Fig. 2. Average receiver operating characteristic curves obtained by 1,000-fold resampling of the original study population for mouth opening (A ), thyromental distance (B ), Mallampati’s classes (C ), and body mass index (D ) (n = 1,655). Distribution of the resampled population is represented by box plots. Two graphs ROC curves with determination of the inconclusive zone (dashed  area) using a diagnosis tolerance of 10% for mouth opening (E ), thyromental distance (F ), Mallampati’s classes (G ), and body mass index (H ). Se = sensitivity; Sp = specificity.