study of demineralized and remineralized enamel and hydroxyapatite using nuclear magnetic resonance (nmr)

The study was conducted to observe if there is any difference in the chemical structure of demineralized and remineralized enamel and hydroxyapatite using solid state 3IP MAS NMR techniques. Chemical structure and composition of enamel and hydroxy apatite powder were analyzed using different acids i.e. hydrochloric acid, citric acid and acetic acid, of different molarities, followed by treatment in remineralizing solution for a time period of 1, 3, 6 and in some cases 7 days, using NMR. We expected to change current concepts of remineralizing and demineralizing processes of enamel and hydroxy apatite

Synthetic hydroxy apatite provided by Plasma Biotal was used for the experiments, while extracted teeth provided by tissue culture labs were used for the enamel. The enamel crowns were converted into powder using Gyro Mill. All the measurements for NMR were done in Bruker NMR spectrometer which had a magnetic field strength of 600MHz or 14.1 Tesla. The nucleus used for the experiments was Phosphorous-31. Changes were observed in the peak positions of HAP as well as enamel powder samples. Remineralized samples [both enamel and HAP] also showed increase in mass which may be due to precipitation of hydroxy apatite on consuming the ions, used from the remineralizing solution

This study provides a better insight into the remineralization and demineralization of enamel and HAP and the changes that take place in the chemical structure after and during the processes. The work also demonstrates that NMR is a very powerful and modern technique which can be used to detect structural changes in different complicated materials

Zinc and flouride containing bioactive glasses in dentistry

The bioactive glasses have been used in the medical field due to their wide spread benefits as implant coatings, bone substitutes and for treatment of dentine sensitivity. The purpose of this study was to incorporate zinc and fluoride in the bioactive glass for potential use in dentifrices as antibacterial and anticaries agents. A series of glass compositions based on SiO2, CaO, CaF2, MgO, and ZnO were prepared with varied amounts of ZnO content ranging from 0% to 15%. Glass synthesis was done by using melt-quench route and fine powder having particle size <38 micro m was obtained by grinding and sieving. Particle size analysis and Differential scanning calorimetry were performed on powder samples. The dissolution study was done in Tris buffer and Acetic acid. Zinc in bioactive glass caused a decrease in glass transition and crystallization temperature. The behavior of zinc free glass was entirely different from zinc containing glass in both Tris and acetic acid. There was rapid release of high concentrations of zinc along with other ions in acetic acid whereas relatively small amount was released in Tris. The fluoride release was slow and small concentrations were recorded in Tris while in acetic acid there was relatively high concentration of fluoride as compared to Tris. The release of calcium and magnesium has been affected in the presence of zinc in Tris and acetic acid. Zinc and fluoride containing bioglasses which are degradable in acetic acid were formulated. But the stability of glass in normal physiological condition has to be further improved with future research work