Influence on periapicai tissues of indigenous oral baclteria and necrotic pulp tissue in monkeys. Scaad. J. Bent. Res. 1981: 89: 475-484. Abstract -Ia nine monkeys (Macaca fascicularis) the pulps of 78 teeth were aseptlcaUy necrotized. Twenty-six of the pulp chambers were kept bacteria-free by scaling, while 52 were infected by the indigenous oral flora. The results were recorded clinically, radiograp hie ally and micro biologic ally at the beginning of the experiment and after 6-7 months. The fmal examination also included histologic recordings. The initially noninfected root canals were all sferile at the flnal samplings, indicating that the risk of contamination (including ihematogenouis) of root canals of this anim.al is verv^ slight. It was shown that noninfected necrotic puip tissue did not induce inflammatory reactions in the apical tissues., By contrast, teeth with infected pulp tissue showed inflammatory reactions clinically (12/52 teeth) aod radiographically (47/52 teeth). Facultatively anaerobic streptococci, coliform rods and o^bligately anaerobic bacterial strains were most frequently foiand. In the final samples the number of obligately anaerobic straims increased. Some microorganisms which were isolated in the initial samples were not detected in the final samples. All infected teeth histologically examined showed strong inflaiomatory reactions in the periapical region.

A retrospective study of 572 teeth treated with periapical surgery was undertaken in order to evaluate the influence of preoperative, operative and postoperative factors in the healing process as well as the operation method used. It was also the aim to assess whether the histophatological diagnosis of biopsies taken at the operation could be correlated to healing. Statistical analyses by the AID method and conventional cross-classification methods were performed. Factors of importance were found to be the extent of the destrucion, the operation method used, the bone surrounding the destruction, the quality of the orthograde root filling, the age of the patient, and the marginal bone buccally. The operation method was of importance in large destructions where root fillings were considered as not having properly sealed the canals, and when treating inflamed cysts. The histopathological diagnosis could not be ascribed any definite prognostic value.

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The oral lesions in 50 habitual snuff‐dippers were graded on a four‐point scale. The patients' tobacco and drinking habits were studied by means of a questionnaire. From each patient a biopsy was taken for histomorphological and histochemical analysis. A correlation between snuff habits and the clinical degrees was found, as well as between the snuff habits and certain superficial and deeply located cell changes. The incidence of keralinized lesions, sialadenitis and slight dysplasia (based on subjective evaluation under a light microscope) was higher than previously reported. Presence of dysplastic changes could not be predicted by means of the parameters which characterise the snuff habit or from the clinical grade. The histomorphological and histochemical results were interpreted as showing that the mucosa react to snuff inducing hyperplasia in the basal cell layers. In the surface layer indications of lethal damage were found. The overall stromal reaction to snuff was weak. However, the salivary glands and excretory ducts exhibited degenerative changes which were found to be more severe than the pathological changes in the surface epithelium.

– When cultures of human epithelial cells were treated for 5 min at 37°C with chlorhexidine in Eagle's medium without serum added, concentrations from 0.05 mM were found to be toxic as measured by growth inhibition and differential staining. About 20 times higher concentrations were needed to obtain a toxic effect, however, when the cells were treated with chlorhexidine dissolved in calf serum. Human whole saliva collected from a single subject had no such protective effect. The intracellular activities of 5′‐nucleotidase, alkaline phosphatase, and NADPH2+ NADH2‐diaphorases decreased upon treatment of the cells with concentrations of chlorhexidine at 0.2 and 2 mM, whereas 0.02 mM had no measurable effect on these enzymes. Treatment with chlorhexidine at 10−4mM had no effect on the hypotonic hemolysis of human erythrocytes, 0.001–0.1 mM stabilized the cells, but increasing the concentration to 1 mM gave 100% hemolysis. A concentration‐dependent inhibition of the Na+–K+–ATPase activity was found when erythrocyte membranes were incubated with chlorhexidine in the range of 0.002–0.2 mM.

– Experimental infections in root canals with Streptococcus faecalisss. liqiuefaciens (Strep‐MG4), Actinomyces bovis (Act‐MO6) and Bacteroides oraiis (Bact‐MC3) were studied in four immunized and five nonimmiLtnized monkeys. The immunization was performed using1 antigens of the homologous strains. The antibody level was checked by gel diffusion. In 56 root canals of the immunized animals and 60 root canals of the nonimmunized animals, viable cells of the three bacterial strains were enclosed in equal amounts in various combinations. After 6 months, samples from the root canals were subjected to qualitative and quantitative bacteriologic analyses and the apical area was radiographically and histologically examined. The analyses revealed no significant difference between the two groups of monkeys, although the viable cell recovery was slightly higher inmost of the root canals of nonimmunized monkeys. The cell proportion of the strains within the different bacterial combinations was equal in root canals of the two groups of animals. The radiograpihic and histologic examinations revealed no significant difference between the two groups of animals regarding the number of teeth with periapical lesions. The radiographic examination, however, showed a more distinct limitation of the process in the immunized than In the nonimmunized monkeys. Histologically the lesions were more encapsulated and had a sparser cell infiltration in immunized than in nonimmunized monkeys. In the latter, inflammatory cells had often infiltrated the bone. Mixed infections gave a more severe periapical reaction than single strain infections in both animal groups.