Nano‐hydroxyapatite and its contemporary applications

Combination of nano‐sized hydroxyapatite (nHA) with restorative materials like glass ionomer cement and composite resins has been reported recently in 2011. The documented effects of these nano‐sized particles on the chemistry of these materials include increased biocompatibility and mechanical strength. nHA has been utilized for various applications like pulp capping agent, root canal sealer, filler for bleaching agents and toothpastes, osseo‐conductive bone graft etc., A nHA has been obtained using natural bovine bone, carbon template technique, hydroxyapatite‐chitosan template technique, wet precipitation technique, plasma spraying technique etc. This paper presents a review of the various aspects of nHA and summarizes the methods of fabrications and potential clinical applications of the same. crystallography and chemical composition to that of human hard tissue.[2] On account of its outstanding properties like biocompatibility, bioactivity, osteoconductivity, non‐toxicity and non‐inflammatory nature,[6] this bioceramic has got a variety of applications which include: Bone tissue engineering; restoration of periodontal defects;[7,8] edentulous ridge augmentation;[9] orthopedic and dental implant coating,[10‐12] endodontic treatment like pulp‐capping, repair of mechanical bifurcation perforations and apical barrier formation,[13‐15] fillers for reinforcing restorative glass ionomer cement (GIC)[4,16‐22] and restorative composite resin;[23‐37] desensitizing agent post bleaching;[38] for treating early carious lesions[39‐41] and as a remineralizing agent in toothpastes.[42] In an article in 1975, Nery et al., for the first time in dentistry, studied the effect of tricalcium phosphate reagent in intrabony defects in dogs, but later it was demonstrated that the phosphate was a mixture of hydroxyapatite and tricalcium phosphate.[43,44] Hydroxyapatite is manufactured in many forms and can be prepared as a dense ceramic,[45] powder,[46] ceramic coating[47] or porous ceramic[48] as required for the particular applications. However, in recent years, nano‐sized hydroxyapatite (nHA) with appropriate stoichiometry, morphology and purity have Correspondence to: Dr. Nidhi Kantharia, 1132/3, Vishnu Darshan, F. C. Road, Shivajinagar, Pune ‐ 411 016, Maharashtra, India. E‐mail: [email protected] Introduction Developments in material science, robotics, and biomechanics have dramatically changed the technique of replacing any component of human anatomy with restorative material. Restorative dental materials are subjected to a very hostile environment, in which pH, salivary flow and mechanical loading fluctuate rapidly and constantly. The toxicity of tissues due to materials is gaining more attention with the availability of variety of materials, thus drawing attention of federal agencies.[1] With the development of nanotechnology, a major impact on materials science has been noted. In this century, the production of materials with nanostructures has gained much attention for adsorption, catalytic, biomaterials and optical applications.[2] Hydroxyapatite is the main biomineral component found in human hard tissues, i.e. tooth and bone. Its stoichiometry is represented by the formula (Ca10 (PO4) 6 (OH)). It is comprised of calcium and phosphorus present in the ratio (Ca/P) of 1.67.[3] It is the main mineral component of the enamel, comprising of more than 60% of tooth dentine by weight [Table 1].[4,5] Hydroxyapatite has attracted much interest as a biomaterial for use in prosthetic applications due to its similarity in Review Article Department of Prosthodontics, M. A. Rangoonwala Dental College, 1Center for Materials for Electronics Te c h n o l o g y, 2D e p a r t m e n t o f Oral Pathology, DPU’s D. Y. Patil Dental Col lege , Pimpri , Pune, Maharashtra, India