Correlation Between The Anteroposterior Relationship Of Dental Arch And Skeletal Jaw Base In Wuhan (Chinese) Population

AIMS AND OBJECTIVE:1. To determine the anteroposterior dental arch relationship and the anterioposteriorskeletal jaw base relationship in Wuhan (Chinese) population with class I, class IIand class III malocclusion and then correlate the association between the sagittaldental arch and the skeletal jaw base relationship.2. To compare between different measurements associated with determining theanteroposterior dental arch and skeletal jaw base relationship.3. To determine the distribution of dental and skeletal malocclusion in Wuhanpopulation.MATERIALS AND METHODS: Lateral cephalometric radiographs, intraoral and extraoral photographs and the orthodontic casts of472untreated orthodontic patients withpermanent full dentition till first molar was collected from the Department ofOrthodontics of Wuhan Union Hospital, Wuhan, China. Then the anteroposterior dentalarch relationship was determined by Angle’s Classification i.e. maxillary and mandibular first permanent molar relationship from the intraoral photographs and the orthodonticcasts. Anteroposterior skeletal jaw-base relationship was determined by ANB Angle,WITS Appraisal and Beta Angle from the lateral cephalometric radiographs. Theanteroposterior relationship of dental arch and skeletal jaw-base were then compared.RESULT: Classification of the anteroposterior dental arch relationship of the472samplepatients on the basis of Angle’s classification of malocclusion showed54%had class Imolar relationship,25%had class II molar relationship and21%had class III molarrelationship.Classification of the anteroposterior jaw base relationship of the472sample patientsassessed by ANB angle showed70.76%had class I skeletal relationship,16.10%hadclass II skeletal relationship and13.13%had class III skeletal relationship. According toWITS Appraisal62%had class I skeletal relationship,16.94%had class II skeletalrelationship and20.33%had class III skeletal relationship. According to BETA Angle73.72%had class I skeletal relationship,11.44%had class II skeletal relationship and14.83%had class III skeletal relationship.Cephalometric analysis of lateral cephalographs of the sample patients showed meanvalue of ANB Angle was2.72°±3.00, mean value of WITS Appraisal was-2.37mm±3.90and mean value of BETA Angle was36.13°±6.30.Independent t-test was done to compare the mean value of472sample patients assessedby ANB Angle, WITS Appraisal and BETA Angle for male and female which showed that there was no significant difference in mean value assessed by ANB Angle, WITSAppraisal and BETA Angle for male and female group.One-way ANOVA was done to analyze the significance of the mean value of ANB Angle,WITS Appraisal and BETA Angle between three molar groups which showed statisticallysignificant differences in the mean value of ANB Angle, WITS Appraisal and BETAAngle across three molar groups (p<0.001).Pearson correlation test analyzing the correlation between ANB angle, WITS Appraisaland BETA angle values in different molar groups were highly significant statistically.Mc Nemmar test shows that there was uneven distribution of different skeletal classesamong the molar classes and also distribution of different molar classes among theskeletal classes was uneven as well. Kappa coefficient showed that there is staticallysignificant agreement between the molar classes and skeletal classes (p<0.0001) assessedby ANB Angle and BETA Angle and less statically significant agreement between themolar classes and skeletal classes (p<0.001) assessed by WITS APPRAISAL.When measured by ANB Angle,56.35%of472sample patients had identicalanteroposterior dental arch and skeletal jaw-base relationship. When measured by WITSAppraisal,54.66%of472sample patients had identical anteroposterior dental arch andskeletal jaw-base relationship. When measured by BETA Angle,57.20%of472samplepatients had identical anteroposterior dental arch and skeletal jaw-base relationship.In molar class I group (256sample patients),78.12%(200sample patients) werecategorized as skeletal class I as assessed by ANB Angle and67.96%(174sample patients) were categorized as skeletal class I as assessed by WITS Appraisal whereas80.46%(206sample patients) were categorized as skeletal class I as assessed by BETAAngle.In molar class II group (116sample patients),27.58%(32sample patients) werecategorized as skeletal class II as assessed by ANB Angle and39.65%(46samplepatients) were categorized as skeletal class II as assessed by WITS Appraisal whereas22.41%(26sample patients) were categorized as skeletal class II as assessed by BETAAngle.In molar class III group (100sample patients),34%(34sample patients) werecategorized as skeletal class III as assessed by ANB Angle and38%(38sample patients)were categorized as skeletal class III as assessed by WITS Appraisal and BETA Angle.In molar class II group (116sample patients),3.44%(4sample patients) were categorizedas skeletal class III by ANB Angle and WITS Appraisal whereas5.17%(6samplepatients) were categorized as skeletal class III by BETA Angle.In molar class III group (100sample patients),12%(12sample patients) werecategorized as skeletal class II as assessed by ANB Angle and6%(6sample patients)were categorized as skeletal class II as assessed by WITS Appraisal and4%(4samplepatients) were categorized as skeletal class II as assessed by BETA Angle.CONCLUSION: Angle’s classification of dental malocclusion does not reflect the trueanteroposterior skeletal jaw-base relationship. The result of this study shows that only around one half of the anteroposterior dental arch relationship coincides with theunderlying skeletal jaw base relationship.Among the measurements means used to assess the anteroposterior jaw base relationship,BETA angle shows the highest correlation or agreement between the anteroposteriordental arch and skeletal jaw base relationship followed by ANB angle and then WITSAPPRAISALMost common dental malocclusion in Wuhan population was molar class I (54%)followed by molar class II (25%) and then molar class III (21%) malocclusion.Most common skeletal malocclusion in Wuhan population determined by ANB Anglewas skeletal class I (70.76%) followed by skeletal class II (16.10%) and then skeletalclass III (13.13%) malocclusion where as by WITS Appraisal it was skeletal class I (62%)followed by skeletal class III (20.33%) and then skeletal class II (16.94%) malocclusion.Similarly by BETA Angle the most common malocclusion was skeletal class I (73.72%)followed by skeletal class III (14.83%) and then skeletal class II (11.44%) malocclusion.