Evaluation of cleft lip bony depression of piriform margin and nasal deformity with cone beam computed tomography: "Retruded-like" appearance and anteroposterior position of the alar base

BACKGROUND: As the nasal platform, the piriform margin is considered the most important nasal structure. An insufficient bony structure has been suggested to be the major factor in secondary nasal deformities such as the "depressed alar base." It is unclear, however, how the piriform margin is depressed or how bony depression influences nasal shape. METHODS: Using cone beam computed tomography, the anteroposterior positions of the cleft-side piriform margin and alar base were compared with those of the noncleft side in 52 postoperative unilateral cleft lip patients with no alveolar bone graft. Patients were divided based on cleft type into either the unilateral cleft lip, alveolus, and palate group or the unilateral cleft lip and alveolus group. RESULTS: In all cases, the cleft-side piriform margin was depressed. The anteroposterior position of the alar base was related to the piriform depression in both groups. However, in contrast with bony depression, the cleft-side alar base was located more anteriorly than the non-cleft-side alar base in 35 of 52 patients. CONCLUSIONS: The authors' study suggests that bony depression does not necessarily lead to postoperative alar depression. The postoperative cleft lip alar position can be maintained independently of the collapsed lesser segment of the maxilla. In addition, in many cleft lip newborns the cleft alar crease is hypoplastic, and the paranasal triangle is easily elevated by operative manipulation because of the muscular dysfunction. This shallowness leads to a "retruded" appearance. For improvement, preservation of the paranasal triangle and alar crease plasty are important.