Defining and predicting outcomes of non-surgical periodontal treatment: a 1-yr follow-up study.

This study reports on 1-yr outcomes of non-surgical periodontal therapy and compares predictive models resulting from different definitions of treatment success. A total of 149 participants, 30-70 yr of age, provided clinical periodontal data and data on sociodemographic status, health status, symptoms, and oral health-care behaviors at baseline. One week later, clinical attachment level and probing pocket depth were recorded again in 148 patients. Participants underwent non-surgical periodontal therapy, including scaling and root planing, during three to four clinical sessions. Three and 12 months later, clinical attachment level, probing pocket depth, and bleeding on probing (BOP) were recorded in 141 and 137 participants, respectively. Using test-retest data, patients were classified as having 'downhill', 'stable', or 'improved' results on three clinical attachment level and three probing pocket depth outcomes, and their classification was found to vary considerably according to outcome. Although the predictors of treatment outcome varied depending on the variable chosen to represent the treatment outcome, some predictors were more commonly noted as predicting improvement, namely a high baseline percentage of sites with subgingival calculus and the presence of suppuration at baseline. The latter was, however, also predictive for tooth loss during the study. Our findings underline the need for uniformity in defining the outcomes in trials of periodontal therapy.