Journal of Oral Rehabilitation 1999 26; 624 – 630 Factors inﬂuencing the development of dental erosion in vitro : enamel type, temperature and exposure time B. T. AMAECHI, S. M. HIGHAM & W. M. EDGAR Cariology Research Group, Department of Clinical Dental Sciences, The University of Liverpool, Liverpool, U.K. were positively correlated (r =0·98, P 0·05) to the SUMMARY The inﬂuence of temperature, duration exposure time. Both parameters were signiﬁcantly of exposure, and enamel type on the development and progression of dental erosion has been deter- greater in bovine enamel than human permanent and deciduous enamel, and in human deciduous mined. Three experiments were devised as fol- lows. Eroded lesions were produced on enamel than permanent enamel. Lesion progression, as measured by mineral loss, was in the ratio samples with orange juice: (1) at different temper- atures; (2) for different lengths of time; and (3) on 2·0:1·5:1·0 for bovine:human deciduous:human per- manent, and by lesion depth, 1·7:1·3:1·0. In conclu- bovine permanent, human deciduous and human permanent enamel. Lesion parameters (mineral sion, the erosiveness of orange juice was less pronounced at a lower temperature, and increased loss and lesion depth) were quantiﬁed using trans- verse microradiography. Both lesion parameters with an increased exposure time. Erosion pro- were signiﬁcantly lower at 4 °C when compared gressed twice as fast in bovine permanent than in human permanent enamel, and 1·5 times more with 20 °C and 37 °C, and at 20 °C when compared with 37 °C. Lesion parameters increased signiﬁ- rapidly in human deciduous than in permanent cantly as the length of exposure increased, and enamel. Introduction Frequent and prolonged ingestion of acidic foods and beverages (Levine, 1974; Ja ¨ rvinen, Ryto ¨ maa & Heinonen, 1991), exposure to acidic environments such as industries that use or produce acidic materials (ten Bruggen Cate, 1968; Tuominen & Tuominen, 1991) or gas-chlorinated swimming pools (Centerwall et al., 1986), as well as illnesses associated with chronic vomiting and/or regurgitation (Clark, 1985; Ja ¨ rvinen et al., 1991; Meurman et al., 1994), have all been shown to predispose teeth to the development of dental ero- sion. Scanning electron microscopy has been used by many researchers (Johnson, Poole & Tyler, 1971; Ry- to ¨ maa et al., 1988; Meurman & Frank, 1991; Millward, Shaw & Smith, 1995; Grando et al., 1996) to demon- strate the progressive destruction of enamel structure with increasing length of exposure to acidic substances. Meurman & ten Cate (1996) stated that any solution with a pH value lower than 5·5 may cause erosion, particularly if the attack is of long duration and re- peated over time, while ten Cate et al., (1991) used polarized light microscopy to demonstrate the direct relationship between the mineral dissolution and the time of dissolution. Most acidic drinks and beverages are usually taken when the drink is either ice-cold, at room temperature, or warm. Like other chemical reactions, the rate of enamel dissolution has been shown to be temperature dependent. This is based mechanistically on the inﬂu- ence of temperature on the rate of diffusion of chemi- cal elements through the enamel (Flim & Arends, 1977; de Rooij & Arends, 1981) and aqueous solutions (Longsworth, 1954), since Gray (1962) reported that the reaction of enamel dissolution is diffusion-con- trolled. This suggests that the development and pro- © 1999 Blackwell Science Ltd 624