Experimental Gingivitis: Reproducibility of Plaque Accumulation and Gingival Inflammation Parameters in Selected Populations during a Repeat Trial.

Objectives: To assess whether and to what extent the experimental gingivitis clinical parameters are reproducible within selected populations with different gingival inflammatory response (high or low) to plaque accumulation. In addition, the consistency in developing a high or low gingival inflammatory response within the selected populations was evaluated. Methods: 37 subjects previously identified as high (HR, n=20) or low responders (LR, n=17) during an experimental gingivitis trial (1st trial) (Trombelli et al. 2004) were enrolled in a “repeat” experimental gingivitis trial. Results: No significant differences in plaque accumulation parameters and bleeding index values were detected between 1st and repeat trial for the 37 participants. Gingival Index (GI) was higher during the repeat trial but behaved consistently in terms of the temporal changes in the course of both trials in both populations. Of the 17 LR participants, 10 manifested low susceptibility to inflammation after repeat trial. Among the 20 HR, 10 manifested high susceptibility to inflammation after repeat trial. Conclusions: these results indicate that our experimental gingivitis model is reproducible to some extent in selected populations. The high reproducibility of plaque and, to a lesser extent, of inflammation parameters under the employed controlled conditions could be a valuable tool in gingivitis research.