Effect of fluoride in amalgam on secondary caries incidence

Clinical efficacy of bioactive restorative materials in controlling secondary caries: a systematic review and network meta-analysis

BACKGROUND

This systematic review and network meta-analysis aimed to compare the clinical efficacy of bioactive and conventional restorative materials in controlling secondary caries (SC) and to provide a classification of these materials according to their effectiveness.

METHODS

A search was performed in Pubmed, Web of Science, Embase, BBO, Lilacs, Cochrane Library, Scopus, IBECS and gray literature. Clinical trials were included, with no language or publication date limitations. Paired and network meta-analyses were performed with random-effects models, comparing treatments of interest and classifying them according to effectiveness in the permanent and deciduous dentition and at 1-year or 2/more years of follow-up. The risk of bias and certainty of evidence were evaluated.

RESULTS

Sixty-two studies were included in the qualitative syntheses and 39 in the quantitative ones. In permanent teeth, resin composite (RC) (RR = 2.00; 95%CI = 1.10, 3.64) and amalgam (AAG) (RR = 1.79; 95%CI = 1.04, 3.09) showed a higher risk of SC than Glass Ionomer Cement (GIC). In the deciduous teeth, however, a higher risk of SC was observed with RC than with AAG (RR = 2.46; 95%CI = 1.42, 4.27) and in GIC when compared to Resin-Modified Glass Ionomer Cement (RMGIC = 1.79; 95%CI = 1.04, 3.09). Most randomized clinical trials studies showed low or moderate risk of bias.

CONCLUSION

There is a difference between bioactive restorative materials for SC control, with GIC being more effective in the permanent teeth and the RMGIC in the deciduous teeth. Bioactive restorative materials can be adjuvants in the control of SC in patients at high risk for caries.

Review on fluoride-releasing restorative materials--fluoride release and uptake characteristics, antibacterial activity and influence on caries formation

OBJECTIVES

The purpose of this article was to review the fluoride release and recharge capabilities, and antibacterial properties, of fluoride-releasing dental restoratives, and discuss the current status concerning the prevention or inhibition of caries development and progression.

METHODS

Information from original scientific full papers or reviews listed in PubMed (search term: fluoride release AND (restorative OR glass-ionomer OR compomer OR polyacid-modified composite resin OR composite OR amalgam)), published from 1980 to 2004, was included in the review. Papers dealing with endodontic or orthodontic topics were not taken into consideration. Clinical studies concerning secondary caries development were only included when performed in split-mouth design with an observation period of at least three years.

RESULTS

Fluoride-containing dental materials show clear differences in the fluoride release and uptake characteristics. Short- and long-term fluoride releases from restoratives are related to their matrices, setting mechanisms and fluoride content and depend on several environmental conditions. Fluoride-releasing materials may act as a fluoride reservoir and may increase the fluoride level in saliva, plaque and dental hard tissues. However, clinical studies exhibited conflicting data as to whether or not these materials significantly prevent or inhibit secondary caries and affect the growth of caries-associated bacteria compared to non-fluoridated restoratives.

SIGNIFICANCE

Fluoride release and uptake characteristics depend on the matrices, fillers and fluoride content as well as on the setting mechanisms and environmental conditions of the restoratives. Fluoride-releasing materials, predominantly glass-ionomers and compomers, did show cariostatic properties and may affect bacterial metabolism under simulated cariogenic conditions in vitro. However, it is not proven by prospective clinical studies whether the incidence of secondary caries can be significantly reduced by the fluoride release of restorative materials.

Fluoride-releasing restorative materials and secondary caries

Secondary caries are responsible for 60% of all replacement restorations in the typical dental practice. Risk factors for secondary caries are similar to those for primary caries development. Unfortunately, it is not possible to predict accurately which patients are at risk for restoration failure. Fluoride-releasing dental materials provide for improved resistance against primary and secondary caries in coronal and root surfaces and have become a part of the dentist's armamentarium. This article discusses the improvement in the properties of dental materials with the ability to release fluoride. It is anticipated that in the near future, the vast majority of restorative procedures will employ fluoride-releasing dental materials as bonding agents, cavity liners, luting agents, adhesives for orthodontic brackets, and as definitive restoratives.

Mutans streptococci and incipient caries adjacent to glass ionomer cement or resin-based composite in orthodontics

Levels of mutans streptococci in plaque adjacent to orthodontic brackets retained with a glass ionomer cement (GIC) (Ketac-Cem) and a resin-based composite (CR) (Concise) were investigated, using the split mouth technique in 11 patients who, before treatment, had more than 10(5) CFU of these microorganisms. After full-term orthodontic treatment (mean 9.5 months), the percentage of mutans streptococci of total CFU count in plaque was lower adjacent to GIC-retained brackets (mean 3.9) than adjacent to CR-retained brackets (6.7), but the difference was not statistically significant. Two subjects harbored S. sobrinus. These subjects were the only ones who developed incipient caries during the orthodontic treatment. Incipient lesion formation occurred only adjacent to CR-retained brackets. This suggests that in patients who have relatively high salivary levels of mutans streptococci before treatment and especially in those who harbor S. sobrinus, the use of GIC for bonding may prevent incipient caries formation during orthodontic treatment.

Outcome measures in split mouth caries trials and their statistical evaluation

The split mouth study design in trials of fissure sealants and restorative materials neatly controls for confounding by many of the variables associated with poor retention of sealants and occurrence of dental caries. Traditionally, the outcome measures used in split mouth trials have been material retention, (per cent) effectiveness and net gain. A survey of the literature revealed that a large proportion of split mouth studies report no statistical evaluation of outcome measures. In those studies in which statistical evaluation had been conducted, McNemar's X2 was the test most frequently used. This statistic is appropriate for comparing differences between "success" and "failure" tooth pairs (or "positives" and "negatives" in split mouth terminology) but it cannot evaluate directly effectiveness and net gain. The distributions of effectiveness and net gain are different and it would be desirable to estimate confidence intervals for them. In this paper, we consider these statistics, suggest methods by which confidence intervals may be calculated, and provide examples of the calculations. We demonstrate the close relationship between effectiveness (as used in split mouth trials) and relative effect and relative risk (as used in general epidemiological analysis) and recommend that relative risk should be the preferred outcome measure for split mouth trials. Whatever outcome measure is chosen in split mouth trials should always be subjected to statistical evaluation, preferably by the calculation of confidence intervals.