Biomechanical evaluation of different types of rigid internal fixation techniques for subcondylar fractures.
OBJECTIVE
The aim of this study was to evaluate the biomechanical stability of various internal fixation systems for subcondylar fractures.


METHODS
Eighteen identical synthetic mandibles were used. Left condylar processes were cut to mimic perpendicular subcondylar fracture and right sides were mimicked oblique subcondylar fracture. The fixation systems used included single 4-hole mini adaptation plate, double fixation with the same plates, single 4-hole mini dynamic compression plate (DCP), Eckelt lag screw system, Wurzburg lag screw plate system and double 4-hole biodegradable miniplates made of poly L-lactide (PLLA). In oblique fractures, one of the screws fixing plates was used bicortically through bone fragments. The loading vector simulated physiologic forces to the condyle on biting with servohydraulic testing machine until failure was reached. Load-displacement curve, maximum load for failure, and stiffness were measured.


RESULTS
In perpendicular fracture, double adaptation plate showed the highest level of tolerance load followed by Eckelt lag and double PLLA plate. In stiffness, double adaptation plate and Eckelt lag screw showed higher level of stiffness, whereas double PLLA was almost at the same level of single DCP. In oblique fracture, double adaptation plate showed the highest strength.


CONCLUSIONS
In this laboratory setting, double adaptation plates fixation proved to have superior biomechanical stability in both fracture conditions. Eckelt lag screw showed good stability in the perpendicular fracture, however, it was weak in the oblique fracture.
Tominaga
Kazuhiro
K
Associate Professor, First Department of Oral and Maxillofacial Surgery, Kyushu Dental College, Kitakyushu, Japan. tominaga@kyu-dent.ac.jp
Habu
Manabu
M
Khanal
Amit
A
Mimori
Yasuhiro
Y
Yoshioka
Izumi
I
Fukuda
Jinichi
J
D001696:Biomechanical Phenomena; D001860:Bone Plates; D001863:Bone Screws; D003799:Dental Stress Analysis / Q000379:methods; D004867:Equipment Design; D004868:Equipment Failure; D005593:Fracture Fixation, Internal / Q000295:instrumentation*; D006801:Humans; D019248:Jaw Fixation Techniques / Q000295:instrumentation*; D019344:Lactic Acid; D008337:Mandibular Fractures / Q000601:surgery*; D008904:Miniaturization; D008953:Models, Anatomic; D011091:Polyesters; D011108:Polymers
D011091:Polyesters; D011108:Polymers; D019344:Lactic Acid; C033616:poly(lactide)