Biological interactions of dental cast alloys with oral tissues

Objective: All dental cast alloys release metal ions into the oral environment which have the potential to interact with the oral tissues. Amount and type of metal elements released are varying and not directly related to the composition of the alloy. The aim of the present literature survey was to describe the interactions of dental cast alloys with living tissues and to relate them to clinically adverse local reactions of the oral tissues. Results: Interactions of dental cast alloys with the oral tissues take place by different mechanisms; e.g. bacterial adherence promotion, toxic and subtoxic effects and allergy. Whereas bacterial adhesion promotion may be counteracted by adequate oral hygiene measures, the other mechanisms may lead to clinically adverse local reactions due to the metal present. However, the number of cases, where such a relation can be safely diagnosed, is small. Safe ground is felt with proven allergies. The comparatively high allergy rate towards nickel should be the impetus to replace those alloys whenever there is a suitable alternative. Medical and dental impairments as well as general medication may lead to symptoms allegedly attributed to metal restorations. Conclusions and Significance: Patients relating oral symptoms to metal restorations should be subjected to a thorough dental and general medical examination in order to exclude non-material related diseases being the cause for their complaints/symptoms. These cases are a challenge for the collaboration between the medical and dental professions.