A Preliminary Study On The Width Of Dental Arch And The Mechanism Of Malocclusion In Mixed Dentition Children

Objective: The aim of this study was to compare the width of upper and lower dental arch between different Angle classification in mixed dentition children,analyze and investigate the role of dental arch width in the mechanism of malocclusion and the affecting factors of the development of dental arch width in Angle class ? malocclusion,so as to provide guidance for accurate and precise diagnosis in orthodontic treatment.Methods: 502 samples were selected from the Department of Stomatology of the first affiliated Hospital of Dalian Medical University(Xigang District),the Department of Stomatology of the second affiliated Hospital of Dalian Medical University(Shahekou District),the Department of Stomatology of Zhongshan Hospital affiliated to Dalian Medica University(Zhongshan District)and the Department of Stomatology of Dalian Youyi Hospital(Zhongshan District)from May to October,2019.They were divided into Angle Class ? group(mean age 8.34±0.69 years),Class ? group(mean age 8.39±0.70 years)and Class ? group(mean age 8.41±0.91 years).The Inter-first molar width(posterior arch width),inter-first primary molar width and inter-first premolar width(middle arch width),inter-primary canine width and intercanine width(anterior arch width)in maxillary and mandibular dental arch were measured on the study model of the selected samples,the transverse difference of anterior,middle and posterior arch width of each group was calculated,and the results were imported to SPSS23.0 statistical software.Mean and standard deviation of 9 measurement items in each group were calculated,variance analysis was used to evaluate the differences among groups,t-test was used to evaluate gender differences between groups.The role of dental arch width in the mechanism of Angle Class ? and Class ? malocclusion was measured,and multiple regression analysis was used to evaluate the correlation between dental arch width and mouth breathing habits,sucking,feeding habits and dental caries in Angle Class ? malocclusion.Results: The mean and standard deviation of arch widths in 502 mixed dentition children were obtained;In different Angle classification subgroups,the arch width of male was generally larger than that of female,statistical difference were only found in the posterior segment of maxillary and mandibular dental arch of Angle Class ?(P < 0.05);The maxillary arch width of Angle Class ? malocclusion was narrower than that of Angle Class ? malocclusion,and there was significant difference in the posterior segment of upper dental arch(P < 0.05);The maxillary arch width of Angle Class ? malocclusion was narrower than that of Angle Class ? and Class ? malocclusion(P < 0.05),and there was significant difference in anterior and posterior arch width(P < 0.05).The width of mandibular dental arch was larger than that of Angle Class ? and Class ?,but there was no significant difference(P > 0.05);The transverse difference of posterior arch of Angle Class ? malocclusion was significantly smaller than that of Angle Class ?(P < 0.05);The difference of anterior,middle and posterior arch width of Angle Class ? malocclusion was significantly smaller than that of Angle Class ? and Class ?(P < 0.05);The width of maxillary anterior arch was affected by sucking habits in the subjects with Angle Class ? malocclusion(p < 0.05),but there was no significant difference in others.Conclusion: 1.The average and standard deviation of the width of upper and lower dental arch in 502 children with different Angle classification were obtained.2.Compared with Angle Class ?,the maxillary arch width of Angle Class ? malocclusion was narrower,while the mandibular arch width is normal;The maxillary arch width of Angle Class ? malocclusion was narrower,while the mandibular arch width is usually larger.3.Maxillary dental arch width deficiency is common in Angle Class ? and Class ? malocclusion.Attention should be paid to the coordination of dental arches in clinical practice,in order to promote normal growth and development of upper and lower jaw,which would be beneficial to stable therapeutic effect.4.Sucking habits are one of factors affecting the width of maxillary anterior arch of Angle Class ?.Preventive and interceptive orthodontic treatment should be provided in circumstances affecting the development of Angle class ? dental arch width.