OBJECTIVETo assess the effect of Spirochetes and Porphyromonus gingivalis (Pg) on the production of volatile sulfur compounds (VSCs) and oral malodor, respectively.

METHODS117 systemically healthy periodontitis patients were divided into two groups according to organoleptic rating (OR) by organoleptic method: 85 subjects with oral malodor (halitosis group, HG) and 32 cases without oral malodor (no-halitosis group, NHG). VSCs measurements were made with halimeter. Subgingival plaques and tongue coating were taken to calculate the proportion of Spirochetes (with 2% Congo Red Smears, S%) and the amounts of Pg (with indirect immunofluorescence method). The examination will be repeated in 46 HG cases after periodontal therapy.

RESULTSS% in PD < 4 mm sites of HG was significantly higher than that in NHG (P < 0.01). S% in PD >or= 4 mm sites and tongue coating, Pg in all three sites were not different between two groups. In HG, OR and VSCs levels were correlated with S% in tongue coating (P < 0.01, P < 0.05) and PD < 4 mm sites (P < 0.05), and not correlated with S% in PD >or= 4 mm sites. OR was related to Pg in PD >or= 4 mm sites (P < 0.05) and there was no relationship between OR and Pg in tongue coating and PD < 4 mm sites. VSCs levels was not correlated with Pg in all three sites. S% in tongue coating and subgingival plaque, Pg in subgingival plaque, OR and VSCs levels were significantly reduced after periodontal therapy (P < 0.01).

CONCLUSIONSThe direct relationship of Spirochetes and Pg respectively to bad breath was not found obviously. But Spirochetes is one of the microorganism on oral malodor. Periodontal therapy can improve oral malodor.