Lip Positional Changes Associated With Upper Incisor AP Correction

Signature Grand, Davie, Florida, USA

Objectives. Determination of any predictable relationship (ratio) of these changes in Caucasian patients was the Objective of this study. Methods. Pre- and post-orthodontic lateral cephalograms from de-identified records of 37 (18 male, 19 female) Caucasian private orthodontic practice “non-extraction” patients (mean age = 14 yrs, 5mos) who originally presented CL I minimal crowding or slight CL II malocclusions were traced, analyzed and compared. UL and LL positions were determined by linear measures from E line. Upper incisor (U1) incisal edge position was measured linearly perpendicularly from NP plane and from E plane. Results. Statistical analysis showed that with a mean retraction of UI-E of 3.30mm, the UL-E retracted by a mean of 1.7mm and LL-E 1.65mm (p < 0.001). For every one mm retraction of U1-NP, UL-E reduced 0.68mm and LL-E 0.65mm (p < 0.05). Conclusion. From this study one can conclude that in Caucasian patients of this age group, one mm upper incisor retraction will result in approximately 1/2mm reduction in lip procumbency; a ratio of 2:1.