A mild form of hypophosphatasia as a cause of premature exfoliation of primary teeth: report of two cases.

Two clinical cases of a mild form of hypophosphatasia were reported. The patients presented with premature xfoliation of the primary incisors as their chief complaints. Phosphoethanolamine (PEA) was elevated in their urine specimens and their serum alkaline phosphatase (APase) was below normal evel. Hypophosphatasia (Rasmussen 1983) is a hereditary condition characterized by (1) decreased level of serum alkaline phosphatase (APase), (2) elevation of phosphoethanolamine (PEA) in urine, (3) premature loss of teeth, and (4) skeletal abnormalities. severe cases, hypercalcemia and hypotonia may also be present (Poland et al. 1972). Four clinical types hypophosphatasia have been recognized: newborn, infant, child, and adult. The classification is based on the time of diagnosis. The newborn group usually has the poorest prognosis. The majority of them die in the first few months of life. Most of the clinical cases of hypophosphatasia reported in the dental literature are of childhood type,’ i.e., when the condition was first diagnosed in children after 6 months of age. In all of these reported cases, the patients’ serum APase levels were at subnormal value or at the lower end of the normal range. The other consistent findings include the elevation of PEA in the urine and premature exfoliation of primary teeth. However, bony abnormality is only an occasional finding. Other dental abnormalities associated with the condition include enlarged pulp chambers, hypocementosis, and loss of alveolar bone. The 2 reports presented in this article describe 2 unrelated patients having a condition that can be considered as a mild type of hypophosphatasia in Fung 1983; Brittain et al. 1976; Baer et al. 1964; Primstone et al. 1966; Bruckner 1962; McCormick and Ripa 1968; Houpt et al. 1970; Casson 1969; Album et al. 1969. which premature exfoliation of primary incisors was the dominant manifestation.