International Journal of Computerized Dentistry, Pre-Print
Olloni, Tetore / Krasniqi, Teuta Pustina / Xhajanka, Edit
Seite 1 – 14
Purpose: Endodontically treated teeth are more susceptible to fractures than vital teeth because of significant coronal and radicular dentin loss during endodontic therapeutic procedures. The objective of this study was to estimate and compare the influence of length and post type on the fracture strength of endodontically treated maxillary central incisors.
Material and methods: In this in vitro study, sixty extracted human maxillary central incisors were decoronated 2 mm above the cemento-enamel junction.They were selected and subjected to standard endodontic treatment ,resulting in preparation with lengths of 5 mm (group 5mm),7,5 mm (group 7,5 mm) and 10 mm (group 10mm). Each group was randomly divided into 2 subgroups according to the post type , zirconia and fiber post. After appropriate surface treatment,they were cementet with resin adhesive cement and restored with zirconia crowns. Thermocycling (5 -55°C, 60 seconds, 1500 cycles) was performed after cementing the zirconia crowns on each tooth. Prepared samples were subjected to compresive static load of 0.5mm / min, at an angle of 130° to the long axis of the roots, using Universal Testing Machine (Matest ) at an cross head speed of 0.5 mm / min, until fracture.The significance of the results was assessed using 2-way ANOVA and the Tukey-Kramer test (α=0.05)
Results:The ANOVA analysis indicated significant differences (P<0.05) between the groups. Tukey test revealed no significant difference among the zirconia posts of 5-mm length (26.5 N ±13.4) 7,5-mm length (25.2 N ±13.9), and 10-mm length (17.1 N ±5.2). Also, in the fiber post group, there was no significant difference when posts of 7.5-mm length (13.4 N ±11.0) were compared with the 5-mm (6.9 N ±4.6) and 10-mm (31.7 N ±13.1) groups. The 10-mm long post displayed superior fracture strength, and the 5mm-long post showed significantly lower mean values (P<0.001).
Conclusion: The fracture strength of zirconia posts (5-mm and 7,5- mm length)was found to be significantly higher than those of fiber posts (5-mm and 7,5- mm length). The 10-mm long fiberpost group demonstrated significantly higher values of fracture strengths and the 5-mm long fiberpost group showed the lowest values for the force resulting in root fracture; these groups were significantly different from each other (P<.001).The fracture strength analysis with Universal Testing Machine is the only method that enables us to estimate the differences between zirconia and fiber posts with different lengths on endodontically treated teeth.