Anin vitromodel to assess effects of a desensitising agent on bacterial biofilm formation

Abstract

Desensitising agents are added to dentifrices to occlude exposed dentine tubules and reduce pain associated with dentine hypersensitivity. In occluding the tubules these agents may alter the surface layer of the dentine and consequently affect bacterial biofilm formation. This research sought to examine the effects of desensitising agents on dentinal biofilms using an in vitro model. A constant depth film fermenter (CDFF) was selected to mimic the oral environment and human dentine with exposed tubules was analysed. Calcium sodium phosphosilicate (CSPS) was selected as a model desensitising agent. Dentine discs were treated with pumice or CSPS-containing dentifrices with or without fluoride, or left untreated (control). Dual-species biofilms of Streptococcus mutans and Streptococcus sobrinus were grown in artificial saliva and analysed by viable counts, polymerase chain reaction (PCR) and scanning electron microscopy (SEM). SEM images confirmed the presence of occluded tubules after CSPS application and demonstrated the formation of biofilms containing extracellular matrix material. Analysis of PCR and viable count data using a one-way ANOVA showed no significant differences for bacterial composition for any of the four treatments. There were, however, trends towards increased numbers of bacteria for the pumice and CSPS treated samples which was reversed by the addition of fluoride to CSPS. In conclusion, CSPS was not found to have a significant effect on biofilms and an in vitro model for testing desensitising agents has been developed, however, further work is required to improve the reproducibility of the biofilms formed and to explore the trends seen.

Oral Microcosm Biofilms Grown under Conditions Progressing from Peri-Implant Health, Peri-Implant Mucositis, and Peri-Implantitis

“…There are a number of in situ and in vitro methods for the investigation of oral biofilms [ 7 , 8 , 9 , 10 , 11 , 12 ]. However, to date, no suitable in vitro models [ 13 ] have been developed that enable the replication of the complex microbial composition of peri-implantitis to allow testing and development of new clinically-relevant therapies [ 14 ], which can shed light on the characterisation and understanding of processes and factors affecting biofilms.…”

“…The constant depth film fermentor (CDFF), a continuous open-surface fluid flow culture AMM, is one of the most widely used in vitro oral model systems for the evaluation of oral biofilms and therapeutic strategies [ 10 , 17 , 18 , 19 ]. Its relevance to the oral cavity mainly relies on (1) the use of an inoculum derived from human whole saliva, (2) the mimicking continuous nutrient flow conditions of the salivary and crevicular fluid flow, (3) the shear forces induced to the biofilms by the PTFE scraper blades, (4) the biofilms can be grown on a range of substrata, and (5) the induction of a range of atmospheric environments [ 11 ]. The steady-state microcosm biofilms can be sampled and qualitatively and quantitatively analysed.…”