Relationship Of The Position Between The Mandibular Anterior Teeth With The Alveolar Bone By CBCT

Objective:Teeth are not arranged vertically in the alveolar bone, but have a certain inclination direction and the inclined angle.In our clinical work, we found that the inclination direction of mandibular anterior teeth and alveolar process of maxilla front there is a certain angle.To provide a reference for the aesthetic treatment of mandibular anterior,this study explore the positional relationship between the long axis of the mandibular anterior teeth with the long axis of the alveolar bone through measuring mandibular anterior’s CBCT imaging of the adult population in Shandong Province with complete mandibular dentition.Methods:Selected from150cases(all75cases of men and women, ages of19-48years old) of oral CT image library in Stomatology Hospital of Shandong University from December2012to December2013and divided into six groups:male’s mandibular central incisor,male’s mandibular lateral incisor,male’s mandibular canine,female’s mandibular central incisor,female’sn mandibular lateral incisor;female’s mandibular canine.The angle(partial tongue is positive, negative bias lip) that the long axis of the mandibular anterior teeth relative to the long axis of alveolar bone bias lip/tongue side、crestal thickness、alveolar ridge thickness、the shortest distance from the apical to the labial cortical plate and the shortest distance from the apical to the lingual cortical plate were measured and recorded.Three measurements of each item, taking an average of the final measured value.The data obtained were used SPSS19.0statistical package for descriptive statistics,and P<0.05was considered statistically significant.Results:(1)Line distance measurement results:The averaged crestal thickness、alveolar ridge thickness、the shortest distance from the apical to the labial cortical plate、the shortest distance from the apical to the lingual cortical plate of the male’s mandibular central incisor were6.54mm、7.51mm、3.36mm、3.36mm.The male’s mandibular lateral incisor were7.28mm、8.19mm、3.67mm、4.72mm.The male’s mandibular canine were9.11mm、10.61mm、4.61mm、6.19mm.The averaged crestal thickness、 alveolar ridge thickness、the shortest distance from the apical to the labial cortical plate、the shortest distance from the apical to the lingual cortical plate of the female’s mandibular central incisor were6.16mm、6.72mm、2.83mm、4.13mm.The female’s mandibular lateral incisor were6.86mm、7.35mm、3.28mm、4.26mm.The female’s mandibular canine8.34mm、9.17mm、3.70mm、5.68mm.(2)Angle measurement results:The averaged angle that the long axis of the mandibular anterior teeth relative to the long axis of alveolar bone bias lip/tongue side of the male’s mandibular central incisors、lateral incisors、canines were4.77°、6.12°、5.01°, and the female’s averaged angle were5.38°、5.81°、6.21°.The angle that tend to lingual was no more than20°,and the angle of deflection labial was not exceeded10°.There was significant difference between men and women in the β angle of the mandibular canine(P<0.05).(3)Gender differences:There was significant differences between men and women in crestal thickness、alveolar ridge thickness、the shortest distance from the apical to the labial cortical plate、the shortest distance from the apical to the lingual cortical plate of the mandibular central incisors、lateral incisors、canines(P<0.05).There was no significant differences between men and women in the angle of the mandibular central incisors、lateral incisor(P>0.05).There was significant difference between men and women in the β angle of the mandibular canine(P <0.05).Conclusion:The inclination direction of mandibular anterior teeth and alveolar process of maxilla front was different.The angle that tend to lingual was no more than20°,and the angle of deflection labial was not exceeded10°,and gender differences exist among the mandibular canine area.The mandibular alveolar ridge thickness from mandibular central incisor、 mandibular lateral incisor、mandibular canine thickening sequentially,and so is the mandibular crestal thickness.The shortest distance from the apical to the lingual cortical plate is greater than or equal the shortest distance from the apical to the labial cortical plate.The crestal thickness、alveolar ridge thickness、the shortest distance from the apical to the labial cortical plate、the shortest distance from the apical to the lingual cortical plate have gender differences.The CBCT’s data that measured in the sagittal plane can provide the positional relationship between the mandibular anterior teeth and alveolar bone and provide a reference for the aesthetic treatment of mandibular anterior teeth.