credo che il termine medico sia retrattore linguale; mi potrei sbagliare, nonostante abbia trovato un sito che parla di divaricatori palatali, ma credo che il divaricatore venga espressamente utilizzato in altri settori, in particolare in ortopedia e ginecologia.
I think it depends on what you are trying to do, there are many instruments that can be used to keep the tongue out of the way. The term retrattore linguale to me is a little bit odd and if you google it there are only 22 results and some of these are dubious and none of the ones I have looked at refer to a particular instrument. Lingual / linguale (to me) refers to an area behind the teeth not the tongue itself. However although I have some experience I would not like to say for certain that it is wrong. This page may help, and an Italian dentist would be of help! http://cosars.com/salute/2011/02/Che-cosa-e-un-divaricatore.html
The tongue retractors on this page http://surgical-instruments.salvin.com/Retractors.html?parentId=245 are called cheek retractors on the Italian pages e.g. http://www.hu-friedy.de/xtc/product...fo=p5187_Wangenhalter-Weider-Cheek-klein.html
I think a retractor/ retrattore is simply that and different dentists would use different retractors depending on preference. Divaricatore likewise, another option would be an ''abbassalingua''. This is just my take on it I don't mind if someone contradicts me !