Hydroxyapatite remineralizes enamel after acid erosion


Tooth erosion is the dissolution of enamel caused by acid. The acids are not from microorganisms, they are either extrinsically from food or from the stomach in patients with bulimia or a reflux disease. In both cases, long-term exposure of the teeth to these acids leads to the increased dissolution of the enamel. The saliva is not longer able to repair these defects and the balance shifts to demineralisation. The buffer effect of the saliva is also reversed so that the enamel continues to erode. This often results in exposed tooth necks and, as a result, hypersensitive teeth. In addition to a change in diet, a dental and oral care product that supports saliva is recommended. Besides the remineralisation of defects, the most important feature of a toothpaste or mouthwash is the prevention of new erosions.


How effective is the erosion protection and the remineralisation potential of a hydroxyapatite toothpaste compared to commercially available products?

Material and methods

For this in vitro study, 50 enamel samples were divided up into a total of five groups: (i) erosion, without toothpaste, (ii) erosion, fluoride-free toothpaste, (iii) erosion, fluoride toothpaste, (vi) erosion, hydroxyapatite toothpaste, (v) erosion, hydroxyapatite toothpaste with zinc PCA. Erosion was initiated with cola for 2 minutes. Erosion was initiated a total of four times and after 0, 8, 24 and 32 hours. The toothpastes were applied to the enamel samples after the acid treatment. The toothpaste was left on the teeth for 3 minutes and then washed off with distilled water. The teeth were stored in artificial saliva between the treatments. The surface hardness (Vickers hardness) of the samples was measured at the beginning (0 hours) and at the end of the samples series (32 hours). Then the groups were compared with each other for statistically significant differences.


Vickers hardness is a measurement of remineralisation of the enamel. The greatest increase after erosion could be seen with (iv) hydroxyapatite toothpaste and (v) hydroxyapatite toothpaste with zinc PCA. The fluoride toothpaste (iii) and toothpaste without fluoride (ii) followed. The differences were statistically insignificant.


Hydroxyapatite toothpastes remineralise the teeth and harden the enamel after acid erosion better than the usual tested oral care products.


The publication of the study can be found here.


Source: Poggio, C., C. Gulino, M. Mirando, M. Colombo and G. Pietrocola (2017). “Protective eff ect of zinc-hydroxyapatite toothpastes on enamel erosion: An in vitro study.” J. Clin. Exp. Dent. 9: e118-e122