A Correlation Of Changes Between Dental Arch And Craniomaxillorfacial Morphology On Skeletal Class ? Adults Treated With Premolars Extraction

Objective: This study aims to know about the relation between changes of dental arch and craniomaxillorfacial morphology by investigating and analysising the changes of dental arch and craniomaxillorfacial morphology on skeletal Class II patients treated with premolars extraction,in order to provide the evidence for treatment in clinical.Methods: Admission criterion of 20 skeletal Class II patients in permanent dentition treated with extraction is deduced strictly,who is between 18-38 years old(mean age26±5.2 years),with ANB between 5°-9°(mean ANB 6.5±1.49°),with SN-MP between 29°-39°(mean SN-MP 35.03±4.23°).14 females,6males were selected.Record models and X-ray cephalometry films before and after treatment were measured by the following variables:dental arch length(UL?UL1/2/3?LL?LL1/2/3),dental arch width(UW?UW1/2/3?LW?LW1/2/3),the depth of the curve of Spee,the variables of craniomaxillorfacial morphology(ANB??SN-MP??U1-NA??L1-NB??L1-MP??L6-MP??L7-MP? the line distance of Ul-NA?L1-NB?L1-MP?L6-MP and L7-MP?ANS-Me/N-Me?BOP?FOP?AOP?POP et al.).The modle and cephalometric data were analyzed statistically by using SPSS17.0 software.Paired t-test was applied to analyze the differences of the modle and cephalometric data before and after treatment.the correlation coefficients between the changes of the dental arch and craniomaxillorfacial morphology were analysed with Pearson correlation analysis.Results:(1)After skeletal Class II treated with premolarss extraction,SNA?ANB??U1-NA??U1-SN,the line distance of Ul-NA?L1NB?L1MP?FOP?POP ?OP-dif decreased,the difference is statistically significant before and after treatment(P<0.05).?SN-MP??U1-L1??L1-MP??L6-MP??L7-MP?the line distance of L6MP?L7MP,lower face height?face height ?ANS-Me/N-Me?BOP?AOP increased,the difference is statistically significant before and after treatment(P<0.05).(2)After skeletal Class IItreated with premolars extraction,UW1?UL1and LL3 increased,the difference is statistically significant before and after treatment(P?0.05).UL2?UL?LL2?LL?UW2?UW3?LW3 and the depth of the curve of Spee decreased,the difference is statistically significant before and after treatment(P<0.05).(3)Aftrer treatment,the change of the line distance of Ul-NA are negatively correlated with the change of UL2.The changes of the depth of the curve of Spee are correlated with the change of LL2?LL3?POP and OP-dif.ANS-Me/N-Me is positively correlated with ?SN-MP and the line distance of L6 MP and L7 MP.Conclusions:(1)Teeth and phatnomas has great changes,while craniomaxillorfacial morphology has no change as before,When skeletal Class II adults treated with premolar extraction.The sagittal relation of maxilla and mandible trend to be better,Upper and lower anterior teeth have retraction,the lower teeth are upright,the inclinations of FOB and POP are redused,the mandibular plane angle and the lower face hight have not been oberseved increased obviously.(2)The upper canine width has increased,UL and LL have decreased,the curve of Spee has been leveled better after treatment.(3)Skeletal Class II adults treated with premolar extraction,the change of the line distance of Ul-NA are negatively correlated with the change of UL2.The changes of the depth of the curve of Spee are correlated with the change of LL2?LL3?POP and OP-dif.ANS-Me/N-Me is positively correlated with ?SN-MP and the line distance of L6 MP and L7 MP.