Functional Outcomes of Cleft Lip Surgery. Part II. Quantification of Nasolabial Movement.
Howard E. Strassler, DMD
Trotman CA, Faraway JJ, Losken HW, van Aalst JA. Cleft Palate Craniofac J. 2007;44(6):607-616.
Abstract
Objective: To explore nasolabial movements in participants with repaired cleft lip and palate.
Design: A parallel, three-group, nonrandomized clinical trial. Subjects: Group 1 = 31 participants with a cleft lip slated for revision surgery (revision), Group 2 = 32 participants with a cleft lip who did not have surgery (nonrevision), and Group 3 = 37 noncleft control participants.
Methods: Three-dimensional movements were assessed using a video-based tracking system that captured movement of 38 landmarks placed at specific sites on the face during instructed maximum smile, cheek puff, lip purse, mouth opening, and natural smile. Measurements were made at two time points at least 1 week and no greater than 3 months apart. Summary measurements were generated for the magnitude of upper lip, lower lip, and lower jaw movements and the asymmetry of upper lip movement. Separate regression models were fitted to each of the summary measurements.
Results: Lateral movements of the upper lip were greater than vertical movements. Relative to the noncleft group, the revision and nonrevision groups demonstrated 6% to 28% less upper lip movements, with the smiles having the most restriction in movement and greater asymmetry of upper lip movement. Having an alveolar bone graft further increased the asymmetry, while a bilateral cleft lip decreased the asymmetry. Lower jaw movement caused a small increase in upper lip movement.
Conclusions: The objective measurement of movement may be used as an outcome measure for cleft lip surgery.
Commentary
Many times dentists focus on the size, shape, position, and color of teeth when evaluating a smile. Of course, the lips are important in how they frame a smile, just as the smile is an important part of the entire esthetic facial package: the lips, cheeks, chin, nose, eyes, ears, forehead, hair, midline, etc. Facial appearance and how esthetics is perceived can be based on the symmetry of the face and a balance of facial proportions. Sometimes dentists forget that a smile is not a static position. The smile is a dynamic act of facial movement—the muscles contracting and moving the facial soft tissue to expose the teeth and then holding that position. Smiles in still photographs are the final position of the dynamic movement but, in real time, the act of smiling involves facial animation, which can be distracting from the final result.
Recently, some exciting changes in three-dimensional (3D) smile analysis have been reported. These analyses look at the facial animation, including how lip movement, size of the lips, and cheek puffing change the smile dramatically. A team at the University of North Carolina has been evaluating the 3D movements of a smile before and after cleft lip surgery. Using sophisticated software and digital movies that record the changes in the soft tissue during a smile, the team was able to quantify the nasolabial movement. Three-dimensional movements were assessed using a video-based tracking system that captured movement of 38 landmarks placed at specific sites on the face during instructed maximum smile, cheek puff, lip purse, mouth opening, and natural smile. Measurements were generated for the magnitude of upper lip, lower lip, and lower jaw movements and the asymmetry of upper lip movement. While this software is expensive, the future of smile analysis should become a more dynamic interaction of facial movements to help the practitioner plan not only the change in tooth appearance but also how that change will be framed by the dynamically changing soft tissue of the smile.
About the Author
Howard E. Strassler, DMD
Professor and Director of Operative Dentistry
Department of Endodontics, Prosthodontics and Operative Dentistry
University of Maryland Dental School
Baltimore, Maryland
