A comparison of in vitro erosion-like mineral loss between continuous and intermittent acidic exposure with and without human saliva Stephen Creanor a, *, Siobhan Creanor b , Nutayla Alharthy c a Peninsula Dental School, Peninsula College of Medicine and Dentistry, The University of Plymouth, Room C407, Portland Square, Plymouth PL4 8AA, United Kingdom b Centre for Health & Environmental Statistics, Room 301, ITTC Building, Tamar Science Park, Plymouth, Devon PL6 8BX, United Kingdom c Oman Dental College, PO Box 835, Muscat MAF 116, Oman 1. Introduction The management of patients with dental erosion is increas- ingly being influenced by sound scientific research. 1,2 The advice that patients might be provided with may take the form of counselling, intentional stimulation of salivary flow (e.g. by means of chewing sugar-free gum), the provision of various fluoride regimen, the modification of potentially erosive beverages, as well as the advising of sound adequate oral hygiene measures. 1 The current level of knowledge relating to our understanding of dental erosion has come largely from observations on patients who have reduced salivary flow for all manner of reasons. 3 Particular attention has been paid to two major themes of investigation: the first of these is the investigation of those patients suffering from loss of tissue as a result of increased intrinsic or extrinsic acid exposure – this can be the result of, a r c h i v e s o f o r a l b i o l o g y 5 6 ( 2 0 1 1 ) 7 0 3 – 7 0 8 a r t i c l e i n f o Article history: Accepted 23 December 2010 Keywords: Enamel Human saliva Demineralisation Dental erosion Microradiography a b s t r a c t Aim: This in vitro study aimed to compare erosion-like mineral loss following intermittent or continuous acidic exposures, and considered the role that human saliva may play. Materials and methods: 180 bovine enamel blocks were divided randomly into four equally- sized groups and exposed to one of the 4 protocols 6 times daily over 6 days (total acidic exposure time of 6 h): Group 1, continuous 10 min in orange juice (OJ) followed by 10 min in deionised water; Group 2, continuous 10 min in OJ followed by 10 min in stimulated saliva; Group 3, ten 1-min OJ exposures alternating with ten 1-min deionised water exposures; Group 4, ten 1-min OJ exposures alternating with ten 1-min stimulated saliva exposures. Specimens were stored in a remineralising solution between acidic exposures. Sections were cut and transverse microradiography was used to measure lesion depth in each specimen. Results: Mean (sd) lesion depths were 21.5 (8.1), 21.2 (6.2), 81.7 (12.2) and 72.8 (12.4) mm for Groups 1–4, respectively. Significant differences existed between all protocols except Groups 1 and 2 (mean difference À0.3 mm, 95% CI: À6.1 to 5.5). The mean difference between Groups 3 and 4 was 8.9 mm (95% CI: 3.2–14.7). Conclusions: Repeated, intermittent exposure to an acidic drink in vitro resulted in greater lesion depth than a continuous exposure of the same duration. Saliva offered some protection against intermittent acidic exposure. # 2011 Elsevier Ltd. All rights reserved. * Corresponding author. Tel.: +44 01752 586830; fax: +44 01752 586788. E-mail address: stephen.creanor@pds.ac.uk (S. Creanor). availab le at www .s cien c edir ect .co m journal homepage: http://www.elsevier.com/locate/aob 0003–9969/$ – see front matter # 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.archoralbio.2010.12.014