Oral Presentation

Remineralizing effect of zinc reinforced synthetic nano- hydroxyapatite on caries like lesion in human permanent teeth – An Invitro Study

Dr E. Maheswari, PG Student

: Saveetha Dental College and Hospital, Saveetha University, Saveetha Institute of Medical and Technical Sciences, Chennai, Tamilnadu, India.

Aim : To evaluate and compare the remineralizing effect of synthetic namo-hydroxyapatite and zinc reinforced synthetic nano-hydroxyapatite on caries like lesion in human permanent teeth.


Dental caries is among the most common chronic disease worldwide. A number of  research projects now focussing on the development of remineralizing agents to cease the progression of initial dental caries. Synthetic nano-hydroxyapatite has the same physicochemical properties as those of apatite in the enamel. It shows strong affinity to the tooth and can strongly adsorb on enamel surfaces. Zinc is a trace element of valuable importance in the oral cavity.  Zinc and synthetic nano -hydroxyapatite has the potential to inhibit demineralization and promote remineralization of incipient caries lesion.

Materials and mathods: Synthetic nano-hydroxyapatite was synthesised using calcium hydroxide and orthophosphoric acid. In this invitro study 21 maxillary premolar extracted for orthodontic reasons were included. There are three groups, first group for demineralised teeth specimen, second group for 10% synthetic nano- hydroxyapatite solution and third group –zinc reinforced synthetic nano-hydroxyapatite solution as treatment agents. Enamel window formation of 4mm(length) ×4mm ( width) was created. Initial enamel lesion were prepared with an acidic buffer followed by tooth specimens are subjected to pH cycling. Analysis of caries lesion depth after demineralization and remineralization of tooth specimens was done using polarized light microscope.


Results: The mean lesion depth in demineralised solution group was 161µm. The mean lesion depth of teeth specimens treated with  10% synthetic nano-hydroxyapatite solution  and zinc reinforced synthetic nano- hydroxyapatite solution  was 135.49µm and 111.78µm


Conclusion: Synthetic nano-hydroxyapatite has a remineralizing effect due to deposition of calcium phosphate  ions in the porosities of demineralised area. Zinc reinforced  synthetic nano-hydroxyapatite  shows a additive  remineralizing potential because tooth can uptake zinc as similar to fluoride ions and hence both the therapeutic agents proved to possess a beneficial action on caries like lesion in human permanent teeth.