| Objective CBCT was used to study the morphological characteristics of alveolar bone in mandibular central incisor with different inclination,which provided a reference for orthodontic treatment in the early stage of permanent dentition.Methods According to the inclusion criteria,90 patients,aged from 11 to 14 years with an average age of 12.80 years,were randomly selected from the department of orthodontics of affiliated hospital of Inner Mongolia medical university.And according to the inclination of mandibular central incisors L1-MP,they were divided into three groups: labial inclination group,normal group and lingual inclination group,with 30 people in each group.All subjects completed CBCT scanning within a certain period of time and under the same shooting conditions,and informed the patient of the purpose and content of the experiment and signed an informed consent form before shooting.CBCT data and 3D image processing software Invivo5.0 were used to complete the measurement of relevant indexes.The measurement items include: The thickness of alveolar bone on the labiallingual side of 1/3 near the neck of the root,1/3 in the middle of the root and apical part on the three measurement groups,and the attachment height of alveolar bone on the labial-lingual side.Besides,the occurrence of fenestration and bone dehiscence of mandibular incisors with different inclination were recorded.The SPSS18.0 statistical software was used to compare the thickness and height of alveolar bone in the mandibular incisor area and the incidence of fenestration and bone dehiscence in different inclination groups.To investigate whether there is a correlation between the alveolar bone morphology and the inclination of the mandibular incisors.The relevant variables were analyzed by pearson correlation test,and the test level was ?=0.05.Results 1.comparison of alveolar bone thickness:The thickness of alveolar bone of mandibular incisors with different inclination was significantly different.(1)1/3 near the neck of the root:(1)thickness of labial alveolar bone: The normal group was larger than lingual inclination group(P<0.05),but there was no obvious difference between normal group and labial inclination group,labial inclination group and lingual inclination group.(2)thickness of lingual alveolar bone: There was no significant difference among the three groups(P>0.05).(3)total thickness of alveolar bone: Normal group was larger than lingual inclination group(P<0.05),but there was no obvious difference between normal group and labial inclination group,labial inclination group and lingual inclination group.(2)1/3 in the middle of the root:(1)thickness of labial alveolar bone: The labial inclination group and the normal group were larger than the lingual inclination group(P<0.05),but the difference between the labial inclination group and the normal group was not obvious.(2)thickness of lingual alveolar bone: Normal group and lingual inclination group were larger than labial inclination group(P<0.05),but there was no significant difference between normal group and lingual inclination group.(3)total thickness of alveolar bone: There was no significant difference among the three groups(P>0.05).(3)apical part:(1)thickness of labial alveolar bone: The labial inclination group was the largest,lingual inclination group was the smallest,normal group was between the two groups(P<0.05).(2)thickness of lingual alveolar bone: The normal group was larger than the labial inclination group(P<0.05),but there was no obvious difference between the normal group and the lingual inclination group.(3)total thickness of alveolar bone: The labial inclination group and the normal group were larger than the lingual inclination group(P<0.05),but the difference between the labial inclination group and the normal group was not obvious.2.comparison of alveolar bone height: For the attachment height of labial alveolar bone,the labial inclination group and the lingual inclination group were larger than the normal group(P<0.05),but the difference between the labial inclination group and the lingual inclination group was not obvious.There was no significant difference in the attachment height of lingual alveolar bone among the three groups(P>0.05).3.correlation analysis: Inclination of mandibular central incisors was significantly positively correlated with the labial alveolar bone thickness of 1/3 in the middle of the root,the labial alveolar bone thickness of apical part,and the total thickness of apical part,which had a linear relationship(P<0.01).4.In the initial stage of permanent dentition without orthodontic treatment,the mandibular incisors also have bone fenestration and bone dehiscence.The occurrence of bone fenestration was mainly concentrated on the labial side,and the difference was statistically significant in different inclination groups(P<0.05).The incidence of bone fenestration was 13.33% in labial inclination group,20% in normal group and 56.67% in lingual inclination group.The lingual inclination group was the highest,while the normal group and labial inclination group were relatively small.Bone dehiscence occurred in both labial and lingual sides.The incidence of bone dehiscence in labial side was statistically significant(P<0.05)in different inclination groups.The incidence of bone dehiscence was 66.67% in labial inclination group,16.67% in normal group and 40% in lingual inclination group.The incidence of lingual bone dehiscence was 23.33% in labial inclination group,43.33% in normal group and 30.33% in lingual inclination group.There was no significant difference in the incidence of lingual bone dehiscence(P>0.05).Conclusion In the initial stage of permanent dentition without orthodontic treatment,alveolar bone morphology in mandibular central incisor is closely related to inclination of incisors.The labial alveolar bone thickness of 1/3 in the middle of the root,the labial alveolar bone thickness of apical part,and the total thickness of apical part are significantly positively correlated with the inclination of mandibular central incisors.Moreover,in the initial stage of permanent dentition without orthodontic treatment,alveolar bone defects also exist in the mandibular central incisors to a certain extent,and the incidence of bone fenestration and bone dehiscence are significantly different among different inclination groups.Bone dehiscence is easy to occur on the labial side of labial inclination group,and bone fenestration is easy to occur on the labial side of lingual inclination group. |
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