Effect of electrophoresis on correlation between mineral content and enamel micro-hardness: a study in New Zealand rabbits

Introduction
This in-vivo animal study investigated the correlation between calcium-to-phosphorus (Ca : P) ratio and enamel micro-hardness, and compared traditional re-mineralization techniques with electrophoresis-aided techniques using different re-mineralizing agents.

Objectives
The null hypothesis of the study was that there is a strong connection between Ca : P ratio and micro-hardness, and electrophoresis technique has a positive effect on the correlation between Ca : P ratio and enamel micro-hardness.

Material and methods
In New Zealand rabbit models, initial enamel lesion was produced, followed by acid etching treated with three re-mineralizing agents: nano-hydroxyapatite (n-HAP), casein phosphopeptide-amorphous calcium phosphate (CPP-ACP), and bio-active glass (BAG). Samples were subjected to de-mineralization and re-mineralization processes, with chemical composition and micro-hardness assessed with energy-dispersive X-ray analysis (EDX) and Vickers hardness testing, respectively. Measurements were obtained at baseline, post-de-mineralization, and post-re-mineralization at different time periods: two weeks and five weeks for traditional technique, and three hours and five hours for electrophoresis-aided technique.

Results
Energy dispersive X-ray spectrometer (EDX) and Vickers micro-hardness tester results revealed significant differences in Ca : P ratios and micro-hardness in re-mineralizing agents. N-HAP exhibited the highest Ca : P ratio, while N-HAP and CPP-ACP showed superior micro-hardness compared with BAG. However, no significant correlation was identified between Ca : P ratio and micro-hardness. Electrophoresis accelerated re-mine­ralization kinetics, but did not enhance the relationship between mineral content and enamel micro-hardness.

Conclusions
The findings highlight the efficacy of electrophoresis in promoting faster re-mineralization, while questioning its impact on the fundamental link between enamel composition and mechanical properties.