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Background: The aim of the present research was to investigate the cytotoxicity of the composite resins applied on dentine samples with different smear layer removal, by using cell cultures and LDH determination., Materials and Methods: Ninety-eight caries-free third molars recently extracted were used. Transversal sections, 500 mu thick, were obtained. A simulated pulpar chamber was constructed allowing to give lodging in the inferior side to the cell culture and in the superior side to the dentine section with the composite resin. LDH activity was then determined by using a spectrophotometer., Background: The results show that the composite resins are surely cytotoxic if directly applied on the dentine. The smear layer is able to reduce the transdentinal diffusion of composite resin toxicity. On the basis of the data obtained it is suggested that in vivo, being necessary to eliminate the smear layer due to its bacterial contents, it is possible in the deep cavities, to partially remove with EDTA maintaining the smear plugs after their disinfection. Nevertheless EDTA application should not exceed 30 seconds.

A number of immunological and non-immunological techniques have been recently used to detect soluble microbial substances in body fluids of patients with acute meningitis, bacteremia, and lobar pneumonia. By the immunological methods capsular highly polymerized polisaccharide group- or type-specific antigens of the most common C. N. S. pathogens (N. meningitidis A, B, and C; Str. pneumoniae, H. influenzae type b, E. coli K1, mucoid Pseudomonas, Cryptococcus neoformans) can be detected and quantitated in spinal fluids, sera, urine and other fluids specimens from meningitic patients. Capsular type-specific antigens from pneumococcus, and likely from H. influenzae as well, can be detected in sputum from patients with lower respiratory infection. Among the various techniques, the radioimmunoassay appears as the most sensitive one, but high diagnostic sensitivity can be also achieved by using the latex agglutination, haemoagglutination inhibition and coagglutination tests. Counterimmunoelectrophoresis, however, is still the far most used technique for determining soluble microbial antigens, albeit its sensitivity is significantly less than the one of the above mentioned methods. High specificity and some advantages in serotyping the causal organisms are probably the main reasons of such preferential employment. Among the non-immunological techniques the evaluation of lactate and lactic dehydrogenase has been used by some Author for differentiating between bacterial and non bacterial meningitis, and the limulus test for detecting Gram-negative bacterial endotoxins with a high degree of sensitivity and specificity. Finally, the liquid gas chromatography has been evaluated in detection of some organic products (microbial?), such as acids, amines, neutral compounds, in spinal fluid, allowing the differential diagnosis between bacterial, tuberculous, viral, and cryptococcal meningitis. In the present review sensitivity, specificity, and other properties of each test alone and in comparison with the conventional microbiological methods (Gram and culture) are evaluated and the biological and pathogenic role and significance of the soluble microbial antigens and endotoxin are discussed.