Influence of different convergence angles on the retention of cast metal post and core / 生物医学工程学杂志

ABSTRACT

Fifty-four simulated tooth roots made of polymethacrylate (PMMA) were divided into six groups according to the root canal convergence angles of 0 degrees, 3.93 degrees, 5.71 degrees, 7.48 degrees, 11.31 degrees, 14.71 degrees. Cast post and cores were manufactured and cemented with Zinc phosphate cement (ZP). The retention capacities of the posts were tested. The bonding strength of ZP at different convergence angles were tested with some casted wafers, and linear regression was made. So the effect of interlocking and the proportion could be calculated. With these results, we made some curvilinear regressions. The results showed that the retention of cast post declined and the bonding strength of ZP fell with the increase of convergence angles. There were significant differences in the bonding strength and retention among groups, P<0.05. The experiment indicates that the dentists should reduce the convergence angles of posts as much as possible to obtain greater retention.