Biofilms and the tongue: therapeutical approaches for the control of halitosis

Due to its location and functions, the tongue is one of the most important anatomic structures in the oral cavity. However, knowledge in regards to its role and implications in oral health and disease is scarce. Moreover, although the dorsum of the tongue seems to harbour one of the most complex microbiological niches in human ecology, the knowledge of the role of tongue flora in health and disease is also very limited. Similarly, the nature of the tongue coating and the factors that influence its development and composition are almost unknown. The interest in the study of the tongue niche has increased in recent years due to its association with oral halitosis and to its role as a suitable reservoir for periodontal pathogens. The structure of the tongue favours a unique and complex bacterial biofilm, in which periodontal pathogens are frequently found. However, little is known about how to control this bacterial niche, and factors affecting tongue coating composition and aspect are not fully understood. Studies available on the influence of mechanical or antimicrobial approaches against tongue biofilm are very limited. Mechanical treatments showed a transient reduction in halitosis-related variables but were limited in time. Different antimicrobials agents have been evaluated: chlorhexidine, chlorine dioxide, metal ions, triclosan, formulations containing essential oils, and hydrogen peroxide. However, most studies were designed as short-term models. Some of these studies demonstrated that the reduction in halitosis-related variables was associated with significant changes in the tongue microflora.