Mentz, Nicolaas Johannes2008-04-102008-04-102008-04-10http://hdl.handle.net/10539/4753Abstract Introduction: Patients with numerous crowns and bridges are at risk of developing secondary caries on cervical margins of the crowns. This recurrent decay accounts for 60% of the reasons for the replacement of restorations. Detection and treatment of subclinical lesions is important to prevent cavitation. An alginate impression material has been used to locate cariogenic bacteria in established carious lesions. Aims: An alginate impression technique was used to assess the level of Streptococcus mutans and Lactobacilli on the crown margins of the teeth of the restored group and control subjects. Conventional caries activity tests were also used to compare these two groups. Methods: Twenty control group subjects with no crowns and a mean DMFS of 16 and 20 the restored group patients with at least 10 crowns and a mean DMFS of 129 were included in the study. Impressions were taken with a hydrocolloid material mixed with culture broth, incubated and examined for the presence of S. mutans and Lactobacilli on the cervical margins. The results were compared using the two-sample t-test, chi-squared test and a generalized logistic regression analysis. Results: More S. mutans and Lactobacilli were cultured on impressions of the restored group than the control patients (p=0.01 and 0.002). A higher proportion of patients in the restored group had high concentrations of S. mutans and Lactobacilli on their teeth than subjects in the control group (p < 0.001). In the restored group, sixty six per cent of teeth in the posterior and 48% in the anterior segment were crowns. S. mutans and Lactobacilli were found in higher concentrations on the posterior than the anterior teeth of the restored group patients than the control patients (p = 0.016 and 0.047). Furthermore, more Lactobacilli were cultured from the saliva of the restored group than control subjects while the buffering capacity of plaque and the ability of saliva to neutralize acids were lower in the restored group than control group subjects. Conclusion: The impression technique showed that S. mutans and Lactobacilli accumulated in the posterior of the mouth and were associated with crowns indicating these particular sites are at risk.875478 bytesapplication/pdfendental cariesalginateimpressionscrownbridgerestorationsThesis