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Hypophosphatasia (HPP) is a rare and intractable metabolic bone disease caused by mutations in the ALPL gene. Here, we undertook a nationwide survey of HPP in Japan, specifically regarding the prominent genetic and dental manifestations of odonto (n = 16 cases) and other (termed "non-odonto") (n = 36 cases) types. Mean serum alkaline phosphatase (ALP) values in odonto-type patients were significantly greater than those of non-odonto-type patients (P<0.05). Autosomal dominant and autosomal recessive inheritance patterns were detected, respectively, in 89% of odonto-type and 96% of non-odonto-type patients. The ALPL "c.1559delT" mutation, associated with extremely low ALP activity, was found in approximately 70% of cases. Regarding dental manifestations, all patients classified as odonto-type showed early exfoliation of the primary teeth significantly more frequently than patients classified as non-odonto-type (100% vs. 56%; P<0.05). Tooth hypomineralisation was detected in 42% of non-odonto-type patients, but not in any odonto-type patients (0%; P<0.05). Collectively, these results suggest that genetic and dental manifestations of patients with odonto-type and non-odonto-type HPP are significantly different, and these differences should be considered during clinical treatment of patients with HPP., Competing Interests: The authors have declared that no competing interests exist.

Among the risk factors causing generalized demineralisation of dental solid tissues in young kids (disturbances during antenatal development of embryo, frequent sickness of infant, etc.) the most important factor is the type of breath feeding of infant. Such factors as the good balance of calcium and phosphor in mother's milk contribute to the maintenance of healthy dental tissues. As our data shows in majority of kids (98%) with artificial feeding type, calcium and phosphorus levels in the blood serum and their rate (<1.30) were decreased, along with that hydrogen ion concentration in oral fluids was also decreased. All above mentioned has influence on physical-chemical reactions occurring in tooth enamel, increases enamel penetration and reduces buffer characteristics of oral fluids. Those problems are especially important for Georgia, where the level of fluoride in the drinking water is very low (0.35-0.45 mg/l).