Study On The Correlation Between The Morphology And Position Of Tongue And The Morphology Of Palate In AngleⅡ Division 1 Patients With Mandibular Retrusion

Objective:The tongue and palate are important structures of the oral and maxillofacial system,which have an important influence on the ventilation of upper airway and facial beauty.Generally,the tongue is located in the palate space,and its shape is in harmony with it.Because of mandibular retraction,the tongue and palate may change adaptively in Angle Ⅱ~1patients.At present,there are different conclusions about the morphology of tongue and palate in AngleⅡ~1patients,and the correlation between them is not clear.In this study,we measured the morphological and position of tongue and palate of AngleⅡ~1patients with mandibular retraction after taking lateral cephalometric and CBCT.To understand the mechanism of this kind of malocclusion from the aspect of tongue and palate and the correlation between them.The aim is to provide a theoretical basis for better clinical diagnosis and treatment of such malocclusion.Methods:25 adult patients in AngleⅡ~1with mandibular retraction,who were treated in the orthodontic department of the first Hospital of Shanxi Medical University from December 2016 to June 2018,were included as the case group,including 10 males and15 females,with an average age of 22 years.Twenty-five adult patients with individual normal occlusion were selected as control group,including 13 males and 12 females,with an average age of 21.5 years.The same imaging physician photographed the patient’s lateral cephalogram and CBCT.Lateral cephalography was used to measure the position and morphology of the tongue.Mimics17.0 software was used to measure the palatal morphology after three-dimensional reconstruction of the patient’s CBCT data.SPSS22.0 software was used to analyze the data,and two independent samples t-test was used to analyze the differences of the indexes of tongue and palate between individual normal occlusion and AngleⅡ~1patients,and the correlation between the indexes of tongue and palate of AngleⅡ~1patients was examined by Pearsom correlation analysis.Results:1.T test results:(1)The difference of palatal morphology between the two groups:the middle palate length and total palate length of Angle Ⅱ~1patients were longer than those of individual normal occlusion(P<0.05)。The lingual inclination angle of maxillary first premolar and first molar was larger than that of individual normal occlusion(P<0.05).(2)Differences in position and shape of tongue between the two groups:The tongue height of AngleⅡ~1patients was higher than that of individual normal occlusion(P<0.05),and there were significant differences in TDP1,TDP2,TDP3 and tongue horizontal position between the two groups(P<0.05).It is suggested that the tongue position of Angle Ⅱ~1patients is posterior to that of individual normal occlusion.2.Pearson correlation test between tongue and palate in Angle Ⅱ~1patients:The vertical position of tongue was positively correlated with the maximum palatal height in AngleⅡ~1patients(r=0.503,P<0.05).TDP2,an index representing the position of tongue relative to hard palate,was positively correlated with the maximum palate height(r=0.475,P<0.05).The tongue inclination of the maxillary first premolar was positively correlated with the horizontal position of the tongue(r=0.527,p<0.05)and negatively correlated with the vertical position of the tongue(r=-0.530,p<0.05).The lingual inclination of maxillary first molar was positively correlated with the tongue horizontal position(r=0.488,P<0.05),and negatively correlated with the tongue vertical position and the tongue relative to TDP2(r=-0.644,-0.552,P<0.05).It is suggested that the lingual position is related to the increase of lingual inclination and palatal height of maxillary posterior teeth.There was no significant correlation between the other measurements.Conclusion:1.The narrow and long palate of Angle Ⅱ~1patients is concentrated in the middle and posterior part.The transverse difference is mainly caused by the lingual inclination of the maxillary posterior teeth.2.The tongue position of Angle Ⅱ~1patients was lower than that of individual normal occlusion,and the tongue height was higher.3.In the AngleⅡ~1,the morphology of the tongue of the patients may be related to the position of the tongue,and it is not related to the morphology of the tongue.