Title : Aspartic acid facilitated calcium ion incorporation a new approach for enamel remineralization outperforming fluoride efficacy
Abstract:
Enamel erosion represents a widespread clinical concern, as prolonged pH reduction disrupts the natural balance between demineralization and remineralization processes normally maintained by saliva, substantially elevating erosion risk. Current therapeutic approaches focus on hydroxyapatite stabilization or calcium/phosphate ion supplementation to promote remineralization. However, these methods exhibit critical limitations: poor solubility, insufficient penetration into deeper enamel layers, formation of calculus and complexes leading to reduced bioavailability, and, in the case of fluoride, risk of fluorosis. Such limitations prompt exploration of novel biomimetic approaches. Aspartic acid, a calcium-binding amino acid abundant in enamel matrix proteins during tooth development, presents promising potential as a remineralization enhancer by directing hydroxyapatite crystallization processes.
The aim of the research was to investigate the remineralization potential of aspartic acid alone and in combination with various calcium sources, comparing their efficacy to fluoride as a conventional market benchmark.
Bovine enamel blocks were sectioned from tooth samples of deceased animals for experimental use. Baseline surface microhardness (SMHR) measurements of enamel blocks were obtained, followed by demineralization in pH 4,5 solution for 60 minutes and subsequent SMHR reassessment. Enamel blocks (n=10 per treatment group) then underwent 16-hour incubation in solutions with test substances. Remineralization efficacy was quantified through percentage recovery of surface microhardness (%SMHR). Three experiments were carried out using aspartic acid alone and in combination with various calcium sources to determine their remineralization efficiency and synergistic effects. In each study, deionized water served as the negative control and 1450 ppm fluoride as the positive control.
In an evaluation of the individual remineralizing efficacy of calcium sources, 1% CaMgZnHAP, 1% tricalcium phosphate (TCP), and 1% nanoXim®CarePaste Hydroxyapatite (nano) demonstrated statistically significant remineralization, resulting in a mean %SMHR values of 27%, 21% and 15%, respectively, however, fluoride exhibited the highest remineralizing effectiveness among the tested products, achieving an average %SMHR of 36%. Individually aspartic acid (Asp) at concentrations of 0,2% and 0,4% caused pronounced demineralization, resulting in mean %SMHR values of -88% and -92% compared to the negative control, deionized water, which achieved a mean %SMHR of -29%. In contrast, a lower concentration of Asp (0,1%) did not exhibit demineralizing effects, instead, a trend toward remineralization was observed, with a mean %SMHR of 3%. Combining aspartic acid with calcium sources markedly enhanced remineralization. The 0,5% aspartic acid + 1% dicalcium phosphate dihydrate formulation achieved the greatest SMHR recovery (45%), followed by 0,5% Asp + 1% CaMgZnHAP (33%), 0,5% Asp + 1% nanoXim®CarePaste Hydroxyapatite (nano) (26%), and 1% Asp + 1,5% TCP (23%). All combinations surpassed fluoride’s 5%. Notably, increasing the concentration of aspartic acid does not enhance remineralization and a lower (0,1%) concentration of Asp with 0,5% TCP achieved 32% SMHR, surpassing fluoride’s 14%. These results highlight the synergistic potential of aspartic acid-calcium formulations, offering a promising alternative to fluoride-based therapies.
