Adil Durrani, Muhammad Anwaar Alam, Mustafa Qadeer, Saira Atif.
The study of demineralized and remineralized enamel & hydroxyapatite using nuclear magnetic resonance (NMR).
Pak Oral Dental J Jan ;36(1):60-5.

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 31P MAS NMR techniques. Chemical structure and composition of enamel and hydroxyapatite 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 hydroxyapatite. Synthetic hydroxyapatite 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 hydroxyapatite 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.

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