The Dimension And Morphology Of Alveolar Bone At Maxillary Anterior Teeth In Periodontitis:a Cone-beam Computed Tomography Evaluation

Objective:This study used cone-beam computed tomography(CBCT)to evaluate the morphology of alveolar bone at maxillary anterior teeth in periodontitis,in order to investigate the distribution of alveolar bone defects for guiding clinical practice.Methods:According to the inclusion and exclusion criteria,90 periodontitis patients and 30 periodontally healthy individuals were collected in 2011-2016.CBCT was used to determine the morphology of alveolar bone at maxillary anterior teeth according to the degree of bone loss,teeth type,gender and age.Relevant measurements included the level of alveolar bone loss,alveolar bone thickness,percentage of teeth with buccal undercut,buccal undercut location and depth,percentage of teeth with fenestration,angulation between long axis of teeth and alveolar process,apical bone height.SPSS 24.0 was used to compare the difference of the dimension between periodontitis patients and healthy individuals,analyze the distribution of alveolar bone defects.A classification was established by comparing the buccal and lingual bone thickness at the mid-root level into type B,M,P,N.Comparing the angulation of the alveolar process with the long axis of the root was classified into type 1,2,3.Results:1.The difference of alveolar bone morphology between periodontitis patients and healthy individuals:there was a statistical difference between two groups(P<0.05).(1)Buccal and lingual residual bone thickness:The buccal bone thickness in periodontitis patients with bone loss was thicker while the lingual bone thickness was thinner than healthy individuals.(2)Buccal undercut and fenestration:Compared with healthy individuals,the buccal undercut location in periodontitis patients was close to alveolar ridge.The percentage of teeth with buccal undercut was differed in the degree of bone loss,which was lower in severe bone loss group.The percentage of fenestration in periodontitis patients was lower than healthy controls.(3)Angulation between long axis of teeth and alveolar process,apical bone height:Compared with healthy individuals,the angle was small and the apical bone height was large in periodontitis patients.In severe bone loss group,the angle was the smallest and the apical bone height was the largest.2.Analysis of the degree of alveolar bone defects at maxillary anterior teeth with periodontitis:The degree of bone loss differed in the teeth type and sites(P<0.05),the degree of lateral incisor bone defects was higher.At the incisors,mesial and distal bone loss was significantly greater than buccal and lingual,no statistical difference was found between the sites of canine.There was no statistical difference in the degree and distribution of bone loss between two sexes(P>0.05)but there was a statistical difference among different age groups(P<0.05).Age<30 years exhibited more mild bone loss,the proportion of moderate and severe bone loss in age>40 years increased3.Analysis of the alveolar bone morphology at maxillary anterior teeth with periodontitis in teeth type,gender and age subgroups:(1)Buccal and lingual residual bone thickness the buccal thickness in canine group was thinner while the lingual thickness in lateral incisor group was thinner.The buccal bone in incisors was thicker at apical level,and the lingual bone of all teeth type increased along the apical direction.It was found that male demonstrated larger thickness compared with female.Age<30 years group buccal bone was thinner while lingual bone was thicker.(2)Buccal undercut and fenestration:The lateral incisor had the highest incidence of buccal undercut and was close to alveolar ridge.However the percentage of buccal undercut and fenestration in central incisor was lower.The incidence of buccal undercut in female who demonstrated a deeper undercut was higher.(3)Angulation between long axis of teeth and alveolar process,apical bone height:The angle was larger but the apical bone height was smaller in canine.The apical bone height of age>40 years group was larger than age<30 years group4.Analysis of the sagittal root position related to the alveolar process in healthy controls and periodontitis patients:Regarding the positions of the maxillary anterior teeth,most were type B.Type M,P and N gradually increased with the aggravation of bone loss Comparing relative position between the long axis of the teeth and the alveolar process,healthy individuals,mild and severe bone loss group were mainly type 2,moderate bone loss group was mainly type 3,only three cases of severe bone loss group existed type 1Conclusions:The morphology of alveolar bone at maxillary anterior teeth was differed between periodontitis patients and healthy individuals,which was related to the degree of bone loss.The buccal bone thickness in periodontitis patients was thicker than healthy individuals while the lingual bone thickness was thinner.Regarding the positions of the maxillary anterior teeth in healthy individuals,most were type B which positioned more buccally.Type M,P and N gradually increased with the aggravation of bone loss.The percentage of fenestration was reduced and the apical bone height was higher in periodontitis patients.The morphology of alveolar bone in periodontitis was related to teeth type,gender and age.According to the distribution of alveolar bone defects could provide guidance for the subsequent treatment of periodontitis.