Effect of different ferrule designs on the fracture resistance and failure pattern of endodontically treated teeth restored with fiber posts and all-ceramic crowns

Objective

This study investigated the effect of different ferrule heights on endodonticallytreated premolars.

Materials and Methods

Fifty sound mandibular first premolars were endodontically treated and thenrestored with 7-mm fiber post (FRC Postec Plus #1 Ivoclar-Vivadent) luted withself-polymerized resin cement (Multilink, Ivoclar Vivadent) while the coronalsection was restored with hybrid composite core build-up material (Tetric Ceram,Ivoclar-Vivadent), which received all-ceramic crown. Different ferrule heightswere investigated: 1-mm circumferential ferrule without post and core (group 1used as control), a circumferential 1-mm ferrule (group 2), non-uniform ferrule2-mm buccally and 1-mm lingually (group 3), non-uniform ferrule 3-mm buccally and2-mm lingually (group 4), and finally no ferrule preparation (group 5). Thefracture load and failure pattern of the tested groups were investigated byapplying axial load to the ceramic crowns (n=10). Data were analyzed statisticallyby one-way ANOVA and Tukey’s post-hoc test was used for pair-wisecomparisons (α=0.05).

Results

There were no significant differences among the failure load of all tested groups(P<0.780). The control group had the lowest fracture resistance(891.43±202.22 N) and the highest catastrophic failure rate(P<0.05). Compared to the control group, the use of fiber post reduced thepercentage of catastrophic failure while increasing the ferrule height did notinfluence the fracture resistance of the restored specimens.

Conclusions

Within the limitations of this study, increasing the ferrule length did notinfluence the fracture resistance of endodontically treated teeth restored withglass ceramic crowns. Insertion of a fiber post could reduce the percentage ofcatastrophic failure of these restorations under function.