Assessment of the soft tissues in patients undergoing orthodontic treatment or corrective jaw surgery plays a crucial role in both diagnosis and treatment planning. Both hard-tissue and soft-tissue morphologies of the patients to be orthodontically treated should be considered in establishing harmonious facial esthetics and an optimal functional occlusion.

Cleft lip and palate (CLP) is a common congenital craniofacial anomaly with a multifactorial etiology. CLP leads to various problems with feeding, hearing, speaking, and dentofacial development; thus, patients affected by CLP should be treated by a multidisciplinary team approach with good interaction among the different specialties. Patients affected by CLP generally have anterior and posterior crossbites and maxillary deficiency with a tendency toward a Class III malocclusion. It appears that the scarring produced by the primary surgical repair is a major etiologic factor for the maxillary deficiency.

A favorable facial morphology is a key aspect of treatment outcome in patients affected by CLP, and the role of orthodontists for these patients’ treatment is substantial, particularly in the improvement of their facial esthetics and dental occlusion. In the literature, several studies have assessed the hard-tissue and soft-tissue morphologies of patients affected by unilateral CLP. However, this topic was almost neglected for patients affected by bilateral CLP (BCLP), probably because of the low frequency of BCLP occurrence. In a recent study, Hasanzadeh et al, who assessed the facial soft-tissue morphology of adolescent patients affected by BCLP using conventional cephalometric lateral films, reported that they had several facial soft-tissue deformities compared with the matched control group.

To the best of our knowledge, no previous study has investigated the facial soft-tissue thickness of patients affected by BCLP using cone-beam computed tomography (CBCT). Since differences after orthognathic surgery in the soft-tissue responses between patients with thick and thin soft tissues were previously reported, it is important to evaluate the facial soft-tissue thickness of patients affected by BCLP before orthodontic and orthognathic treatment. Therefore, the aims of this study were to assess the facial soft-tissue thicknesses and craniofacial morphologies of patients affected by BCLP and to compare the findings with well-matched controls without clefts using CBCT. Additionally, the effects of some craniofacial measurements on soft-tissue thickness were investigated with multiple linear regression models.

Material and methods

The CBCT images used in this study were part of the diagnostic records collected to determine dental and orthodontic treatment needs at the Departments of Oral and Maxillofacial Radiology and Orthodontics at Erciyes University in Kayseri, Turkey. The patients and their parents had signed an informed consent form allowing their data to be used for scientific purposes, and the study was approved by the ethical committee of Erciyes University. CBCT images had been taken for orthognathic surgery planning, airway assessment, and cleft presence in cleft group, whereas the reasons for the control group had been impacted tooth localization, temporomandibular joint disorders, and airway assessments. No patient was contacted and no CBCT image was taken for the purpose of this retrospective study.

Sample calculation of the study was based on a formula, a significance level of 0.05, and a power of 80% to detect a difference of 1.4 mm (±1.5 mm) for subnasale thickness (distance from Point A to subnasale) between the groups using the findings of Liu et al. The power analysis showed that 18 patients were needed in each group. To increase the power of the study, the study group included 20 patients affected by BCLP (8 female, 12 male; mean age, 13.78 ± 3.20 years; range, 8-20 years) who had no other syndrome or congenital anomaly and had the same surgical procedure (lip and hard-tissue closure) before 3 years of age. The control group included 20 patients (8 female, 12 male; mean age, 13.94 ± 2.52 years; range, 8-20 years) with normal sagittal and vertical growth patterns without clefts, other syndromes, or congenital anomalies. No patient in either group had previous orthognathic surgery, pharyngeal flap for velopharyngeal insufficiency, orthodontic treatment, prosthodontic restoration, and a body mass index higher than 28. All patients had the same ethnic and racial origin.

The CBCT images were obtained in a standard supine position (scanning time, 14-18 seconds; collimation height, 13 cm; exposure time, 3.6 seconds; voxel size, 0.3 mm ³ ) on the same device (NewTom 5G; QR, Verona, Italy). Simplant Pro software (version 13.0; Materialise, Leuven, Belgium) was used to perform craniofacial (SNA, SNB, ANB, SN-MP, Co-A, CoGn, U1-SN, and IMPA) and facial soft-tissue thickness (glabella, nasion, rhinion, subnasale, labrale superior, stomion, labrale inferior, labiomental, pogonion, and gnathion) measurements ( Figs 1 and 2 ) on the cephalometric lateral radiographs obtained from CBCT images. The definitions of the soft-tissue thickness measurements were previously described in the literature. All measurements were performed in a blinded manner by 1 author (S.K.B.) randomly.

Craniofacial measurements used in this study: SNA (°), SNB (°), ANB (°), SN-MP (°), Co-A (mm), CoGn (mm), U1-SN (°), and IMPA (°).

Facial soft-tissue thickness measurements used in this study: glabella (G-G′), nasion (N-N′), rhinion (Rhi-Rhi′), subnasale (A-Sn), labrale superior (Pr-Ls), stomion (U1-Sto), labrale inferior (Id-Li), labiomental (B-Labm), pogonion (Pog-Pog′), and gnathion (Gn-Gn′).