Effect of pH and Lidocaine on the Compressive Strength of Calcium Enriched Mixture Cement

Statement of Problem: The pH of the human abscess has been measured as low as 5.0. This low pH could potentially inhibit setting reactions, affect adhesion, or increase the solubility of root end filling materials hence affect the compressive strength. Moreover, root end filling materials might expose or even mix with lidocaine HCL during periapical surgery. Objectives: The aim of this in vitro study was to evaluate the effect of acidic pH and lidocaine on the compressive strength of calcium-enriched mixture (CEM). Materials and Methods: CEM was mixed according to the manufacturer’s instructions or with lidocaine (L), and condensed into 6 × 4 mm split moulds. The samples were exposed to phosphate buffered saline (PBS) at pH 5 or 7.4 for 7 or 28 days. Cylindrical blocks of CEM (total number = 120 and 15 for each group) were subjected to compressive strength test using a universal testing machine. Data were analysed using three-factor analysis of variance (ANOVA). Results: Regardless of pH and time, significant differences were not found between lidocaine groups and the groups that were mixed according to the manufacturer’s instruction (p = 0.083). For both mixing agents, regardless of time, there were no significant differences between the two pH levels (p = 0.157). Regardless of the material and pH, there was a significant increase in the compressive strength from days 7 to 28 (p < 0.001). Conclusions: Mixtures with lidocaine and exposure to an acidic environment had no adverse effects on the compressive strength of CEM Cement.