ABSTRACT
Research suggests that the tongue is the primary site in the production of OM. The dorsoposterior surface of the ton e has been identified as the principal location of the f' intraoral generation of VSC's [' . The tongue is an excellent site for the growth of microorganisms since the papillary nature of the tongue dorsum creates a unique ecological site that provides an extremely large surface area, favoring the accumulation of oral bacteria. The proteolytic, anaerobic bacteria that reside on the tongue play an essential part in the development of oral malodour. The presence of tongue coating has been shown to have a correlation with the density or total number of bacteria in the tongue plaque coating [''I. The weight of the tongue coating in periodontal patients was elevated to 90mgs, while the VSC was increased by a factor of 4 and CH3SHM2S ratio was increased 30-fold when compared with individuals with healthy periodontium20. This high ratio of amino acids can be due to free amino acids in the cervicular fluid when compared with those of L-cysteine ['I. The BANA (Benzoyl -DL-arginine-2 napthylamide) test has been used to detect Treponerna denticola and Porphyromonas gingivalis and Bacteroides forsythus. The three organisms that may contribute to oral malodour can be easily detected by their capacity to hydrolyze BANA, a trypsin-like substrate. BANA scores are associated with a component of oral malodour, which is independent of volatile sulfide measurements, and suggest its use as an adjunct test to volatile sulfide measurement ["I. Higher mouth odour organoleptic scores are associated with heavy tongue coating and correlate with the bacterial density on the tongue and it also correlates to BANA-hydrolyzing bacteria -T.denticola, P gingivalis, and B. forsythus [231
The actual bacterial species that cause OM have yet to be identified from among the 300 plus bacterial species in the mouth. Putrefaction is thought to occur under anaerobic conditions, involving a range of bacteria such as Fusobacterium, Veillonella, T. denticola, P. gingivalis, Bacteroides and Peptostreptococcus [231[241. Studies have shown that essentially all odour production is a result of gram-negative bacterial metabolism and that the gram-positive bacteria contribute very little odour Fusobacterium nucleaturn is one of the predominant organisms associated with gingivitis and periodontitis and this organism produces high levels of VSCs. The nutrients for the bacteria are provided by oral fluids, tissue and food debris. Methionine is reduced to methyl mercaptan and cysteine. Cysteine is reduced to cystine, which is further reduced to hydrogen sulfide in the presence of sulfhydrase-positive microbes. This activity is favored at a pH of 7.2 and inhibited at a pH of 6.5 [1111131[151 [I6]. Isolates of Klebsiella and Enterobacter emitted foul odours in vitro which resembled bad breath with concomitant production of volatile sulfides and cadaverine both compounds related to bad breath in denture wearers [261 .The amounts of volatile sulfur compounds (VSC) and methyl mercaptanhydrogen sulfide ratio in mouth air from patients with periodontal infection were reported to be eight times greater than those of control subjects [I6].
