Microbial Considerations in Oral Malodour Control

Objectives: To investigate the topographic distribution of bacterial types and loads associated with oral malodour and lack of malodour, on the tongue surface in healthy subjects. Possible associations between bacterial counts and mid-morning oral malodour intensity scores were also investigated.

Methods: 50 healthy volunteers with good oral health and at least 20 natural uncrowned teeth were recruited. Samples were taken with sterile brushes from dorsal anterior (DA), dorsal middle (DM), dorsal posterior (DP) and dorsal posterior to the circumvallate papillae (DPCP), lateral posterior (LP) and ventral posterior (VP) tongue surfaces. Samples were cultured on appropriate media for anaerobic bacteria, aerobic bacteria, Gram negative anaerobic bacteria, VSC producing bacteria and Streptococcus salivarius. Malodour was assessed by trained judges on an organoleptic basis and scored as low, medium or high.

Results: The counts of all bacterial groups were consistently highest at the DPCP surface. Whereas, the lowest counts were found at the VP surface. Mean VSC producing bacterial counts (cfu/brush x 10⁵) were 1.46, 5.67, 32.52, 88.94, 6.47 and 0.34 at DA, DM, DP, DPCP, LP and VP surfaces respectively. At DPCP surfaces anaerobic, Gram negative and VSC counts increased with malodour score, whereas aerobic and S. salivarius counts decreased.

Conclusion: Detailed mapping of the tongue surface has demonstrated that the dorsal area posterior to the circumvallate papillae consistently carried the highest load of bacteria capable of contributing to oral malodour. This study demonstrates that tongue surfaces not accessible to routine oral hygiene procedures can contribute to oral malodour.