Change Of The Dentai And Basai Bone Arch Forms And Soft And Hard Tissue In Patient With Skeletal Class Ⅲ And Permanet Dentition By Nonextraction

Objective The aim of this article is to study the change of dental and base bone arch,soft and hard tissue before and after orthodontic treatment by non-extraction of skeletal Class Ⅲ malocclusion in permanent dentition.Methods The sample consisted of pretreatment and posttreatment models and laterral cephalometric radiograph obtained from 10 skeletal Class Ⅲ malocclusion in permanent dentition with non-extraction treament.Their ages ranged from 13 to 26years(mean age,18.3±5 years),SNA angle mean(80.7±2.5)°,SNB angle mean(84.0±3.0)°,-4°≤ ANB ≤-1°,SN-MP angle mean(29.9 ±7.4)°.Measure the length of dental arch and basal bone,intercanine,interpremolar,intermolar area width of dental arch and basal bone,cephalometry of craniofacial items,measurements were analyz-ed by SPSS version 17.0.Paired t-test and Pearson correlation analysis were used.P-value less than 0.05 was considered a statistically significant level.Results(1)Change of craniofacial soft and hard tissue:after treament ∠ANB increased,upper anterior teeth libial inclination and lower anterior teeth lingually inclination(P≤0.05).∠FCA,∠B’-LL-FH,H angle and the distance of UL-E increased(P <0.05),∠A’-UL-FH and Z angle induced(P<0.05).(2)Correlation of soft and hard tissue:after treament a negative correlation between the change of ∠U1-NA/∠U1-SN and ∠FCA,∠NLA were found.The change of∠L1-NB/∠L1-MP was positively correlated with the change of LL-E.(3)Change of dental arch form:after treament the front lenght of upper arch and lower intermolar width were significant increased(P < 0.05).The width of upper intercanine,interpremolar,intermolar and lower intercanine,first interpremolar were significant reduced(P<0.05).(4)Change of basal bone arch form:after treament upper basal bone arch lenght and lower intermolar width were significant increased(P < 0.05).The lenght of lower basal bone arch and the width of upper intercanine,second interpremolar,intermolar were significant reduced(P<0.05).(5)Correlation of dental and basal bone arch form:after treament a postive correlat-ion between the change of dental arch width and basal bone arch width,especially in maxillary second interpremolar intermolar and mandibular intercanine areas.(6)Correlation between dental,basal bone arch form and soft,hard tissue:after treament a positive correlation between the length of upper dental arch and∠U1-NA/∠U1-SN,UL-E(P<0.05).The length of upper dental arch and NLA,L1 and ∠B’-LL-FH were found negative correlation(P<0.05).Conclusions(1)After non-extraction orthodontic treament of skeletal Class Ⅲ malocclusion inpermanent dentition,ANB angle increase,tip the relationship between maxillary and mandibular tend to be coordinated.Upper anterior teeth and ∠NLA,∠FCA were negatively correlated.Lower anterior teeth positively correlated with LL-E.Further prove it can controll the upper and lower anterior teeth labial inclination,to improve positive and profile esthetics.(2)The change of dental arch width and basal arch width was found a positive correlation between lower intercanine area,upper second interpremolar area,upper intermolar area,after non-extraction orthodontic treament of skeletal Class Ⅲmalocclusion in permanent dentition,tip dental arch form can cause base bone reconstruction.Then,it can coordinate the relationship between maxillary and mandibular by tooth and dental arch compensatory change.