Abstract
Calcium phosphate remineralizing slurry (CPRS), consisting of an equimolar mixture of tetracalcium phosphate (TTCP) and dicalcium phosphate dihydrate (DCPD), has previously been shown to form hydroxyapatite (HAp) spontaneously at physiological pH. Since considerable amounts of HAp may be formed in situ by CPRS, it may be effective for desensitizing hypersensitive dentin by obturating exposed dentinal tubule openings.In the present study, the effects of topically applied CPRS to etched dentin surfaces were investigated.The samples were randomly divided into 3 groups: (1) the control specimens were soaked in a saliva-like (SL) solution (2) the specimens received either 10-minute or 1-hour treatment with CPRS and (3) the specimens ware treated with viscous CPRS, containing carboxymethyl cellulose (CMC) gel.for 8 hours. The SEM observations revealed that the control specimens were covered with a thin layer of Plate-like crystals indicative of octacalcium phosphate (OCP). No significant penetration of the crystals into the dentinal tubules was detected. In CPRS group, the 10-minute treatment produced a 10 to 15μm thick dense layer of precipitation consisting of needle-, rod-, and plate-like crystals.The 1-hour treatment produced a similar precipitation except that th crystals were mostly needle-like.A cross section view of the samples indicated remarkable penetration of the crystals into the tubules, thus providing significant obturation of tubule openings.Samples in the CMC-gel group were covered with an even more impervious layer of precipitation consisting of crystals of a variety of morphologies. The methylene blue penetration test results confirmed that the precipitation formed on the dentin surface significantly obturated the tubule openings and reduced the dye penetration into the dentin.Since the crystals formed by CPRS and CMC-gel are HAp, they are relatively stable in the oral environment.The HAp similar to the dentin minerai appeared to adhere firmly to the dentinal surfaces thus forming an effective barrier to dye penetration.Both the CPRS and CMC-gel treatments, which can be easily applied in practice, are potentially useful for treating dentin hypersensitivity. (This study was supported by the NIDR Research Grant DE 05354)
