Studies on migration of metal ions originated from cast post and antigen presenting ability of periodontal ligament cells.

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We have been seeing allergic patients for more than fourteen years in our metal allergy clinic. Currently, one of our major questions is whether we should remove metal cast post that contains allergens out of allergic patient's mouth, in case of the metal is not directly exposed to the oral cavity. Because there should be certain risks removing cast post out of the tooth. The purpose of this study was to investigate the distance of corroded ions from cast post migrating outward along the root dentinal tubules to seek the guideline for removal of cast post in case of metal allergy.First, we investigated the extracted teeth that had metal post inside and whose treatment histories were known using the highest resolution EPMA. However, there were no detectable metal ions when we investigated the cut surface of the teeth. Then we carried out several types of in vitro experiments simulating intra oral mouth conditions using orthodontically extracted teeth. As far as we found using most sensitive machine we have currently, there were only negligible copper migrated to root dentine from cast post in several hundred micrometer. We could not conclude that there was no possibility for corroded metal ions from cast posts exit the outer root surface. However, the removal of cast posts that are not exposed, out of allergic patients may have less priority than other treatments because it is less likely for the patients to be exposed to the allergen at high concentration.Further careful investigations will be needed.