Development, characterization and comparison of two strontium doped nano hydroxyapatite molecules for enamel repair/regeneration

Abstract

Objectives. Enamel damage resulting or arising from/associated with orthodontic treatmentsuch as white spot lesions and surface deterioration after debonding brackets along withincipient carious lesions are considered problems not amenable for routine restorations dueto its invasive nature. The present study was aimed at synthesizing and characterizing nHApand 25 and 50 mol% strontium nHAp as a surface application modality for dental enamelremineralization/repair.Methods. 25 and 50 mol% Sr nHAp was synthesized and characterized in comparison withcustom made pure nHAp initially with the help of transmission and scanning electronmicroscopy as well as toxicological assessment. Further, comparative evaluation of thesenovel synthesized strontium substituted particles was assessed for its efficacy in repairingdamaged enamel with the help of atomic force microscopy, scanning electron microscopyand micro indentation testing.Results. There is increase in crystallinity and reduced particle size favoring dissolution andre-precipitation through small incipient carious lesions and soft white spot areas with 25%Sr-nHAp. Sr doped specimens showed more cell viability in comparison with pure nHAPmake it less cytotoxic and hence a biologically friendly material which can be safely appliedin patient’s mouth. AFM images obtained from 25% and 50% Sr nHAp treated specimensclearly indicated increased roughness in surface topography and performed well with microindentation test.Significance. The novel synthesized Sr doped nHAp forms an improved treatment modality totackle the long standing quest for solving the problem of enamel loss with incipient cariouslesions and WSL from orthodontic procedures.