J Korean Assoc Oral Maxillofac Surg.  2015 Jun;41(3):133-138. 10.5125/jkaoms.2015.41.3.133.

An in vitro comparison between two different designs of sagittal split ramus osteotomy

• Andrade VC
• Luthi LF
• Sato FL
• Pozzer L
• Olate S
• Albergaria-Barbosa JR

• KMID: 1797843
• DOI: http://doi.org/10.5125/jkaoms.2015.41.3.133

Abstract

OBJECTIVES
To evaluate the influence of the type of osteotomy in the inferior aspect of the mandible on the mechanical performance.
MATERIALS AND METHODS
The study was performed on 20 polyurethane hemimandibles. A sagittal split ramus osteotomy (SSRO) was designed in 10 hemimandibles (group 1) with a vertical osteotomy in the buccal side (second molar level) and final osteotomy was performed horizontally on the lingual aspect, while the mandible body osteotomy was finalized as a straight osteotomy in the basilar area, perpendicular to the body. For group 2, the same osteotomy technique was used, but an oblique osteotomy was done in the basilar aspect of the mandibular body, forming continuity with the sagittal cut in the basilar area. Using a surgical guide, osteosynthesis was performed with bicortical screws using an inverted L scheme. In both groups vertical compression tests were performed with a linear load of 1 mm/min on the central fossa of the first molar and tests were done with models made from photoelastic resin. Data were analyzed using Student's t-test, establishing a statistical significance when P <0.05.
RESULTS
A statistical difference was not observed in the maximum displacements obtained in the two osteotomies (P <0.05). In the extensiometric analysis, statistically significant differences were identified only in the middle screw of the fixation. The photoelastic resin models showed force dissipation towards the inferior aspect of the mandible in both SSRO models.
CONCLUSION
We found that osteotomy of the inferior aspect did not influence the mechanical performance for osteosynthesis with an inverted L system.

Keyword

Mandibular osteotomy; Rigid internal fixation; Sagittal split ramus osteotomy

MeSH Terms

Mandible
Mandibular Osteotomy
Molar
Osteotomy
Osteotomy, Sagittal Split Ramus*
Polyurethanes
Polyurethanes

Figure

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  Fig. 1 Osteotomy design for group 1, showing a strength basilar cut (double-headed arrows).

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  Fig. 2 Osteotomy design for group 2, representing the oblique basilar cut (double-headed arrows).

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  Fig. 3 Hemimandible from group 1 installed on the platform with the extensometers positioned in each one of the screws.

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  Fig. 4 Photoelastic model from group 1 demonstrating homogeneity in the load distribution.

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  Fig. 5 Photoelastic model from group 2 demonstrating a greater number of fringes in the T2 and dispersion of force towards the base of the mandible.

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