Avaliação "in vitro" do comportamento de dois agentes termicos e da influencia da espessura amelo-dentinaria na variação de temperatura em dentes humanos

Abstract

Este estudo determinou as variações de temperatura na face externa da coroa e na junção dentina/polpa correspondente, provocadas pela aplicação de dois agentes térmicos - bastão de gelo e diclorodifluorometano - em dentes incisivos inferiores e canino superiores; avaliou também, a influência da espessura de tecidos duros - esmalte e dentina - sobre essa variação térmica. Abstract : This research had the purpose to determine "in vitro" the temperature variations after the ice stick and the DDM (diclorodifluoromethane) were applied in the buccal surface of the crown and in the dentine/pulp wall in the same plane, in the lower anterior teeth and in the upper canines; and determinate the enamel/dentine thickness according to these thermical variations . The teeth were joined in 2 groups of 10 specimens each and were tested in 4 conditions. Each specimen was prepared and receaved 2 termopair (" body test") . Each "body test" was fixed in a fibberplate and was dived in a hotwater device at 37°C. The data was taken in a computer system and about 150 measures of external and internal temperatures ( Te, Ti ) were recorded corresponding each one a time of 1/3 second . The next time of the tests the specimens were cut in the middle ( longitudinal plane) and measures of enamel/dentine thickness were taken in a optical microscope. The results determined the temperature variations at the buccal surface of the specimens (Te) and in the dentine/pulp wall (Ti) and the thickness of hard tissues in the tested teeth . The author concluded, in the tests conditions, that the ice stick application resulted in a decreasing of Te of about 37°C and the DDM deoreased the Te in about 60°C . He also concluded that the ice produced a constant temperature during the time of the application and the DDM has a high capacity of refrigeration in the first five seconds of the experiment, gaining temperature after this time. Yet, the author observed that in the thicker specimens the decreasing of Ti was less than in the specimens of less thickness of enamel/dentine for the two cool agents. Nevertheless, determinated that the enamel/dentine thickness was less on the lower incisors than on the tested canines.