| Objective: The study aims to evaluate the alveolar bone morphology of the upper and lower central incisors in skeletal Class Ⅲ adults with different vertical facial types before orthodontic treatment,and to analyze the correlation between the alveolar bone morphology and the vertical patterns,and the correlation between the alveolar bone morphology and the inclination of the lower central incisors,thereby improving the reliability and safety of clinical diagnosis and treatment,and reducing the occurrence of periodontal complications such as iatrogenic bone fenestration,bone dehiscence and root resorption.Methods: From June 2020 to June 2022,142 adult patients with skeletal Class III malocclusion who were hospitalized at Hospital of Stomatology Lanzhou University were selected to undergo CBCT.The data was imported into Dolphin11.95 software for head position calibration and three-dimensional reconstruction.According to mandibular plane angle(MP-FH),the patients were divided into low angle(44),average angle(53),and high angle(45).The absolute and relative cancellous bone thickness,total alveolar bone thickness and corresponding area of the labial and lingual sides at different locations,such as 3 mm,6 mm,9 mm below the CEJ,middle of the root and apex of the root of the bilateral maxillary central incisors and bilateral mandibular central incisors were measured by using Dolphin software to evaluate the alveolar bone morphology.Statistical analysis was conducted using SPSS software to compare the differences of the alveolar bone morphology among the three groups and to analyze the correlation between alveolar bone morphology and vertical facial types,and the relationship between alveolar bone morphology and inclination of lower incisor.Results:Comparison of relative and absolute alveolar bone thickness at different levels of the lower central incisor indicated that in the apical region,the thickness of labial alveolar bone,the thickness of lingual alveolar bone,and the relative thickness of alveolar bone in patients with high angle were thinner than those in patients with average angle and low angle,and there were statistically significant differences(P <0.05).Comparison of alveolar bone area of lower central incisor indicated that there were significant differences in the areas of labial and lingual cancellous bone,cortical bone,and total alveolar bone area among high,average,and low angle patients.Except for lingual cortical bone,the areas of other alveolar bone in high angle patients were lower than those in low and average angle patients,and there were significant differences in the areas of labial cancellous bone,labial cortical bone,labial alveolar bone,lingual cancellous bone among high angle patients compared to those in average and low angle patients(P < 0.05).Comparison of relative and absolute alveolar bone attachment heights of the lower central incisors indicated that there were differences in the labial alveolar bone attachment height and relative alveolar bone attachment height among the three groups of patients,with the order of high angle > average angle > low angle,and the alveolar bone of the patients with high angle was in a lower position.Compared with the average angle and the high angle,the root is more wrapped by alveolar bone in the low angle,and there is a statistical difference(P < 0.05).Difference in inclination of lower incisors indicated that there were differences in inclination of lower incisors at high,average,and low angles,in the order of high angle < average angle < low angle,and there was a statistical difference between patients with high angle and patients with average and low angle(P < 0.05).Comparison of relative and absolute alveolar bone thickness at different levels of the upper central incisor indicated that the thickness of labial cancellous bone and labial alveolar bone of upper central incisors in patients with high angle were thicker than those in patients with low angle and average angle at the apex of the root,where there was a statistically significant difference(P < 0.05).The lingual cancellous bone thickness,lingual alveolar bone thickness,and relative alveolar bone thickness of upper central incisors in patients with high angle were thinner than those in patients with low angle and average angle at 3 mm below CEJ,where there was a statistically significant difference(P < 0.05).Comparison of alveolar bone area of upper central incisor indicated that the areas of lingual cancellous bone in high angle patients were lower than those in low and average angle patients,and there were statistical differences in lingual cancellous bone in high angle patients compared to average and low angle patients(P < 0.05).The lingual alveolar bone of high angle only had a statistically significant difference compared to the average angle(P < 0.05).The labial cancellous bone area and labial alveolar bone area of patients with high angle were larger than those of patients with low angle,and there was a statistical difference compared to those of patients with low angle(P < 0.05).Comparison of relative and absolute alveolar bone attachment heights of upper central incisors indicated that there was a difference in the height of labial alveolar bone among the three groups of patients.The attachment height of the alveolar bone at the buccal side of the high angle was higher than that at the average angle,which meant that the alveolar bone wrapped the root shorter,with a statistically significant difference in the high angle compared to the average angle(P < 0.05).Correlation between the alveolar bone morphology of the lower central incisor and the vertical facial types and inclination of the lower incisor showed that with the increase of the vertical facial types,the inclination of the lower incisors tended to decrease,the height of the alveolar bone decreased,and the thickness and area of the alveolar bone gradually decreased.Correlation between alveolar bone morphology of upper central incisor and vertical facial types and inclination of lower incisor showed that most indicators of alveolar bone morphology of upper central incisor had no correlation with inclination of lower incisor.The vertical facial type was only significantly negatively correlated with the thickness of lingual cancellous bone in the middle of the root.The relative thickness of the upper central incisor,as well as the thickness and area of the lingual alveolar bone,decreased with the increase of the vertical facial type.Conclusion: The alveolar bone morphology in the upper and lower central incisors of patients with different vertical patterns in skeletal Class III has some compensation.As the vertical facial surface type increases,the inclination of the lower incisor decreases,the height of the alveolar bone of the lower central incisor decreases,and the thickness and area of the alveolar bone gradually decreases.The relative thickness of the upper central incisor,as well as the thickness and area of the lingual alveolar bone,decreases.Therefore,before orthodontic treatment,physicians should make full use of CBCT to have a full understanding of the tooth and alveolar compensation of patients with different vertical facial types of skeletal Class III,in order to avoid risks and avoid a series of problems such as bone fenestration and bone descience better,so as to ensure the patient’s periodontal health. |
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