A Study Of Mandibular Asymmetry In Adolescent Orthodontic Patients

Objective:In this experiment,we spotted and measured on both sides of the mandible in orthopantomography,using Habet’s method to calculated the condyle height,ramus height and the total mandible vertical height’s asymmetry index(AI),to studied the symmetry of mandible in adolescent orthodontic patients and to explored the possible etiology of the pathogenic factors,provide some help for the early prevention,diagnosis,and treatment of mandibular asymmetry.Methods:200 cases of 9-16-year-old adolescent patients who hospitalized in the Departments of Orthodontics the Affiliated Stomatology Hospital of Kunming Medical University from 2015 to 2017 were collected.When the patient first went to the Orthodontics department,the professional orthodontic doctor carried out a detailed clinical examination and inquiry,the patient’s basic condition,dentition type,malocclusion type,whether the patients have bad oral habits were collected.Through the model analysis,record the width of the mandibular and maxillary arch.All of the patients took orthopantomography and X-ray cephalometric imaging examination under the same condition by the same Department of Radiology physician.And the same orthodontic doctor measured and analyzed the patient’s condyle and ramus asymmetry index.In SPSS 19.0 software,using X2 test to compared the difference of asymmetry index in different types of dentition,sex,malocclusion,bad oral habits and caries.Results:1.50.50%of the 200 cases of adolescent orthodontic patients in this study appeared asymmetry in condylar height or ramus height of the mandibular,the incidence of the MA has no significant difference between gender and age.But the incidence of female is slightly higher than male.2.There was significant difference of the prevalence rate in different types of Angle malocclusion patients.In all malocclusions,the incidence of mandibular asy-mmetry is highest in AngleⅢ,then in Angle Ⅱ,the lowest in Angle Ⅰ.3.There was no significant difference in the incidence of MA in patients with different vertical skeletal patterns.4.The inharmonious of the mandibular and maxillary arch widths have a significant correlation with the occurrence of MA.5.There were significant differences in the incidence of MA between patients with different occlusal disturbances and those with individual normal occlusion.The incidence of MA in patients with different malocclusion was different,in descending order:unilateral posterior crossbite,unilateral posterior crossbite,anterior crossbite,deep overbite,deep overjet,open bite.6.For oral bad habits,there was no significant difference in the MA prevalence of between biting lips or buccal,thumb sucking and no obvious bad habits.There was statistically significant difference in the MA prevalence of patients with mouth breathing,unilateral chewing with no obvious bad habits.7.The incidence of MA was significantly different between patients with dental caries and no caries,and the incidence of MA was significantly higher when caries occurred in the teeth of occlusal function surfaces or the first molar.Conclusions:1.MA is very common in mixed dentition and early permanent dentition adolescents with a high prevalence rate.2.The occurrence of MA in adolescent orthodontic patients is caused by multiple factors.3.The incidence of MA had no significant difference in age and gender,but the incidence of female is slightly higher than male,which may be related to the female entering the peak period of growth and development earlier.4.The inharmonious of the mandibular and maxillary arch widths is a risk factor of MA.5.MA is closely related to occlusal factors.Occlusions that affect the mandibular movement,such as unilateral posterior crossbite,unilateral posterior crossbite,anterior crossbite etc,are all the risk factors of MA.6.Among oral bad habits,bite lips and buccal,mouth breathing and unilateral chewing during the day relate to the MA pathogenesis.7.Caries is a risk factor of MA,especially when the caries occurred in the teeth of occlusal function surfaces or the first molar.