Influence of Fluoride on Remineralization Via the Polymer-Induced Liquid-Precursor Process on Dentine Hardness

Polymer-induced liquid-precursor (PILP) process used polyaspartic acid as an analog non-collagenous protein to prevent spontaneous nucleation of calcium and phosphate before entering the intrafibrillar compartment. Fluoride was added for the formation of fluorapatite crystals. Objective of this study is determining the effect on dentinal hardness when fluoride is added in the PILP process. Twenty-four dentin blocks were divided into four groups. Group I (normal dentin) was the control, Group II comprised demineralized dentin stored in PILP remineralization solution, Group III comprised demineralized dentin stored in remineralized PILP solution with 5 ppm fluoride, Group IV comprised demineralized dentin stored in remineralized PILP solution with 25 ppm fluoride. All samples were stored in an incubator with continuous shaking at 37 °C for 14 days. A Vickers hardness test was performed to measure dentin hardness along with an X-ray diffraction (XRD) test to determine the percentage of hydroxyapatite and fluorapatite crystals. There are significant differences between the hardness values of dentin after storage in PILP solution, PILP solution with 5 ppm fluoride, and with 25 ppm fluoride. The conclusion is remineralization via PILP process with the addition of 5 ppm fluoride and 25 ppm fluoride yields higher dentinal hardness value than without fluoride.