Three-dimensional Evaluation For Age-related Changes In Lip Morphology Of Adolescents With Normal Occlusion In Shandong Province By CBCT Reconstruction

ObjectiveFacial esthetics has become a key motivation for people to seek orthodontic intervention along with the development of modern society. Knowledge on the age-related morphologic changing of the nasolabial tissues is the basis for a successful aesthetic improving treatment, which is essential in the treatment planning and time control. Given there seemed to be no sufficient data or comprehensive investigations on the 3D changing of the nasolabial region for the Chinese till now, a systematic description of the lip morphology remained to be established urgently. In this study, we aimed to evaluate the age- and sex- related changing of lip morphology for elder children, adolescents and young adults with normal occlusion in Shandong Province by three-dimensional reconstruction of CBCT (cone-beam computed tomography) images.Materials and MethodsCBCT images of 144 cases (75 males and 69 females, aged from 9 to 26 years) were strictly selected from patients with near normal occlusion and normal lip morphology, who required CBCT examinations as part of their clinical diagnosis and treatment. These CBCT images were three-dimensionally reconstructed to assess changing of the width, length and thickness of lip morphology. Statistical comparisons of these changes among different groups in both sexes were made with SPSS 19.0.Results1. Age and sex related changes of the horizontal measurementsThe horizontal measurements in orolabial region increased from late childhood to young adulthood for both sexes, and the involved values for males kept larger than for females. During young adulthood, these measurements kept more stable for females than for males.For males, obvious increase was observed for width of the basenose between 9-10 (34.42±0.38mm) and 11-12 (36.92±0.38mm) yrs; and for breadth of oral fissure, VBb-width, VBc-width and VBd-width between 11-12 (46.39±0.66mm; 40.22±0.74mm; 37.06±0.63mm; 25.93±1.01mm) and 13-14 (47.96±0.33mm; 41.47±0.39mm; 40.19±0.67mm; 29.04±0.43mm) yrs. For females, obvious increase was observed for basenose width between 9-10 (33.22±1.03mm) and 13-14 (37.01±0.73mm) yrs, breadth of oral fissure and VBb-width between 11-12 (44.29±1.50mm; 37.40±0.91mm) and 13-14 (46.47±0.94mm; 38.76±1.01mm) yrs, as well as for VBc- and VBd-width between 11-12 (36.67±1.41mm; 26.44±0.89mm) and 17-18 (38.44±0.53mm; 28.31±0.54mm) yrs.2. Age and sex related changes of the vertical measurementsFor males, significant decrement in lower cutaneous lip height, total lower lip height and total lip height were noted between 9-10 (9.86±1.03mm; 17.95±1.01mm; 37.56±1.08mm) and 11-12 (8.38±0.87mm; 16.31±0.85mm; 36.35±0.78mm) yrs. The growth spurt occurred at 17-18 yrs in total lower lip height and total lip height (19.58±0.75mm; 41.58±0.57mm). For females, similar growth patterns to the males were observed, except for a slight increment for lower cutaneous lip height between 15-16 (8.43±0.98mm) and 17-18 (9.33±0.41mm) yrs, for total lip height between 13-14 (35.27±0.62mm) and 15-16 (37.08±0.65mm) yrs, as well as a decrement for total lower lip height between 11-12 (16.29±0.85mm) and 13-14 (15.88±0.57mm) yrs. Besides, there was no significant sexual difference in total upper lip and height-width ratio. Minimal increment in total upper lip from late childhood to young adulthood was shown in both sexes.3. Age and sex related changes of the sagittal measurementsEarly increment of Ls-upperl thickness occurred in females between 9-10 (12.58±0.72mm) and 11-12 (13.14±0.65mm) yrs, which was followed with a four-year-decreasing before the final increasing growth since 15-16 (10.88±1.01mm) yrs period. The changing pattern in males was similar but two-years later than females. In addition, no significant difference was observed between the males and females in VBbr-Chr-Ch1 angle with a rapid increment at 9-10 (59.87±2.44°; 59.85±2.11°) yrs period and then a gradual decrement.ConclusionObvious changes of normal lip morphology from elder children to young adults in Shandong Province were investigated three-dimensionally. For elder children, adolescents and young adults, changing of normal lip morphology should be taken into consideration when diagnosing and making treatment plan, so as to achieve an optimal and aesthetic outcome.