Survey of Patients Referred to Our Hospital for Screening of Hypophosphatasia

Abstract

Bone calcification disorders and/or premature loss of primary teeth before the age of four may indicate a possible diagnosis of hypophosphatasia （HPP）, warranting the evaluation of serum alkaline phosphatase levels. Occasionally, dental manifestations lead to a diagnosis of mild-type HPP. Our clinic has been working to establish an effective HPP diagnosis system in collaboration with the Department of Pediatrics, The University of Osaka Hospital.

This report presents findings from 63 children obtained at their initial visit to the outpatient clinic of the Department of Pediatric Dentistry, The University of Osaka Dental Hospital, with dental findings of suspected HPP such as premature loss of primary teeth during about 16-year period from December 2008 to December 2024. All underwent dental examinations, and 25 were subsequently referred to the Department of Pediatrics for suspected HPP based on clinical findings. Of those patients, 12 were subsequently diagnosed with HPP, 10 with odonto HPP and 2 with childhood HPP.

Root resorption was the most common dental finding used to rule out HPP. All patients with a medical diagnosis of HPP had early loss of primary teeth at less than 4 years of age, with the mandibular primary central incisor most commonly affected. The results obtained suggest that premature loss of mandibular central incisors without root resorption under 4 years of age is an important factor for differential diagnosis of HPP.

During the study period, approximately 20％ of children referred to our outpatient clinic from a local dental clinic for premature loss of primary teeth were diagnosed with HPP. It is now possible to screen for HPP in pediatric patients with growth and developmental problems who have yet to be diagnosed.