OBJECTIVETo study the effect of para-aminobenzoic acid (PABA) on the growth and metabolism of Porphyromonas gingivalis (P.g).

METHODSAfter adding different concentrations of PABA into the medium, anaerobic technique was applied to culture P.g. The products' A value and action of TLP was assayed, and P.g grew in the medium was observed by a scanning electron microscope.

RESULTSPABA promoted the growth of P.g and action of TLP, which would reach the highest level when PABA was 1 mg/L, and would decrease with the increasing of concentration of PABA. When the concentration arrived at 100 mg/L, PABA had no effect on them. In the mean time, PABA had effect on the form and adherence of P.g. When the concentration was 1 mg/L and 100 mg/L, this effect was strong, but as the concentration was 10 mg/L, the effect disappeared.

CONCLUSIONSPABA influences the growth and metabolism of P.g, which indicate that Streptococcus sanguis has regulative effect on the microecology of subgingival plaque.