[Properties of titanium dioxide-polymer composite with titanate coupling agents].

Titanium dioxide-polymethacrylate composites were prepared with triethyleneglycol dimethacrylate (TEGDMA), 1,6-bis(methacryloxy-2-ethoxycarbonylamino)-2,4,4-trimeth ylexane (UDMA) and rutile structure titanium dioxide. The coupling agents used were isopropyldimethacrylisostearoyl titanate (KR7), isopropyltri (dioctylphosphate) titanate (KR12) and 4-methacryloxyethyl trimellitate anhydride (4-META). Compressive and transverse strengths of composites were determined under various experimental conditions. Compressive strength of composite with KR 7-treated titanium dioxide was higher than that with untreated titanium dioxide. Transverse strength of the composite with 4-META-treated titanium dioxide was higher than that with untreated titanium dioxide. Both compressive and transverse strengths increased when the titanium dioxide was treated with the mixture of KR7 and 4-META. Scanning electron microscopic observations of fractured composite surfaces showed titanium dioxide polymer interface failure with untreated specimens and polymer cohesive fracture with KR7 + 4-META-treated specimens. The results suggest that titanium dioxide treated with both KR7 and 4-META is useful as a pigment of the opaque material of fixed prosthodontic composite.