Quantitative evaluation of lip symmetry in skeletal asymmetry

Abstract

The objective of this study was to investigate whether skeletal mandibular asymmetry associated with unilateral and anterior crossbite will lead to lip asymmetry. The subjects were 26 females, 13 controls and 13 true skeletal asymmetric age-matched patients (24-50 years). The study group was diagnosed as asymmetric according to visual and panoramic radiographic examination and exhibited a unilateral anterior crossbite, an asymmetric mandible, and a deviation of the chin. The control group was visually symmetric and exhibited all forms of tooth malalignment without the presence of a crossbite. Digitized images of the frontal facial photographs of all the subjects, taken in an intercuspal contact position, were analysed for upper and lower lip symmetry pre- and post-orthodontic treatment. The upper and lower lips were subdivided into two quadrants each and the surface area of each quadrant was measured and expressed as a percentage of the total surface area of the relevant lip. The degree of lip asymmetry was obtained by calculating the difference in percentage area between the two quadrants of each lip. In the study group, the lower lip quadrant on the crossbite side was increased pre-treatment (56.85 +/- 1.75 per cent), while the contralateral side was reduced (43.15 +/- 1.75 per cent, P < 0.005), resulting in 13.7 per cent asymmetry. After treatment, the respective lip areas were 52.12 +/- 0.64 and 47.88 +/- 0.64 (P < 0.01) and asymmetry was significantly reduced (4.25 +/- 1.29 per cent). In the control group, the differences between the lower lip quadrant areas (range 48.5-51.5 per cent) were small (less than 3 per cent asymmetry) and did not change post-treatment. The findings demonstrate that in this study group, lower lip symmetry was mainly controlled by the support provided through the dental interarch relationships and less by skeletal factors.

Single-Splint Technique in Orthognathic Surgery: Intraoperative Checkpoints to Control Facial Symmetry

“…To the best of the authors' knowledge, there has been very little work on the correction of midline asymmetry 11,12 with orthognathic surgery in nonsyndromic and nontraumatic patients, 10 perhaps because of the difficulty in planning an adequate soft-tissue correction. However, this problem remains highly relevant in clinical practice, as a large proportion of patients seeking orthognathic surgery do present some degree of facial asymmetry.…”

Single-Splint Technique for Correction of Severe Facial Asymmetry: Correlation between Intraoperative Maxillomandibular Complex Roll and Restoration of Mouth Symmetry

“…Very little is known about differential vertical movements of the commissures when lip asymmetry is present. In patients with skeletal asymmetry or functional asymmetry who have not been operated on, orthodontic correction of an anterior crossbite has been shown to affect lower lip symmetry, 8,19 but nothing is mentioned about commissure positioning. This study therefore offers an insight into the mechanics of restoring a better intercommissural plane.…”

“…Some information is available on the mechanics of lip changes in the sagittal and vertical dimensions, 4,15-17,20 but almost none is reported on differential movements of the mouth commissures in the vertical plane. 8,19 For such prediction purposes, however, other factors will need to be identified. It should be noted that a predicted result remains the mean of a predicted range and is therefore unlikely to match perfectly the aesthetically desired result.…”

“…Unfortunately, there are almost no articles addressing the link between skeletal movements and differential vertical commissure movements when lip asymmetry is present. 8 Our center has been working extensively on the development of a "single-splint" surgical technique for correction of dentofacial anomalies for the past 4 years. Once the maxillomandibular complex has been mobilized and put into intermaxillary fixation with the final occlusal splint, its position is adjusted intraoperatively to obtain the best aesthetic result.…”

Analysis of Association between Posterior Crossbite, Median Line Deviation and Facial Asymmetry

“…Recently, the relation between occlusion and posture has been noted by researchers. In dentistry and orthopedic surgery many investigations have been carried out, demonstrating the relation between cervical curvature and facial morphology (Gazit-Rappaport et al, 2007). Pathological alterations can lead to motor problems and influence posture.…”