An experimental evaluation of a new craniofacial implant using the rabbit tibia model: Part II. Biomechanical findings.

HYPOTHESIS: This experimental study was undertaken to test the hypothesis that a new design of a craniofacial implant is more stable and shows faster integration than the currently used implant.

MATERIALS AND

METHODS

A total of 60 newly designed Cochlear Baha titanium implants (test) and 60 of the current design (control) were placed in the tibiae of 30 adult loop-eared rabbits. The animals were euthanized after 5, 14, or 28 days. The stability of the implants was measured with Implant Stability Quotient measurements and removal torque (RTQ) tests. The Student's t test for paired statistics were used for comparisons and a difference considered if p < 0.05.

RESULTS

The test implants showed a significantly higher RTQ at all time points and a steeper increase with time than the controls. The RTQ values were 19.0 (standard deviation [SD], 9.1) and 9.8 (SD, 5.6) Ncm for test and control implants, respectively, after 5 days; 27.6 (SD, 9.6) and 11.2 (SD, 3.9) Ncm after 14 days; and 43.3 (SD, 9.6) and 20.7 (SD, 14.1) Ncm after 28 days. Higher Implant Stability Quotient values were measured for the test implant at all time points. Calculations of shear stress to compensate for implant diameter revealed significantly higher values for test than for control implants after 14 and 28 days.

CONCLUSION

It is concluded that the new craniofacial implant was more stable and showed a faster integration than the currently used implant. The data from the present study suggest that the new implant may be suitable for early loading protocols.