Evaluation of dentinal crack formation during post space preparation using different fiber post systems with micro computed tomography

Objective: The effects of different post preparation systems and post preparation lengths on cracks of root dentin were aimed to evaluate using micro-CT (µCT). Materials and Methods: Forty extracted maxillary bifurcated first premolars were randomly divided into 4 groups (n=10). The teeth were decoronated as root length was 18 mm and then access cavities were prepared. After root canal shaping and obturation, the teeth were kept in an incubator at 37°C for 1 week, and then teeth were scanned with µCT first time. After that, in Group 1(Rebilda-1/2), post space was prepared to 1/2 of the root canal length, in Group 2 (Rebilda-2/3) post space was prepared to 2/3 of the root canal length using Rebilda post drills; in Group 3 (RelyX-1/2), post space was prepared to 1/2 of the root canal length and in Group 4 (RelyX-2/3), post space was prepared to 2/3 of the root canal length using RelyX post drill. After all, teeth were scanned with µCT second time. Cracks on root dentin were detected as first and second µCT scans were analysed and classified as "new cracks", "progressive cracks" and "completed cracks". Statistical analysis was performed using Chi-square test. Results: There was no statistically significant difference between the completed cracks group and the progressive cracks group (p>0.05). In new cracks group, Rebilda-2/3 group formed statistically significantly more cracks than RelyX-1/2 group and RelyX-2/3 group also formed more than RelyX-1/2 group (p<0.05). Conclusion: Within the limitations of our study, completed crack and propagation of the cracks in the post spaces were observed in all groups. New cracks were not observed only in the RelyX-1/2 group. It was concluded that less crack formation of root dentin was in post space ½ length of the root canal. Keywords: Post space, dentinal crack, microcomputed tomography