Premature loss of baby teeth may signal hypophosphatasia, a rare inherited bone disease, according to new research from scientists at Osaka University in Japan. The condition disrupts the body's ability to properly mineralize bones and teeth, often remaining undetected in its earliest stages.
The findings, published in the scientific journal JBMR Plus, demonstrate that dental issues can reveal the disorder even in mild cases where skeletal changes are virtually unnoticeable.
The publication is an official peer-reviewed journal of the American Society for Bone and Mineral Research, which specializes in studies on musculoskeletal biology and metabolic bone conditions.
Mouse models reveal early dental damage
To investigate how the disorder affects dental health, researchers recreated mouse models of the condition by reproducing three specific variants of the ALPL gene found in human patients suffering from hypophosphatasia.
The study focused closely on milder forms of the disease. Hypophosphatasia is a rare genetic metabolic disorder caused by mutations in the ALPL gene, which provides instructions for producing tissue-nonspecific alkaline phosphatase, an enzyme essential for depositing minerals into developing bones and teeth.
Tissue-nonspecific alkaline phosphatase regulates mineral deposition by breaking down compounds that inhibit bone formation. When gene mutations reduce enzyme activity, bone and tooth structures fail to harden properly.
Even when animals showed only minor bone disruptions elsewhere in the body, the researchers recorded a significant reduction in bone density around their teeth. In addition, the specialized tissues that hold teeth firmly in place within the jaw were noticeably weakened.
Structural changes across tooth layers
Microscopic analysis of the affected teeth revealed structural abnormalities across multiple tissue layers. Disruptions were identified in the outer enamel, the underlying dentin, and the cementum, which is the hard calcified tissue covering the tooth root.
Human teeth rely on these distinct structural layers for strength and function. Enamel forms the hard protective outer shell, dentin makes up the bulk of the tooth structure beneath it, and cementum anchors the root to the surrounding jawbone.
The researchers found that the severity of these dental problems depended on two main factors: the overall level of the TNAP enzyme required for normal hard tissue formation, and the specific variant of the ALPL gene present in the subject.
Early diagnosis through dental visits
The study authors noted that in human patients, hypophosphatasia is sometimes first identified only after a child experiences an unusually early loss of primary teeth. Primary teeth, commonly known as baby teeth, typically shed according to a predictable schedule as children grow.
Because dental problems may precede visible skeletal deformities, the authors explained that noticing premature tooth loss could help dentists and doctors identify hypophosphatasia before more severe skeletal changes develop.
Osaka University, located in Osaka Prefecture, is one of Japan's leading public research institutions, widely recognized for its contributions to genetics, medicine, and dentistry research.
