Probiotics- insufficient evidence for use in caries management

The potential for probiotic species to have a beneficial effect on cariogenic or periodontal pathogens has been demonstrated in vitro studies and a number of clinical studies and reviews have been conducted.

The aim of this review was to synthesise available randomised controlled studies investigating effects of probiotics on oral caries or periodontal disease (gingivitis and periodontitis)

Methods

Searches were conducted in the Cochrane Central Register of Controlled Trials, Medline and Embase databases.Randomised controlled trials (RCTs) in any language published since 1967 that reported on dentate humans who consumed oral probiotics, regardless of the way of consumption or the probiotic species with control interventions of placebo or alternative treatments (eg. chlorhexidine, xylitol) were considered.

Two reviewers carried out data abstraction and risk of bias assessment independently. Random effect meta-analysis was performed with the patient as the unit of analysis.

Results

50 studies involving 3247 patients were included.
The majority were parallel group studies (40) with 9 crossover and 1 split mouth study.
Studies were mainly performed in children and used lactobacilli (45); bifidobacteria (12) or other genus (3).
Interventions lasted 2 days to 84 weeks (mean: 8 weeks)
8 studies had low risk of bias, 34 unclear risk and 8 high risk
Probiotics significantly increased the chance of reducing Streptococcus mutans (OR: 2.20, 95% CI: 1.23-3.92) or lactobacilli (OR: 2.84; 1.34- 6.03)<10⁴CFU/ml. Such reduction was confirmed for Streptococcus mutans counts (standardized mean differences: -1.18, 95% CI: -1.64 to-0.72), but not lactobacilli (SMD: 0.33; 0.15 – 0.52).
For periodontal pathogens, no significant difference was found.
Probiotics significantly reduced bleeding-on-probing (SMD: -1.15; -1.68 to -0.62) and gingival index (SMD: -0.86; -1.52 to-0.20), but not plaque index (SMD: -0.34; -0.89 to 0.21).
Probing-pocket depths (SMD: -0.86; -1.55 to -0.17) were significantly reduced.
Data was quantitatively insufficient for conclusive findings; overall the evidence supporting probiotic therapy was graded as very low for all outcomes
25 studies indicated they monitored adverse effect. No serious adverse effects were reported. One study reported mild gastrointestinal irritations.

Conclusions

The authors concluded

There is a relatively large and growing number of controlled trials investigating probiotic management of caries or periodontal diseases. Most of them measure surrogate markers with limited validity. Future studies should only record such surrogates alongside accepted markers or indicators of caries (like incidence or experience increment) or periodontitis (like pocket probing depth and clinical attachment level). Current evidence is insufficient for recommending probiotics for managing dental caries. A growing number of studies support probiotic therapy to prevent or treat gingivitis and periodontitis.

Comments

While this review has identified a large number of studies the most commonly measures outcomes were surrogate measures (bacterial numbers) and while the caries studies reported non-significant benefits in a range of age groups the studies were prone to publication bias and of limited validity as highlighted by the authors. Benefits were also demonstrated for some periodontal outcomes but again the data was limited. The authors also highlight the possibility of publication bias. While this review provides an update to earlier review of this topic and includes some additional studies the quality of the evidence is low.

Links

Primary paper

Gruner D, Paris S, Schwendicke F. Probiotics for managing caries and periodontitis: Systematic review and meta-analysis. J Dent. 2016 Mar 8. pii: S0300-5712(16)30027-6. doi: 10.1016/j.jdent.2016.03.002. [Epub ahead of print] Review. PubMed PMID: 26965080.

Review protocol on PROSPERO database