The Comparative Analysis Of Compensatory Tilt Of Upper And Lower Anterior Teeth With Different Vertical Skeletal Profiles In Patients With Anterior Crossbite

Objective Through the cone beam CT study of anterior crossbite patients with different vertical skeletal profiles,the correlation between compensatory tilt of anterior teeth and mandibular angle of anterior crossbite patients was compared,so as to achieve reasonable design and formulation of orthodontic schemes for patients with different vertical skeletal profiles.Methods The untreated anterior crossbite patients in the department of Orthodontics of the hospital from September 2016 to December 2017 were divided into three groups according to the size of FMA: high angle type(group A),equal angle type(group B)and low angle type(group C).Twenty patients were randomly selected from each group,with a total of 60 patients aged 18-30 years.CBCT was taken before orthodontic treatment,and the data were transmitted to Invivo Dental 5.0 software for measurement.The measurement items include:(1)FH/MP;(2)U1/PP;(3)U1/NA;(4)L1MP;(5)L1/NB;(6)the root angle of upper and lower incisor;(7)BCest(mm);(8)BCest-3(mm);(9)BCest-6(mm);(10)BApex(mm);(11)LCest(mm);(12)LCest-3(mm);(13)LCest-6(mm);(14)LApex(mm).SPSS 21.0statistical software was used for statistical analysis.All data were analyzed by one-way ANOVA(x ±s).The difference of measurement data was compared between the three groups.The test level was ?=0.05,P > 0.05,the difference was not statistically significant,P < 0.05,the difference was statistically significant.Results(1)The lip inclination of incisors in group A was lower than that in group B and group C.The differences of U1/PP,U1/NA,L1/MP and L1/NB were significant(P<0.05),in group A were lower than those in group B and group C,and those in group B were lower than those in group C,the difference was statistically significant(P < 0.05);`(2)The root angles of upper and lower incisors in group Awere compared with those in group A,B and C,the difference was significant(P < 0.05).Group A was larger than group B and group C,and group B was larger than group C,the difference was statistically significant(P < 0.05);(3)Compared with group A,B and C,there were significant differences in Bcest,Bcest-3,BApex,Lcest-3 and LApex in the thickness of alveolar bone(P < 0.05).The results showed that group C was larger than group A and group B,and group B was larger than group A;(4)Compared with groupA,B and C,the differences of Bcest,Bcest-6,Lcest-3 and LApex in the thickness of alveolar bone in group A were significant(P < 0.05).The results showed that group C was larger than group A and group B,and group B was larger than group A.Conclusions Compared with the equal angle group and the high angle group,the upper and lower anterior teeth in the low angle group had more lip inclination,and the relationship between the long axis of the upper and lower anterior teeth was more upright than the other two groups.The upper and lower incisors in the low angle group had thicker alveolar bone thickness on the lip and tongue side of the upper incisors,so the requirements for torque and root control were more relaxed during the treatment.In the process of clinical diagnosis and treatment,we should consider both sagittal and vertical relations,so as to achieve a more comprehensive diagnosis and treatment plan.