A review of the dental management of cleidocranial dysplasia

General

CCD is characterized by defective endochondral and intra-membranous bone formation. Table 2 summarizes the general skeletal, craniofacial and dental features of the condition.

Aplasia (10%), or hypoplasia, of the clavicles, permits a wide range of shoulder movements, including the ability to approximate the shoulders in front of the chest (Figure 1). The short stature is accompanied by spinal scoliosis. There are varying anomalies of the pubis and hip bone. Absence of the pubic symphysis and hypoplasia of the pelvis is common in female individuals. In children under 5 years old, an abnormal curvature of the lower legs can be observed. This results in a large gap between the feet and ankles when the knees are touching (known as genua valga or knock knees) and flat feet (pes planus).¹² The endochondral bones present with a shortening of the long bones of the axial skeleton and digits (brachydactyly).

The maxilla, zygoma and nasal bones are hypoplastic, resulting in hypertelorism and a wide, flat nasal bridge. The mandible may be relatively prognathic as a consequence of the shortened cranial base. The fontanelles and sutures fail to ossify, often for life. However, premature coronal suture fusion can lead to pronounced parietal and occipital bossing and frontal flattening. Sometimes, there is a depression overlying the metopic suture, which may extend from the nasion to the sagittal suture. The development of sutural ossification centres can lead to the formation of several Wormian bones, particularly within the lambdoid suture of older subjects. The paranasal sinuses are usually underdeveloped and narrow. Pneumatization of the mastoid air cells sometimes does not occur at all.¹³

Other features of CCD included brachycephaly, with a high-arched palate and sometimes a cleft palate.¹⁴ A narrow coronoid process and parallel borders of the ascending mandibular ramus have also been described as common features.¹⁵

Dental

The dental phenotype is highly penetrant and can result in several dental anomalies. The dentition is characterized by delayed or failure of eruption of both the primary and permanent teeth. Permanent teeth may become impacted or have an ectopic location.

Dorotheou et al¹⁶ studied the genes relevant to tooth eruption and bone remodelling. The study concluded that disturbed paracrine signalling in individuals with CCD could be a reason for impaired tooth eruption.¹⁶ Diminished alveolar bone resorption, leading to failure of exfoliation of primary teeth, and the presence of numerous supernumerary teeth can result in crowding of the dental arches. Hitchin and Fairley¹⁷ believed that the lack of tooth eruption in patients with CCD is a result of the failure of resorption of the overlying alveolar bone. There can be an increased density of the alveolar crest bone over unerupted teeth.¹⁵ Hitchen and Fairley¹⁹observed that when the teeth were uncovered, they could sometimes erupt simultaneously, showing a normal eruption pattern.

There is a complete absence of cellular cementum and an increase in the amount of acellular cementum of the roots of the affected impacted teeth.^18,19 There have also been reports of disorganized dentinal tubules in the roots of extracted teeth.²⁰ The crowns of the teeth may be abnormal, the enamel may be hypoplastic, and taurodontism can also occur.¹⁵

Additionally, mechanical interferences can be caused by impacted supernumerary teeth, and the removal of these can facilitate the eruption of permanent teeth. Follicular cysts and eruptive pseudocysts sometimes accompany the supernumerary elements. Supernumerary teeth are most commonly found in the premolar region.²¹

CCD is sometimes underdiagnosed, owing to the low incidence of medical complications and where oral manifestations can be the most significant causes of morbidity.²² In some countries, there have been reports of a CCD diagnosis only after a patient presented for a routine dental review, such as those of a 15-year-old girl in India²³ and a 28-year-old male in Italy.²⁴

Treatment strategies

The management of a patient with CCD presents many challenges to the dental team. Multiple strategies have been described in the literature to manage these patients. The common aim is to correct the aesthetic and functional dentofacial deformities.

Prosthetic rehabilitation with removable complete or partial prostheses

Historically, treatment of the dental problems of a patient with CCD consisted of no treatment or prosthetic replacement of the permanent teeth. This was advocated by several authors, with most reports being in childhood.^{33,34,35,36,37} This approach was completed with or without dental extractions of the impacted or erupted primary, permanent and supernumerary teeth, and followed by the fabrication of full or partial dentures.³⁷

Pusey and Durie suggested the removal of only the erupted teeth and the use of a removable prosthesis.³⁸ A case report by Tripathi et al³⁹ discussed how, although orthodontic and surgical correction may be the treatment of choice, the need to preserve the alveolar ridge by avoiding extractions and surgical procedures may make the fabrication of removal dentures in patients with CCD a viable option. The patient that this report described presented at the age of 30 years with extreme mobility of several teeth. He adapted well to the complete dentures that were constructed, and had a significant improvement in self-esteem. This is one of the few case reports where the impact of treatment on a patient's quality of life is described through a Likert scale questionnaire.⁴⁰ Other authors stressed the need for good patient motivation and psychological support.⁴¹

Complications can arise if supernumerary or unerupted teeth are left in situ, including mucosal ulceration because of the eruption of embedded teeth, odontogenic cysts and osteomyelitic processes, requiring further surgery and prosthesis adjustments.⁴² D'Allesandro et al⁴³ described an alternative technique where overdentures were constructed for edentulous saddles over unerupted teeth, which subsequently required surgery. Another option is to surgically expose the unerupted teeth to provide support for an overdenture.¹⁹ Dental implants could also be used to support the overdenture.⁴⁴

Prosthetic rehabilitation with fixed prostheses

Alternatively, the rehabilitation of edentulous saddles can be completed with a fixed prosthesis, using spontaneously erupted permanent teeth as abutments, with either conventional or resin-retained bridges.⁴⁵ This approach can be problematic because there is sometimes a lack of a sufficient number of abutment teeth. Also, conventional prosthetic preparation may damage the pulp of young permanent teeth. This risk is worsened in patients with CCD as they often have a delayed and decreased ability to produce reactive dentine.⁴⁵

Implant prosthodontic rehabilitation

The difficulty with prosthetic teeth replacement in patients with CCD, owing to the lack of abutment teeth and difficult dental bases, has been noted in the literature. There are a few case reports where the final restorations were implant-retained prostheses.^46,47,48,49

Lombardas and Toothaker⁴⁶ used a double onlay bone graft from the iliac crest after surgical extraction of primary and unerupted supernumerary teeth at the implant site. The first graft was bonded at the time of extraction. The second was bonded 3 months later. However, implants can only be used where growth is complete, and there are few data in the literature regarding their long-term prognosis in subjects with CCD. Figures 4 and 5 show an example of prosthetic rehabilitation.

Auto-transplantation of permanent teeth

Several authors have discussed auto-transplantation of permanently impacted teeth after surgical extraction of supernumerary teeth.^50,51,52 Advocates of this technique feel it is advantageous since there are often abundant donor teeth, with delayed dental maturation allowing for the preservation of pulp vitality when transplantation is performed at a later age.

The procedure involves the preparation of the alveolar cavity immediately after extraction, with the transplanted tooth exposed to extra-oral conditions for no more than 5 minutes. It is then re-implanted, and a dental splint with braided thread is placed for 3 weeks. Another splint with light thread is placed for 4 weeks. It is recommended that endodontic treatment starts 2 months after transplantation. Calcium hydroxide should be placed in the canal as an interim dressing, and the final root canal treatment should be completed 4 months later.⁵³ In teeth with incomplete apexogenesis, it may be possible to maintain vitality.⁵⁴

Hazalonetis and Hazalonetis⁵³ described the case of a 24-year-old subject with CCD. Although 17 teeth had previously been extracted, the four upper incisors were transplanted. The authors reported good stability at 5 years with no root resorption, no ankylosis, normal periodontal health, normal functionality and good aesthetics. However, the literature is lacking in other long-term reports of patients with CCD who have had auto-transplantation of teeth, and some authors have reported subsequent bone loss.^54,55

Surgical removal of overlying bone, extraction of supernumerary and primary teeth⁶¹

Following a longitudinal study, Jensen and Kreiborg advocated early diagnosis of CCD.⁶¹ They suggested that it is possible to diagnose supernumerary incisors at age 5–7 years and supernumerary canines and premolars a few years later. They recommended that when the root length of the normal permanent teeth is one-third of its final length, the overlying supernumerary teeth, overlying bone and primary teeth should be removed. They stated that in areas where no supernumerary teeth have formed, the eruption of the normal permanent teeth can be improved by removal of the primary teeth and surgical exposure of the underlying permanent teeth. Conventional orthodontic treatment and auto-transplantation may still be needed in the future, but the strategy of early intervention would reduce the extent of surgical and orthodontic interventions, which are often of long duration, tedious to patients and of limited success.

Toronto–Melbourne approach^62,63

This is a combined surgical and orthodontic approach, with the subject undergoing at least two procedures under general anaesthetic. Primary teeth are extracted in multiple stages, depending on the stage of root development of the permanent teeth. The primary incisors are extracted at age 5–6 years, and the posterior primary teeth are extracted at age 9–10 years. The first permanent molars erupt spontaneously and are banded. At this time, the permanent incisors are surgically exposed, packing is placed, and brackets are attached at a later date, after a period of healing. The permanent premolars are surgically exposed between the ages of 9 and 12 years, and the supernumerary teeth are removed. Brackets are placed on the premolars following a healing period. This approach did not give details of the orthodontic mechanics used.

Belfast–Hamburg approach^64,65

This is a single-surgery approach. All primary and supernumerary teeth are extracted, and all unerupted permanent teeth are exposed simultaneously under one general anaesthetic. Surgical packing is placed and changed frequently. Healing occurs by secondary intention. Orthodontic brackets are placed onto the teeth once healing healing has occurred. The authors mention that some teeth erupted spontaneously; however, others required active extrusion. Orthodontic appliances were placed on the few fully erupted teeth, and elastics tied to the unerupted teeth to encourage eruption. Reported problems included difficulty maintaining good oral hygiene and a perception of bad taste or halitosis.

Jerusalem approach^51,55,56

This is a two-stage method of surgically uncovering and bonding the permanent teeth. First, the incisors are guided into occlusion (at a chronological age of 10–12 years old, dental age of 7–8 years when the anterior permanent teeth have completed two-thirds of their root development). The approach assumes that at the first surgery, there are sufficient teeth for anchorage in the arch, usually the first permanent molars and often one or two permanent incisors. During the operation, the primary incisors and supernumerary unerupted teeth are extracted, permanent incisors that did not erupt are exposed, attachments are bonded to first permanent molars and incisors, and the surgical flap is closed. In the second-stage operation, the remaining permanent teeth are guided into occlusion (between 13 and 15 years of age, dental age 10–11 years when the canines and premolars had two-thirds of their roots developed). The primary canines and molars are extracted, permanent canines and premolars are exposed, attachments are bonded, and the surgical flap is closed. Healing by primary intention is encouraged. Surgical procedures are followed by the application of low extrusion forces using a rigid arch to oppose distortion owing to excess space in the arch.

A reported advantage of this two-stage technique is that by aiding the eruption of the permanent incisor teeth at the appropriate time, the patient's smile aesthetics and self-image are enhanced.⁴⁸ However, the dental age of these patients lags 3 years behind their chronological age.⁴¹ The anchorage in the first stage can be supported by including the first permanent molars, the primary canines and the molars in the orthodontic appliance, and using a transpalatal arch. Expansion of the maxillary arch can be used to gain additional space for tooth alignment, for example, using a quad helix.⁴⁸ Alternatively, Suba et al⁶⁶ suggested that after the surgical extraction of primary and supernumerary unerupted teeth, transverse expansion of the maxillary bone could be completed with a removable orthodontic appliance and use of a Delaire face mask.

The Jerusalem approach can also take a long time, being reported as up to 8 years and thus placing a significant burden on patient compliance.⁴⁸ The authors discussed how it was difficult to correct severe tooth rotations and the labio-lingual positioning of the front teeth. Problems included the risk of brackets debonding on the unerupted teeth. Some cases reported that oral hygiene is better with this technique than with the Belfast–Hamburg approach.

The aim of the Jerusalem approach is to achieve as normal an occlusion as possible, with good smile aesthetics, if there is only a mild or no skeletal discrepancy.^51,56,57 This is possible since extractions are not accomplished all at once, and a strategic staged approach is used in order to maintain the vertical occlusal dimension while different groups of unerupted teeth are exposed and moved into their ideal position. As with routine orthodontics, if there is a Class III occlusion and it is amenable to orthodontic camouflage, extraction of lower premolars to aid retraction of the lower labial segment is an option to be considered.⁴⁸

The Bronx approach⁴¹

Berg et al⁴¹ reported on the Bronx approach for managing two patients with CCD. This approach can have up to three stages. The first intervention involves the extraction of all primary and supernumerary teeth. An interim partial overdenture is provided to maintain cosmesis. Transpalatal arches with magnet keepers were used to aid retention of the overdenture, with windows in the denture base where needed to allow the eruption of permanent teeth. They reported that the use of the transpalatal arch is advantageous because it can be used while patients are undergoing orthodontic treatment, with the addition of buccal tubes to help retain denture clasps. However, the prosthesis often needs frequent adjustment or modification. The second intervention, if needed, involves exposure and immediate bonding of all unerupted teeth. The third intervention, if needed, comprises orthognathic surgery, with a Le Fort I osteotomy and the placement of dental implants.

The University of Southern California (UCSF) approach⁴⁷

These authors presented two cases that described the UCSF approach. It combined the Belfast–Hamburg and Bronx approaches. It is organized into five steps with the appropriate timing of removal of supernumerary and retained primary teeth, surgical exposure of impacted permanent teeth, orthodontic extrusion and alignment, Le Fort I advancement and implant-retained prosthesis. Two cases are presented where this approach was used.

Le Fort I osteotomy

If there is a skeletal discrepancy, typically a skeletal III pattern, and the occlusion is not amenable to orthodontic camouflage, once skeletal growth is complete, orthognathic surgery may be indicated.^42,62,63 Dann et al⁷⁸ presented a case of a patient with CCD who had maxillary hypoplasia and underwent orthognathic surgery. The surgical technique consisted of a Le Fort I osteotomy, insertion of alloplastic material between the osteotomy lines and covering the osteotomy sites with an onlay graft from the iliac crest. This was followed by a period of inter-maxillary elastics. After 3 years, the patient's occlusion showed good stability. Park et al⁴⁷ reported on 17 patients with CCD, for whom they estimated 59% did or would need a Le Fort I advancement. However, it is important to note that patients with CCD will often have had numerous lengthy previous orthodontic interventions prior to the completion of growth. This can potentially lead to them sometimes becoming demotivated at the stage when they are ready for a discussion of options with regard to orthognathic surgery.

Maxillary distraction osteogenesis

Lida et al⁷⁹ described a patient with severe midfacial retrusion where distraction osteogenesis was performed using a two-stage surgical technique. However, there are no specifically reported cases of patients with CCD where distraction osteogenesis has been completed.

Rehabilitation with craniofacial surgery

The use of a polyurethane Dacron-coated mesh reinforced with bone paste has been described. However, there can still be residual facial defects.⁸⁰ McGuire et al⁸¹ suggested craniofacial surgery with the reduction of frontal eminences and filling of metopic sutures with autologous bone tissue grafts, using fibrin glue and mono-cortical fixation using a titanium mesh.