Title: 0113 - Hexagonal Boron Nitride UDMA Resin Composites


Jiawei Yang, The University of Manchester
Xiaojing Chen, Central South University
Zheling Li, The University of Manchester
Owen Addison, University of Birmingham
Xiaohui Chen (Presenter)
The University of Manchester


Objectives: To evaluate the potential of Hexagonal Boron Nitride as a reinforcing filler for light curable UDMA resin composites.

Methods: Experimental resin composite formulated by incorporating 40 wt% hydroxyapatite into a UDMA monomer matrix with a photo-initiator system of CQ and DMAEM was used as control for the present study. Four hexagonal Boron Nitride (hBN) resin composites were fabricated by introducing 0.25 and 0.5 wt% of two hBN with difference morphology into the control. Cylindrical specimens (5 mm x 1/2 mm) were light cured and the real time transmitted irradiance at the bottom specimen surface was recorded using a calibrated spectrometer (MARC Resin Calibrator). The degree of conversion immediate and 7 d after cured (DC0 and DC7d), post-irradiance hardness (VHN0 and VHN7d) and 7 d post-cured flexural strength were measured by a FTIR spectroscopy, a Vickers indenter and a universal testing machine respectively (n=5). Difference between the results was analysed using one way ANOVA (p<0.05) followed by Tukey`s post hoc test.

Results: The presence of hBN did not change the overall shape of the irradiation curve, but resulted in a reduction in the maximum transmitted irradiance (Imax) at the bottom sample surface compared with control. Sample thickness in contract had a dramatic influence on Imax. The addition of hBN did not significantly change DC for the 1 mm specimens; however, 0.5 wt% h-BN has a detrimental influence on DC for the 2 mm specimens. Post-irradiance hardness increased after 7 d, but no significant difference was noticed between groups. The addition of hBN led to a significant increase in flexural strength compared with the control group.

Conclusions: Small amount of hBN did not change the curability of experimental UDMA resin composite but led to increased flexural strengths indicating that hBN has the potentials as a reinforcing filler for dental resin composites.

Disclosure Statement:
The submitter must disclose the names of the organizations with which any author have a relationship, the nature of the relationship, and the clinical or research area involved. The following is submitted: None