Showing papers by "Bart Van Meerbeek published in 2008"

Critical analysis of the influence of different parameters on the microtensile bond strength of adhesives to dentin.

Abstract: Purpose To evaluate how six different test parameters (TP) of the microtensile bond strength (microTBS) methodology influence the test outcome. Materials and methods The microtensile bond strength of adhesives bonded to dentin was measured, and the resultant failure patterns and stress-time graphs were analyzed, varying the microTBS specimen-fixation mode (TP1), the microspecimen geometry (TP2), the microspecimen bond surface area (TP3), the remaining dentin thickness of the microspecimens (TP4), the procedure employed to glue the microspecimen to the microTBS jig (TP5), and the microTBS crosshead speed (TP6). Results The orientation of the microspecimens to the actual interface primarily influenced the resultant microTBS value and the eventual failure pattern. A notched jig consistently yielded significantly higher mciroTBS values than samples fixed onto a flat jig or following a "top-bottom" design (TP1). A higher bond strength, a lower standard deviation/coefficient of variation, a failure closer to the interface, and a more representative number of specimens per tooth were obtained for nontrimmed, square microspecimens (TP2). The most reproducible results were obtained using square specimens of 1 mm2 (TP3), which could also be most easily prepared. The remaining dentin thickness (TP4) was an influential factor as well, whereas the microspecimen gluing protocol (TP5) and the crosshead speed (TP6) appeared less influential. Conclusion As several test parameters significantly influenced the microTBS outcome, sufficient attention should be paid to these methodology variables with regard to the microTBS-test reliability and reproducibility.

Effect of polyphosphoric acid pre-treatment of titanium on attachment, proliferation, and differentiation of osteoblast-like cells (MC3T3-E1).

Abstract: Purpose: To evaluate the effect of polyphosphoric acid (PPA) pre-treatment of titanium (Ti) on the initial attachment, proliferation, and differentiation of mouse osteoblast-like cells (MC3T3-E1). Materials and methods: Adsorption of PPA to Ti was achieved by immersing Ti disks (15 mm in diameter) into 0, 1, and 10 wt% PPA and 10 wt% orthophosphoric acid (OPA) for 24 h. On each pre-treated Ti disk, 5.0 × 104 MC3T3-E1 cells were seeded, and 1, 3, and 5 h later cell attachment was evaluated. Cell proliferation was also determined 1, 3, and 5 days after cell seed. Cell differentiation was evaluated 5, 10, and 15 days after cell seed using osteoblast marker gene expression. Total RNA was purified from each culture and Type-I collagen, alkaline phosphatase, and osteocalcin mRNA expression levels were measured by real-time reverse transcription polymerase chain reaction. Results: Adsorption of PPA or OPA to Ti significantly accelerated initial cell attachment at every time point (P<0.0001). As with cell attachment, cell proliferation was also accelerated on the PPA-treated Ti disks in a dose-dependent manner at every time point (P<0.0001). However, OPA-treated Ti disks did not enhance the cell proliferation. Regarding osteoblastic differentiation, PPA-treated Ti significantly accelerated the Type-I collagen gene expression at 5 and 10 days after cell seed. Regarding alkaline phosphatase and osteocalcin gene expression, no significant difference was found among the different Ti surface conditions. Conclusion: The accelerated cell behavior following Ti pre-treatment with PPA is a promising new strategy to fabricate bioactive Ti implants.