Integrity of craniofacial plating systems after multiple sterilization procedures

To determine the effect of multiple autoclave sterilization cycles on the integrity of titanium plates and screws used in craniofacial reconstruction.

Torque to fracture was evaluated for 36 titanium 6AL-4V (Ti 6/4) screws divided evenly into 3 groups and tested as machined (control), after 10 cycles of autoclaving or after 50 cycles of autoclaving. Sterilization was carried out by autoclaving for 15 minutes followed by 8 minutes of drying at 270 degrees to 272 degrees F. The maximum torque attained before fracture was recorded. Rotating beam specimens were crafted from single lots of Ti 6/4, commercially pure titanium grade 4 (CP4) and commercially pure titanium grade 2 (CP2), and then subjected to testing in a standard rotating beam device as machined (control), after 10 cycles of autoclaving or after 50 cycles of autoclaving. The cycles required to fracture the specimen at a given applied stress were recorded for each material and for the number of autoclavings carried out before testing.

Although there was a trend toward decreased strength and increased ability to fracture with increased number of autoclave cycles, this did not reach statistical significance. Torque to fracture testing for 7 mm Ti 6/4 screws showed no significant difference in the maximum torque reached before fracture between controls, those screws that had been autoclaved 10 times (P < .500 +/- 5.70) and those that had been autoclaved 50 times (P < .398 +/- 4.08). Rotating beam specimens of Ti 6/4, CP4, and CP2 showed no significant difference in cycles to fracture regardless of the number of sterilization cycles to which the material was subjected.

Repeated cycles of autoclaving had no significant effect on the integrity of titanium plates and screws routinely used in craniofacial surgery.