Adverse effects of dental materials : clinical and experimental observations

Abstract

Possible side effects of dental amalgam restorations were investigated in a group of 50 referred patients who related their symtoms to their dental restorations. This group of patients was compared with a matched control group. All patients were subjected to an oral and medical as well as an psychiatric/psychological examination, and the symptoms were related to mercury levels in blood, urine and hair. A psychiatric diagnosis was established in 70% of the patients in the index group versus 14% in the control group. The prevailing symptoms were, anxiety, asthenia and depression. Somatic diseases were more common in the index group (38% versus 6%) and symptoms related to cranio-mandibular dysfunction were reported by 74% of the patients in the index group versus 24% in the control group, and were diagnosed in 62% and 36%, respectively. Mercury levels in blood, urine and hair were similar in both goups, and far below critical values of mercury intoxication. No correlation was found between mercury levels and the severity of reported symptoms.The effect of selective replacement of dental amalgam fillings on lichenoid contact lesions (CL) was studied in a group of 142 patients. Ninety-five % of the lesions resolved or improved markedly within an observation period of one year. The corresponding figure for oral lichen planus (OLP) patients were 63%. OLP lesions in sites not in contact with amalgam were not affected. The healing response in patients who received noble gold crowns was superior to treatment with metal-ceramic crowns (p<0.05).The differential diagnosis between OLP and CL is based on clinical findings, since it is not possible to differentiate by means of histopathological methods. As these two lesions are regarded to have different etiologies, the frequencies of different T cell V-families were examined by immunohistochemistry. It was not possible to discriminate between OLP and CL by this method. No increased expression of any of the investigated V-families was revealed.The effects of resin components and eluates of root canal sealers were tested in a con-A driven proliferation of both spleen cells and purified T cells which were activated by pulpal cells. The proliferative response, in both assays became suppressed in a concentration-dependent fashion by several of the tested materials. It was noticed that some materials also had a stimulatory effect on spleen cells at low concentrations. These in vitro studies show that resin components and extracts from root canal sealers may evoke either immunosuppression or immunstimulation on mitogen-driven proliferation of purified T cells and spleen cells.The observations made in this thesis support the view that potential adverse effects of dental materials have to be analyzed by different methods which follow formalized and harmonized standards. Thus, information about possible risks should be based on observations from both experimental tests in vitro and in vivo, and from studies of documented clinical side effects.