Objective: To evaluate two methods for assessing the changes in periodontitis grading in patients undergoing supportive periodontal therapy 10 years (T10) after retrospective baseline grading.
Method and materials: The periodontitis grade of 51 supportive periodontal therapy patients was assessed using indirect evidence as the primary criterion for periodontitis progression at baseline and T10 (radiographic bone loss/age index, periodontitis phenotype). Grading at T10 was also performed using the direct evidence for periodontitis progression (clinical attachment loss over the previous 5 years). The use of indirect evidence for periodontal progression at baseline and T10 was defined as method 1 to assess the changes in periodontitis grading. The use of indirect evidence at baseline and direct evidence at T10 was defined as method 2. Changes in periodontitis grading using methods 1 and 2 were evaluated (Wilcoxon signed-rank test). Agreement between methods 1 and 2 was assessed (Cohen kappa).
Results: Indirect baseline grading revealed five grade B and 46 grade C patients. The indirect grading at T10 revealed 17 grade B and 34 grade C patients. The direct T10-grading classified all patients as grade C. Method 1 led to an overall improvement in periodontitis grading after 10 years of supportive periodontal therapy (P = .0030), whereas method 2 led to a deterioration (P = .0369). The comparison between methods 1 and 2 showed that they led to different results in terms of grading (Cohen kappa = 0.116208).
Conclusions: Periodontitis grading may change during supportive periodontal therapy. Using indirect or direct evidence as the primary grading criterion during supportive periodontal therapy may lead to different results.