Torsion strength of biodegradable and titanium screws: a comparison.
OBJECTIVE
To determine 1) the differences in maximum torque between 7 biodegradable and 2 titanium screw systems, and 2) the differences of maximum torque between "hand tight" and break of the biodegradable and the titanium osteofixation screw systems.


METHODS
Four oral and maxillofacial surgeons inserted 8 specimens of all 9 screw systems in polymethylmethacrylate plates. The surgeons were instructed to insert the screws as they would do in the clinic (hand tight). The data were recorded by a torque measurement meter. A PhD resident inserted 8 specimens of the same set of 9 screw systems until fracture occurred. Likewise, the maximum applied torque was recorded.


RESULTS
1) The mean maximum torque of the 2 titanium screw systems was significantly higher than that of the 7 biodegradable screw systems, and 2) the mean maximum torque for hand tight was significantly lower than for break in 2 biodegradable, and both titanium screw systems.


CONCLUSIONS
Based on the results, we conclude that the 1.5 mm and 2.0 mm titanium screw systems still present the highest torque strength compared with the biodegradable screw systems. When there is an intention to use biodegradable screws, we recommend the use of 2.0 mm BioSorb FX (Linvatec Biomaterials Ltd, Tampere, Finland), 2.0 mm LactoSorb (Walter Lorenz Surgical Inc, Jacksonville, FL), or the larger 2.5 mm Inion (Inion Ltd, Tampere, Finland) screws.
Buijs
Gerrit J
GJ
Department of Oral and Maxillofacial Surgery, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. g.j.buijs@kchir.umcg.nl
van der Houwen
Eduard B
EB
Stegenga
Boudewijn
B
Bos
Rudulf R M
RR
Verkerke
Gijsbertus J
GJ
D020341:Absorbable Implants; D001672:Biocompatible Materials / Q000737:chemistry; D001863:Bone Screws; D004146:Dioxanes / Q000737:chemistry; D004867:Equipment Design; D004868:Equipment Failure; D006801:Humans; D019344:Lactic Acid / Q000737:chemistry; D008422:Materials Testing; D011091:Polyesters; D011100:Polyglycolic Acid / Q000737:chemistry; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011108:Polymers / Q000737:chemistry; D019904:Polymethyl Methacrylate / Q000737:chemistry; D012399:Rotation; D013314:Stress, Mechanical; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry; D019415:Torque
D001672:Biocompatible Materials; D004146:Dioxanes; D011091:Polyesters; D011108:Polymers; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; C443643:trimethylene carbonate; C033616:poly(lactide); D019904:Polymethyl Methacrylate; D014025:Titanium