In-vitro Methods to Evaluate Plaque Biofilm Removal from Interproximal Locations

Objective: It is difficult to compare two oral hygiene regimens for their ability to remove true in vivo interproximal plaque (plaque that can’t be visualized). This is due to poor sampling and quantification methods in vivo and wide day-to-day and subject-to-subject variations in interproximal plaque development. The objective of this research was to develop an in vitro assay to assess interproximal plaque removal of oral hygiene products. Methods: Streptococcus mutans biofilm was grown onto a specific 12.75mm² proximal surface of a typodont tooth. Following 48 hours biofilm formation, the tooth was placed in a typodont arch and the biofilm-coated proximal tooth surface exposed to an oral hygiene regimen. The following three regimens were followed: 1) an unexposed control, 2) flossing with a customized mechanical flossing device, and 3) exposure for 15s to the fluid forces of a sonic toothbrush (Sonicare®, Philips Oral Healthcare, Inc.). After exposure, the teeth were removed and the biofilm remaining on the tooth removed. The samples were diluted and cultured on Typtic Soy Agar supplemented with 5% sheep blood and incubated at 37°C 24 hours before enumeration. Control teeth containing biofilm were placed in the device in the absence of treatment. Experimentation included at least 3 observations for each device, replicated 3 times on different days. Results: Flossing and exposure to the fluid dynamics of the sonic toothbrush reduced biofilm adherent to the proximal surfaces of the teeth by 38% (p=0.3140) and 63% (p=0.0407), respectively, as compared to the control. Conclusion: The data suggest that this novel in-vitro methodology, along with the described techniques are useful in the determination of a oral hygiene product’s effectiveness in the removal of interproximal biofilm as compared to floss.