Methods for fungiform papillae assessment: A collaborative study among European research units

Fungiform papillae (FP) are the anatomical structures dedicated to gustatory and somatosensory signal triggering. Whether the density of FP (FPD = FP/cm2) is associated with oral responsiveness is controversial, and the disparity in previous findings may be partially due to the diversity in methods used to quantify FP. The present study aims at mapping methods used to estimate FPD and at tentatively assessing the impact of the main procedure variables in FPD estimation. An on-line survey was specifically developed and launched among the European Sensory Science Society members to collect information on methods and procedure variables and to share datasets on FP counting. Seven European research centres responded to the survey. Manual counting was the most popular methodology, and a merged dataset of 1006 observations was obtained. The type of device used for tongue picture acquisition (low-resolution - LR vs high-resolution - HR) was the main procedure variable. FPD mean values were lower when assessed by LR (35.8) than with HR devices (41.5). Distribution of FPD for LR and HR datasets were similar thus comparisons among studies in which different resolution devices have been used are reliable. Picture modifications and data validation did not significantly affect FPD estimation obtained from HR devices, while both these variables significantly affected FPD values collected with LR devices. Both HR and LR procedures were able to capture the differences in FPD due to age and gender. Overall, measures from HR devices appear the best option to depict the inter-individual variability in FPD. Automated procedures appear underutilised.