Journal of Clinical Case Reports

Report of Two Dental Patients Diagnosed with Hypophosphatasia

Abstract

Rena Okawa, Taichi Kitaoka, Kanae Saga, Keiich Ozono and Kazuhiko Nakano

Hypophosphatasia is a rare inherited skeletal disorder characterized by defective bone mineralization and tissue non-specific alkaline phosphatase (TNSALP) deficiency, with mutations in the gene encoding the TNSALP isozyme the cause. As for dental manifestations, premature loss of primary teeth due to disturbed cementum formation is well known and tooth roots in affected patients are not able to adequately attach to absorbed alveolar bone due to malformed cementum. We report spontaneous early exfoliation along with mild to severe mobility of primary anterior teeth in 2 child patients referred to pediatric dentists from a general dental practitioner. Case 1 was a 1-year-7- month-old boy with 3 mandibular incisors exfoliated, while Case 2 was a 3-year-3-month-old girl with 1 mandibular central incisor exfoliated. The possibility of hypophosphatasia was considered and the patients were referred to the Pediatric Clinic of Osaka University Medical Hospital, where each was diagnosed with hypophosphatasia (odonto type). We performed repeated periodontal treatments and applied removable partial dentures in both cases, which solved esthetic and functional problems. Although the incidence is quite low, it is important to diagnose hypophosphatasia as early as possible for planning general and dental preventive approaches. In patients with mild forms, such as odonto and childhood types, early exfoliation of primary teeth identified in a dental examination can occasionally lead to early diagnosis of hypophosphatasia. In addition, dental findings obtained by a dentist are useful to identify patients with a risk of hypophosphatasia, who can then be immediately referred to a pediatrician for more detailed systemic examinations. Thus, a cooperative relationship between pediatricians and pediatric dentists should be regarded as necessary. This is the first known report to describe cases of hypophosphatasia diagnosed after referral from a pediatric dentist because of typical dental findings for the disorder.