Abstract
Many studies have been performed on the static facial appearance after cleft lip surgery in patients with unilateral lip and cleft palate （ULCP）, and morphological improvements in the soft and hard tissue have been demonstrated. However, the movement of soft tissues during smiling remains unclear. Therefore, we investigated the three-dimensional movement of the lips and cheeks during smiling in patients with ULCP after cheiloplasty.
The subjects were 14 boys with ULCP （mean age 5.3 years） who consulted the Department of Orthodontics at Matsumoto Dental University Hospital. The subjects’ three-dimensional lip and cheek movements during smiling were analyzed using stereo images, and their frontal craniofacial morphology was assessed using posterior-anterior cephalograms. The relationship between the frontal facial morphology and the lip and cheek movements during smiling were analyzed.
The affected side of the angulus oris moved significantly outward, upward, and rearward compared with the non-affected side. The downward movement of the central part of the lower lip was significantly larger than the upward movement of the central part of the upper lip. On the other hand, there was no significant difference in the movement of the cheek between the affected and non-affected sides.
Regarding the relationship between the movement of the lips and cheeks and the frontal facial morphology, the differences in mandibular width between the affected and non-affected sides, and the amount of menton deviation were significantly positively correlated with the difference of the horizontal movement of the angulus oris between the affected and non-affected sides. The differences in maxillary and mandibular height between the affected and non-affected sides were significantly negatively correlated with the difference of the vertical movement of the angulus oris between the affected and non-affected sides.
This suggested that the angulus oris on the affected side moved more upward, outward, and rearward than the non-affected side during smiling, resulting in an asymmetric smile in patients with UCLP. An asymmetric smile is related to the frontal facial morphology.
