Ten-year changes of periodontitis grading using direct and indirect evidence: a retrospective evaluation

To evaluate two methods for assessing the changes in periodontitis grading in patients undergoing supportive periodontal therapy 10 years (T10) after retrospective baseline grading.

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).

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).

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.