Laboratory Erosion Model to Assess Restorative Activity

Objectives: The purpose of this study was to develop a robust laboratory model to assess individually and collectively the intraoral parameters and dynamics of partially demineralized enamel when exposed to oral care agents, dietary factors and life style choices. Methods: Enamel specimens were mounted in epoxy and polished to an optical flat. Profilometer scans documented the enamel surface after each step in the process. The ends of the optical flat were covered with 3M tape to leave a 1-3mm window of enamel that was etched with 5% citric acid for 10 sec. This etched surface together with the optical flat surface served as profilometer reference areas for the all subsequent steps. Results: Oral care agents and food items were applied to this partially demineralized enamel surface and then the treated surface equilibrated with stimulated or simulated saliva to consolidate the treated surface. The experiment could end at this point or cycles of typical oral milieu factors were then used to assess the stability and other parameters of the treated partially demineralized enamel surface. The surface was stressed with mechanical, chemical and combinations to characterize the treated surface. Typically, tooth brushing with and without toothpaste, acidic liquids such as simulated fruit juices and sonication were used to characterize the treated, partially demineralized enamel surface. Typical dentifrice ingredients restored as much as 20% of the initial acid demineralization; however, the stability of treatments varied with stress procedures. Conclusions: Human and bovine enamel has served as useful and uniform model substrates. Mechanical stylus profilometer permitted multiple substrate scan measurements. Chemical etching produced a physically friable, chemical reactive substrate to simulate a multitude of oral responses and reactions. Treatments and cyclic stability sequences were completed in one day using profilometer scans to measure surface loss and roughness as the initial surface parameters.