A new method of plaque scoring: a laboratory comparison with other plaque indices

The aim of this study was to propose a simple, clear and as sensitive as possible numerical plaque index for the use in clinical oral hygiene trials known as the New Method of Plaque Scoring (NMPS), and to evaluate this index for simplicity, clarity and examiner agreement in comparison with the Distal Mesial Plaque Index, Proximal Marginal Index and a modification to the modified Navy plaque Index.

The scoring system proposed for the NMPS is based on a numerical range from 0 to 10 representing the total stained plaque on the facial or lingual tooth surfaces with the greatest weight of scores placed at the gingival and proximal regions of the surface. For scoring purposes, a horizontal boundary is imagined on the smooth facial or lingual tooth surfaces between the gingival third (A) and coronal two/thirds, the latter being subdivided vertically into thirds, mesial (B), middle (D) and distal (C). Depending on the extent of plaque coverage, whole number scores 0-3 are assigned to A, B, C and 0 or 1 for D. Ten examiners scored four selected tooth surfaces on an acrylic model according to the NMPS and the three comparative indices. The time required for each examiner to score according to each index was recorded. The scores obtained from this trial were analyzed for examiner agreement and correlation between the four indices.

The time required for scoring according to the NMPS was found to be significantly less than the three comparative indices. The variability between examiners was found to be least for the NMPS compared to the three comparative indices. A strong correlation was found between all pairs of indices.

The proposed new method of plaque scoring seems to be simpler, clearer and more reproducible than the three comparative indices. However, clinical testing is warranted.