Table 2.

List of the articles treated in the discussion divided in the four groups, and corresponding references.

Group	Total Articles	References
Oral cavity	24	[8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31]
Airways	21	[32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52]
Gut	16	[53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68]
Other Organs	3	[69,70,71]
Total	64