A new optical detection method to assess the erosion inhibition by in vitro salivary pellicle layer S.C. Brevik a , A. Lussi b , E. Rakhmatullina * Department of Preventive, Restorative and Paediatric Dentistry, University of Bern, Freiburgstrasse 7, Bern CH-3010, Switzerland 1. Introduction Possibilities for the quantitative in vivo diagnosis of early dental erosion and monitoring of the treatment efficiencies in vivo are very attractive long-term goals in dentistry. It is known that the in vivo enamel etching proceeds slower than in vitro or in situ erosions, 1 involving repeated demineraliza- tion/remineralization processes together with attrition and abrasion effects. 2 Therefore, clinical monitoring of dental erosion requires systematic and, preferably, quantitative assessment of dental tissues over long time periods. On the other hand, detection of those little alterations of the enamel tissue in vivo is a challenge because the majority of the analytical tools in the field can be applied only in vitro due to, for example, long X-ray exposure times, 3 destructive mea- surement effects (indentation analysis, 4 permeability tests 5 ), or time-consuming sample preparation (scanning electron j o u r n a l o f d e n t i s t r y 4 1 ( 2 0 1 3 ) 4 2 8 – 4 3 5 a r t i c l e i n f o Article history: Received 26 October 2012 Received in revised form 15 February 2013 Accepted 16 February 2013 Keywords: Reflection intensity Dental erosion Pellicle Prevention Microhardness SEM a b s t r a c t Objectives: Application of the recently developed optical method based on the monitoring of the specular reflection intensity to study the protective potential of the salivary pellicle layer against early enamel erosion. Methods: The erosion progression was compared between two treatment groups: enamel samples coated by the 15 h-in vitro-formed salivary pellicle layer (group P, n = 90) and the non-coated enamel surfaces (control group C, n = 90). Different severity of the erosive impact was modelled by the enamel incubation in 1% citric acid (pH = 3.6) for 2, 4, 8, 10 or 15 min. Erosion quantification was performed by the optical method as well as by the microhardness and calcium release analyses. Results: Optical assessment of the erosion progression showed erosion inhibition by the in vitro salivary pellicle in short term acidic treatments (4 min) which was also confirmed by microhardness measurements proving significantly less ( p < 0.05) enamel softening in the group P at 2 and 4 min of erosion compared to the group C. SEM images demonstrated less etched enamel interfaces in the group P at short erosion durations as well. Conclusions: Monitoring of the specular reflection intensity can be successfully applied to quantify early erosion progression in comparative studies. In vitro salivary pellicle (2 h) provides erosion inhibition but only in short term acidic exposures. Clinical significance: The proposed optical technique is a promising tool for the fast and non- invasive erosion quantification in clinical studies. # 2013 Elsevier Ltd. All rights reserved. * Corresponding author. Tel.: +41 31 6328603; fax: +41 31 6329875. E-mail addresses: cathrine.brevik@zmk.unibe.ch (S.C. Brevik), adrian.lussi@zmk.unibe.ch (A. Lussi), ekaterina.rakhmatullina@zmk.unibe.ch (E. Rakhmatullina). a Tel.: +41 31 6328603; fax: +41 31 6329875. b Tel.: +41 31 6322510; fax: +41 31 6329875. Available online at www.sciencedirect.com journal homepage: www.intl.elsevierhealth.com/journals/jden 0300-5712/$ – see front matter # 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jdent.2013.02.011