The management of occlusal caries still remains a major challenge for researchers as well as for general practitioners. The present paper reviews and discusses the most up-to-date knowledge and evidence of the biological principles guiding diagnosis, risk assessment, and management of the caries process on occlusal surfaces. In addition, it considers the whole spectrum of the caries process on occlusal surfaces, ranging from the molecular ecology of occlusal biofilms to the management of deep occlusal caries lesions. Studies using molecular methods with focus on biofilms in relation to occlusal caries should explore the relationship between the function and the structural composition of these biofilms to understand the role of occlusal biofilms in caries development. State-of-the-art measures to evaluate risk for occlusal caries lesion activity, caries incidence, and progression should include the assessment of the occlusal biofilm and the stage of tooth eruption. Careful clinical examination of non-cavitated lesions, including assessment of the lesion activity status, remains the major tool to determine the immediate treatment need and to follow on the non-operative treatment outcome. Even medium occlusal caries lesions in the permanent dentition may be treated by non-invasive fissure sealing. By extending the criteria for non-invasive treatments, traditional restoration of occlusal surfaces can be postponed or even avoided, and the dental health in children and adolescents can be improved. Selective removal (incomplete) to soft dentin in deep carious lesions has greater success rates than stepwise excavation. Selective (complete) removal to firm dentin has a lower success rate due to increased pulp exposure.

Streptococcus mutans, consisting of serotypes c, e, f and k, is an oral aciduric organism associated with the initiation and progression of dental caries. A total of 135 independent Streptococcus mutans strains from caries-free and caries-active subjects isolated from various geographical locations were examined in two versions of an MLST scheme consisting of either 6 housekeeping genes [accC (acetyl-CoA carboxylase biotin carboxylase subunit), gki (glucokinase), lepA (GTP-binding protein), recP (transketolase), sodA (superoxide dismutase), and tyrS (tyrosyl-tRNA synthetase)] or the housekeeping genes supplemented with 2 extracellular putative virulence genes [gtfB (glucosyltransferase B) and spaP (surface protein antigen I/II)] to increase sequence type diversity. The number of alleles found varied between 20 (lepA) and 37 (spaP). Overall, 121 sequence types (STs) were defined using the housekeeping genes alone and 122 with all genes. However π, nucleotide diversity per site, was low for all loci being in the range 0.019–0.007. The virulence genes exhibited the greatest nucleotide diversity and the recombination/mutation ratio was 0.67 [95% confidence interval 0.3–1.15] compared to 8.3 [95% confidence interval 5.0–14.5] for the 6 concatenated housekeeping genes alone. The ML trees generated for individual MLST loci were significantly incongruent and not significantly different from random trees. Analysis using ClonalFrame indicated that the majority of isolates were singletons and no evidence for a clonal structure or evidence to support serotype c strains as the ancestral S. mutans strain was apparent. There was also no evidence of a geographical distribution of individual isolates or that particular isolate clusters were associated with caries. The overall low sequence diversity suggests that S. mutans is a newly emerged species which has not accumulated large numbers of mutations but those that have occurred have been shuffled as a consequence of intra-species recombination generating genotypes which can be readily distinguished by sequence analysis.

The aim of this study was to compare the genotypic diversity and virulence traits of Streptococcus mutans isolated from carious dentin before and after partial dentin caries removal (PDR) and sealing. Carious dentin samples were obtained three months before and after the PDR and cavity sealing. Up to seven isolates of each morphological type of S. mutans were selected and strain identity was confirmed using gtfB primer. Genotyping was performed by arbitrary primer-PCR (AP-PCR). Acidogenesis and acidurance of the genotypes were evaluated as virulence traits. A paired t-test and a Wilcoxon test were used to compare the virulence of genotypes. A total of 48 representative S. mutans isolates were genotyped (31 before and 17 after the sealing). At least one of the genotypes found before the sealing was also found on dentin after the sealing. The number of genotypes found before the sealing ranged from 2 to 3 and after the sealing from 1 to 2 genotypes. No difference was observed in the acidogenesis and acidurance between genotypes isolated before and after the sealing. In conclusion, genotypic diversity of S. mutans decreased after the PDR and sealing, but the virulence traits of S. mutans remained unchangeable.

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The aim of the present study was to evaluate the effect of two chlorhexidine rinsing solutions (0.12% and 0.2%) on plaque and gingival bleeding. Ten dental students participated in this double-blind, cross-over study, rinsing twice a day, for one minute, with each one of the tested solutions for fourteen days. A wash-out period of one week between treatments was observed. In order to assess gingival bleeding, the van der Weijden et al. 1 (1994) index was used. The plaque indexes used were those of Quigley, Hein 2 (1962) and Silness, Löe 3 (1964). In the pre-experimental period, subjects received oral hygiene instructions and dental prophylaxis. The results revealed no significant differences between both concentrations in relation to plaque and gingival bleeding. Mean values (± standard deviation) of the Quigley & Hein index were 0.25 ± 0.16 for the 0.12% solution and 0.23 ± 0.26 for the 0.2% solution (p = 0.4838). Mean values (± standard deviation) of the Silness-Löe index were 0.12 ± 0.10 for the 0.12% solution and 0.11 ± 0.11 for the 0.2% solution (p = 0.7592). The bleeding index mean values at the end of the study were not different for both concentrations with mean values (± standard deviation) of 14.93% ± 6.68% and 13.95 ± 9.24% for the 0.12% and 0.2% solutions, respectively. Although an increase in gingival bleeding was observed, both concentrations were able to control dental plaque.