Comparative case report of segmental odontomaxillary dysplasia and regional odontodysplasia

Case reports

Case 1: SOD

A 6-year-old healthy Caucasian male was referred to the paediatric dentistry department complaining of a bony swelling in the right maxilla (Figure 1a). On examination he had good oral hygiene, and had a full primary dentition along with both lower first permanent molars.

He was caries free and had a restoration in the URD. There was generalized toothwear. The URD and URE were spaced and there was a hard bony expansion bucco-palatally in this region as well as gingival enlargement. Radiographic investigation revealed:

No coronal visible pulp in the URD and URE;

Resorption of alveolar bone around the URD;

Missing UR4;

Delayed eruption of UR6;

Abnormality of UR5; and

Abnormal bone quality (Figure 1b).

Treatment

For a definitive diagnosis and to exclude FD, the patient was referred for surgical exploration of the bony expansion in the right maxilla under general anaesthetic (GA). The URD was extracted, along with attached soft tissue and separate bone fragments which were sent for histological examination (Figure 1c). The tooth fragments showed dentine with abnormally wide tubules in places and resorption of parts of the tooth with evidence of attempted repair by osteodentine. The bone was vital with a mixture of lamellar and woven bone with prominent reversal lines. There was no evidence to suggest a diagnosis of FD. These features are non-specific, but in combination with the clinical and radiographic features, a diagnosis of SOD was made.

Follow-up

The patient has been reviewed regularly for the last two years without complication. There has been no increase in the bucco-palatal width of the right maxillary alveolus, the UR6 has fully erupted and the alveolar bone around the URD has healed well.

Case 2: ROD

A 4-year-old healthy Caucasian girl was referred due to pain and swelling in the upper left quadrant and missing teeth (Figure 2a). On examination, she had a full primary dentition but the ULD and ULE were found to be badly broken down in a mouth which was otherwise caries-free. Radiographically, permanent successors in the upper left quadrant were not forming as expected at this stage, in comparison with other areas of the jaws. ‘Ghost-like’ outlines of the UL3, 4, 5, 6 and ULD, E were present, with all dental hard tissues affected (Figure 2b.)

Treatment

She was also referred for GA extraction of the ULD and ULE, along with bony curettage that were sent for histological examination. The submitted teeth had large pulp chambers with a thin abnormal dentine shell. The enamel was structurally very abnormal with small enameloid masses in the surrounding soft tissue (Figure 2c). The combination of clinical, radiographic and histological features led to a diagnosis of ROD.

Follow-up

The patient was reviewed after the extraction of these teeth with no further complications.

Discussion

SOD is probably under recognized as it may be misdiagnosed as hemimaxillofacial dysplasia (HMD), fibrous dysplasia (FD), hemifacial hyperplasia or regional odontodysplasia (ROD). In HMD, ipsilateral facial hypertrichosis (abnormal amount of hair growth) is present in addition to the SOD symptoms. FD causes enlargement of bone tissue, and affected bone growth is out of proportion with that of unaffected bones, and tooth malformations and missing premolars are not characteristic of the disease. Hemifacial hyperplasia results in unilateral facial enlargement and precocious eruption and enlarged teeth in the affected region.4

Table 1 compares and contrasts the main features of SOD and ROD.

Most cases of SOD are diagnosed in childhood or adolescence,2 and there is no predilection for gender. It has been described as non-progressive and the long-term outcome remains largely unknown.3 SOD is characterized by abnormal growth and maturation of the bone, teeth and the covering gingiva. It mainly affects the posterior segment of the maxilla, causing bucco-palatal expansion of the alveolus and gingival fibrous hyperplasia, which can result in facial asymmetry.3 Other features include delayed eruption, most commonly of the first permanent molars,3^,9 hypoplasia of primary teeth and absence of one or more premolars in the affected segment.3 The primary molars often have abnormal morphology and are spaced due to segmental expansion.1^,2 The most useful radiographic findings for diagnosing SOD are the following:

Histological findings for SOD show that the bone is immature, woven bone with reversal lines, lacking osteoblastic and osteoclastic rimming.6 The primary teeth show enlargement of pulps and an irregular pulp/dentine interface. Tubular defects in the coronal dentine are present and widespread external resorption is also observed.10

ROD affects both the primary and permanent dentitions.5 The age at time of diagnosis varies between 4 and 23 years, and females are more often affected than males at a ratio of 1.7:1.8 The maxilla is typically affected twice as often as the mandible and is usually unilateral and rarely crosses the midline. The teeth are likely to be small, brown, grooved and hypoplastic. Eruption failure or delay is frequently seen, as well as abscesses or fistulae in the absence of caries.5 Radiographically, the teeth are hypoplastic with thin layers of enamel and dentine around a large pulp chamber, giving them a ‘ghostly’ appearance. Pulp calcifications may be identified in the coronal pulp, and periapical lesions can develop in association with the anomalous teeth.5^,11 Histologically, the dentine is dysplastic with irregular tubules and there are large areas of globular and interglobular dentine and a widened predentine layer. Enamel is variably present and is abnormal with enameloid masses in the associated soft tissue.5

For both conditions, the aetiology and pathogenesis is largely unknown, although several factors have been suggested. In both cases, developmental problems during pregnancy have been suggested,6^,9 along with cell mutations affecting ectodermal and mesodermal tissues.6^,12 SOD has been associated with unilateral defects of the branchial arches.13

Treatment of SOD and ROD varies and requires to be tailored to the individual case. There have been no publications regarding the best treatment for patients with SOD as so few have been reported with long-term follow-up. The majority of reported cases had undergone bone biopsy to aid diagnosis, however, due to the benign nature of this developmental disorder and classical radiographic features, it may not be necessary. Long-term treatment will require a multidisciplinary approach. An osteoplasty may be required if the swelling is large and this should be done after growth has stopped. If there are missing teeth with spacing, the space can be managed by orthodontic or prosthetic treatment.

In a child with ROD, conservative treatment should be applied to keep the teeth for as long as possible to allow normal jaw development. However, if teeth have to be extracted, it is recommended that edentulous areas be restored with an acrylic removable appliance to maintain aesthetics and masticatory function. As the bone itself is not affected, autotransplantation is an effective treatment option and has been used successfully in some patients with ROD.5 Osseo-integrated implants would be a viable option after pubertal growth.

No treatment protocol has been established for either diagnosis since treatment has to be based on the degree of SOD or ROD, characteristics of the affected areas and the aesthetic and functional needs of each case.5^,14

Conclusion

SOD and ROD may appear clinically similar but further knowledge of these two rare diseases should allow the dentist to distinguish between them and refer or manage appropriately.

Tracking and long-term management of patients with SOD and ROD is vital to understand more fully the progression of the two diseases. Regular monitoring of the patient with clinical and radiographic examinations is essential. Future management will require a multidisciplinary approach, depending on the patient's needs.14

Long-term follow-up of each documented case is encouraged to provide guidance in the management of these rare disorders.