Title: 0458 - The Influence of Hardness and Chemical Composition on Enamel Demineralization and Subsequent Remineralization


Rana Alkattan (Presenter)
Indiana University School of Dentistry

Frank Lippert, Indiana University
Masatoshi Ando, Indiana University
Qing Tang, Indiana University School of Medicine


Objectives: To investigate the hardness and chemical composition of sound, demineralized (demin) and remineralized (remin) bovine enamel and their influence on demineralization and remineralization.

Methods: Demineralization was chemically induced in 94 bovine enamel specimens at three different times [(24h (n=33), 48h (n=30), 96h (n=31)]. The specimens were then pH-cycled using either 367 ppm F sodium fluoride or deionized-water. Surface microhardness (SMH) and energy dispersive X-ray spectroscopy (measured-elements: Ca, P, F, C, Mg, N) were performed at three stages (sound, demin, remin) and transverse microradiography was performed at demin and remin. Comparisons were determined by ANOVA.

Results: SMH, integrated mineral loss (ΔZ) and lesion depth (L) were significantly different between stages, demineralization times and treatments. Surface zone mineralization (SZmax)was significantly different between stages and treatments, but not demineralization times. The weight% of F at the surface was significantly affected by treatment, irrespective of demineralization time. Both fluoride and deionized-water specimens were remineralized. For SMH, a weak positive correlation was found between sound and demineralization (r=0.31, p=0.002), however, there was no correlation between sound and after pH-cycling (r=0.07, p=0.49). The Ca:P ratio remained stable at all stages.

Conclusions: Harder specimens at the sound stage remained hard after demineralization and pH-cycling, respectively. Additionally, harder lesions showed less ΔZ and L, and greater SZmax, and were thus less susceptible to demineralization. Finally, specimens with greater surface F weight% had greater SZmax, which in turn had less ΔZ and L, and were therefore less susceptible to demineralization.

Student Presenter

This abstract is based on research that was funded entirely or partially by an outside source:
Dental Master’s Thesis Award Program from Delta Dental Foundation

Disclosure Statement:
The submitter must disclose the names of the organizations with which any author have a relationship, the nature of the relationship, and the clinical or research area involved. The following is submitted: NONE