Effect of the action of diamond burs with high speed on the tensile strength of cores cemented with zinc phosphate at different preparation times

Vanilde Rocha Rodrigues

doi:10.1590/1981-8637201500032000052821

Abstract

Objective: To know the finishing effect, in order to be able to safely proceed with the cores preparation in the daily clinic, without compromising the prosthetic restoration longevity. Methods: This study used 48 human single-rooted premolars, which after the section of its crowns, were endodontically treated, and its root canal prepared 8 mm deep to receive cores casting in cobalt-chrome alloy. Cementing was made with zinc phosphate and the tensile test performed at different preparation times: G1 - without re-preparation after cementation (control); G2 - re-prepared 24 hours after cementation, and G3 - re-prepared 15 minutes after cementation. Results: Statistical analysis showed no significant difference in the tensile strength values in the different groups (p = 0.233), in other words, the core re-preparation 15 minutes or 24 hours after the cementation caused no significant reduction in tensile strength between the core and the root remaining when using the zinc phosphate cement. Conclusion: The metallic core re-preparation cast 15 minutes or 24 hours after cementation caused no significant reduction in tensile strength between the cast metallic core and the root remaining, although in absolute values there was an important difference.

Highlights

RGO, Rev Gaúch Odontol, Porto Alegre, v.63, n.4, p. 405-410, out./dez., 2015Cast metallic cores have been used over the years as a means to reconstruct teeth with large coronary destruction, in cases where the remaining no longer offers structural strength to support the filling material, in order to make on them, prosthetic crowns.Sometimes, there is a finishing requirement on the coronary portion of these cores once cemented, in order to correct their shape, improve the future crown insertion axis and promote a better esthetics
Statistical analysis showed no significant difference in the tensile strength values in the different groups (p = 0.233), in other words, the core re-preparation 15 minutes or 24 hours after the cementation caused no significant reduction in tensile strength between the core and the root remaining when using the zinc phosphate cement
The metallic core re-preparation cast 15 minutes or 24 hours after cementation caused no significant reduction in tensile strength between the cast metallic core and the root remaining, in absolute values there was an important difference

Summary

Introduction

RGO, Rev Gaúch Odontol, Porto Alegre, v.63, n.4, p. 405-410, out./dez., 2015Cast metallic cores have been used over the years as a means to reconstruct teeth with large coronary destruction, in cases where the remaining no longer offers structural strength to support the filling material, in order to make on them, prosthetic crowns.Sometimes, there is a finishing requirement on the coronary portion of these cores once cemented, in order to correct their shape, improve the future crown insertion axis and promote a better esthetics. The cast metallic core positioning in the dental remaining without cementing makes its coronary portion finishing difficult, because the diamond burs action in high rotation tends to displace it. For this reason, some professionals do this finishing in the same session, after cementation. Zinc phosphate is the pattern cement, used for the intraradicular posts fixation with great success for over 100 years, supported by numerous scientific papers This does not show adhesion to the dental structure or to the post, but provides the retention by the mechanical imbrication in the roughness of the surfaces to be cemented[2]

Methods

Results

Conclusion