Objectives: To develop a method for quantifying changes in gingival inflammation levels by recording gingival redness levels and tooth surface area and assess the method for reliability of measurement.
Method: Digital images were acquiredfrom 20 subjects attending a Periodontology Clinic. A red dot of standard size and colour was included in each image for later calibration of linear scale, by its diameter and of redness. The visible gingival area surrounding the upper and lower anterior teeth was thresholded and the average red pixel value noted, as well as the average red pixel value of the red dot. The two were subtracted to give a final red value. Inflammation was also assessed by recording variation in labial tooth surface area between the gingival margin and a line that was drawn across the tooth between the tips of the inter-dental papilla. This area reflected changes in gingival encroachment. The first attendance measurements were used for reliability calculations and duplicate images were obtained by each of 2 operators. The 20 subjects had subsequent visits over a period of one year.
Results: Fleiss' Coefficient of Reliability was used to assess operator reliability for gingival and disc redness and the tooth surface area.
|
AREA |
Intra–operator Operator 1 Operator 2 |
Inter-operator |
|
|
Upper Right Central Incisors |
0.975 |
0.989 |
0.947 |
|
Upper Left Central Incisors |
0.978 |
0.970 |
0.936 |
|
AVERAGE RED PIXEL LEVEL |
|
|
|
|
Red Dot |
0.968 |
0.998 |
0.878 |
|
Gingivae |
0.987 |
0.998 |
0.769 |
R of 0.81-1.00 = Excellent reliability.
Conclusions: This method of measuring changes in gingival colour and tooth surface area covered by gingival tissue is a reliable means of assessing the clinical effects of therapeutic agents on gingival inflammation. All but one are within Fleiss' range of excellent reliability.