Site-specific mouth rinsing can improve oral odor by altering bacterial counts

Objectives: To determine whether site-specific mouth rinsing with oral disinfectants can improve oral odor beyond the traditional panoral mouth disinfection with mouth rinses by targeting specifically oral malodor implicated anaerobic bacteria. Methods: Twenty healthy fasting subjects volunteered for a blinded prospective, descriptive correlational crossover cross-section clinical trial conducted during the month of Ramadan between July and August 2013 in Albaha province in Saudi Arabia involving the application of Listerine® Cool Mint® mouth rinse by either the traditional panoral rinsing method, or a site-specific disinfection method targeting the subgingival and supragingival plaque and the posterior third of the tongue dorsum, while avoiding the remaining locations within the oral cavity. The viable anaerobic and aerobic bacterial counts, volatile sulfur compounds (VSCs) levels, organoleptic assessment of oral odor, and the tongue-coating index were compared at baseline, one, 5, and 9 hours after the treatment. Results: The site-specific disinfection method reduced the VSCs and anaerobic bacterial loads while keeping the aerobic bacterial numbers higher than the traditional panoral rinsing method. Conclusion: Site-specific disinfection can more effectively maintain a healthy oral cavity by predominantly disinfecting the niches of anaerobic bacteria within the oral cavity. T oral cavity, in health and disease, is a highly diverse topographical and biological environment containing many surfaces, fissures, and sulci harboring bacterial biofilms.1 Dental caries, periodontitis, and halitosis are among the most common infectious diseases known to humans.2,3 It is estimated that 85-90% of halitosis originates from the oral cavity.4 Gram-negative anaerobic bacteria, such as Porphyromonas, Prevotella, Actinobacillus, and Fusobacterium are implicated in producing foul volatile sulphur compounds (VSCs), predominately hydrogen sulfide (H2S), and methyl mercaptan (CH3SH) produced by putrefaction of proteins which cause halitosis. A correlation has been established a long time ago between halitosis and the shift in the oral microbiota from predominately Grampositive aerobes to Gram-negative anaerobes.5 It is now hypothesized that the tongue dorsum is an important site for anaerobic putrefaction, and an origin for malodor.5,6 Moreover, tongue dorsum malodor and the amount of coating present on it were found to be proportional to periodontal probing depths, and correlated with the existence of surface fissures on the tongue dorsum.5,6 There is a correlation between VSCs and periodontal disease since it was shown that periodontal disease could increase the presence of these aforementioned anaerobic bacteria in the subgingival plaque and tongue dorsum.5,6 Oral bacteria show site-specific or preferential colonization of different surfaces, fissures, and sulci in the oral cavity.1 That is, different oral locations contain noticeably different bacterial communities.7 Malodor-producing anaerobic bacteria have been found to accumulate in anaerobic environments, such as, subgingival and supragingival plaque material, and the coating of the crypts and fissures of the posterior dorsum of the tongue. Nonetheless, oral bacteria include not only pathogenic bacteria, but also commensal bacteria,1 and strains that have been identified, isolated, and re-administered as health-promoting oral probiotic bacteria.8 Moreover, oral probiotics have been shown to deliver noteworthy success in the prevention of dental caries, plaque formation, streptococcal pharyngitis and oral malodor.8 Furthermore, molecular techniques failed to detect the anti-halitosis probiotic Streptococcus salivarius strain k12 on teeth surfaces and sulci.9 The literature contains many reports on the effects of mouth rinses,10 and chewing gums11 on oral malodor reduction. All of these methods, however, include a non-selective chemical antimicrobial regimen, which we hypothesize will reduce the non-pathogenic commensal, and potentially essential probiotic-like bacteria more than the Gram-negative anaerobic bacteria accumulating within plaques, crypts, and fissures.5 This study sought to investigate whether halitosis treatment could be improved by the selective targeting of Gram-negative anaerobic pathogens though the site-specific application of antimicrobial mouth rinses on the subgingival and supragingival plaque, and on the fissures and crypts of the posterior third of the tongue dorsum, while sparing the natural microbiota located on the remaining oral locations. The study design is based on the evaluation of aerobic-to-anaerobic salivary bacterial count ratios, and amount of VSCs after the use of selective site-specific