The thermal damage to the normal tongue was studied. Fortyone hamsters were devided into single heating group (SH) at 42°C, 43°C and 44°C each for 20min. and 40 min., repeated heating group (RH) at 42°C for 40 min. 4 times for 2 weeks, and sham group (SG) with a sensor inserted into the tongue. The tongue was heated by the 13.56 MHz RF capasitive heating system with a pair of applicators 10 mm in diameter filled with jelly.
In SH at 42°C for 20 min., slight to moderate redness and/or swelling were observed and the reaction increased slightly after heating for 40 min. The occurence of moderate redness increased in SH at 43°C for 20min., and the 40 min. heating resulted in the formation of vesicle, erosion and deep ulcer. In SH at 44°C for 20 min., necrosis of more or less than 50% of the heated region was observed, the necrosis involved more than 50% or all of the heated region after 40 min heating.
In RH, slight to moderate redness of the first heating remained until the second heating, but erosion was the severest damage encountered after the successive procedures. In SG, slight redness was observed.
In conclusion, single heating at 42°C was tolerated by the tongue and a little damage and no cumulative effect were noted by repeated heating at 42°C.