title: Development, characterization and comparison of two strontium doped nano hydroxyapatite molecules for enamel repair/regeneration.
abstract: OBJECTIVE
  Enamel damage resulting or arising from/associated with orthodontic treatment such as white spot lesions and surface deterioration after debonding brackets along with incipient carious lesions are considered problems not amenable for routine restorations due to its invasive nature. The present study was aimed at synthesizing and characterizing nHAp and 25 and 50 mol% strontium nHAp as a surface application modality for dental enamel remineralization/repair.
  
  
  METHODS
  25 and 50 mol% Sr nHAp was synthesized and characterized in comparison with custom made pure nHAp initially with the help of transmission and scanning electron microscopy as well as toxicological assessment. Further, comparative evaluation of these novel synthesized strontium substituted particles was assessed for its efficacy in repairing damaged enamel with the help of atomic force microscopy, scanning electron microscopy and micro indentation testing.
  
  
  RESULTS
  There is increase in crystallinity and reduced particle size favoring dissolution and re-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 nHAP make it less cytotoxic and hence a biologically friendly material which can be safely applied in patient's mouth. AFM images obtained from 25% and 50% Sr nHAp treated specimens clearly indicated increased roughness in surface topography and performed well with micro indentation test.
  
  
  CONCLUSIONS
  The novel synthesized Sr doped nHAp forms an improved treatment modality to tackle the long standing quest for solving the problem of enamel loss with incipient carious lesions and WSL from orthodontic procedures.
authors.affiliation: Department of Orthodontics, Sri Sankara Dental College, Thiruvananthapuram, Kerala, India. Electronic address: vikrishnan@yahoo.com.
authors.forename: Vinod
authors.initials: V
authors.lastname: Krishnan
authors.affiliation: Bioceramics Laboratory, Biomedical Technology Wing, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala, India.
authors.forename: Ankit
authors.initials: A
authors.lastname: Bhatia
authors.affiliation: Bioceramics Laboratory, Biomedical Technology Wing, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala, India.
authors.forename: Harikrishna
authors.initials: H
authors.lastname: Varma
mesh_terms: D003731:Dental Caries; D003743:Dental Enamel; D017886:Durapatite; D006801:Humans; D008855:Microscopy, Electron, Scanning; D012038:Regeneration; D013324:Strontium
chemical_list: D017886:Durapatite; D013324:Strontium
keywords: Crystallinity; Hydroxyapatite; Nanoparticle; Orthodontics; Surface texture