Evaluation of intersegmental displacement according to osteosynthesis method for mandibular setback sagittal split ramus osteotomy using cone-beam computed tomographic superimposition.
OBJECTIVE
To compare intersegmental displacements after mandibular setback sagittal split ramus osteotomy with reference to the fixation system applied: miniplate with monocortical screw, 3 bicortical screws, and 1 bicortical screw and 2 resorbable screws.


METHODS
The 42 subjects were divided into 3 groups according to the osteosynthesis method applied. To evaluate the intersegmental displacements from immediately after surgery (T0) to 6 months after surgery (T1), 2 cone-beam computed tomographic data sets were superimposed on the symphyseal area and the lower part of the mandible below the root apex. On the superimposed 3-dimensional images, the mean and standard deviation of the differences of the coordinates (x, y, z) between T0 and T1 were calculated.


RESULTS
From T0 to T1, group B (bicortical screws) manifested the greatest condylion (Cd) and coronoid process (Cp) displacements (P < .05). In group A, the right Cd moved anteriorly and the left Cd moved anteriorly and inferiorly, whereas the right and left Cps moved anteriorly. In group B, the right and left Cps moved laterally and inferiorly. In group C, the right Cd moved anteriorly and inferiorly, the left Cd changed laterally and anteriorly, the right Cp moved anteriorly, and the left Cp moved anteriorly and inferiorly.


CONCLUSIONS
In the present study, group B (bicortical screws) showed the greatest displacement after the healing period. In view of these findings, surgeons should consider carefully their choice of osteosynthesis method to effectively decrease intersegmental displacement.
Department of Orthodontics, Biomedical Research Institute, Pusan National University Hospital, Busan. kimyongil@pusan.ac.kr
Yong-Il
YI
Kim
Soo-Byung
SB
Park
Yun-Hoa
YH
Jung
Dae-Seok
DS
Hwang
Jae-Yeol
JY
Lee
D020341:Absorbable Implants; D001860:Bone Plates; D001863:Bone Screws / Q000145:classification*; D002508:Cephalometry / Q000379:methods*; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D004867:Equipment Design; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D019248:Jaw Fixation Techniques; D008297:Male; D008334:Mandible / Q000000981:diagnostic imaging* / Q000601:surgery; D008335:Mandibular Condyle / Q000000981:diagnostic imaging; D059229:Osteotomy, Sagittal Split Ramus / Q000295:instrumentation*; D011378:Prognathism / Q000000981:diagnostic imaging / Q000601:surgery; D012189:Retrospective Studies; D019227:Tooth Apex / Q000000981:diagnostic imaging; D014945:Wound Healing / Q000502:physiology; D055815:Young Adult