A minimally destructive technique for removing the smear layer from dentine surfaces

Objectives To develop a minimally destructive technique for removing the smear layer produced by cutting and polishing specimens of dentine prepared for use in experimental studies e g on occlusion of dentinal tubules by oral health products The aim was to avoid the damage caused by conventional techniques utilising short exposures to solutions with very low pH Methods Two acetate buffers pH 5 5 containing different concentrations of calcium and phosphate, with -log(ion activity product with respect to hydroxyapatite) (pI(HA)) of 55 or 56 were tested on slices of dentine using scanning electron microscopy (SEM) Results A solution which from previous work was slightly undersaturated with respect to dentine mineral with a pI(HA) of 56 was found to remove smear layers produced by cutting and/or polishing after 15 min However to reliably remove debris occluding the tubules an exposure time of 2 h followed by brief ultrasonication was necessary After 2 h treatment with this buffer only a small amount of demineralization of the surface was detectable by SEM while calcium and phosphorus were detectable by X ray dispersive spectroscopy Conclusion It is possible to remove smear layers and to open dentinal tubules by a reasonably short exposure to an acidic buffer which is undersaturated with respect to dentine mineral (C) 2010 Elsevier Ltd All rights reserved