The Correlation Analysis Of The Changes In Dental Arch Form And Buccal Corridor And Lateral Profile By Extraction Treatment With Skeletal Class ? Malocclusion

Objective The firstly aim is to study the change of the dental arch forms with skeletal class?malocclusion after extraction treatment;The secondly aim is to analysis the relationship between the changes of the dental arch form and buccal corridor and lateral profile after treatment.Methods Selected 15 cases permanent dentition patients of skeletal class? malocclusion(10 cases of women,5 cases of men),aged from 12 to 28 years(mean age,17.60±5.08years),79°?SNA angle ?90°(Mean 83.5±3.56°),73°?SNB angle ?85°(Mean 77.53±3.43°),5°?ANB angle ?9°(Mean 5.76±1.08°),26°?SN-MP angle ?43°(Mean 35.93±5.27°).All patients were treated by extraction treatment with straight wire appliance,according to the design requirements adopt anchorage,such as implant anchorage and transpalatal arch or intermaxillary traction.Research models and lateral cephalgrams and frontal smile photographs were taken before and after treatment.Analyzed the changes of the profile hard and soft tissues bycephalometric technique.Use vernier calipers and Adobe Photoshop CS6 software to measure and analyze dental arch forms and frontal smile before and after treatment.SPSS20.0 statistical software paired test for the measured data,and Pearson correlation analysis was used for correlation analysis.Results(1)After orthodontic treatment,?SNA??SNB and ?ANB were decreased,?U1-NA was decreased,?NLA was increased,UL-E and LL-E were reduced,which differences was statically significant(P<0.05).(2)After treatment,the width of the dental arch in the middle and posterior segment of the maxillary was decreased,and the width of the dental arch in the posterior segment of the mandibular was decreased,the entire length of dental arch and the posterior segment was decreased in the maxillary and mandibular,which differences was statically significant(P<0.05).(3)The distance between the corners of the mouth and buccal corridor width and buccal corridor ratio was increased,the visible dentition in maxillary was decreased,but all the differeces was not statically significant(P>0.05).(4)The changes of the entire length in the maxillary arch dental was positively correlated with the changes of UL-E,The changes of the entire length in the mandibular arch dental was positively correlated with the change of the LL-E and ?L1-NB;The width of the middle segment of the arch dental in maxillary and the width of the anterior segment of the mandibular arch dental were negatively correlated with the width of the buccal corridor and the buccal corridor ratio.The changes of the distance between the corners of the mouth was negatively correlated with ?U1-NA and UL-E,it was positively correlated with ?SNA.The width of buccal corridor was negatively correlated with the?L1-NB.The buccal ratio was negatively correlated with ?L1-NB(P<0.05).Conclusions(1)Skeletal class ? malocclusion after extraction treanment,The sagittal disalignment of the upper and lower jaw was improved to some and the upper and lower front teeth and upper and lower lip were effectively adduced.(2)the width of the dental arch in the middle and posterior segment of the maxillary and mandibular was decreased,the entire length of dental arch and the posterior segment was decreased in the maxillary and mandibular.If the width of the middle segment of the arch dental in maxillary decrease,the buccal corridor will be increse when smile.However,the changes of the buccal corridor were influenced by multiple factors,such as the width of the arch dental,the inclination of the anterior teeth,the protrusion of the upper lip and the sagittal position of the jaw.Therefore,the increase of buccal corridor is not the certain result of tooth extraction treatment.(3)There is a positive correlation between the changes of the total length of the arch dental and the change of the upper and lower lip protrusion.It prompt that the effective anchorage control of skeletal class ? malocclusion in orthodontic treatment is the basis for the reconstruction of craniofacial soft and hard tissue and the coordination and beauty of the patient's orthodontic appearance.