2010 Volume 60 Issue 5 Pages 563-568
While the pH-lowering activity and ammonia productivity of dental plaque are known to be associated with caries, the association with periodontal diseases is not clear. Thus, the pH-lowering activity and ammonia concentration of dental plaque were compared between teeth with and without periodontitis. Plaque samples (approximately 2.4μL) were obtained from marginal areas of sound buccal surfaces of upper first or second permanent molars of 71 subjects, and the probing depth (PD) and bleeding on probing (BOP) of the same tooth were recorded. Samples were measured for minimum pH after glucose addition and ammonia concentration. The ammonia concentration in subjects with PD≥3mm and BOP(+)(6.81±3.22mM) was significantly higher than in subjects with PD≥3mm and BOP(-)(3.50±2.38mM) and subjects with PD<3mm and BOP(-)(2.92±2.23mM). The minimum pH was in the order of subjects with PD≥3mm and BOP(+)(5.28±0.57), PD≥3mm and BOP(-)(5.54±0.74), and PD<3mm and BOP(-)(5.75±0.76), although there was no significant difference between subject groups. In addition, the ammonia concentration was weakly correlated with the minimum pH in each subject group. Marginal plaque from teeth with PD≥3mm and/or BOP(+) contained a significantly higher concentration of ammonia, indicating that periodontitis increases the ammonia level in marginal plaque. The inverse association between the ammonia concentration and minimum pH may be due to the metabolic characteristics of microbial flora in marginal dental plaque.
