Chlorhexidine mouthwash and sodium lauryl sulphate dentifrice: do they mix effectively or interfere?

Focused question: What is the effectiveness of a chlorhexidine (CHX) mouthwash used in combination with a sodium lauryl sulphate (SLS) dentifrice on the parameters of plaque and gingivitis? Material and methods: MEDLINE-PubMed, Cochrane-CENTRAL, EMBASE and other electronic databases were searched up to July 2014. The inclusion criteria were (randomized) controlled clinical trials, subjects >= 18 years of age with good general health. Papers evaluating the effect of CHX mouthwash used in combination with SLS dentifrice or a dentifrice slurry compared with CHX mouthwash as a single oral hygiene intervention or in combination with an SLS-free dentifrice were included. From the eligible studies, data were extracted, and a meta-analysis was performed when feasible. Results: Independent screening of 83 unique papers resulted in four eligible publications, with nine comparisons. The meta-analysis showed that when an SLS dentifrice was used as a slurry rinse, the interference on the plaque-inhibiting effect of a CHX mouthwash was significantly decreased (MD 0.33; P <= 0.00001; 95% CI: <0.24; 0.42>). No significant difference was observed when SLS dentifrice was applied as a paste in combination with CHX mouthwash (MD 0.08; P = 0.42; 95% CI: < -0.26; 0.11>). Descriptive and subgroup analyses support these findings. Moreover, the observed effect for the dentifrice paste occurred regardless of the order of use. Conclusion: This review demonstrates that when CHX mouthwash is recommended, it can be used in combination with an SLS dentifrice without any interference regarding its inhibiting effect on dental plaque, regardless of the order of use. Consequently, the collective evidence indicates that the combined use of dentifrice and CHX mouthwash is not contraindicated. However, this recommendation has been graded as moderate taking into account a potential publication bias because three of the four included studies emerged from the same research group.