Comparing Measures of Reliability for Indices of Gingivitis and Plaque

Abstract

The purpose of this methodological study was to compare methods used to assess reliability for gingival inflammation and plaque. Duplicate examinations were conducted by one examiner on 17 subjects (506 scoring sites), using the gingival index (GI), bleeding points index (BPI), and plaque index (PI). The percentage of agreement, the weighted and unweighted kappa coefficients, and Pearson correlation coefficients were calculated as statistics of reliability for mesial buccal site scores and whole mouth mean scores when appropriate. For mesial buccal sites the respective values of the GI, BPI, and PI for weighted kappas were: 0.47, 0.49, and 0.75; for the correlation coefficients: 0.47, 0.49, and 0.76; for unweighted kappas, 0.39, 0.49, and 0.39; and for percentage of agreement 66.2%, 76.1%, and 51.2%. For whole mouth means the correlation coefficients for the GI, BPI, and PI were 0.87, 0.59, and 0.87, respectively. In conclusion, the most useful statistics in assessing the intraexaminer reliability of a solo examiner in descending order were the weighted kappa coefficient, Pearson correlation coefficient, the unweighted kappa coefficient, and percentage of agreement.

Modulation of clinical expression of plaque‐induced gingivitis

“…Duplicate examination was then performed after at least 1 h. The measurement of inter-and intra-examiner agreement on PlI and GI was based on unweighted k-statistics at both site-specific and subject levels (Fleiss & Chilton 1983, Spolsky & Gornbein 1996. They were screened to ensure they fulfilled inclusion/exclusion criteria, but no attempt was made to change their oral hygiene regimen.…”

Interexaminer reproducibility of ordinal and interval‐scaled plaque indices

“…When reviewing the dental literature on the reproducibility of clinical parameters, authors use different statistical tools for its assessment. While Clemmer & Barbano (1974) recommend using the proportion agreement rather than the paired t ‐test or the correlation coefficient, more recently Spolsky & Gornbein (1996) advise the use of, in descending order, the weighted κ coefficient, the Pearson correlation coefficient, the unweighted κ efficient and the percentage of agreement. The authors could demonstrate, indeed, that the percentage of agreement is sensitive to the number of ranks used to measure (i.e.…”

“…Unweighted κ statistics showed fair to good agreement (0.60 and 0.53, respectively). If the Spearman correlation coefficient values are considered as weighted κ ‐values (Spolsky & Gornbein 1996), their interpretation shows fair to good agreement for lingual VPI (0.64) and good to excellent agreement for buccal VPI (0.84) (Cohen 1960).…”

“…The reproducibility of plaque indices is scarcely reported in the literature. For the plaque index (PlI) of Silness & Löe (1964), which is one of the most used plaque indices in toothbrush trials, Spolsky & Gornbein (1996) report an intraexaminer correlation coefficient of 0.76, an unweighted κ of 0.39 and 51% percentage agreement for site‐based scores, while Kiyonobu et al (1999) report intra‐ and interexaminer κ coefficients of 0.71 and 0.53, for subject‐based averages. When dental practitioners are adequately trained, they can even achieve interexaminer κ scores between 0.78 and 0.85 for PlI (Eaton et al 1997).…”

The motivational effect of multicolored dental restoration on dental behavior of first preliminary school children

“…The tools used for assessment of the gingival condition and the oral hygiene were modified Silness and Loe plaque index and gingival index, which were found to be highly sensitive and reproducible (Spolsky & Gornbein, 1996).…”