Three-dimensional assessment of upper lip positional changes according to simulated maxillary anterior tooth movements by white light scanning

Abstract

ObjectiveEsthetic improvements during orthodontic treatment are achieved by changes in positions of the lips and surrounding soft tissues. Facial soft-tissue movement has already been two-dimensionally evaluated by cephalometry. In this study, we aimed to three-dimensionally assess positional changes of the adult upper lip according to simulated maxillary anterior tooth movements by white light scanning.MethodsWe measured changes in three-dimensional coordinates of labial landmarks in relation to maxillary incisor movements of normal adults simulated with films of varying thickness by using a white light scanner.ResultsWith increasing protraction, the upper lip moved forward and significantly upward. Labial movement was limited by the surrounding soft tissues. The extent of movement above the vermilion border was slightly less than half that of the teeth, showing strong correlation. Most changes were concentrated in the depression above the upper vermilion border. Labial movement toward the nose was reduced significantly.ConclusionsAfter adequately controlling several variables and using white light scanning with high reproducibility and accuracy, the coefficient of determination showed moderate values (0.40-0.77) and significant changes could be determined. This method would be useful to predict soft-tissue positional changes according to tooth movements.

Evaluation of the marginal and internal gaps of three different dental prostheses: comparison of the silicone replica technique and three-dimensional superimposition analysis

“…Furthermore, both the LC and ZC exhibited positive and negative errors in the inner face generated during the process of combining the digital impressions of the crown. These findings support those of previously published studies on this topic 29303132333435363738394041. The quantitative evaluation of the marginal adaptation is not yet standardized and can be misleading 42.…”

Accuracy evaluation of tridimensional images performed by portable stereophotogrammetric system

“…While direct anthropometry has always been accepted as the gold standard in facial analysis because of its simplicity and low cost, the need for long clinical sessions and well-trained examiners has been a hindrance [30][31][32] . Stereophotogrammetry presents a safe, non-invasive technique free of ionizing radiation in longitudinal studies 33 .…”

Unpredictability of soft tissue changes after camouflage treatment of Class II division 1 malocclusion with maximum anterior retraction using miniscrews

“…1 Among the facial soft tissue changes resulting from orthodontic treatment, there is particular interest in changes in the position and contour of the lips, and various methods of predicting posttreatment soft tissue changes have been reported to establish a diagnosis and treatment plan. [2][3][4][5] Choi et al 2 reported that in adult female patients with Class II Division 1 malocclusion, the ratios of movement between labrale superioris (Ls) and labrale inferioris (Li) to the extent of anterior teeth retraction are 1:0.45 and 1:2.08, respectively, and that the amount of posterior movement of Ls is correlated with posterior movement of the maxillary incisal edge.…”