Enamel Surface Restoration by Toothpastes

Objectives:

Current anti erosion studies mainly focus on the inhibition of tooth substance loss. The potential of products to restore eroded surfaces is, however, much less investigated. The purpose of this study was to compare in vitro the enamel surface restoring potential of 3 toothpaste formulations with varying active systems. A prototype paste containing a Hydroxyapatite-Protein-Composite (HPC) (P1) served as test. Two marketed pastes served as controls: A dual chamber paste with 1000ppm fluoride which mixes calcium and phosphate components upon brushing, Enamel Care (P2) and a fluoride toothpaste containing 1450ppm fluoride (NaF) (P3).

Methods:

12 bovine enamel specimens were mounted in cold cure acrylic, polished flat, eroded (30sec, 5% citric acid) and randomly divided into 3 groups of four. The amount of eroded enamel (WeAr) was measured in µm using a Scantron Proscan 3D profilometer. The eroded surfaces were brushed (1min, 150g load, RT) with 1:1 slurries of the pastes (direct application for P2) followed by equilibration in simulated saliva (37°C, 5 cycles in total). During erosion and treatment reference areas were covered by adhesive tape. Treated surfaces were rescanned by profilometry. The restoration was determined by subtraction of WeAr values from post- and pre-treatment scans at three positions per specimen using customized software.

Results:

The model proved suitable for the measurement of restorative effects. P1 yielded a net restoration of +2.3±0.3µm, which was stable against brushing. The control pastes left the etched area largely unchanged (P2: -0.4±0.5µm, P3: -0.2±0.3µm).

Conclusion:

Under the chosen conditions restoration was clearly detectable after 5 treatments for P1. HPC presumably adheres to the etched enamel surface and by additional support through fluoride, nucleates material that binds to the surface. Adherence of formed depositions is possibly lower for the controls. The properties of P1 can be discussed within the framework of anti erosion efficacy.