Evaluation Of Orthodontic Treatment Outcome Of Angle ? Malocclusion Type Tooth Extraction And Non-tooth Extraction Using PAR Index And Cephalometrics

Objective:In this study,through review of finished cases of Angle ? malocclusion treated with tooth extraction and non-tooth extraction methods,by applying PAR index and X-ray cephalometric measurements to evaluate the after-treatment soft and hard tissue changes of the two methods,to confirm bones,teeth and soft tissue variables that are contributed to the treatment plan.This can be as a reference for developing treatment plan and specifying indications for the related type of patients.Methods:1.To perform PAR index scoring for plaster models of 42 patients that meet the inclusion criterias.Analyzing level of malocclusion improvement between the two methods.2.To perform cephalometric analysis base on x-ray films of the 42 patients pre and after treatment.This includes measurements of 10 hard tissues:SNA(°),SNB(°),ANB(°),U1-SN(°),U1-NA(°),L1-NB(°),U1-NA(mm),L1-NB(mm),U1-L1(°),MP-FH(°),and 10 soft tissues:FH-N'Pm',Pm-Sn,upper lip sulcus depth,Sn-H line spacing,upper lip base thickness,U1-Ls,H angle,Li-H line spacing,chin-lip sulcus depth and Pog-Pm'.It is intented to study the sensitive indicators that play an important role before the development of orthodontic plans for the related type of cases.Results:1.PAR index measurement and analysis results:before treatment,the median,tooth dislocation and total score of the two groups were showing difference(P<0.05).The total scores before treatment were 13.45±1.82 and 10.05±1.73 respectively.No difference was found between the two groups(P>0.05).After treatment,the score of the extraction group is reduced compare to the score of pre-treatments(P<0.05).Grouping by correction effect,it is observed that 2 cases(9.09%)were having significant improvement while 20 cases(90.91%)were improved.None case was getting worse or having no improvement.Meanwhile after treatment,the score of the non-extraction group is also reduced compare to the score of pre-treatments(P<0.05).Grouping by correction effect,it is observed that 1 case(5%)was having significant improvement while 19 cases(95%)were improved.None case was getting worse or having no improvement.2.Results of hard tissue measurement for pre and after treatment:the two groups were not having indicator difference before treatment.After treatment,the U1-SN(°),U1-NA(°)and L1-NB(mm)were lower than the non-extraction group(P<0.05).U1-L1(°)in the extraction group was higher than the non-extraction group(P<0.05).The difference is statistically significant.After extraction,L1-NB(°),U1-SN,U1-NA(°)and L1-NB(mm)were lower than pre-treatment(P<0.05).U1-L1 was higher compare to pre-treatment(P<0.05).By comparing pre and after treatment,no difference was observed for the indexes of non-extraction group(P>0.05).3.Results of soft tissue measurement for pre and after treatment:the upper lip groove depth and U1-Ls were higher in the extraction group than in the non-extraction group(P<0.05).Sn-H line distance,Li-H line distance and Pog-Pm'after orthodontic treatment were lower than non-extraction group(P<0.05).U1-Ls was larger compare to non-extraction group(P<0.05).H-angle and Li-H line spacing of the extraction group were showing difference for both pre and after treatments.H-angle and Li-H line distance after treatment were lower than pre-treatment(P<0.05).Difference was found for non-extraction group in terms of FH-N'Pm',upper lip groove depth,Sn-H line distance,H angle and Pog-Pm'.FH-N'Pm',the upper lip groove depth,Sn-H line distance and Pog-Pm' after treatment were found higher compare to pre-treatment(P<0.05).The H angle was found lower compare to pre-treatment(P<0.05).Conclusion:1.For patients with Angle ? malocclusion type,to apply both tooth extraction and non-tooth extraction methods can help to improve malocclusion condition.2.Sensitive indicators of soft and hard tissues that help to assist in the development of the correction plan should include:U1-SN(°),U1-NA(°),L1-NB(°),U1-NA(mm),L1-NB(mm),U1-L1(°),upper lip groove depth,U1-Ls,H angle and Li-H line spacing.When the measured value of U1-L1(°)is smaller compare to normal value while the measured value of other indicators is larger,then it is more likely to adapt extraction treatment method and vice versa.