Effect of garlic (Allium sativum) extract on salivary streptococcus mutans: a systematic review and meta-analysis

Background: Oral and dental diseases are among the common health conditions which can have different effects on the individuals’ health and quality of life. The objective of this study was to examine the effect of garlic (Allium sativum) extract on saliva Streptococcus mutans (primary outcome) and its side effects (secondary outcome).

Methods: In the present systematic review and meta-analysis, English and Persian databases(PubMed, Cochrane Library, Google Scholar, Scopus, SID, and Magiran) were systematically searched until February 25, 2021. The quality of the included studies was examined using Cochranehandbook, and the meta-analysis was carried out using RevMan 5.3. Heterogeneity of the studies was analyzed by index I2. Moreover, the quality of the evidence was assessed through GRADE approach.

Results: A total of 93 studies were found on the databases; 89 articles were screened by title and abstract review and were removed as 19 studies were repetitive and 70 studies were unrelated to the subject under study. Ultimately, 4 articles with a sample size of 171 participants were included in this study, and two of the four studies were meta-analyzed. In all four studies, garlic extract was effective in reducing the number of saliva Streptococcus mutans colonies compared to the control group. The results of the meta-analysis showed that using garlic extract mouthwash significantly decreased the average number of saliva Streptococcus mutans colonies (Mean Difference: -3.32; 95%CI: -4.39 to -2.26; P<0.00001).

Conclusion: Although this review study indicated the significant effect of garlic extract in reducing saliva Streptococcus mutans, the evidence is not sufficient enough to recommend garlic extract to fight saliva Streptococcus mutans, and more clinical trials with stronger designs and larger sample sizes are needed.