Enterococcus Faecalis
Enterococcus faecalis is a gram-positive facultative anaerobic bacterium, and it frequently is isolated from endodontic cases requiring retreatment. It can infect dentinal tubules up to 800 micrometers from the root canal wall. E. faecalis was found in many studies to be resistant to most of the used intracanal medications. Sodium hypochlorite and chlorhexidine have proved to be effective against E. faecalis in vitro, but they require direct contact.(106,107)
The effect of intracanal medications on the Physical properties of root dentin couldn’t be neglected. Acids are commonly added to some antibiotics to maintain chemical stability, control tonicity or to ensure physiological compatibility. However, long-term exposure of dental hard tissues
to acidic antibiotics might cause demineralization and negatively affect their mechanical properties. Minocycline, a component in the TAP, has been found to chelate calcium and demineralize dental hard tissues. Furthermore, enamel exposure to aqueous tetracycline solutions for one and 25 hours caused dramatic and continuous reduction in microhardness.(108) Similarly, highly alkaline Ca(OH)2 medicaments have been suggested to significantly decrease root resistance to fracture within
1 month.(109)
Neither antibiotics nor calcium hydroxide based pastes, when used as intracanal medications, can be completely eliminated from root canals. Residual medicament, by acting as a physical barrier between root canal dentin and the sealer, adversely affects penetration of sealers into the root canal dentin walls.(110-112)
The effect of intracanal medications on the Physical properties of root dentin couldn’t be neglected. Acids are commonly added to some antibiotics to maintain chemical stability, control tonicity or to ensure physiological compatibility. However, long-term exposure of dental hard tissues
to acidic antibiotics might cause demineralization and negatively affect their mechanical properties. Minocycline, a component in the TAP, has been found to chelate calcium and demineralize dental hard tissues. Furthermore, enamel exposure to aqueous tetracycline solutions for one and 25 hours caused dramatic and continuous reduction in microhardness.(108) Similarly, highly alkaline Ca(OH)2 medicaments have been suggested to significantly decrease root resistance to fracture within
1 month.(109)
Neither antibiotics nor calcium hydroxide based pastes, when used as intracanal medications, can be completely eliminated from root canals. Residual medicament, by acting as a physical barrier between root canal dentin and the sealer, adversely affects penetration of sealers into the root canal dentin walls.(110-112)