Effect of Prefabricated Surface Coating of Short Root Posts

Objectives: Recently introduced short root posts (6 mm length) are produced with a surface coating in order to enhance the bonding and prevent microleakage along the cement layer. The posts are offered in titanium (Ti) and FRC. The aim of the study was to evaluate the effect of the surface coating of the short posts on their micro-pushout bond strengths (µPBS) compared to those without coating regarding 2 materials for insertion. Methods: The clinical crowns of 80 freshly extracted anterior human teeth were cut perpendicular. All roots undergone root canal treatment and post space preparation for the short posts. Short posts of Ti and FRC with (6CO) and without coating (6UN) respectively (n=20) were inserted using a resin cement RelyX Unicem (RX) and a core-buildup composite DentinBuild (DB). 8 test groups (n=10) were formed and stored wet. After thermocycling (5°/55°C, 5000x), the roots were cut horizontally into 1 mm thick slices. µPBS were measured and calculated regarding the various surface areas. Statistical significant differences were calculated (ANOVA, Bonferroni correction, α=0.05). Results: Higher µPBS were obtained for 6CO compared to 6UN regardless of the post and the insertion material for these comparing groups, yet the differences were proven not to be significant (p>0.05). The average µPBS of all segments along the root amounted for 6CO: 8.8±6.9 N/mm2 Ti-RX, 8.8±6.0 N/mm2 Ti-DB, 8.1±4.3 N/mm2 FRC-RX, 8.9±6.4 N/mm2 FRC-DB and for 6UN: 7.1±4.5 N/mm2 Ti-RX, 4.3±2.6 N/mm2 Ti-DB, 7.3±5.4 N/mm2 FRC-RX, 6.7±5.1 N/mm2 FRC-DB. Also µPBS did not differ significantly comparing the post or the insertion materials (p>0.05). Conclusions: The surface coating of the short posts has a beneficial effect on the µPBS. RX as well as DB could be recommended for insertion of the tested posts of both materials.