Osteogenesis imperfecta (OI) is a congenital disorder characterized by increased bone fragility and low bone mass. It results from mutations in the genes COL1A1 and COL1A2 that encode for either chain of type 1 collagen 1. The disease causes either a decrease in collagen synthesis or the production of abnormal collagen; thus, all tissues rich in type 1 collagen can be affected 1. Patients therefore present with multiple long bone fragility (osteoporosis), bone deformity, joint laxity and hypermobility, blue sclera, hearing loss, skin thinness, and growth deficiency 2. The original classification of OI into four types (OI type I, II, III, and IV) was based on clinical and radiological findings and mode of inheritance 3. Type I includes patients who have the mild form, almost normal stature, and blue sclera. Type II is considered the most severe form and is lethal in the prenatal period. Type III includes patients with the classic disease manifestation, usually with moderate deformity at birth, and progressively deforming bones. Type IV includes patients with extensive phenotypic variability, including mild to severe forms of OI 3. Although these clinical features provide the bases for classifications, a significant proportion of patients cannot be classified in this way 4. In 2004 and 2007, this classification was expanded with OI types V–VIII because of distinct clinical features and/or different causative gene mutations 5,6.
There are significant oral problems that occur in different types of OI including dentinogenesis imperfecta (DI), class III dental malocclusion, and delay in dental development 2,7,8. DI is sometimes associated with OI, but no relationship has been found between the numbers of bone fractures or deformity and the degree to which the teeth are affected 8. In contrast, other patients with OI have normal teeth 7.
The purpose of this case report is to present the systemic and the dentofacial features of OI and discuss special considerations that should be kept in mind in the case of dental management of this condition.
Case description and management
A 10-year-old Saudi female child was referred by her pediatrician to the medically compromised Pediatric Dentistry Clinic at the Faculty of Dentistry, King Abdulaziz University in Jeddah, Saudi Arabia (Fig. 1). The patient’s main dental complaint was bleeding upon brushing, swollen gums, and broken teeth. She is the eldest among two siblings. Parents are first-degree cousins. The mother had full-term pregnancy and the patient was delivered by normal vaginal delivery. Medical history indicated that the patient is a known case of OI and osteoporosis. There was no history of a similar family condition. After birth, she was discovered to have facial bone fracture, but she had normal white sclera of eye and did not experience any discoloration. She had multiple bony fractures of both hands in her first year of life. After the first year, she was started on infusion doses of bisphosphonate (Zoledronic acid 0.05 mg/kg over 30 min) every 3 months to increase bone density. She is on a daily dose of vitamin D and calcium syrup (Osteocare, Vitabiotics Ltd., London, United Kingdom). She started to walk at 2 years of age. She had a ventricular septal defect that was corrected by surgery when she was 6 years old. Before 2 years, she complained of a swelling in the sole of the right foot, with severe pain upon walking. It was surgically removed under general anesthesia, and biopsy report indicated the diagnosis of neuofibroma. This lesion has recurred after 1 year and excisional biopsy was performed, which indicated the same diagnosis of neurofibroma. She is on regular recall visits with both the pediatric endocrinologist and the pediatric cardiologist. The patient had only one previous dental visit, where the dentist refused to treat her because of her medical problems.
The patient appeared to be well adjusted, healthy, and intelligent. She was 131 cm tall and weighed 23.6 kg at the initial visit. Extra oral examination showed that the patient had abnormal facial features (Fig. 1). She had a smaller figure according to her age. Both her hands and feet showed digital deformity (Fig. 2). She wears specially prescribed custom orthopedic shoes. Intraorally, tongue thrust swallowing pattern, generalized gingival hyperplasia, and anterior open bite were observed. She had prognathic maxilla and a retrognathic mandible. She had a mesial step primary molar relationship as permanent molars were unerupted. The upper central incisors were erupting labially. The patient had mixed dentition, with delayed eruption of permanent teeth compared with chronological age. The patient was also found to have multiple carious teeth and swollen fibrotic gingiva (Fig. 3).
Panoramic and lateral cephalometric radiographs showed that the patient was in the mixed dentition stage and had no missing teeth. Teeth #55, 54, 53, 63, 64, 65, 75, 83, and 85 were retained and their successors were developing together with third molars. Teeth #25, 35 and second molars were associated with enlarged tooth follicles. The mandible showed osteoporotic features including low-density bone trabeculation and very thin inferior cortical bone. The patient had class II malocclusion with an anterior open bite. There was thickening of the superior orbital ridge (bossing). In summary, the patient had osteoporotic bone, delayed eruption, and malocclusion. The radiographic features are consistent with the patient’s medical history of OI (Fig. 4).
The risk of caries was assessed and found to be high. A treatment plan was formulated to extract one remaining root and to restore the others and construct a band and loop space maintainer. Dental treatment was performed as planned under local anesthesia and the patient was cooperative (Fig. 5). The patient was placed under a recall program every 3 months.
Orthodontic consultation was conducted in the third recall visit after eruption of first permanent molars and after analysis of all orthodontic records including panoramic and lateral cephalometric radiographs (Fig. 4), intraoral photographs (Fig. 6), and diagnostic casts (Fig. 7). The patient was diagnosed with mandibular deficiency and maxillary excess, maxillary constriction, hyperdivergent mandible, moderate dental crowding, convex profile, retruded chin, protruded upper lip, and delayed dental development.
The present case report highlights a number of issues related to OI that are of relevance to a pediatric dentist. The patient’s short stature compared with age, delayed walking at 2 years of age, her multiple fractures during infancy, and digital deformity in hands and feet are all consistent with the general features of patients with OI 4.
In terms of the cardiac abnormality, this patient had ventricular septal defect. It is known that cardiac valvular abnormalities can be found in many patients of OI, which might be because of the decrease in myocardial collagen diameter and amount associated with a significant decrease in fiber and chamber stiffness. Myocardial collagen contributes directly toward ventricular stiffness at high and low loads and can influence stress-free state and myofiber architecture 9. When evaluating patients with OI, careful attention should be paid to cardiovascular findings and if valvular lesions are noted, patients should be instructed on the need for antibiotic prophylaxis for dental and surgical procedures 10.
The patient had normal white sclera of the eye and did not have DI. OI does not always have to be accompanied by DI. The reported prevalence of DI in patients with OI type I varies from 8 to 40%, from 43 to 82% in type III, and from 37 to 100% in type IV 7. The patient may experience severe delay of permanent teeth eruption because of the bone deformity or because of the prolonged use of bisphosphonates. Results from a study on rats suggested that administration of bisphosphonates during tooth development has the potential to inhibit tooth eruption and formation and to induce several types of dental abnormalities 11. Kamoun-Goldrat et al. 12 reported a mean delay of 1.67 years in tooth eruption in OI children who were under treatment with bisphosphonates, which may be attributed to altered osteoclastic activities.
A delay in dental development was observed in 21% of patients with type III OI, whereas accelerated development was noted in 23% of the patients with type IV OI. In addition, ectopic eruption occurred in 13 patients in a study that evaluated 40 children (age range, 1–17.5 years) with types III and IV OI 2. In the same study, about 70–80% of patients were described to have skeletal class III malocclusion 2. However, in contrast to this, our case showed a developing skeletal class II malocclusion. Anterior open bite, and anterior and posterior crossbites have also been reported 2,13.
There has been no mention in the literature of bone quality in panoramic or lateral cephalometric radiographs. In contrast, in this report, we have described osteoporotic bone quality in both jaws obvious in panoramic and lateral cephalometric radiographs. The mandible showed osteoporotic features including low-density bone trabeculation and very thin inferior cortical bone. In the lateral cephalometric radiograph, there was thickening of the superior orbital ridge (bossing), which reflects the abnormal facial appearance.
The patient is on infusion doses of bisphosphonate (Zoledronic acid 0.05 mg/kg over 30 min) every 3 months. Bisphosphonates are primary agents in the current pharmacological arsenal against osteoclast-mediated bone loss, because of osteoporosis, OI, and Paget’s disease of bone and bone malignancies. The use of bisphosphonates has been found to be associated with osteonecrosis of the jaw 14. Other studies concluded that despite long-term intravenous monthly treatment of bisphosphonate in children with severe OI, no clinical signs of osteonecrosis of the jaw were found in any of the patients following dental surgery 15. In a study of 15 patients with OI who underwent extraction of 60 primary teeth, none of them had osteonecrosis of the jaw. It was found that unlike adults, osteonecrosis of the jaw is not a pediatric disease, and that it occurs rarely, if at all, in children 16. Intravenous bisphosphonate treatment improves symptoms of chronic bone pain, recurrent fracture rate, and bone mineral density in children with OI. However, bisphosphonate treatment creates multiple sclerotic metaphyseal bands (zebra lines) on long bones that are parallel to the growth plates and correspond to the number of treatment cycles 17,18. This was observed in the hand radiograph of this patient (Fig. 8).
The goals of dental treatment in OI patients are the maintenance of both primary and permanent dentition, a functional occlusion, optimal gingival health, and overall appearance. In terms of the dental management of children with OI, it is noteworthy that many clinicians appear reluctant to provide dental care to such children. This could be because of the possible fear of causing maxillary or mandibular fractures because of bone fragility or the fear of the possibility of osteonecrosis of the jaw following dental surgery in patients undergoing biphosphonate therapy. These complications should not deprive the patients from receiving required dental interventions. It should be emphasized that these children should be handled gently with great attention when using behavior management techniques. Physical restraints and exertion of extra pressure on bone should be avoided. As anxiety can be an issue with these children, premedication for anxiolysis, such as nitrous oxide analgesia or midazolam, can be used for treatment in a clinical setting 19. Special attention should be paid to patient treatment under general anesthesia. This include proper positioning on the operating room table, for which egg crate foam is recommended 19. The dentist should be conservative in dental treatment. Prevention, restorations, and endodontic treatment are preferred to extraction or surgery. Considerations should be given to oral antibiotic prophylaxis 1 h before extraction especially in patients with cardiovascular findings 10. For OI patients who are under oral or intravenous treatment of bisphosphonates and to avoid the development of osteonecrosis of the jaw, some preventive measures should be taken into consideration. In case of dental surgery in patients who are treated with bisphosphonates, Barker and Rogers 14 have suggested the use of chlorhexidine mouthwash before and after extractions with careful follow-up until healing of the socket has completed. Schwartz et al. 16 suggested waiting 8–15 days after the last infusion of the bisphosphonates and to have a good radiograph of the surgical site to confirm healing before administration of more bisphosphonates. However, Khan et al. 20 concluded that osteoporosis patients receiving oral or intravenous bisphosphonates do not require a dental examination before initiating therapy in the presence of appropriate dental care and good oral hygiene.
Orthodontic treatment can be initiated but great care must be taken to prevent easy fracture of the brittle teeth and bone with orthodontic appliances 19. The objectives of orthodontic treatment in this patient are to reduce maxillary growth and enhance mandibular growth, and stop the tongue thrust habit that might have contributed to the proclination of upper incisors. The patient was found to be best managed by an orthognathic surgery team (including an orthodontist, a maxillofacial surgeon, a plastic surgeon, and a pediatrician).
The case presented showed the maxillofacial, clinical, and radiographic features that might be present in patients with OI. A pediatric dentist plays an important role in caring and diagnosing abnormal features in those patients. He/she should be careful when planning treatment for these patients. There should be close collaboration between a dentist and a pediatric endocrinologist and a cardiologist or physicians of any specialty dealing with these patients. Physicians treating these patients are highly encouraged to educate patients and their parents on the importance of prevention by maintenance of good oral hygiene and frequent semiannual dental examinations.
Conflicts of interest
There are no conflicts of interest.
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