙中上颌中切牙46颗,侧切牙10颗。46颗患牙(82%)折断形态为S形走行,10颗(18%)为斜线形走行,S形折断线的折断角度(47.85°±10.02°)显著大于斜线形(28.30°±8.07°)(P<0.001)。98%(55/56)的病例折断最低点平齐牙槽嵴顶和位于牙槽嵴顶以下。少年组折断深度[(1.75±0.73)mm]显著大于青年组[(1.21±0.68)mm](P=0.042)和中老年组[(1.12±0.90)mm](P=0.001)。56例患者的折断宽度为(4.75±1.44)mm,不同性别、不同年龄组和不同牙位的折断宽度差异均无统计学意义(P>0.05)。上颌中切牙折断后的冠根比(1.18±0.13)与上颌侧切牙(1.14±0.20)相比差异无统计学意义(t=1.90,P=0.373)。结论单一斜行复杂冠根折的折断形态主要为S形走行和斜线形走行;折断最低点绝大部分位于腭侧骨下2.0 mm以内。

Objective To study the morphological pattern of single oblique complex crown fracture and its relative location to periodontal hard tissues from a three-dimensional perspective by using cone-beam CT,which provides a more intuitive and comprehensive understanding for the pathological features and rules of single oblique complex crown fracture.Methods Primary cone-beam CT images of 56 maxillary permanent anterior teeth with oblique complex crown root fractures were collected from the Department of Integrated Emergency Dental Care,Capital Medical University School of Stomatology during January 2015 to January 2019.Fracture pattern,fracture angle,fracture depth,fracture width,and the relative location of the fracture line to the crest of the adjacent alveolar ridge were retrospectively analyzed.Independent samples t-test was used to compare the differences in angle,depth and width of fractures between sexes and tooth locations,as well as the pre-and post-fracture crown-to-root ratios between different tooth locations.Then the affected teeth were divided into juvenile group(≤18 years),young group(19-34 years)and middle-aged and elderly group(≥35 years).One-way ANOVA was applied to compare the differences in angle,depth and width of fracture between age groups,and Fisher exact test to compare the differences in fracture pattern of the teeth and the relative position of the fracture line to the crest of the adjacent alveolar ridge.Results There were 35 males and 21 females in 56 patients,aged(28.2±13.2)years.Among the 56 affected teeth,forty-six were maxillary central incisors and 10 were lateral incisors.According to the patients′age and growing stage,they could be divided into the juvenile group(19 cases),the young group(14 cases),and the middle-aged and elderly group(23 cases).Forty-six(82%)affected teeth had an S-shaped fracture pattern,and ten(18%)had a diagonal pattern,in which the fracture angle of the S-shaped fracture line(47.85°±10.02°)was significantly greater than that of the diagonal line(28.30°±8.07°)(P<0.001).The fracture nadir was flush with or below the top of the alveolar crest in 98%(55/56)of cases.The fracture depth was significantly greater in the juvenile group[(1.75±0.73)mm]than in the young group[(1.21±0.68)mm](P=0.042)and in the middle-aged and elderly group[(1.12±0.90)mm](P=0.001).The width of fractures among 56 patients was(4.75±1.44)mm,which had no statistically significant differences between different age,sex and tooth location groups(P>0.05).There were no statistically significant differences in the crown-to-root ratios after fracture of maxillary central incisors(1.18±0.13)compared to maxillary lateral incisors(1.14±0.20)(t=1.90,P=0.373).Conclusions The fracture patterns of single oblique complex crown fracture were mainly S-shaped and oblique alignment;the fracture nadir was mostly located within 2.0 mm below the palatal alveolar crest.