Facial Soft-Tissue Asymmetry in 3D Cone Beam Computed Tomography Images of Children with Surgically Corrected Unilateral Clefts

Cleft lip with or without cleft palate (CL/P) is a relatively common craniofacial malformation involving bony and soft-tissue disruptions of the nasolabial and dentoalveolar regions. The combination of CL/P and subsequent craniofacial surgeries to close the cleft and improve appearance of the cutaneous upper lip and nose can cause scarring and muscle pull, possibly resulting in soft-tissue depth asymmetries across the face. We tested the hypothesis that tissue depths in children with unilateral CL/P exhibit differences in symmetry across the sides of the face. Twenty-eight tissue depths were measured on cone beam computed tomography (CBCT) images of unilateral CL/P children (n = 55), aged 7-17 yrs. , using Dolphin software (v 11.5). Significant differences in tissue depth symmetry were found around the cutaneous upper lip and nose in unilateral CL/P patients. Introduction Human faces exhibit a wide range of variation in facial form and appearance due to various factors including environment, ethnic background, age, gender, and congenital anomalies. Human facial morphogenesis occurs during development as several facial prominences fuse and grow harmoniously to produce a functional craniofacial unit. Age-related changes in facial proportions, tissue thickness, and facial appearance occur as individuals grow and throughout senescence. Congenital craniofacial anomalies arise when facial prominences fail to fuse or grow in a coordinated fashion and can result in asymmetry affecting the skull and face on a global or local scale. Cleft lip with or without cleft palate (CL/P) is a relatively common craniofacial birth defect affecting 1 in 1500 children per year. CL/P is caused by an embryologic failure of the nasal and maxillary facial prominences to fuse correctly on the 36 or 37 day of gestation and results in asymmetric muscle pull on the nasal septum during osteogenesis of the midface. Archaeological and historical evidence suggest that methods of CL/P surgical correction have existed for at least 1600 years; however, it wasn’t until the nineteenth century that these methods began to be employed frequently. Today, the lips and alveolus of children with clefts are surgically repaired around the third month of life with the intention of reducing facial stigmata during childhood. The combination of congenital clefts and subsequent functional and aesthetic surgical grafts/corrections might result in changes to nasal septum growth, abnormal tooth morphogenesis and eruption patterns, missing or supernumerary teeth, malocclusion, midfacial deficiency, maxillary asymmetry, reductions of nasal airway size, defects in upper lip musculature, and increased mouth breathing. These factors can affect facial soft-tissue development and growth by causing scarring, muscle pull, changes to nasal form and function, and thinner and less elastic tissues around the site of surgical repair. Morphological asymmetry across the face, and particularly in the nasolabial regions, has previously been reported in CL/P. Kane and colleagues quantified craniofacial asymmetry in preoperative infants and found that asymmetry is most extreme near the cleft, but subtle asymmetry is also present in other parts of the face and cranial base. Follow up of 11 month old patients who had undergone primary cleft repair at 3 months revealed that primary surgical repair significantly reduced asymmetry across the face, particularly in the oronasal regions, and provided sufficient tensional forces to mold and improve symmetry of underlying osseous structures. In a longitudinal study investigators found facial oronasal asymmetry in 10-year old unilateral CL/P patients and noted that faces which were more symmetric after primary surgery were more likely to be more symmetric at the age of 10, thereby underscoring the importance of achieving symmetry during the primary cleft repair. Bugaighis and investigators found the most extreme asymmetry near the nasolabial regions of the unilateral CL/P face, but also found asymmetry across the rest of the face, particularly near the orbits. The results from these studies suggest that perturbations to facial morphogenesis and growth can affect the entire craniofacial complex, likely by altering morphological integration of component parts of the face during development. Although it is useful for surgeons to have a complete picture of the relationship between osseous and soft-tissue surgical repair(s), symmetry of unilateral CL/P tissue depths has seldom been