Modern problems with clever solutions and clinically proven: enamel repair and treatment of hypersensitive teeth with hydroxyapatite


The loss of hard tooth substance is not a major issue at a young age. However, the dissolution of enamel increases with age, which means that around a quarter of adults suffer from hypersensitive teeth due to a loss of hard tooth substance. The term erosion is often used in this context. However, this must be differentiated more precisely: Erosion describes the wear of enamel caused by acid with no bacterial involvement. Attrition is the wear of enamel caused by tooth-on-tooth contact (e.g. bruxism). Abrasion is the "grinding" of enamel from cleaning the teeth or using an unsuitable toothpaste. These enamel defects frequently result in hypersensitive teeth. The tooth can be preserved from this dissolution by means of a protective layer, which can counteract hypersensitive teeth.


Can hydroxyapatite form a protective layer on the teeth under in vivo conditions?

Material and methods

This in vivo study was integrated in a large study to investigate hypersensitive teeth. In this context, the teeth were extracted form a total of 12 participants after they gave their consent. The participants were divided up into three groups and observed over a period of 8 weeks. Once group (5 participants) used a hydroxyapatite toothpaste (Biorepair) for daily oral care, the second group (5 participants) used a KNO3/NaF toothpaste and the third group (2 participants) used an unspecified fluoride toothpaste. All participants had hypersensitive teeth, healthy gums and were between 18 and 75 years old. After 8 weeks, the teeth were extracted and examined under a microscope (scanning electron microscopy and IR spectroscopy) to review the formation of a protective layer.


Hydroxyapatite forms a protective layer on the surface of the enamel. As with enamel itself, this is made up of calcium and phosphate ions. The KNO3/NaF toothpaste did not form a protective layer. Fluorides could not be detected on the surface. The teeth of the participants who used an unspecified fluoride toothpaste showed enamel defects.

Abbildung: Schutzschicht mit Hydroxylapatit
Abbildung: Schutzschicht mit Hydroxylapatit


A hydroxyapatite toothpaste is the only toothpaste that can form a protective layer on the tooth in vivo and protect it from erosion, attrition and abrasion.

The publication of the study can be found here.

Source: Lelli, M., M. Marchetti, I. Foltran, N. Roveri, A. Putignano, M. Procaccini, G. Orsini and F. Mangani (2014). “Remineralization and repair of enamel surface by biomimetic Zn-carbonate hydroxyapatite containing toothpaste: a comparative in vivo study.” Front. Physiol. 5: 333.