Applicability of Common Methods for Short Time Erosion Analysis In Vitro

Purpose: Dental erosion can be measured by different methods. The aim of the present study was to check the applicability of common methods to determine initial erosive effects. Materials and Methods: Enamel surfaces (4.5 mm2) were eroded in vitro by treatment with hydrochloric acid (pH 2, 2.3 and 2.6) for 5 to 60 s or 240 s, respectively. Erosive effects were assayed with three different methods: Knoop's diamond indentation, profilometry and the determination of the dissolved calcium ions (Ca2+) in a colorimetric assay based on the arsenazo-III-reaction. Results: Erosivemineral loss of > 1 lmaremeasurable with profilometry. This corresponds to the erosive effects that occur after 60 s or more. Profilometric data yielded variance of up to 50%. Knoop's diamond indentation also showed some limitations: the depth of indentation reached a plateau after 30 to 120 s and the measurements showed variance of up to 85%. With the colorimetric assay, short time erosive effects occurring within 5 s could be assessed precisely and kinetically. The method allowed small amounts of 400 pmol Ca2+ per well to be quantified in small volumes with little variability. Conclusions: For evaluation and quantification of short time erosive effects, the colorimetric method is superior to diamond indentation and profilometry. Keywords: calcium, erosion, microhardness, photometry, profilometry