| Objective: The aims of this study is to evaluate the relationship between the esthetic profile and the sagittal distance between the upper incisor(UI)and the anterior nasal spine(ANS)to provide the basis for repositioning UI,including two aspects: 1.To verify the sagittal stability of the anterior nasal spine in the adult before and after orthodontic treatment.2.To study the aesthetic evaluation of the sagittal distance between the upper incisor and the anterior nasal spine on profile.Methods: This study including two parts:1.Verification of the stability of the anterior nasal spine:53 adult patients who had completed the whole orthodontic treatment,were selected,and the distance from the ANS to the pterygomaxillary fissure(Ptm)and the angle of the ANS-Ptm line between the true horizontal(HOR)were comparesd before and after orthodontic treatment,to verify the sagittal stability of the anterior nasal spine.2.The aesthetic evaluation of the UI-ANS sagittal distance on profile: Experienced orthodontists evaluated photographs of males and females who had completed orthodontic treatment,and selected the most attractive photographs.With the help of VTO(visual treatment objective)in Dolphin,move UI on the HOR and these photographs were edited to simulate the profiles at different UI-ANS sagittal distances on the HOR.9 male and female profile photographs were coming into being separately,and perceived by orthodontists and laypersons.This aim of this part was to evaluate the relationship between the adult esthetic profile and UI-ANS sagittal distance,and to explore the range of UI-ANS sagittal distances corresponding the aesthetic profile.Results:1.The length of ANS-Ptm in pretreatment was 50.67±0.96 mm,and in posttreatment was 50.61±0.45 mm.The angle of the ANS-Ptm line between HOR in pretreatment was 4.37±0.53°,and in postpretreatment was 4.75±0.53°.No significant differences were found for the ANS-Ptm distances and the angle between the ANS-Ptm and HOR during orthodontic treatment(P>0.05).2.For male profile,orthodontists gave the highest evaluation to M7 with the change of UI-ANS sagittal distance at(±0 mm),and laypersons gave the highest evaluation to M1 with the change of UI-ANS sagittal distance at(-1 mm)(P<0.05).For female profile,orthodontists and laypersons gave the highest evaluation to the F7 with the change of UI-ANS sagittal distance at(±0 mm)(P<0.05).3.Evaluated by the professional group,the aesthetic male profile photographs were M1(-1 mm)?M7(±0 mm)?M8(-2 mm),and the corresponding UI-ANS sagittal range was-0.76 mm ~ 1.24 mm;the aesthetic female profile photographs were F3(+1 mm)?F4(+2 mm)and F7(±0 mm),and the corresponding UI-ANS sagittal range was-1.87 mm~0.13 mm.Conclusion:1.The stability of the anterior nasal spine in sagittal was verified.In the process of adult orthodontic treatment,its sagittal position did not have changes.Therefore,the anterior nasal spine is a stable anatomical structure,and can be used as a reference point for the assessment of the convexity of the upper central incisors.2.In the analysis of gender group,comparing with female profile,both the professional group and non-professional group tended to male with plump profile,and the UI position was more forward referring to the ANS.In clinical treatment,the location of UI should be considered according to the gender of the patients.3.In the analysis of professional group,both the professional group and the non-professional group agreed on the female profile with more straight profile,and tended to locate UI in the rear of ANS.In male profile,professional group and non-professional group tend to locate UI in front of ANS,but non-professional tend male with more straight profile,and UI positioning is closer to ANS.In clinical treatment,orthodontics should communicate well with the patients,and have acquaintance with the aesthetic needs of the patients,helping make the treatment planning. |
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