Analysis Of Upper Lip Profile Features In 300 Dentate Subjects Of Different Ages By Three-dimensional Measurement Of Cone Beam Computed Tomography

Objective By using cone beam computed tomography(CBCT)and three-dimensional measurements to analyze upper lip profile features in dentate subjects of different age groups in Chongqing,and to study the aging changes of upper lip profile features,so as to provide objective references for the facial esthetics in complete denture restoration.Methods Three hundred of dentate CBCT images were selected,which were divided into one of the following three groups by age:Youth Group(20 to 39 years),Middle-aged Group(40 to 59 years),Elderly Group(60 to 89 years),and one hundred cases in each group.The length of the upper lip and upper lip vermilion,the thickness of the upper lip were measured,and morphological analysis of the upper lip profile was performed.Results With aging,the upper lip became longer,and the exposure of upper lip vermilion,the thickness of the upper lip gradually decreased.Thedistance from the edge of upper incisor to the edge the upper lip in the three groups was(1.9622±1.1071)mm,(0.8353±1.2066)mm,and(0.0141±1.2256)mm,respectively.And the thickness of upper lip vermilion was(12.3558±1.9503)mm,(10.6342±1.7824)mm,and(9.9249±1.9514)mm,respectively.The gender differences in each group were compared,and the results showed that there was no significant difference in the thickness of upper lip between men and women in the young group.And the measurements of the length of upper lip and upper lip vermilion were not sufficient to indicate significant differences between men and women.In the middle-aged group,the thickness of upper lip vermilion(Ls-UP)was(11.6494 ± 1.6581)mm in male,which was greater than the measurement(9.7147 ± 1.3459)mm in female.The ratio of the thickness of middle lip to the thickness of base lip(Sm-Hm/Sn-A)in male was greater than that in female,which indicated that the thickness of middle upper lip and upper lip vermilion were greater in male than that in female,and there was no significant difference in the the length of upper lip and upper lip vermilion between men and women.In the elderly group,there were no significant differences in the length of the upper lip and upper lip vermilion,the thickness of the upper lip between men and women.According to morphological analysis of the upper lip profile,the upper lip profile was presented in four shapes:concave,straight,wavy andconvex.And there were differences between groups,the young group showed the largest proportion of concave(68%),the middle-aged group showed largest proportion of concave and straight(80%),and the elderly group showed largest proportion of wavy and convex(67%).Further research on the subjects in the elderly group showed that in the 60-69 age group,straight showed the largest proportion(36.4%);in the 70-79 age group,wavy showed the largest proportion(44.1%);and in the 80-89 age group,convex showed the largest proportion(63.6%).Conclusion According to the results of this study,during the aging process from youth to middle age to old age,the upper lip will gradually become longer,the exposure of upper lip vermilion will gradually decrease,the upper lip will gradually become thinner,and the lateral contour of the upper lip will also change in stages.The general trend is concave to straight to wavy and to convex at last.Therefore,the upper lip changes related to aging should be fully considered when complete denture restoration is performed for edentulous patients.When arranging artificial anterior teeth,we should pay attention to the distance from the edge of upper incisor to the edge the upper lip consistent with the patient's age.And when plumping up upper lip by complete denture,we should try to make the effect consistent with the dentate people of the same age.