Failure rates for stainless steel versus titanium alloy infrazygomatic crest bone screws: A single-center, randomized double-blind clinical trial

OBJECTIVES: To compare failure rates for stainless steel (SS) and titanium alloy (TiA) bone screws (BSs) placed in the infrazygomatic crest (IZC). MATERIALS AND METHODS: A total of 386 consecutive patients (76 male, 310 female; mean age 24.3 years, range 10.3-59.4 years) received IZC BSs (SS or TiA) via a double-blind, split-mouth design. BSs penetrated attached gingiva (AG) or moveable mucosa (MM) with 5 mm of soft tissue clearance. All BSs were immediately loaded and reactivated monthly with ≤14 oz (397 g or 389 cN) applied directly to the upper archwire bilaterally for 6 months to retract the maxilla to correct Class II or bimaxillary protrusion. RESULTS: Of the 772 devices, there were 49 (6.3%) failures: 27 SS (7.0%) and 22 TiA (5.7%). The 1.3% difference was not statistically significant ( P = .07). There was no significant relationship between SS or TiA failures relative to (1) right vs left side, (2) unilateral vs bilateral, or (3) age at failure. Significantly ( P < .05) increased failure rates were noted for SS screws in only two subgroups: AG site (7.4%) and right side (7.8%). Unilateral failure occurred in 21 patients (5.4%), and bilateral failures occurred in 14 of the total 772 patients (1.8%). CONCLUSIONS: The overall success rate of 93.7% indicates that both SS and TiA are clinically acceptable for IZC BSs.