Evaluation of Plaque Biofilm Kill Activity of Representative Global Mouthrinses

AADR Abstracts

1.  Evaluation of Plaque Biofilm Kill Activity of Representative Global Mouthrinses

Objective: Two studies were conducted to compare the killing activity of Listerine Antiseptic Mouthwash (LMW) with three Plax antiseptic mouthrinses containing 0.05% CPC: Overnight (PO), Cool Mint (PCM) and Soft Mint (PSM), in a previously established saliva-derived biofilm model. Methods: Unstimulated saliva was collected, pooled, diluted in BHI supplemented with 1% sucrose, 1% mannose and 1% glucose, and centrifuged (10min @ 2,000rpm) to remove large particles. The microorganism containing supernatant was inoculated into chambered coverglasses and incubated overnight in an anaerobic chamber (N₂ 85%, H₂ 10%, CO₂ 5%, 37°C).  After incubation the growth medium was exchanged for fresh medium.  Growth continued to reach a total of 16-18 hrs for single dose treatment or to maturity for repeated treatments. Growth medium was removed and biofilms were washed before being treated with the respective mouthrinses (100µl for 30 or 60s).  25% microorganism-free saliva in BSA-saline and 70% EtOH served as negative and positive controls respectively. Biofilms undergoing two treatments were grown anaerobically (6hr) between treatments.  Treatment effectiveness was quantified using image analysis software and proportion of damaged/dead cells was calculated. Results: LMW demonstrated statistically significantly greater killing activity than Plax mouthrinses at 2x30 and 2x60s in study I and study II. All other treatment tested also showed statically significant differences between the groups.

 

% Dead/Damaged Cells After Treatment
Study I	Treatment	1x30s	1x60s		2x30s
	LMW	22.2±2.3	64.9±14.5		19.4±5.4
	PSM	7.5±3.5 (p<.0001)	21.5±7.4 (p<.0001)		9.4±3.9 (p<.0002)
	PCM	12.9±3.5 (p<.0001)	20.1±8.1 (p<.0001)		9.6±3.3 (p<.0001)
Study II	Treatment	2x30s		2x60s
	LMW	19.5±7.5		26.7±11.1
	PO	11.2±5.1 (p<.014)		13.5±3.5 (p<.034)

Conclusions: Both confocal imaging and quantitative analyses via live-dead staining of biofilms demonstrated that LMW was up to two times more effective in biofilm killing than PO, PCM and PSM.