A novel designed screw with enhanced stability introduces new way of intermaxillary fixation.

Abstract

INTRODUCTION: This article represents new design of a fixation screw-spike

screw-for the intermaxillary elastic fixation application after the first surgery

in orthognathic surgery. This new type called spike screw is easily placed and

provides enough rigidity for the intermaxillary fixation (IMF) with increased

stability that was a common problem using screw-type fixation. MATERIALS AND

METHODS: Spike screw has a unique design: a washer with soldered stainless hook

that adds stability and fixation to the screw done by a miniscrew. It increases

stability by reducing the high peak stress-often occurs in miniscrew-and

obtaining the advantage of miniplate system with miniscrew fixation. It allows

noninvasive screw placement unlike miniplate. The 8 spike screws were placed on

the posterior lesion to provide secure IMF, and 2 I-type C-tubes were placed on

the anterior lesion. RESULTS: By modifying the length of the hook attached to a

washer can accommodate each patient's IMF length variation like a custom-made

screw. The stability of the screw was kept well for 6 weeks even with minor

gingival irritation in some of the area. This proved that spike screw could be

one of the methods for IMF. The closeness of the hook to the teeth eliminated

further gingival irritation around the elastic attachment site. Finally, it

provided easy manipulation of the hook to change vectors of the elastic force

application. CONCLUSIONS: The novel design of the screw permits easy placement

and removal for the IMF. In addition, its advantages include increased stability

with unique design, less gingival irritation, and simple vector modification of

the IMF elastics by adjusting the hook length and shape.