2005 Volume 46 Issue 7 Pages 1545-1550
The mechanical properties and fatigue strength of Ti–15Zr–4Nb–4Ta castings were compared with those of Co–Cr–Mo and Ti–6Al–7Nb castings, which have been clinically used in Japan. The mechanical properties of buffed and chemically polished dental castings were almost the same. The 0.2% proof strength (σ0.2%PS), ultimate tensile strength (σUTS) and total elongation (TE) of the buffed Ti–15Zr–4Nb–4Ta castings were 832±41 MPa, 964±69 MPa and 7±3%, respectively. The σ0.2%PS, σUTS and TE of the buffed Ti–6Al–7Nb castings were 873±30 MPa, 982±27 MPa and 11±4%, respectively. The σ0.2%PS, σUTS and TE of the buffed Co–Cr–Mo castings were 589±23 MPa, 773±19 MPa and 10±2%, respectively. The fatigue strength of the Ti alloy castings at 1×107 cycles was lower than that of the Co–Cr–Mo castings. The fatigue strengths of the Ti–Al–7Nb and Ti–15Zr–4Ta–4Nb castings at 1×107 cycles were approximately 100 and 80 MPa, respectively. Clinical trials were carried out for complete and partial dentures made of the Ti–15Zr–4Nb–4Ta alloy. Clinical observation was conducted over a one year period for patients wearing complete or partial dentures. During the clinical observation, all five patients felt comfortable with the dentures, and fracture of the clasp was not observed.
