Reliability of toluidine blue vital staining in detection of potentially malignant oral lesions--time to reconsider.

Being simple and inexpensive toluidine blue has been in use for more than two decades for the detection of potentially malignant oral lesions (PMOL's) and malignant lesions. Although there has been concensus that staining often assists in the identification of these lesions, results have been diverse. In most studies false negative were not recorded as biopsies of lesions that did not retain toluidine blue were not performed. Thus the present study attempted to evaluate the efficacy of toluidine blue vital dye for detection of PMOL's. The study included 47 biopsies (TBP:35 and TBN:12), of which 23 cases were confirmed as dysplastic (TBP=17 and TBN=6), 7 as hyperkeratosis (TBP=4 and TBN=3), 8 as epithelial hyperplasia (TBP=6 and TBN=3) and 5 as other benign lesions (TBP=4 and TBN=1). The validity test revealed a senstivity of 73.9% and specificity of 30%. The positive predictive value was 54.8% and negative predictive value of 50%. The study intends to highlight the false negative result (26.1%) which was mainly attributed to mild dysplasia and the false positive (32.6%) which included hyperkeratosis, hyperplasia, lichen planus and traumatic ulcer. The study concludes that toluidine blue staining should not blindly direct the clinician's opinion, and strongly discourages the use of toludine blue as a screening test and the results should be interpreted with caution.