[Photoelastic analysis of the biomechanical behavior of the bone interface of Tension More implants].

OBJECTIVE: To photoelastically investigate the difference in load distribution of Tension More (TM) implants with different conical angle designs. METHODS: The following five groups of implants of different conical angles were designed: cylinder implant, upper 1/3 TM implant (taper length of 3 mm); 1/2 TM implant (taper length of 5 mm); lower 1/3 TM implant (taper length of 7 mm); and bottom TM implant (taper length of 10 mm). The implants were centrally located in individually photoelastic models consisting of a simulated trabecular bone and a 1 mm-thick layer of cortical bone. Vertical and 45 degrees oblique static loads were applied at the center of the superstructures. The resulting stresses were monitored photoelastically and recorded photographically. RESULTS With vertical loading, the cylinder implant showed higher stress levels in the cortical bone and trabecular bone than the upper 1/3 TM implant, 1/2 TM implant, and lower 1/3 TM implant. The four groups of TM implants showed lower stress levels in the cortical bone than the cylinder implant under oblique loads. The least favorable stress concentration in cortical bone was observed in the upper 1/3 TM implant under vertical and oblique loads. CONCLUSION: TM implants of rational conical angle designs seem to be effective in stress distribution. For all designs and load directions, the upper 1/3 TM implant is the most favorable around the crest.