| ObjectiveThe purpose of this study is to assess the cant of occlusal plane in adultclass III malocclusions with the different vertical skeletal patterns by using the x lateral cephalograms.compare the different of the cant of occlusal plane with different vertical skeletal patterns, understand its class Ⅲ malocclusions occlusal plane characteristics, and determine the correlation of these parameters with the vertical skeletal patterns. in order to provide ideas and strategies basis for orthodontics orthognathic treatment of class Ⅲ malocclusions.MethodsA total of119class Ⅲ malocclusions adult patients and36normal occlusal individuals with a x-ray scan were enrolled from department of orthodontic of tianjin stomatology hosptial, aged from18to30years old, which met the selection criteria. The subjects were divided into three groups according to the mandibular plane angle and the ratio of between the posterior face height and the anterior face height. The low-angle group comprised of36subjects (20male,16female), the average-angle group comprised of49subjects(29male,20female), the high-angle group group comprised of34subjects(18male,16female). While36cases selected individual normal occlusal individuals (20males,16females), as a control group.The captured image measurement and analysis software to import the head shadow winceph8.0(Rise Corporation, Japan) to measure the posterior and anterior occlusal plane inclination, dentition height and axial inclination of teeth, upper and lower jaw relative to the skull base position. Morphological analysis of the characteristics occlusal plane inclination.SPSS20.0(Statistic Package for Social Science) was used to compare the differences,the parameters among the different vertical skeletal pattern. All the values are statistically analysed by the means of SPSS20.0. The statistical methods used in this study are One-way ANOVA and multiple comparisons between groups (LSD), Pearson correlation analysis, which used to compare the differences of the cant of occlusal plane with different vertical skeletal patterns,and determine the correlation of these parameters with the vertical skeletal pattern.Results1. The posterior and anterior occlusal plane angles of the155cases were compared by t test.there was no significant difference (P>0.05) between men and women, so men and women will be discussed merger.2. The feature of normal occlusal plane inclination:the mean of posterior occlusal plane angle was12.69±3.86°, anterior occlusal plane angle was9.06±2.69°and maxillary occlusal plane was8.82±2.45°.3. The occlusal plane inclination features of different vertical facial types class Ⅲ malocclusions:The occlusal plane inclination of different vertical facial types class Ⅲ malocclusions were different. In the high-angle group, the mean of anterior occlusal plane angle was9.26±4.55°and the mean of posterior occclusal plane angle was15.47±4.38°.In the average-angle group, the mean of anterior occlusal plane angle was8.95±3.42°and posterior occlusal plane angle’s was9.67±3.43°. In the low-angle group, the mean of anterior occlusal plane angle was7.74±3.66°and posterior occlusal plane angle’s was8.20±3.78°.4. The comparison of posterior occlusal plane angle between the normal occlusion group and the different vertical facial types of class Ⅲ malocclusions exists a highly significant difference (P<0.05). There was no significantly statistical differences (P<0.05)in posterior occlusal plane between the normal group and the class III high-angle group. But the posterior occlusal plane of the normal group was steeper than the average-angle group’s and the low-angle group’s (P<0.05).There was no significant difference in anterior occlusion plane (P>0.05). The incilination of class III high-angle group’s posterior occlusal plane was steeper than the average group’s and the low-angle group’s (P<0.05), but there was no significant difference in anterior occlusion plane (P>0.05).5. Correlation analysis showed that in class Ⅲ malocclusions,in sketeal,anterior occlusion plane was correlated with mandibular plane angle, mandibular ramus height and overall length (Co-Gn)(P<0.05),while posterior occlusion plane and mandibular plane angle, mandibular angle, mandibular ramus height and overall length (Co-Gn) are closely related (P<0.05). in teeth, anterior occlusion plane and U1-FH, U1-PP, U5-PP,L7-MP closely related (P<0.05), posterior occlusion plane and U1-PP, U6-PP, U7-PP, U6-FH closely correlation (P<0.05).6. Correlation analysis showed posterior occlusal plane with representatives of the mandibular position (SNB, APDI, Y-axis angle) had a significant correlation (P<0.01), with representatives of the mandibular sagittal position (SNB angle) was negatively correlated (r=-0.378, P<0.00), and a negative correlation APDI values (r=-0.256, P<0.01), a positive correlation was with the Y-axis angle (r=0.481, P<0.000). anterior occlusal plane angle and mandibular position no significant correlation (P>0.05).Conclusion1. Class III malocclusion occlusal plane less inclination than normal level. For different vertical facial types class III occlusal plane inclination after study shows that:class III high-angle group occlusal plane angle were compared with class III group, the low-angle occlusal plane flat. But with the normal occlusal plan angle no significant difference.2. Different vertical facial types class Ⅲ occlusal plane with the maxillary-mandibular dentition vertical height and axial inclination of teeth, bone parameters were significantly correlation. the results suggest that patients can change the maxillary and mandibular teeth vertical height,inclination,so as to achieve occlusal plane control.3. There is a possible relationship between the inclination of the maxillary posterior occlusal plane and mandibular position, consistent with the etiology of different vertical skeletal patterns. Thus, a more comprehensive etiologic approach based on the inclination of the maxillary posterior occlusal plane should be considered in the correction of the classⅢmalocclusion. |
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