Endodontic sealer zinc oxide-eugenol

Zinc oxide-eugenol is a somewhat old-fashioned material, but it is widely used as an endodontic sealer [18]. It has relatively poor mechanical properties, but is easy to use in the dental clinic [19] and outcomes are good, which explains its continuing popularity. When set, it is biocompatible towards dental hard tissues, though it is cytotoxic towards soft tissues [20]. Zinc oxide-eugenol is susceptible to hydrolysis, which causes the material to decompose and release eugenol. It is this latter substance which is responsible for the cement s adverse effects on soft tissues, but which also makes the material bactericidal. 

Overall, despite not having completely ideal properties as sealing materials, zinc oxide-eugenol is an effective material. Its many years of satisfactory clinical service demonstrate this, and outcomes with it are generally good. There is little current research on zinc oxide-eugenol endodontic sealers, bnt this is a reflection on the fact that it is a mature material with a proven track record. It ranains one of the most widely used materials for endodontic sealing [18], and is likely to remain so for the foreseeable future. 

Since the launch of Ketac Endo, other glass-ionomer products for use as endodontic sealers have appeared on the market. They typically have reasonable physical properties [50,52], certainly better than those of zinc oxide-eugenol canents and they are less susceptible to hydrolytic degradation. 

Glass-ionomers are known to have strong anti-bacterial properties when newly placed [57], a feature which is attributed to the combined effects of their low early pH and their ability to release fluoride in an early burst shortly after forming [58]. These effects have been confirmed for glass-ionomer endodontic sealers [59], but anti-bacterial effects were transient, and had disappeared after 24h. This contrasts with zinc oxide-eugenol canent, which has been shown to maintain its anti-bacterial... 

In endodontic treatment, the aim is to completely seal the root canal. Traditionally this has been carried out with cones of gutta percha, also containing added zinc oxide, barium sulfate, plasticizers and coloring agents (Friedman et al, 1975), packed into the canal with a sealer - usually a cement containing zinc oxide and eugenol. A concern with this material system is that there is no adhesion between gutta percha and the sealer, or between the sealer and the tooth dentin. Further, complete adaptation of the material to completely obturate the root canal is not always achieved. 

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