Mechanical stability of 2-plate versus 4-plate osteosynthesis in advancement Le Fort I osteotomy. An in vitro study.
BACKGROUND
Stability in orthognathic surgery is nowadays considered as efficient and adequate. The objective of this study was to determine and to compare the mechanical resistance to vertical load of a Le Fort I advancement osteotomy stabilized by mean of two different osteosynthesis techniques, one using two 10-hole pre-bent T-shaped plates, the other using four manually bent 4-hole L- and J-shaped plates.


METHODS
Standardized Le Fort I advancement osteotomies have been made on polyurethane models. The maxillary advancement was 5mm. Two groups of five models each were created. Group 1 was stabilized by mean of two 10-hole pre-bent T-shaped plates fixed by monocortical screws in the paranasal region. Group 2 was stabilized by mean of manually bent four 4-hole L-shaped plates fixed monocortical screws in the zygomatic and paranasal regions. A testing machine was used to load vertically the models at the range of 1mm/min linear displacement until peak load and system failure. Statistical analysis was realized using ANOVA and t-test, considering P as significant if <0.005.


RESULTS
The maximal tolerated load was 15N in group 1and 42.71N in group 2 (P=0.003).


CONCLUSIONS
The use of two T-shaped 10-holes pre-bent plates allows for less resistance in vertical loading than the use of four 4-holes manually bent L-shaped plates.
Division of Oral and Maxillofacial Surgery, State University of Campinas, Piracicaba, SP, Brazil.
L
L
Pozzer
Division of Oral and Maxillofacial Surgery, Universidad de La Frontera, Temuco, Chile; Center for Biomedical Research, Universidad Autónoma de Chile, Temuco, Chile. Electronic address: sergio.olate@ufrontera.cl.
S
S
Olate
Division of Oral and Maxillofacial Surgery, State University of Campinas, Piracicaba, SP, Brazil.
L
L
Cavalieri-Pereira
Division of Oral and Maxillofacial Surgery, Universidad de La Frontera, Temuco, Chile.
P
P
Navarro
Division of Oral and Maxillofacial Surgery, State University of Campinas, Piracicaba, SP, Brazil.
J R
JR
de Albergaría Barbosa
D001860:Bone Plates / Q000009:adverse effects; D001863:Bone Screws / Q000009:adverse effects; D004867:Equipment Design; D004868:Equipment Failure; D019544:Equipment Failure Analysis; D005593:Fracture Fixation, Internal / Q000295:instrumentation / Q000379:methods; D006801:Humans; D066298:In Vitro Techniques; D008422:Materials Testing / Q000379:methods; D055595:Mechanical Phenomena; D008953:Models, Anatomic; D019340:Osteotomy, Le Fort / Q000295:instrumentation / Q000379:methods; D013314:Stress, Mechanical
Internal fixation; Le Fort I; Pre-bend plate