Abstract
Orthognathic surgery in patients with osteogenesis imperfecta is rare. Most cases result in a successful outcome with stable and good occlusion. Two patients with, probably severe types III and IV, and malocclusion class III with retrognathic maxilla and prognathic mandible, were treated with orthodontic treatment and bimaxillary surgical correction. The surgical outcome and follow up are presented together with a review of published cases of orthognathic surgery in patients with different types of osteogenesis imperfecta. The authors conclude that it is possible to perform combined orthodontic and orthognathic surgery in patients with osteogenesis imperfecta despite the greater risk of complications. The treatments were successful with follow up times of 5–6 years.
Osteogenesis imperfecta (OI) is an inherited genetic disorder, autosomally dominant, and known as ‘brittle bone disease’ . The incidence is 6–20 per 100,000 newborns.
The connective tissues, developed from mesenchymal cells in the embryo stage and differentiate to osteoblasts, chondroblasts or fibroblasts, are affected throughout the whole body, including the dentition. Collagen is the most common protein in the body and is part of the connective tissue in bone, cartilage and blood vessels. There are 19 types of collagen and the most common one, collagen type 1, provides mechanical strength. The disease is a result of mutations in the genes COL1A and 1B.
The features of the disease are classified into types I–IV according to S illence et al. Later, three uncommon groups were added: types V–VII . Types I–IV involve mutations in the genes COL1A and 1B; types V–VII lack the gene mutation of collagen 1. Type I is a mild form of OI, type II is severe and prenatally lethal, type III is deforming and type IV is mildly deforming ( Table 1 ).
| Type | Characteristics |
|---|---|
| I | Mild form, normal stature, minimal or no deformity, fragile bone, blue sclera, hearing losses, autosomal dominant and recessive inheritance |
| II | Severe and perinatally lethal type, poor cranial mineralization, fragile bone and severe long bone deformity, autosomal dominant inheritance |
| III | Deforming type, fragile bone and long bone deformities, short stature, sclera variable in colour, dentinogenesis imperfecta and hearing losses common, autosomal dominant and recessive inheritance |
| IV | Mildly deforming, variable short stature, fragile bone, normal sclera, dentinogenesis imperfecta common, hearing loss variable, autosomal dominant inheritance |
In patients with OI, types I–IV, multiple fractures of the long bones are frequently observed due to bone fragility caused by defects in the synthesis of type I collagen. Disturbance of the permanent dentition is found in types III and IV, it is called dentinogenesis imperfecta and presents with brittle, grey, brown or yellow tooth surfaces. Other disease characteristics of OI are a blue sclera of the eyes, hearing loss, disturbed growth, wormian bones in the cranial sutures and fragile blood vessels. Characteristically the face is triangularly shaped with a broad forehead and an overhanging occiput. A Class III malocclusion is seen in 75% of adults with OI .
Treatment of OI is palliative and designed to promote normal function . Physical therapy interventions improve muscle strength and functional strength. Surgical interventions include corrections or reductions of deformities and orthopaedic stabilization of long bones and spine to avoid repeated fractures . Odontological interventions for oral health are mainly preventive for caries and periodontal risks but dental corrections of the teeth and occlusion are also performed . The malformation of the face, with subsequent malocclusion and wrong jaw positioning, such as a retrognathic maxilla and a prognathic mandible, can be corrected by orthodontic and maxillofacial surgical interventions.
Medical treatment includes calcitonin, sodium fluoride, growth hormone, cortisone, anabolic steroids, vitamins C and D, minerals and bisphosphonates. The most effective treatment is bisphosphonates, which minimize osteoclast activity. Reported effects of pamidronate, given intravenously, are decreased pain, increased sense of well-being and increased vertebral bone mineral mass. There are no conclusive reports of whether bisphosphonates should be administered intravenously or orally. The side effects are unknown in patients with OI so it is recommended that this therapy is used in children with moderate to severe OI, not the mild form . In the light of the increasing development of bisphosphonate-associated osteonecrosis, the dental status of OI patients should be monitored. Appropriate precautions should be planned for. Bone marrow transplantation, which increases osteoblast activity, or gene therapy are other interventions under development .
Prior to orthognathic surgery, it is important to consider several surgical and anaesthetic issues . Bone and teeth fractures easily, so precautions have to be taken during anaesthetic procedures . Small fractures in the bone have been reported during a Le Fort I osteotomy Vascular disorders or impaired platelet aggregation are common and can lead to bleeding peri- or postoperatively . In some cases, excessive perioperative or postoperative bleeding, due to the collagen deficiency in the vessels, has been reported. In one case, the patient experienced steady bleeding although no major vessels were involved. The preoperative haematological tests were normal and precautions were taken with diathermy cutting, avoiding big vessels and hypotensive anaesthesia. Despite this, the patient had to be transfused with plasma and blood. Postoperatively, no abnormality was found in the haematological examinations except of a slightly raised international normalized ratio (INR) value .
Problems arise if the patient does not accept blood transfusions for religious reasons. K indelan et al. reported a case with severe class II malocclusion, osteogenesis imperfecta and dentinogenesis imperfecta . The patient was a Jehovah’s Witness and could not accept blood transfusion. Bimaxillary surgery was planned but two surgical episodes were performed instead of one, to minimize the risk of haemorrhage. The outcome was successful.
There are also risks of metabolic defects, for example OI patients experience a greater incidence of hyperthermia with general anaesthesia, which can develop into malignant hyperthermia . There may also be intubation difficulties due to the patient’s short neck, large tongue and thoracic deformity, which may result in respiratory dysfunction . Cardiac abnormalities may also be present such as valvular incompetence or septal defects .
Orthognathic surgery in patients with OI is rare but has been reported . In most cases, the outcome is successful with stable and good occlusion. Owing to the small number of cases presented and the limited experience of orthognathic surgery in OI patients, the authors present two cases treated with bimaxillary surgery, with long term follow up, as well as a review of published cases ( Table 2 ).
| A izenbud et al. | A 17-year-old female. Probably type I, her mother was diagnosed as type I. severe class III | One piece Le Fort I with advancement and impaction, intra orally vertical ramus osteotomy with setback | Overall, facial aesthetics were improved, no negative events reported |
| B ell & W hite | One 40-year-old white male. Osteogenesis imperfecta type I. Normal dentine and enamel | Le Fort I osteotomy. Maxillary advancement | Good healing after surgery. And the occlusion is still stable after 9 years |
| C ole et al. | One 19-year-old white male. Probably osteogensis imperfecta type I | Le Fort I osteotomy. Maxillary advancement. And oblique osteotomies of the mandibular ramus followed by a set back | Small fractures of when performing the Le Fort I osteotomy. Life threatening pneumonia and bleeding |
| Freedus et al. | A 22-year-old white woman. Does not mention the type of osteogenesis imperfecta | Bilateral mandibular osteotomy | Good healing after surgery |
| K indelan et al. | A female 18 and 19 years old | Surgery in two sessions, 7 months between. A Le Fort I with maxillary advancement and a body osteotomy for mandibular set back | Good healing after surgery |
| Lewis et al. | A 19-year-old Latin American male. Probably osteogenesis imperfecta type III. Normal dentine | Bilateral sagital split osteotomy. Mandibular setback | Good healing after surgery and a fairly stable occlusion |
| O rmiston & T ideman | One 23-year-old Chinese female. Osteogenesis imperfecta type III. Dentinogenesis imperfecta | Le Fort I, maxillary advancement. Mandibular body step osteotomy, mandibular setback | Good healing after surgery |
| R odrigo | A 23-year-old female. Type I osteogenesis imperfecta. Dentinogenesis imperfecta | Le Fort I advancement. Mandibular body step osteotomy, 2 premolars removed | No negative events reported |
| Whitestone et al. | A 21-year-old male. Probably osteogenesis imperfecta type I. Normal dentine | Bilateral vertical oblique ramus osteotomy. Mandibular setback | Uneventful postoperative healing |
Materials and methods
Case 1
A 26-year-old man was referred by his orthodontist with a chewing complaint ( Fig. 1 ). He had earlier been diagnosed as having OI, the subclass was unclear but probably type IV. There was no clear family history of this condition. Since childhood he had been treated for 18 fractures of the limbs and hips, the latest one of the right hip. The patient was in good physical shape, well trained and an active handball player. The clinical examination showed the patient had normal stature (175 cm), but was slightly overweight (87 kg) due to an immobile life style during the last few months because of the hip fracture. The patient had normal eye sclera. Maxillofacial examination revealed a retrognathic maxilla, a prognathic mandible, and a class III occlusion relationship with posterior cross bite. The overjet was negative, −10 mm. The teeth were brownish and oral radiography indicated features of dentinogenesis imperfecta with opalescent dentine, curved roots and obliterated pulp canals ( Fig. 2 ). His oral hygiene and periodontal health was good.
Presurgical orthodontic treatment with levelling and alignment lasted for approximately 1 year. Radiographs and face bow recordings were taken for final surgical planning 2 weeks prior to the surgery. The cephalometric analyses showed SNA and SNB to be 73° and 89°. The profile angle was 0° ( Table 3 ). The analysis indicated that a maxillary advancement of 8 mm using a Le Fort I osteotomy and a mandibulary set back of 4 mm using the vertical ramus osteotomy technique were suitable. The patient was prepared for intermaxillary fixation for approximately 5 weeks. Presurgical laboratory tests, blood status and coagulation were within normal. The anaesthetist’s preoperative assessment was normal.
