EFFECT OF SODIUM-HYPOCHLORITE TREATMENT ON REMINERALIZATION OF HUMAN ROOT DENTIN IN-VITRO

Dentine consists simplified of mineral and of several organic componen ts. Sodium hypochlorite (NaOCl) is a well-known nonspecific proteolyti c agent capable to remove organic material. The aim of this study was to investigate the influence of organic material removal from artifici al dentine lesions by means of NaOCl pretreatment on subsequent remine ralization with and without fluoride. Human root dentine samples were demineralized in an acidic gel (pH = 5) at 37 degrees C for 2 weeks. A fter 2 min of pretreatment with a 0.4, 2 or 10% NaOCl solution, the sa mples were remineralized in a 20 mM HEPES buffer (pH = 7) containing 1 .5 mM Ca2+ and 0.9 mM phosphate with or without addition of 10 ppm F- as NaF at 37 degrees C for 8 days. Mineral profiles were assessed by m eans of transversal microradiography after diol treatment to avoid shr inkage caused by drying. In a separate experiments the dentine contrac tion caused by 10% NaOCl was assessed. The contraction (negligible for sound dentine) was found to be about 12% for the lesions. The reminer alization results showed that pretreatment with a 10% NaOCl solution f or 2 min, increased lesion remineralization. After NaOCl treatment, th e amount of accumulated mineral increased by about 27% without F in th e remineralization solution, and by about 4% with 10 ppm in solution. The in vitro results suggest that removal of organic materials from de ntine lesions is an interesting approach to enhance remineralization.