Introduction

Osteogenesis imperfecta (OI) is a characteristic bone disease which affects an individual through birth or, early in life. This disease has a range of morbidity and mortality depending on the type of the disease. OI has a birth prevalence of approximately 6-7/100,000. (van Dijk FS et al., 2011) The prevalence and incidence of OI types are different from each other with OI type I and OI type IV accounting for considerably more than half of all the OI cases reported. (van Dijk FS et al., 2011) The clinical symptoms vary and include multiple fractures which is most commonly seen in type 2 in addition to blue sclerae, (scleral thinness allows the pigment of choroid to become visible), advancing deafness, beading of the ribs, osteoporosis, and deformity of the skull. The present case report presents the difference in approach to management of a simple dental condition such as chronic irreversible pulpitis in a patient with OI highlighting the importance of a thorough history-taking in revealing the underlying systemic condition. The report, also, discusses the pathogenesis, types, clinical features, dental manifestations and special considerations in patients with OI.

1 Case Report

A male child patient aged 3 years (Figure 1) visited the Outpatient Department (OPD) with a chief complaint of pain in upper front tooth region since one week. The patient's parent stated that the child complained of pain intermittently which occurred while having food and remained for a while and that he could localize the offending tooth. At the time of examination, the patient was afebrile and there were no associated systemic symptoms. It was patients first dental visit. During interview of patient’s past medical history with the parents, they casually disclosed that the child had suffered several fractures of his long bones within a span of the last one year while playing. The child was under treatment for the same and was, also, on calcium supplements. The patient's parents gave history of consanguineous marriage. There was absent positive history of repeated fractures in the family in childhood. On general physical examination, the patient was moderately built and nourished and gait was close to normal while knock knees were evident (Figure 2). A very slight bluish tinge was appreciated in the sclerae (Figure 3). On intra oral examination, there was loss of crown structure with discoloration in relation to tooth # 51, 52, 61 and 62. Intra-oral peri-apical (IOPA) radiographs were advised in the same region for the above mentioned teeth which, however, showed no changes in the periapical region (Figure 4). Orthopantomograph (OPG) of the patient, also, revealed no significant findings (Figure 5). Although the child presented with a simple diagnosis of chronic irreversible pulpitis, he was suffering from a major systemic disease. Based on the history of repeated fractures and presence of bluish tinge in the sclera, a provisional diagnosis of Osteogenesis Imperfecta (OI) was arrived-at. The patient's parents were advised to get medical reports in the following visit. The child was managed symptomatically for his dental complaint. The other skeletal diseases which could have presented with childhood fractures in the differentials included juvenile Paget’s disease, rickets and juvenile osteoporosis for which the patient's parents were reported to have opinion for to rule-out their possibility and associated adverse effects as for the preventive strategy (Table 1). In the following visit, the patient presented with medical records confirming with the diagnosis of Osteogenesis Imperfecta (OI) type 2. His most recent lab investigations were, though, within normal limits including serum alkaline phosphatase level of 274 IU, a serum calcium level of 8.8 and serum phosphate level of 5.7. The patient was on oral alendronate once a week along with calcium supplements. Based on the above, a final diagnosis of chronic irreversible pulpitis (CIP) in Osteogenesis Imperfecta (OI) type 2 was given. No dental procedure was done considering the patient’s general health condition as per the pediatric orthopedician’s advice. The parents of the patient were made to realize the need for importance of maintenance of oral hygiene. A good attempt was made to demonstrate oral hygiene instructions to the child. Osteogenesis Imperfecta (OI) type 2 is considered to be the most severe type of OI with most of the patients succumbing to death before or, few year after birth. The patient was kept on regular follow-ups for any needful.

Figure 1 Frontal profile of the patient

Figure 2 Bowed long bones with knock knees

Figure 3 Bluish tinge in sclera

Figure 4 Intra-oral peri-apical (IOPA) radiograph revealing no changes in the peri-apical region

Figure 5 Orthopantomograph (OPG) revealing no significant findings

Table 1 Differential Diagnosis of Repeated Childhood Fractures

2 Discussion

Around 30% of bone tissue is composed of organic compounds of which 90 to 95% is collagen type I. Type I collagen is, also, the most abundant protein in the skin, bone, tendons and ligaments, blood vessels, placenta and other tissues providing strength and structure to the body. (FM Pope et al., 1983) In OI, the bone matrix is affected with abnormal type I collagen which may be through inheritance or, mutation. Type I collagen is a triple helical structure consisting of two A1 chains and one A2 chain. The A1 chain is controlled by the COL1A1 gene in the 17th chromosome while the A2 chain is controlled by the COL1A2 gene in the 7th chromosome. Disturbance in alignment of the peptides in the triplet structure caused by the said gene changes eventually leads to the production of abnormal type I collagen. (Gerhard DS et al., 2004) Sillence classified OI initially in 1979 into four types (Table 2). (Sillence DO et al., 1979) The said classification was later extended to eight types in the year 2004 by Rauch et al. (van Dijk FS et al., 2011) OI patients are medically compromised and need cautious dental care. Patients with OI have increased vascular fragility (abnormal type 1 collagen). The coagulation defect appears to be primarily related to the effects of the abnormal collagen on platelet-endothelial cell interactions. Also, there is reduced clotting factor VIII (as it interacts with collagen type 1) aiding in clotting and abnormal platelet function (collagen induced platelet aggregation is affected). Even in cases with normal coagulation, post-operative bleeding is still possible. If the platelet count is less than 20,000/L and with reduced factor VIII concentration, blood transfusion becomes mandatory and fresh blood containing all clotting factors is the best choice. (Oakley I and Reece LP et al., 2010) Patient with OI can, also, suffer from airway obstruction as the strength of the chest muscles is weak. (Edge G et al., 1997) Also, abnormal type I collagen in OI patients makes them prone to delayed wound healing. Most often patients with OI are on oral or, intra-venous bisphosphonate therapy, so, there are increased chances of osteonecrosis of the jaws as bisphosphonates reduce the bone turnover. (Gl Borromeo et al, 2011) Management of OI patients includes various disciplines. It consists of pharmacological treatment, orthopedic treatment, physical medicine, dental treatment, treatment for hearing deficits and prevention of primary (e.g. basilar impression) and secondary (e.g. problems due to general medical disciplines) complications. (van Dijk FS et al., 2011) Oral and intra-venous bisphosphonates are commonly prescribed for all types of OI in adults as well as in children.

Table 2 Differentiating Features of Types of Osteogenesis Imperfecta (OI)