Comparison Of Normal Occulusion Arch Forms And Basal Bone Between Uyghur And Han Populations

Introduction:The aim of this study was to compare the mandibular dental arch form and the mandibular basal bone arch form of Uyghur with Han subjects.Methods:The sample included 50 Uyghur subjects(23 males and 27 females)and 50 Han subjects(26males and 24 females).The Uygur group was composed of Uygur students from Xinjiang Medical University.There were 23 males(mean age 21.46 ±1.24)and 27 females(mean age 21.25 ±1.63 years old).The Han nationality group was composed of Han nationality students from the School of Stomatology of Lanzhou University.There were 26 males(mean age 22.29 ±1.49 years old)and 24 females(mean age 22.37 ±1.58 years old).There was no significant difference in age and sex ratio between the two groups.Impressions were taken with alginate materials and then infused into plaster casts.The electronic digital vernier digital caliper(accuracy is 0.02mm)was used to measure the dental arch length,width and basement width.Measurement items consist of FA3:the distance between the bilateral canines FA points,FA6: the distance between the bilateral first molars FA points,WALA3:the distance between the bilateral canines WALA points,WALA6:the distance between the bilateral first molars WALA points,mandibular intercanine width(W3):the distance between the cusp tips of the right and left mandibular canines.,mandibular intermolar width(W6): the distance between the centra fossa of the right and left first mandibular molars,mandibular intermolar width(D6): the distance between the mesiobuccal cusp tips of the right and left first mandibular molars,mandibular anterior arch length(L3): the vertical distance betwen the mesial contact point of the incisors and the connection of bilateral canines cusps,mandibular middle arch length(L5): the vertical distance betwen the mesial contact point of the incisors and the connection of the mesial contact point of bilateral first molars.Two weeks later,20 models were randomly selected for repeated measurement,and the intra-group correlation coefficient was more than 0.8.Error within acceptable range.The distances between corresponding points of intercanine and intermolar widths were analyzed and arch length were compared and also explored the relationship between arch and basal bone by using different crown landmarks.Results:1.Both ethnic incisors were negative from FA point to WALA point,and from canine to molar area were both positive,and from middle incisor to first molar.The difference gradually increased.It was suggested that the labial inclination of the incisors of the two peoples decreased gradually from the middle incisor to the lateral incisor,but from the canine to the lateral incisor,the teeth gradually tilted to the tongue.2.No matter what mark is adopted,the teeth arch of Uygur group is less than that of the Han group,and the difference is statistically significant(p < 0.01).There was no statistically significant difference between the two groups in the FA ratio,WALA ratio,and the distance between the width of the WALA ridge and the FA width in canine and molar regions(p > 0.05).3.In the canine region,the correlation between FA point and the basal bone was higher than that of the cusp and basal bone.Similarly,in the molar region,FA point was used as the mark point.Its correlativity with the basal bone was higher than that with the first molar mesiobuccal tip and the central fossa as the arch marker.4.There is no significant difference in arch length between the two groups(p > 0.05).The length of arch in the middle and posterior segments of Uygur group was smaller than that in the Han nationality group,and the difference was statistically significant(p < 0.05).Conclusions:There was a difference between the dental arch and the basal bone width of the Uyghur and Han nationality groups,especially in the molar area.Therefore,there are no arches that can be used simultaneously for both peoples.There was a high linear correlation between FA points and WALA points in the canine and molar regions of the two populations.Therefore,FA points are more suitable for individual arch design than other crown markers.The arch width,basal bone width and the length of the posterior arch in the Uyghur group were smaller than those in the Han group.For orthodontic treatment of Uyghur patients,the high elastic archwire used by Han patients should be modified.