Influence of an interdental full pin on stability of an acrylic external fixator for rostral mandibular fractures in dogs.
OBJECTIVE
To determine total stiffness and gap stiffness of an external fixation system in a canine mandibular fracture gap model incorporating a full interdental pin as the only point of rostral fixation in a bilateral type-I external fixator.


METHODS
10 canine mandibles.


METHODS
Bilateral mandibular ostectomies were performed between premolars 3 and 4. A type-I external fixator incorporating a full interdental pin was placed to stabilize a 0.5-cm fracture gap. Four pin configurations (intact mandibular bodies with fixator; ostectomized mandibular bodies and complete fixator; ostectomized mandibular bodies with caudal pins of rostral fragment cut; ostectomized mandibular bodies with all pins of rostral fragment cut) were tested in dorsoventral bending 5 times on each mandible. The full interdental pin remained intact in all configurations. Total stiffness and gap stiffness were determined for each configuration on a materials testing machine.


RESULTS
Total stiffness of intact mandibles was significantly greater than that of ostectomized mandibles, regardless of external fixator configuration. However, total stiffness and gap stiffness were not significantly different among different external fixator configurations applied to ostectomized mandibles.


CONCLUSIONS
External fixator configurations with only the full interdental pin engaging the rostral fragment were as stiff as configurations that had 2 or 4 additional pins in the rostral fragment for the applied loads. External fixators for rostral mandibular fractures may be rigidly secured with rostral fragment implants applied extracortically, avoiding iatrogenic trauma to teeth and tooth roots.
Cook
W T
WT
Department of Small Animal Clinical Sciences, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg 24061, USA.
Smith
M M
MM
Markel
M D
MD
Grant
J W
JW
D000818:Animals; D003772:Dental Pins / Q000662:veterinary*; D004285:Dogs / Q000601:surgery*; D016267:External Fixators / Q000662:veterinary*; D005592:Fracture Fixation / Q000379:methods / Q000662:veterinary*; D008337:Mandibular Fractures / Q000601:surgery / Q000662:veterinary*; D019904:Polymethyl Methacrylate
D019904:Polymethyl Methacrylate