Periodontal changes for individual sites and subjects in therapy trials

Objectives: Summary statistics often obscure individual clinical subject and site changes post-therapy. The present study examined the effects of periodontal therapy in individual subjects and at individual sites. Methods: 180 moderate to advanced chronic periodontitis subjects were assigned to 4 treatment groups all of which received SRP. Additional therapy included: surgery + amoxicillin and metroninidazole (AM) (N=41); surgery (N=43); AM (N=49); None (N=47). Pocket depth (PD) and attachment level (AL) were measured at 6 sites per tooth at baseline and 24 months. For subject-based analyses, data were averaged for PD and AL at baseline and 24 months separately and plotted for each subject in each treatment group after sorting on baseline values. Similarly, pre and post-therapy PD and AL site data were plotted separately in each treatment group after sorting on baseline values.

Results: The graphic presentations revealed the heterogeneity in clinical response both on a subject and site level. Mean PD reduction occurred in the majority of subjects in each treatment group with greatest reductions in the most diseased subjects. 7/47 subjects showed a mean increase in PD post-therapy in the SRP only group compared with one or none in the other groups. 27% of subjects receiving antibiotics showed ALoss, compared with 41% of subjects not receiving antibiotics. ALoss was greatest in subjects with the least initial disease in all groups. PD increases were observed most frequently at sites with BPD <4 mm particulalry in subjects not receiving antibiotics. ALoss was common at sites with initial AL values <4mm and most pronounced in subjects who received surgery without antibiotics. Conclusions: Although the individual subject and site data reflected the results of summary statistics for each treatment group, they provided insights into the nature of the subjects and sites that accounted for the therapeutic changes. Supported by NIDCR grant DE12861.