The aim of the present study was to evaluate the remineralizing effect of (hydroxyapatite nano particles,sodium hexametaphosphate, hydroxyapatite nanoparticles and sodium hexametaphosphate in combination) with and without use of artificial saliva on enamel and dentin. Forty freshly extracted human premolars were used in this study.
They should be free from caires, macroscopic cracks, abrasion or extensive staining.
The teeth were kept in normal saline until use. Each tooth was horizontally cut to separate the crown from the root by using a low – speed double faced diamond disc. Each crown were then sectioned longitudinally in to two parts (buccal and lingual) then put it in normal saline to avoid dehydration.The samples were divided into (2) main groups of (15) samples, where group one consist of (15) teeth (2 halves) not immersed in artificial saliva, while group two included the samples which immersed in artificial saliva. According to the substrate tissue they devided into enamel group (B1) and dentine group (B2). Each group was then subdivided into four subgroups of 5 samples each, according to the treatment solution, Subgroup (A1): treated with hydroxyapatite nanoparticle, Subgroup (A2): treated with sodium hexametaphosphate and Subgroup (A3): treated with combination of two materials (HA + SHMP).Sample were subjected to the following
testing procedure: 1) The qualitative micro-morphological changes that occurred in enamel surface and in the dentin after etching and after the application of the remineralizing solutions.2)The quantitative analyzed using Energy dispersive X-ray spectrometric Analysis (EDXA) to determine the calcium and phosphorous mineral content and the change in the levels of these elements percentage due to demineralization. As well, the fluoride content was deduced in respect to these subgroups treated with HA solutions. The results was found that (HA+SHMP+AS) group in enamel recorded the highest
total mean mineral contents, followed by (HA+AS) group in enamel, then group (HA+SHMP) in dentine,while the mean for control (HA) in enamel group recorded the lowest total mean mineral contents. The difference between groups was statistically