Phenolic compound-derived natural antimicrobials are less effective in dental biofilm control compared to chlorhexidine.

Summary Selection Criteria Two independent investigators searched numerous electronic databases, including PubMed, Scopus, Cochrane Library, Web of Science, and Virtual Health Library (LILACS, BBO), as well as the Open Grey, International Association for Dental Research (IADR), Trip Database, Google Scholar, and Thesis databases, for studies examining the effectiveness of natural antimicrobial compounds as compared to synthetic compounds for the control of dental biofilm through May 2019. The selection criteria included randomized and non-randomized clinical trials. The study population comprised children and adolescents 4 to 18 years of age. Full text of all the articles considered were read by the two investigators for further analysis. In case of any disagreement, a third independent investigator resolved the disagreement. In vitro, animal, and cross-sectional studies, case reports, and literature reviews were excluded. In addition, studies investigating two natural compounds, eucalyptol and thymol, were excluded. Key Study Factor The key study factor investigated was the efficacy of natural phenolic compounds as compared to a synthetic compound for the control of oral microbes in children and adolescents. The natural antimicrobials that are derived from phenolic compounds are less effective in reducing the microbial biofilm and plaque index. In these studies, a single synthetic antimicrobial (Chlorhexidine) was used in concentrations between 0.1% and 0.2% for comparison with multiple antimicrobials made of naturally derived compounds used in concentrations between 0.2% and 10%. These products were tested for a range of durations (minimum 5 to a maximum of 270 days). Main Outcome Measure The main outcome measures included plaque index and microorganism counts (Streptococcus mutans, and other Streptococcus species). The studies used various indices to measure oral hygiene, including the Simplified Oral Hygiene Index (OHI-S), Patient Hygiene Performance (PHP), Silness-Loe Plaque Index (PI), and Quigley–Hein plaque index (QHI). The microorganism count was evaluated by counting the colonies of various species such as Streptococcus mutans, Lactobacillus, and Streptococcus viridans. The mean and standard deviation of PI, the microorganisms (Mos) count before and after the administration of either natural antimicrobials derived from phenolic compounds (NAPs; experimental group) or synthetic antimicrobial (SA; control group), and the number of participants in each group were included in the Comprehensive Meta-Analysis software to calculate the difference between these groups. Because the studies report their outcomes using similar parameters for PI evaluation and different parameters for MOs count, the mean difference (MD) and standard mean difference (SMD) were applied, respectively, with a 95 % confidence interval. Main Results Among the included studies, fourteen were randomized control trials and two were non-randomized control trials. The final meta-analysis was performed on twelve studies; four studies were excluded due to either using a different plaque index (Quigley–Hein plaque index) or not stating the standard deviation values of bacterial counts. The determined risk of bias for most of the studies included in the meta-analysis was very high, while the quality of the evidence was moderate to low. Although most studies included in the review reported a remarkable reduction in the plaque index by natural antimicrobials (mango; mean difference: 0.250, p=0.00, CI: 0.145 - 0.355, and, neem; mean difference: 0.236. p= 0.00, CI: 0.129 - 0.344), these products are not suggested to substitute the synthetic antimicrobials due to inadequate evidence. Natural antimicrobials were less efficacious in improving the plaque index (p 87 %) and reducing biofilm over time (p 87 %), but presented a reduction in micro-organisms count similar to that of synthetic antimicrobials (p=0.3, I2=0%). Nevertheless, further studies are necessary to confirm these results and to improve the quality of the evidence. Conclusions The natural products derived from phenolic compounds for oral biofilm reduction and bacterial counts are less effective than the synthetic antimicrobial.