evaluation of alkaline phosphatase levels and salivary hydroxyapatite ion activity in 6‒12-year-old children with different caries severity

introduction: salivary calcium and phosphate levels might have a relationship with dental caries severity. evaluation of different indexes such as alkaline phosphatase, which increases salivary phosphate levels, and hydroxyapatite ion activity, which reflects salivary calcium and phosphate levels, might help determine the risk of dental caries. the aim of the present study was to compare salivary alkaline phosphatase activity and hydroxyapatite ion activity index in 6‒12-year-old children with different rates of dental caries.   materials and methods: in this descriptive-analytical study the teeth were examined in 152 children, aged 6‒12, by a dentist and were placed into three experimental groups according to the dental caries severity as follows: group 1: severe dental caries ( dmft ≥ 6); group 2: moderate dental caries rate (1 < dmft < 6); and group 3: mild dental caries rate (dmft ≤ 1). after collection of saliva, salivary alkaline phosphatase levels and hydroxyapatite ion activity were measured for each sample. data was analyzed using one-way anova and a post hoc tukey test (α = 0.05). results: the means and standard deviations of alkaline phosphatase levels in groups 1 to 3 were 5.39 ± 2.96, 5.71 ± 3.68 and 5.83 ± 4.53 unit/dl, respectively. hydroxyapatite ion activity rates were 25.80 ± 0.70, 28.28 ± 0.76 and 28.50 ± 0.56 in groups 1 to 3, respectively. the results of one-way anova showed no significant differences between the experimental groups in alkaline phosphatase levels (p value = 0.830) and hydroxyapatite ion activity (p value = 0.065). conclusion: according to the finding of the present study, alkaline phosphatase level and hydroxyapatite ion activity have no effect on tooth caries severity in 6‒12-year-old children. future studies are recommended.