The Study On Sensitivity Of Asethetic Index From Six Kinds Of Profile Soft Tissue Analysis Methods On Female Adult In Liaoning Province

Objective: The main purpose of this study is to explore the differences in the facial profile of female adult in Liaoning province among Individual normal occlusion("INO" group),Angle ? class bimaxillary protrusion malocclusion("A1" group),Angle class ?1 malocclusion("A2" group)and Angle class ? malocclusion("A3" group)patients by suing 6 kinds of soft tissue analysis(Ricketts analysis,Holdway analysis,Steiner analysis,Burstone analysis,Merrifield analysis,Epker analysis).In order to find a simple way for clinical orthodontists to classify and evaluate the pattern of facial profile of different class of malocclusion conveniently.Subjects and methods:According to the inclusive criteria,a total of 125 cases were included in this study,among which the control group of individual normal occlusion(30 cases in group INO)and the experimental group(35 cases in group A1,30 cases in group A2,30 cases in group A3)are totally 95 cases.All samples are taken Cone Beam CT(Cone Beam Computed Tomography,CBCT).Then transform the CBCT reconstruction data into cephalometric for the author's measurement(14 indicators from the six kinds of soft tissue analysis).Then in SPSS21.0 software,use one-way ANOVA or Kruskal-Wallis test(base on the distribution type of the cephalometric data)to compare the difference among all groups.Next perfomed stepwise discriminant analysis of multiple factors(Fisher's linear discriminator)to the 14 indicators,in order to screen out the most sensitive indicator and get the linear discriminant function to discriminate the facial profile from different class of malocclusion.Finally,performed the receiver operating curve(ROC)analysis to them for evaluation of their ability of discriminant.Results: There were significant difference among all groups in all measurements of 14 indicators.Four indicators(Bs-H line,H angle,LL-B line and Z angle)were screened out by Fisher's linear discriminator,which the most sensitive indicators to discriminate the facial profile from different class of malocclusion.According to their Youden index and the area under curve(AUC)of ROC,the most powerful for discrimination of group INO was the Fisher's linear discriminator from this study;the most powerful for discrimination between group A1 and group INO was LL-B line;the most powerful for discrimination between group A2 and group INO was Z angle;the most powerful for discrimination between group A3 and group INO was Bs-H line.Conclusions:The difference in measurement of indicator of soft tissue profile showed that the no influence to the position of lip and chin by maxillary or mandibular deficiency,but the maxillary or mandibular protursion will make a more forward position of lip and chin.This finding maybe suggested that the profile and development of soft tissue are independent to the skeletal development.Our study indicated that it is more powerful to evaluate the soft tissue profile which chose different indicator for different class of malocclusion.Four indicators(BsH line,H angle,LL-B line and Z angle)were screened out by Fisher's linear discriminator,which the most sensitive indicators to discriminate the facial profile from different class of malocclusion.Meanwhile,we also got the boundary value for discrimantion of different class of malocclusion.For the Angle ? class bimaxillary protrusion malocclusion,the most powerful indicator for discrimination is the LL-B line and its value should less than 5.85 mm if their facial profile is normal;For the Angle III class malocclusion,the most powerful indicator for discrimination is the Z angle and its value should larger than 69.85 degree if their facial profile is normal;For the Angle III class malocclusion,the most powerful indicator for discrimination is the Bs-H line and its value should less than-2.25 mm if their facial profile is normal.Consideration of the accuracy rate(93.3%)of our Fisher's linear discriminator for discrimination of individual normal occlusion,we recommend that using our Fisher's linear discriminator to evaluate the soft tissue profile of patients who finished orthodontic treatment.