The Early Effect Of OMT To Class ? Division 1 Malocclusion With Perioral Muscle Dysfunction

Objective:The perioral muscle dysfunction is mutually affected the development of malocclusion,and interceptive orthodontics is often recommended for that with the Angle's class ? division 1.The aim of this study was to comprehensively evaluate the therapeutic effects of MRC used for oral myofunctional therapy to class ? division 1 malocclusion with perioral muscle dysfunction in growing individuals by investigating the three-dimensional changes of hard tissue and improvements of soft tissue profile and perioral muscle function,so as to provide a reference for the clinical application of MRC.Methods:43 patients were included in the study in total.23 patients,aged 8.0±0.89 years,were selected as the treatment group who were Angle's class ? division 1 with perioral muscle dysfunction.All patients in treatment group were required to wear MRC and taught to train perioral muscle function every day.Another 20 patients,aged 8.1±0.83 years,were selected as the control group who were Angle's class ? division 1 and no treatment was given.Perioral muscle functions were examined at the initial state(T1)and 12 months later(T2)in treatment group while both groups were taken the record models and the lateral cephalograms at the same stages.The measurement items of the record models included 3 occlusal relation indexes(occlusion relation of molars,overbite and overjet),6 arch width indexes and 4 arch length indexes.The measurement items of lateral cephalograms included 13 hard tissue indexes to evaluate the growth and relationship of the maxilla and mandible and the rotation of the mandibular and occlusal plane.3 soft tissue indexes to evaluate the change of profile.SPSS 24.0 software was used to horizontally compare the differences between groups and longitudinal compare the changes within groups,so as to comprehensively analyze the improvement of perioral muscle and the changes in the three-dimensional direction of hard tissue and profile.Results:1.In the treatment group,the results of hard tissue measurement showed that the values of ANB,U1-SN and Po-NB decreased,while the values of SNB,L1-MP,FH-MP,NP-FH,Go-Po and Co-Go increased,all the changes were statistically significant(P<0.05).SNA,SNB,NP-FH,Po-NB,ANS-Ptm,Go-Po and Co-Go values significantly increased(P<0.05)in control group.SNA,SNB,ANB,U1-SN,Po-NB and ANS-Ptm were found to have a significant difference between two groups(P<0.05).NLA increased and UL-E decreased in the treatment group(P<0.05),while LL-E increased in the control group(P<0.05).Changes in NLA,UL-E and LL-E between groups were statistically significant(P<0.05).2.Both the anterior and middle width increased in the upper and lower arch in treatment individuals.The anterior length decreased in the upper arch,which increased in lower.Overbite and overjet were decreased,and the occlusion relationship of molars was improved.Differences of these indexes in longitudinal comparison within groups and the horizontal comparison between groups were both statistically significant(P<0.05).Posterior width of lower arch was significant increased after treatment,while the difference of magnitude between groups was not obvious.3.Six in eight patients with open lips obtained labial closure at the natural state after treatment with statistically significant changes(P=0.032)and both two patients with buccal sucking habit had broken down.The correction rate of inferior tongue position was 87%in twenty-three patients and showed significant difference(P=0.005).Conclusion:MRC used for OMT demonstrates effective changes at the malocclusion of class? division 1 with perioral muscle dysfunction:1.MRC can correct the class ? division 1 malocclusion effectively.In the sagittal direction,the imbalance between the maxilla and mandible was reduced by means of restricting the growth of maxillary protrusion and length and improving the growth of mandibular protrusion.Overjet was improved by moving lower dentition forward,retroclinating upper incisors and proclinating lower incisors.In the horizontal direction,MRC can effectively expand the anterior and middle width to increase oral space inside dentition.In the vertical direction,MRC improved the deep overbite and achieved the better occlusion.2.MRC can effectively correct the open lips,the buccal-sucking habits,and the inferior tongue position.The profile was improved by increasing nasolabial angle and decreasing the protrusion of the upper and lower lips after treatment.