Antimicrobial and anti-inflammatory agents in experimental gingivitis

The main objectives of the present series of experiment was to evaluate i) the microbial changes that occurred in plaque during de novo plaque formation, ii) the influence of the number of bacteria in saliva on de novo plaque formation, iii) the effect of a chlorhexidine regimen on the recolonization of bacterial species in plaque and saliva, iv) the effect of systemic administration of ibuprofen on gingivitis development and de novo plaque formation and v) the effect of a mouthrinse containing Listerine® on gingivitis development and de novo plaque formation.Subjects with no signs of periodontal disease were recruited. After preparatory periods, including mechanical plaque control and/or the use of various chlorhexidine regimens, the subjects accumulated plaque in periods ranging from 4 to 14 days. During the 14 days periods of no mechanical plaque control, the subjects rinsed with either chlorhexidine, Listerine®, or saline or were given ibuprofen tablets. It was demonstrated that:1) At the initiation of plaque formation periods, plaque samples exhibited high proportions of Actinomyces species. During plaque accumulation periods, there was a small increase in the total number of microorganisms as well as a modest increase in the proportion of disease-associated taxa such as species of the orange complex , 2) the daily use of chlorhexidine as an adjunct to mechanical tooth cleaning markedly reduced the number of microorganisms in saliva, 3) the number of salivary bacteria influenced the amount of plaque that formed during the early phase of no oral hygiene, 4) the number of microorganisms present in dental plaque after 4 days of plaque accumulation was affected by the use of chlorhexidine. A substantial number of bacteria in the Day 4 plaque samples belonged to the genus Actinomyces, 5) the levels of red complex species in plaque samples from Day 0 through Day 4 of no mechanical cleaning were only minimally altered by a 2-week pre-experimental oral hygiene period including repeated administration of chlorhexidine, 6) when oral hygiene procedures were withdrawn, the microbiota rapidly returned to its climax community status, 7) systemic administration of ibuprofen retarded gingival inflammation but not de novo plaque formation, 8) the effect of Listerine® was more pronounced on gingivitis than on plaque formation indicating that topically applied phenolic compounds may have anti-inflammatory effects, and 9) the outcome of antimicrobial measures, mechanical as well as chemical, in the prevention and treatment of gingivitis is more predictable than that obtained by the systemic administration of anti-inflammatory compounds