Effect of different demineralizing solutions and different exposing times on artificial initial caries lesion formation - an in vitro study

Introduction/Objective. Artificial enamel caries lesions are commonly created to simulate in vivo caries development and to examine the effect of non-invasive and microinvasive approaches in treatment of initial caries lesions. The objective of the present study was to compare three different demineralizing solutions and exposing times in terms of the formation of artificial white spot lesions and to evaluate their demineralization effect through Scanning Electron Microscopy observations. Methods. Twenty intact human premolars, extracted for orthodontic reasons, were thoroughly cleaned, stored in 0.1% thymol solution at room temperature and cut at the cementoenamel junction before demineralizing process. The specimens were randomly divided into three experimental groups, according to the used demineralization agent and the time of exposure: Group I (Acetic acid; pH = 4.4; 96 hours); Group II (Lactic acid; pH = 4.5; 120 hours); Group III (Lactic acid; pH = 4.3; 504 hours) and one control group (saline). After demineralisation, macroscopic appearance was checked and all specimens were observed under Scanning Electron Microscope to evaluate the enamel characteristics and caries lesion depths. Results. In Group I and II enamel subsurface porosity with dissolution of enamel crystals is detected and the mean depths of white spot lesions were 48.55 ?m (SD = 1.11) and 43.23 ?m (SD = 6.74), respectively. In Group III structural integrity of enamel surface was not preserved. Conclusion. Demineralizing solutions used in experimental groups I and II resulted in artificial initial caries lesions with satisfactory characteristics and similar appearance on Scanning Electron Microscopy. The outcome of demineralizing process which lasted 504 hours were cavitated enamel lesions.