Effectiveness of a Pre-procedural Mouthwash in Reducing Bacteria in Dental Aerosols and Splatters: a Randomized Clinical Trial

The propagation of oral microorganisms in the dental office during different oral procedures has been a concern. The use of certain equipment such as ultrasonic devices, highspeed dental handpieces or three-way syringes may spread aerosols and splatters containing microorganisms in the environment. These microorganisms may cause cross-infections in the dental office, jeopardizing the health of patients and dental professionals. Different procedures, materials and antimicrobial agents have been proposed to minimize microbial cross-contamination in the dental office. Chlorhexidine (CHX) is considered the gold standard substance in controlling oral biofilm growth in the oral cavity or microbial spread by oral aerosols due to its broad antibacterial spectrum and substantivity of 8 to 12 hours. However, other antiseptics have also been used as pre-procedural mouthwashes. CPC has an important antimicrobial activity and is considered a safe product for marketing. In this context, the present trend has been to combine more than one active substance in mouthwash and toothpaste formulations with the aim of increasing the efficacy of the products, or treating more than one clinical problem, such as plaque accumulation and halitosis, caries or gingival inflammation. Therefore, the aim of this randomized clinical trial (RCT) was to evaluate the effectiveness of a new mouthwash formulation containing 0.075% CPC, 0.28% zinc lactate and 0.05% sodium fluoride (CPC+Zn+F) in reducing viable bacteria present in oral aerosol/splatter. Sixty systemically healthy volunteers receiving dental prophylaxis were randomly assigned to one of the following experimental groups (15 per group): i) rinsing with 0.075% CPC, 0.28% Zn and 0.05% F (CPC+Zn+F), ii) 0.12% chlorhexidine digluconate (CHX), iii) no rinsing and iv) rinsing with water. Viable bacteria were collected from different locations in the dental office on enriched TSA plates and anaerobically incubated for 72 hours. The colonies were counted and species were then identified by Checkerboard DNA-DNA Hybridization. The total number of colony-forming units (CFUs) detected in the aerosols/splatters from volunteers who rinsed with CPC+Zn+F or CHX was statistically significantly (p<0.05) lower than of those subjects who did not rinse or who rinsed with water. When all locations were considered together, the aerosols/splatters from the CPC+Zn+F and CHX groups showed, respectively, 70% and 77% fewer CFUs than those from the no rinsing group and 61% and 70% than those from the water group. The mean proportions of bacterial species from the orange complex were statistically significantly (p<0.05) lower in aerosols/splatter from the CPC+Zn+F and CHX groups compared with the two negative controls. In conclusion, the results of the present investigation showed that a mouthwash containing 0.075% CPC, 0.28% Zn and 0.05% F, is effective in reducing viable bacteria in oral aerosol/splatter after a dental prophylaxis with ultrasonic scaler. This finding is highly relevant to the clinical practice, as it may greatly reduce the risk of cross-contamination in dental offices.