Cleidocranial dysplasia (CCD), also referred to as cleidocranial dysostosis, is a rare genetic skeletal condition occurring in approximately 0.5 cases per 100,000 live births. Although typically inherited as an autosomal dominant trait, there are instances in which the disorder arises sporadically.

CCD is characterized by underdevelopment of the clavicles and incomplete bone formation of the anterior fontanelle, which are the main distinctive traits. Patients affected by this condition display a distinct facial appearance characterized by a prominent forehead, hypertelorism, and underdevelopment of the midface.

They may also exhibit skeletal abnormalities, such as short stature, shortened terminal phalanges, misalignment of the spine, genu valgus (knock knees), and pes planus (flat feet). Moreover, affected patients might experience frequent infections. Patients with this condition typically experience minimal disability. On radiographs, additional small bones, known as Wormian bones, may be noticeable within the cranial sutures.

CCD involves mutations in the RUNX2 gene within dental follicle cells. These mutations disrupt the activities of receptor activator of nuclear factor κB and receptor activator of nuclear factor κB ligand and cause an imbalance between osteoclastogenesis and osteogenesis, leading to difficulties in tooth eruption. Therefore, common dental characteristics of this condition include increased bone density in the jaw bones and the presence of multiple supernumerary teeth that erupt late during the development of permanent dentition.

The primary objectives of dental treatment focus on guiding the eruption of the permanent dentition to restore proper masticatory function and enhancing the patient’s overall appearance. Because of the complexity of the dental impactions, a multidisciplinary comprehensive approach is essential. Depending on the type and severity, a team of maxillofacial surgeons, orthodontists, and prosthodontists may collaborate to create a personalized treatment plan.

Several treatment approaches have been suggested, including those from Toronto-Melbourne, Belfast-Hamburg, Jerusalem, and the Bronx, all of which involve staged operation. ^,

The Toronto-Melbourne approach rationale is to encourage the natural eruption of impacted permanent teeth and eliminate the necessity for orthodontic traction. It is based on the patient’s age, with the optimal treatment window starting at approximately 5-6 years old. The serial extraction timing depends on how much the roots of permanent teeth have developed; at the same time, supernumerary teeth are also extracted.

The Jerusalem approach involves a 2-phase surgical process. In the initial phase, anterior primary teeth and any supernumerary teeth are extracted, and the permanent incisors are exposed when the patient is aged 10-12 years. In the second phase, posterior primary teeth are extracted, and the impacted permanent canines and premolars are exposed after 13 years old. This surgical procedure eliminates obstacles in the path of eruption and encourages the natural eruption pattern of impacted teeth. However, because approximately two-thirds of the roots in permanent teeth have already developed in this approach, additional orthodontic traction is typically required.

The Belfast-Hamburg approach does not specify a particular age. It recommends a single surgical procedure under general anesthesia to extract all primary and supernumerary teeth and expose the impacted permanent teeth. After the healing process, orthodontic traction is performed.

In the Bronx approach, the initial step involves the extraction of primary and supernumerary teeth, along with exposing the impacted teeth. Removable partial overdentures are employed for both esthetic and functional reasons. Orthodontic treatment commences once the permanent teeth have naturally erupted to provide adequate posterior support. After this, a LeFort I osteotomy is performed, and dental implants are placed to address the dentition deficiency.

One of the most challenging aspects in managing patients with CCD is providing adequate anchorage for orthodontic traction. To minimize anchorage loss, the procedures may sometimes have to be staged, which could extend orthodontic treatment duration.

The introduction of temporary skeletal anchorage devices (TSADs) to orthodontics allowed clinicians to use absolute anchorage to facilitate treatment and allow for en-masse forced eruption of the impacted dentition. ^, The insertion site of TSADs is an important factor in their success, and the palate has been identified as a favorable insertion site, as it offers both sufficient quality and quantity of bone sites. ^,,,,,, Kuroda et al reported the successful use of TSADs for a patient with CCD in a case report, but there is a scarcity of literature regarding this topic.

The palatal region was found to have a favorable cortical bone thickness and bone depth except in the posterior superior region. This makes the palate one of the most suitable sites for TSADs placement.

Accordingly, the use of TSADs in the management of CCD for impacted teeth traction is advantageous as it allows for controlling the anchorage while providing a solution for en-masse traction of impacted teeth in one stage, potentially minimizing the treatment and number of procedures, and enhancing anchorage control.

As the palate is a favorable insertion site for TSADs, this study aims to compare palatal bone thickness between patients with CCD and a control group using cone-beam computed tomography (CBCT). We hypothesize that patients with CCD have less palatal bone thickness than the control group.

Material and methods

This was a retrospective cross-sectional study designed to compare palatal bone thickness using CBCT scans between patients diagnosed with CCD and a healthy control group. The study was conducted at the Department of Orthodontics at Case Western Reserve University, using existing patient records from January 2015 to December 2020. All patients included in this analysis had undergone CBCT imaging as part of their standard diagnostic workup. Ethical approval was obtained from the institution’s review board (Institutional Review Board).

Subjects included patients with CCD with available pretreatment CBCT and a control group. In contrast, subjects were excluded if they had any other syndrome or condition, had any bone or metabolic disease that could affect bone density and development, and those with history of trauma and orofacial surgeries. All eligible patients with CCD and available diagnostic CBCTs (n = 7) during the study period were included ( Figs 1 and 2 ). The control group consisted of 59 patients selected from a previously published dataset, who met the same inclusion criteria—namely, the presence of a pretreatment CBCT scan of diagnostic quality, Class I malocclusion, absence of skeletal or craniofacial anomalies, and absence of any bone disorders based on their medical histories. Two potential control patients were excluded because of nondiagnostic scan quality. Specifically, the CBCT scan exhibited excessive noise, making it difficult to discern details and measure the palatal bone accurately. The records of the control group patients were evaluated by an orthodontist, and cephalometric tracing was conducted. Subjects were included only if the models, radiographs, and photographs showed Class I molar relationships, and cephalometric tracing showed a normal anteroposterior relationship between the maxilla, mandible, and cranial base. Patients consented to treatment and the use of their data for research purposes as part of the routine consent process implemented at our institution.

CBCT images of patients in the CCD group (Group 1).

Panoramic x-rays of patients in the CCD group (Group 1).

Patients included in this study were aged 6-17 years. Matching between the 2 groups in terms of age and sex was not performed because of the discrepancy in sample size, which can be explained by the rarity of CCD.

All CBCT scans were taken with a CB MercuRay (Hitachi Healthcare Americas, Twinsburg, OH) with custom low-dose settings of 2 mA, 120 kVp, 12-in field of view, 512 slices, 0.377-mm slice thickness, resolution of 1024 × 1024 pixels, 12 bits per pixel, and 4096 gray scale.

CBCT data were segmented and analyzed using Dolphin 3D Imaging software (version 11.95; Dolphin Imaging and Management Solutions, Chatsworth, Calif), and bone thickness was measured across 9 anatomically defined zones following the classification by Ryu et al. Measurements were performed as described below.

The incisive foramen and midpalatal suture were set to be the reference landmarks and were located in the sagittal and coronal views of the CBCT. Palatal bone thickness was assessed at different points: 0, 2, 4, and 6 mm away from the midpalatal suture in the coronal plane ( Fig 3 ), and from 0 to 24 mm in increments of 4 mm behind the posterior margin of the incisive foramen in the sagittal plane ( Fig 4 ). The measurements were taken in which reference lines intersected, forming a grid of 49 equally sized areas covering a total of 288 mm.

Measuring the palatal bone thickness at 0, 2, 4, and 6 mm points away from the midpalatal suture in the coronal plane.

Measuring the palatal bone thickness at 0-24 mm in increments of 4 mm behind the posterior margin of the incisive foramen in the sagittal plane.

In the sagittal view, the image was adjusted with a slice thickness of 0.5 mm. Subsequently, the image orientation was manipulated to align the posterior margin of the incisive foramen and the posterior nasal spine on the same horizontal plane. Afterward, the palatal bone thickness was gauged at each specified location by measuring it at a right angle to the horizontal plane. To facilitate the analysis, the measurements for each subject were grouped into 9 zones as reported by Ryu et al. The zones were grouped as follows: 3 mediolateral zones—a midline zone located at the midpalatal suture, a medial zone defined by positions 2 and 4 mm lateral to the suture—and a lateral zone positioned 6 mm lateral to the midpalatal suture. Similarly, the analysis defined 3 anteroposterior zones: an anterior zone spanning 0, 4, and 8 mm; a middle zone covering 12 and 16 mm; and a posterior zone located at 20 and 24 mm posterior to the incisive foramen. Accordingly, 9 different areas were included in the analysis.

All measurements were performed by a single calibrated examiner. To test interreliability, 10 randomly selected scans from both groups combined were measured by another examiner. Randomization was performed using the ‘RANDBETWEEN’ function in Excel.

The primary outcome variable was palatal bone thickness, analyzed as a continuous variable. Aggregation into anatomic zones was done to enable consistent intergroup comparison. Age and gender were considered potential confounders but could not be adjusted for statistically because of the small sample size of the CCD group.

Statistical analysis

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