Avaliação de um novo protocolo para remoção de retentores metálicos por meio do ultrassom em dentes multirradiculares

Abstract

The purpose of this paper is to evaluate in vitro a new protocol for intra-radicular posts removal for multi-radicular teeth by applying ultrasonic vibration. Forty lower molars were endodontically treated in order to receive cast posts and cores, being distributed in 4 groups: GI – control without slot; GII – control with slot; GIII – ultrasound application in core without slot; GIV – ultrasound application in core with slot. After the cast posts fixation using zinc phosphate cement, the ultrasonic vibration was applied in group III for 1 minute, dividing 15 seconds on each surface and in group IV 15 seconds on facial and lingual surface, and 30 seconds inside the slot totaling 1 minute. Thereafter, samples were subjected to tensile test in Universal Assay Machine at the speed of 1mm/min. The maximum tensile strength needed for intra-radicular posts removal was registered in Newton and its data were subjected to statistical analysis ANOVA e Tukey-Kramer. The results presented statistically significant differences between the tested groups (GI – 234,34 N; GII – 201,67 N; GIII – 139,57 N; GIV – 83,23 N), with the smallest average of the tensile strength obtained when ultrasonic vibration on the core slotted applied (p<0,05). It is concluded that the implemantation of a slot in the core and ultrasonic application on all the surfaces and inside the slot caused a reduction of force required for removing cast posts and cores fixed with zinc phosphate in multi-radicular teeth.