An in vitro study evaluating the effect of ferrule length on fracture resistance of endodontically treated teeth restored with fiber-reinforced and zirconia dowel systems
Section snippets
Material and methods
One hundred twenty-three freshly extracted canines free of cracks, caries, fractures, and restorations were selected for the study. All external debris was removed with an ultrasonic scaler (Mini Piezon; EMS Piezon Systems, Nyon, Switzerland), and the teeth were stored in saline solution until testing. The anatomic crowns of all teeth were removed perpendicular to the long axis of the tooth, from the most incisal point of the approximal cementoenamel junction (CEJ), with the use of a
Results
Mean failure loads were calculated for all groups (Table II). Two-way ANOVA was performed to test the 2 main effects, dowels, and ferrule lengths on the fracture strength. The result of the analysis revealed a significant difference in both the main effect dowel (P<.0001) and ferrule length (P<.0001). Significant dowel by ferrule-length interaction was also encountered (P<.0001) (Table II).
Further analysis with the Tukey HSD test indicated that the within-group differences for all dowel
Discussion
In the present study, 2-way ANOVA was used to test the 2 main effects on the fracture resistance of endodontically treated teeth restored with 4 esthetic dowel systems and 3 different ferrule lengths. Significant within-group differences were observed for all subgroups except for the quartz-fiber groups with 1.0-mm and 1.5-mm ferrule lengths (P=.084) and glass-fiber groups with 1.0-mm and 1.5-mm ferrule lengths (P=.119). The low elastic modulus of quartz- and glass-reinforced dowels, which
Conclusions
Within the limitations of this in vitro study, the following conclusions were drawn.
- 1.
There was a significant difference in the mean fracture loads of endodontically treated teeth prepared to 2.0-mm ferrule length compared with 1.0-mm and 1.5-mm ferrule lengths regardless of the dowel system tested (P<.001).
- 2.
Among the 1.0-mm, 1.5-mm, and 2.0-mm ferrule-length specimens, significantly higher fracture loads were observed in teeth restored with quartz-fiber dowels compared with teeth restored with
Acknowledgements
The author acknowledges RTD, Brasseler-Komet, Dentsply-Maillefer, Ivoclar Vivadent, and 3M for generous support in the form of donated materials. The author thanks Professor M. Babur Caniklioglu for his expertise, Dr Gunay Can for statistical analysis of the data, and Dr Atakan Elter for assistance with the illustrations.
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