A follow-up study 3 years after metronidazole therapy for chronic periodontal disease

In a previous study, a double-blind between subject comparison of the effects of metronidazole and placebo tablets was completed over 22 weeks in 45 subjects with chronic periodontal disease ranging in severity from moderate (PI = 2.0-3.9) to high (PI = 4.0-6.0). The results showed a significantly greater reduction in the mean probing depth of pockets with the use of metronidazole, but this reduction was apparent only in subjects with severe periodontal disease (PI = 4.0-6.0). 3 years later, 28 subjects attended. All groups still showed statistically significant improvements in all parameters when compared with those at the first visit. However, when compared with those at the end of the trial, there were statistically significant increases in gingival bleeding and calculus scores. An increase in plaque levels was also observed but this was not statistically significant. When subjects with moderate and severe periodontal disease were grouped together, there were no significant differences in any of the parameters between test and control groups. Moreover, the significantly greater reductions in mean probing depth of pockets, achieved with the use of metronidazole in the severe group at the end of the trial, had disappeared after 3 years. However, in subjects with mild disease, statistically significant reductions in pocket probing depth, not originally apparent, were observed 3 years later.