Cephalometry
Azita Tehranchi; Setrareh Sohrabi; Farnaz younessian; Fatemeh Zahedipour
Abstract
Aim: Following maxillary impaction, the mandible rotates around a center. Inaccurate determination of mandibular rotation can have profound effects on orthognathic surgical treatment planning and final surgical outcome. The present study determined the relationship between the cephalometric characteristics ...
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Aim: Following maxillary impaction, the mandible rotates around a center. Inaccurate determination of mandibular rotation can have profound effects on orthognathic surgical treatment planning and final surgical outcome. The present study determined the relationship between the cephalometric characteristics of candidates for maxillary impaction surgery using sagittal and vertical locations of the center of rotation of the mandible.Methods: In a descriptive and cross-sectional trial, 36 candidates for LeFort I maxillary impaction surgery were selected. Two lateral cephalograms were obtained in open and closed mouth positions. The center of rotation of the mandible was determined by the Reuleaux technique. Cephalometric measurements of the patients with the determined center of mandibular rotation locations (regions 1 and 4 of the coordinate axis) were done and the results were subjected to the student t-test.Results: The center of mandibular rotation was located in region 1 of the coordinate axis in 17 (50%) and in 17 (50%) in the 4th region of the coordinate axis. Statistically significant differences existed regarding the MP-SN (p<0.006), CO-GO (p<0.006), and CO-GN (p<0.04) at two regions of 1 and 4 for the center of rotation of the mandible in the coordinate axis.Conclusion: With the decreased length of the ramus and increased inclination of the plane, the center of rotation of the mandible tended to be situated at region 1 of the coordinate axis, and together with the increased length of the ramus and decreased plane inclination, the center of mandibular rotation tended to be located at region 4 of the coordinate axis.
Delaram Shahbodaghi; Tahereh Hosseinzadeh Nik; Mohammad Sadegh Ahmad Akhundi; Shahab Kavousinejad; Atefe Saffar Shahroudi
Abstract
Background: Due to significant effect of joint orthodontic and surgical treatment planning on the patients’ facial appearances, precise prediction of surgical outcomes is of great importance.
Objectives: The aim of this study was to determine the maxillary and mandibular centers of rotation and ...
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Background: Due to significant effect of joint orthodontic and surgical treatment planning on the patients’ facial appearances, precise prediction of surgical outcomes is of great importance.
Objectives: The aim of this study was to determine the maxillary and mandibular centers of rotation and its distance to center of condyle (CC) in patients who underwent maxillary impaction surgery concomitant with mandibular advancement or setback surgery and also to determine the correlation between maxillary center of rotation (MxCR) with that of mandible (MnCR) and also the direction of rotation in distal and proximal segments of the mandible.
Methods: Preoperative and postoperative lateral cephalograms of 24 adult non-syndromic patients were studied. Using cephalometric tracings MxCR was located as the intersection of ANS-PNS (preoperative) and ANS’-PNS’ (postoperative) lines. MnCR was located using Reuleaux method, where perpendicular bisectors of B-B’ and Go-Go’ lines meet. Using statistical analysis of correlation and comparison, all the points’ coordinates and centers of rotation were compared. Results: The average distance of MnCR to CC was 10.45 cm and the average distance of MxCR to CC was 8.39 cm. MxCR and MnCR had positive correlation in horizontal plane and they had negative correlation in vertical plane but the correlation was insignificant (P > 0.05). In addition, there seemed to be no specific pattern in the direction of mandibular proximal and distal segments’ rotations.
Conclusions: The results showed that: (1) The center of rotation calculated for mandible after bimaxillary surgery was not located within the condylar area. But generally whenever MxCR was closer to ANS, MnCR was located more anteriorly. (2) In patients with decreased distance between MxCR and SN line, MnCR would be located more superiorly. Also, whenever MxCR had greater distance from condyle, the MnCR to condyle distance was greater too. (3) The direction of rotation in proximal and distal segments of mandible had no specific pattern.
