Plaque fluoride and mutans streptococci in plaque and saliva before and after discontinuation of water fluoridation

Mass spectrometry-based proteomic approaches for salivary protein biomarkers discovery and dental caries diagnosis: A critical review

Dental caries is a multifactorial chronic disease resulting from the intricate interplay among acid-generating bacteria, fermentable carbohydrates, and several host factors such as saliva. Saliva comprises several proteins which could be utilized as biomarkers for caries prevention, diagnosis, and prognosis. Mass spectrometry-based salivary proteomics approaches, owing to their sensitivity, provide the opportunity to investigate and unveil crucial cariogenic pathogen activity and host indicators and may demonstrate clinically relevant biomarkers to improve caries diagnosis and management. The present review outlines the published literature of human clinical proteomics investigations on caries and extensively elucidates frequently reported salivary proteins as biomarkers. This review also discusses important aspects while designing an experimental proteomics workflow. The protein-protein interactions and the clinical relevance of salivary proteins as biomarkers for caries, together with uninvestigated domains of the discipline are also discussed critically.

Does cessation of community water fluoridation lead to an increase in tooth decay? A systematic review of published studies

Background

Cessation of community water fluoridation (CWF) appears to be occurring with increasing frequency in some regions. Our objective was to comprehensively review published research on the impact of CWF cessation on dental caries.

Methods

We searched 13 multidisciplinary databases. Results were synthesised qualitatively and quantitatively.

Results

We identified 15 instances of CWF cessation (‘intervention’) in 13 countries, which covered a broad time frame (1956–2003) and diverse geographical and political/economic contexts. Overall, results were mixed, but pointed more to an increase in caries postcessation than otherwise. For example, of the 9 studies with at least moderate methodological quality based on criteria we developed for this review, 5 showed an increase in caries postcessation. 3 studies did not show an increase in caries postcessation; however, important postcessation changes (eg, implementation of alternative fluoride delivery programmes) and/or large-scale social change may have contributed to those effects. Of the 3 study groupings that permitted quantitative synthesis, 2 showed statistically significant mean overall increase in caries postcessation; however, quantitative synthesis results must be interpreted cautiously.

Conclusions

Overall, the published research points more to an increase in dental caries post-CWF cessation than otherwise. However, the literature is highly diverse and variable in methodological quality. To build this literature, it is important to exploit research opportunities presented by CWF cessation. Remaining knowledge gaps include the impact of CWF cessation on the distribution of dental caries (ie, equitable or not) and understanding the decision-making circumstances around CWF cessation.

Nanomechanical and chemical characterization of incipient in vitro carious lesions in human dental enamel

OBJECTIVE

The research was designed to examine the growth of in vitro carious lesions in dental enamel using nanoindentation and time-of-flight secondary ion mass spectroscopy (TOF-SIMS). This was intended to give maps of mechanical properties and chemistry over the cross-section of the lesions.

METHODS

Incipient carious lesions were grown on the buccal faces of 20 human premolars by exposure to acid for 3, 5, 7 or 14 days. The lesions were then cut in cross-section normal to the exposed surface. The lesions' cross-sections were then examined using nanoindentation and TOF-SIMS.

RESULTS

The earliest lesions (3 days of acid exposure) showed little evidence of lesion growth, but the 5, 7 and 14 days of exposure all gave lesions with a weak, demineralized interior, but a stronger, less demineralized surface zone. The thickness of the surface zone was found to diminish with the length of exposure to acid, but it was still present even after 14 days of exposure.

CONCLUSION

The results indicate that carious lesions develop subsurface and that the surface zone forms by a coupled diffusion process. Mechanically the lesion has a strong surface layer, but a very weak interior which makes the lesion vulnerable to mechanical loading. However, the presence of a surface zone that retains a high mineral content and is mechanically strong suggests that lesion development can be arrested and possibly reversed even when the lesions are relatively mature.

Influence of a Fluoride Mouthrinse on Mutans Streptococci in Schoolchildren

This study aimed to determine whether the long-term use of a fluoride mouthrinse affects the salivary levels of mutans streptococci. Two hundred and fifteen schoolchildren (aged 9-10 years) participated. One hundred and forty-nine of these children had used a fluoride mouthrinse since 5 years of age at nursery school, and the remaining 66 children had not. DFT (decayed and filled teeth) was recorded, and the salivary levels of Streptococcus mutans and Streptococcus sobrinus were measured using mitis salivarius bacitracin agar. The group that had used a fluoride mouthrinse had a significantly lower prevalence of both S. mutans and S. sobrinus (p = 0.038) and a significantly lower DFT score (p < 0.001) than the other group. Using logistic regression analysis including caries experience at baseline as a dependent variable, the odds ratio of carrying S. mutans alone was 8.0 (p = 0.066) and that of carrying both S. mutans and S. sobrinus was 16.5 (p = 0.022) in the group that had not used the fluoride mouthrinse. Children carrying both S. mutans and S. sobrinus had a higher caries incidence in 1 year than the others, with odds ratios of 5.73 (p = 0.067) in the group with a fluoride mouthrinse and 3.47 (p = 0.035) in the group without it. These results show that the long-term use of a fluoride mouthrinse is associated with reduced salivary levels of mutans streptococci and this bacterial reduction may partly contribute to the suppression of dental caries in children using a long-term fluoride mouthrinse.