Summary
Several plastic-insulated instruments (unipolar, standard and modified parallel bipolar instruments) were developed and tested in comparison with standard metal instruments. Thermal modification and damage were evaluated with histological sections, in either animal or human tissue. Different patterns of tissue coagulation were recorded depending on the instrument used. With the modified parallel bipolar forceps, coupling one plastic and one metal insert allowed the possibility of achieving different degrees of coagulation on the same tissue at the same power. Possible explanations for the modified electrical behaviour are given.