Evaluation of an optical instrument for objective assessment of oral mucosal erythema

This study evaluated the sensitivity and reproducibility of an optical instrument, the Erythema Meter, for quantifying erythema of palatal mucosa. The instrument is based on the principle that haemoglobin in the vasculature selectively absorbs green light but has little effect on red light and allows derivation of an 'erythema index'. Non-clinical investigations were carried out by taking a series of Erythema Meter readings from each colour block on a red check-standard used by graphic artists for colour reproduction. For clinical assessment, 20 dentate patients with healthy palatal mucosa and 40 complete denture wearers (20 with denture stomatitis and 20 with healthy palatal mucosa) were enrolled, and palatal erythema determined both visually and using the Erythema Meter. Two weeks later the Erythema Meter readings for the 40 patients with healthy palatal mucosa were repeated, to allow assessment of the reproducibility of the Erythema Meter scores. The median erythema index was 12 (range 2-38) for dentate patients with healthy palatal mucosa and 5 (range 0-29) for denture wearers with healthy palatal mucosa. For denture stomatitis patients the median erythema index was 95 (range 36-117). The overall reproducibility coefficient was 88%. Visual scoring correlated poorly with the Erythema Meter scores for those with moderate degrees of erythema. The Erythema Meter provides an objective and reproducible means of measuring the degree of erythema of the palatal mucosa.