An in vitro investigation into the antimicrobial activity of some endodontic medicaments and their bases using agar diffusion, biofilm testing and medicament inactivation by dentine

Basil Athanassiadis

Research output: ThesisMaster's Thesis

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There is no question that micro-organisms are at the centre of the cause of pulpal and periradicular pathoses. Antimicrobial agents have been used in endodontic therapy for more than a century. It is well known that after instrumentation and irrigation some type of further disinfection is required to enhance the chances for treatment success; hence various types of medicaments have been used over the last century. Currently calcium hydroxide is the most commonly used medicament but others include antibiotic/steroid combinations of which Ledermix paste is the most popular. Although these ingredients are the active components of the medicaments, their vehicles play an important role in determining the ionic dissociation of the active components as well as the handling properties of the product. This study used three different testing models to compare, by in vitro means, the efficacy of a number of medicaments in terms of their antimicrobial spectrum, medicament inactivation and ability to penetrate Enterococcus faecalis biofilms. Their bases were also tested separately to establish what effect these components had. The medicaments used in each test model were Ledermix paste, Pulpdent paste, Ultracal paste, and a 50:50 mixture of Ledermix and Pulpdent pastes, while the bases tested included methyl cellulose and water, polyethylene glycol (PEG), and PEG combined with zinc oxide, calcium chloride and the remainder of ingredients which form the base for Ledermix paste. Well diffusion assays were used to test the antimicrobial action of the above commercial products and their bases. The zones of inhibition were recorded and compared to assess the relative antimicrobial actions. Each medicament and base was also applied to biofilms of E. faecalis generated on cellulose nitrate membrane filters. Each of these biofilms were transferred to a saline solution which was seeded onto agar plates and then the colony forming units were counted to determine the number of bacterial cells destroyed. The final experiment investigated the antimicrobial effect of some current medicaments and their bases on E. faecalis in the presence of dentine, and evaluated the extent of inactivation of the antibacterial activity by dentine. The results of the three studies showed that none of the bases had any major antimicrobial effects against the bacteria tested. The combination of Ledermix paste and Pulpdent paste produced the best antibacterial results in the agar diffusion assay. Pulpdent and the Ledermix/Pulpdent combination produced the highest percentage "kills" in E. faecalis biofilms, and this effect was also repeated whilst in the presence of dentine. Taken as a whole, the results of this series of studies suggest that of the medicaments tested (Ledermix, Pulpdent, Ledermix/Pulpdent 50/50) the calcium hydroxide containing medicaments have the greatest antimicrobial properties.
Original languageEnglish
Publication statusUnpublished - 2007


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