Midsagittal Reference Research Articles

Using the anterior cranial base to provide a reliable reference plane for patients with or without facial asymmetry

This study aimed to investigate the midsagittal reference plane (MSP) reliability derived from the 3-dimensional characteristics of patients with or without facial asymmetry in the anterior cranial base (ACB). We divided the cone-beam computed tomography (CBCT) images of 60 adult patients into maxillofacial symmetry and asymmetry groups. The ACB models were 3-dimensionally constructed, and then symmetrical characteristics were evaluated with surface asymmetry for each group. The reliability of the MSP derived from the symmetry of the anterior cranial base (MSPACB) was assessed in comparison with the true craniofacial symmetry plane determined using the morphometric method. The ACB was symmetrical, as demonstrated by slight surface asymmetry. The MSPACB was reliable for maxillofacial asymmetrical analysis as the intraobserver and interobserver measurements using the MSPACB were of excellent agreement, and there was no significant difference between MSPACB and morphometric method in asymmetrical measurements in both groups. The MSPACB remained stable (maximum deviation<0.32 mm) when cranial landmark identification errors (1 mm and 4 mm) were simulated. MSPACB is reliable for patients with or without facial asymmetry in maxillofacial asymmetry analysis, which is beneficial to patients with severe midfacial asymmetry or trauma when conventional landmarks are displaced or disappear. When using MSPACB for patients with cranial malformations or those whose ACBs differ from normal dimensions, caution should be taken.

Association between the temporomandibular joint disc position on magnetic resonance imaging and the mandibular deviation on posteroanterior cephalogram: a cross-sectional study in adolescents.

The aim of this cross-sectional research was to analyze the association between the disc position of the temporomandibular joint (TMJ) evaluated by magnetic resonance imaging (MRI) and the mandibular deviation evaluated by posteroanterior cephalometric (PA) in adolescents. The sample was 53 adolescents aged 11-18 years. This cross-sectional study was based on the analysis of PA and bilateral TMJ MRI images retrospectively selected. The mandibular deviation was evaluated by PA and defined by the amount of menton (Me) deviation from the midsagittal reference line. The temporomandibular disc position was evaluated by MRI: normal (N), disc displacement with reduction (DDR) and disc displacement without reduction (DDNR). The DDNR was considered more severe than the DDR. The patients were classified into three groups based on the bilateral disc position: group I, the same bilateral disc position; group II, disc displacement more severe on the ipsilateral side of the menton deviation; group III, disc displacement more severe on the contralateral side of the menton deviation. ANOVA followed by post hoc Tukey's test was used to evaluate the interaction between the menton deviation and the bilateral disc position. There was an association statistically significant between the bilateral disc position and the Me deviation (p<0.05). There were significant differences in the mean of the menton deviation between group II (4,40 ±2,26), and group I (2,17±1,93) and III (2,10±1,70). The menton deviation was significantly correlated with the disc position in the TMJ exhibit more deflection to the side more affected.

Three novel methods to measure the postoperative displacement of lower urinary tract structures following radical prostatectomy in a sample of Korean patients

BackgroundThere is a change in the position of the remaining anatomical structures of the lower urinary tract system following radical prostatectomy. The aims of this investigation were to describe three novel methods used to measure the displacement of i) the vesico-urethral junction (VUJ), proximal membranous urethra (PMU) and anorectal junction (ARJ) and ii) the VUJ angle of displacement in men following radical prostatectomy and determine their intra- and interrater reliability.MethodsRetrospective comparative measurement of twenty pre- and postoperative MRI scans was undertaken by one observer on two separate occasions and on one occasion by another observer. Three standardized midsagittal pelvimetry reference lines were used to describe three X, Y axis measurement systems. The displacement (mm) of the VUJ, PMU and ARJ, and the angle of displacement (degrees) of the VUJ was measured for each of the three methods. Interrater reliability of VUJ, PMU and ARJ displacement and the VUJ angle of displacement measurements was assessed using a two-way mixed-effects agreement intra-class correlation coefficient (ICC) with 95% confidence intervals (CI). Test-retest (intrarater) reliability was calculated using a two-way random effects consistency ICC with 95% CI for all displacement measures of the VUJ, PMU and ARJ for one observer between two days.ResultsThe pubococcygeal line (PCL) axis measurement system demonstrated good to excellent intrarater and interrater reliability (ICC 95% interval lower bound > 0.75) for the VUJ and PMU displacement and the VUJ angle of displacement measurements. Other measurement systems were less reliable and more variable.ConclusionsIn this sample of 20 Korean patients with median prostate volume 27.5 mL and maximum volume 70 mL, the measurement methodology using the PCL consistently demonstrated good to excellent reliability and the lowest variability for the measurement of the displacement of the VUJ and PMU and the VUJ angle of displacement. The PCL methodology is recommended as the method of choice. Further studies should validate these results in patients with large prostate volumes.

Cone beam computed tomography evaluation of the relationship between atlantodental interval and skeletal facial morphology in adolescents

IntroductionIn the pediatric population, computed tomography examination of the upper cervical spine plays an important role in the diagnosis of neurological injuries involving that region. Due to the interconnected nature of the craniofacial structures, a structural change in one is expected to also cause changes in the other structures. ObjectiveThe aim of this study was to evaluate relationships between atlantodental interval, cervical vertebral morphology, and facial structure in healthy adolescents using cone beam computed tomography. MethodsThirty subjects aged 14–20 years (10 males, mean age: 17.2 years; 20 females, mean age: 17.9 years) were included in the study. The anterior, lateral and posterior atlantodental intervals, and vertical and anteroposterior dimensions of the first and second cervical vertebrae were evaluated from cone beam computed tomography images. Facial morphology was evaluated using 7 parameters on lateral cephalometric cone beam computed tomography images and 6 parameters on posteroanterior images. The Mann–Whitney U test and Wilcoxon test were used for statistical analyses. ResultsComparisons between males and females showed that most parameters were larger in males, with significant differences in vertical facial dimensions (anterior lower face height: p = 0.05; anterior upper face height: p = 0.001), (distance between the most internal point of the frontozygomatic suture and midsagittal reference plane; p = 0.01), (the distance between the deepest point of the right alveolar maxillar process and midsagittal reference plane; p = 0.001), and C2 vertebral dimensions. The anterior and lateral atlantodental interval values correlated with maxilla position relative to the mandible angle, and the anterior atlantodental interval correlated with lower anterior facial height (p = 0.05). Dimensional measurements of the C1 and C2 vertebrae were correlated with both anterior facial heights and some posteroanterior parameters. ConclusionSagittal, vertical, and transverse facial dimensions and positions were strongly associated with C1 and C2 vertebral dimensions, and the maxillomandibular relationship may affect atlantodental interval. Therefore, including craniofacial features in assessment of the atlantodental area and vertebral distances in adolescents may be beneficial.

Comparison of the three-dimensional structures of mandibular condyles between adults with and without facial asymmetry: A retrospective study.

ObjectiveThis retrospective study compared the three-dimensional (3D) structure of mandibular condyles between adults with and without facial asymmetry, and whether it influences menton deviation.MethodsSixty adult patients were classified into symmetry and asymmetry groups based on the menton deviation on postero-anterior radiographs. The right/left differences of 3D measurements were compared between the two groups, and measurements were compared separately on the right and left sides. The correlations between menton deviation and the right/left differences were analyzed.ResultsThe mediolateral dimension, neck length, condylar angles to the anteroposterior reference (PO) and midsagittal reference planes, and neck and head volumes showed significantly larger right/left differences in the asymmetry group compared to the symmetry group. Separate comparisons of the right and left sides between the two groups showed that the neck was significantly shorter and neck and head volumes were significantly smaller on the left side, which was deviated side in the asymmetry group. Pearson's correlation analysis showed significant positive correlations of menton deviation with right/left differences in neck length, condylar angle to the PO plane, and neck and head volumes in the asymmetry group.ConclusionsIn individuals with facial asymmetry, menton deviation is associated with the right/left differences caused by a smaller condyle on the deviated side, particularly in neck length and neck and head volumes.

Preliminary Study to Determine the Reference Plane of Patients With a Unilateral Cleft Lip and Palate.

The objective of this study was to determine the three-dimensional midsagittal reference planes for unilateral cleft lip and palate (UCLP) patients that can be easily applied in a clinical setting. This was a retrospective analysis. There were 35 UCLP patients (25 men, 10 women; 28.1 ± 6.9 years old) in this study. With landmark's three-dimensional coordinates obtained from cone-beam computed tomography, the symmetric midsagittal reference planes were calculated by applying the ordinary Procrustes superimposition method using the original and mirror images. Procrustes analysis was also used to find the closest landmarks to the calculated symmetric midsagittal reference plane and test its compatibility with the symmetrical midsagittal reference plane. The three nearest landmarks to the symmetric midsagittal reference plane were Opisthion, Basion, and Nasion. The averages of the sums of the squared Euclidean distance and squared Procrustes distance differences between the two configurations and shapes fabricated by the symmetrical and landmark-based midsagittal reference planes, respectively, were calculated as 1.836 ± 3.295 and 1.519 × 10-5 ± 2.351 × 10-5. It was confirmed that the midsagittal reference planes from these selected landmarks for UCLP patients were compatible with symmetric midsagittal reference planes from the Procrustes analysis and the asymmetric measurements.

Analyzing Menton Deviation in Posteroanterior Cephalogram in Early Detection of Temporomandibular Disorder.

Introduction Some clinicians believed that mandibular deviation leads to facial asymmetry and it also had a correlation with temporomandibular disorders (TMDs). Posteroanterior (PA) cephalogram was widely reported as a regular record in treating facial asymmetry and craniofacial anomalies. The objective of this study was to analyze the relationship of menton deviation in PA cephalogram with temporomandibular disorders (TMDs) symptoms. Materials and Methods TMJ function was initially screened based on TMD-DI questionnaire. PA cephalogram of volunteer subjects with TMDs (n = 37) and without TMDs (n = 33) with mean age of 21.61 ± 2.08 years was taken. The menton deviation was measured by the distance (mm) from menton point to midsagittal reference (MSR) horizontally, using software digitized measurement, and categorized as asymmetric if the value is greater than 3 mm. The prevalence and difference of menton deviation in both groups were evaluated by unpaired t-test. Result The prevalence of symmetry group showed that 65.9% had no TMDs with mean of 1,815 ± 0,71 mm; in contrast, the prevalence of asymmetry group showed that 95.5% reported TMDs with mean of 3,159 ± 1,053 mm. There was a significant difference of menton deviation to TMDs (p = 0.000) in subjects with and without TMDs. Conclusion There was a significant relationship of menton deviation in PA cephalogram with TMDs based on TMD-DI index.

Statistical shape analysis-based determination of optimal midsagittal reference plane for evaluation of facial asymmetry.

The purpose of this study was to determine, by statistical shape analysis of original and mirroredskeletal landmarks, the optimal landmark-based midsagittal reference plane for evaluation of facial asymmetry. The study sample comprised 69 patients with facial asymmetry (36 men, 33 women; mean age, 23.0±4.1years). All landmarks were obtained with cone-beam computed tomography using a 3-dimensional coordinate system. For identifying the landmark-based midsagittal reference plane, the 3 landmarks nearest to the symmetric midsagittal reference plane were selected by ordinary and generalized Procrustes analyses. To verify the 3-landmark-based midsagittal reference plane's compatibility with the symmetric midsagittal reference plane, asymmetry measurements were calculated and tested for each. The 3 nearest landmarks (nasion, anterior nasal spine, and posterior nasal spine) were selected for the 3-landmark-based midsagittal reference plane. The averages of the sums of the squared Euclidean distance and the squared Procrustes distance differences between the 2 configurations and shapes fabricated by the symmetric and landmark-based midsagittal reference planes, respectively, were calculated as 0.121±0.241 mm and 1.69×10(-6) ± 3.25×10(-6). The testing results for the symmetric and landmark-based midsagittal reference planes were almost the same. The results indicated that a 3-dimensional midsagittal reference plane constructed of nasion, anterior nasal spine, and posterior nasal spine could be a valuable tool for the evaluation of patients with facial asymmetry.

Orthodontic intrusion of maxillary incisors: a 3D finite element method study

Objective: In orthodontic treatment, intrusion movement of maxillary incisors is often necessary. Therefore, the objective of this investigation is to evaluate the initial distribution patterns and magnitude of compressive stress in the periodontal ligament (PDL) in a simulation of orthodontic intrusion of maxillary incisors, considering the points of force application. Methods: Anatomic 3D models reconstructed from cone-beam computed tomography scans were used to simulate maxillary incisors intrusion loading. The points of force application selected were: centered between central incisors brackets (LOAD 1); bilaterally between the brackets of central and lateral incisors (LOAD 2); bilaterally distal to the brackets of lateral incisors (LOAD 3); bilaterally 7 mm distal to the center of brackets of lateral incisors (LOAD 4). Results and Conclusions: Stress concentrated at the PDL apex region, irrespective of the point of orthodontic force application. The four load models showed distinct contour plots and compressive stress values over the midsagittal reference line. The contour plots of central and lateral incisors were not similar in the same load model. LOAD 3 resulted in more balanced compressive stress distribution.

The location of midfacial landmarks according to the method of establishing the midsagittal reference plane in three-dimensional computed tomography analysis of facial asymmetry.

PurposeThe purpose of this study was to evaluate the influence of methods of establishing the midsagittal reference plane (MRP) on the locations of midfacial landmarks in the three-dimensional computed tomography (CT) analysis of facial asymmetry.Materials and MethodsA total of 24 patients (12 male and 12 female; mean age, 22.5 years; age range, 18.2-29.7 years) with facial asymmetry were included in this study. The MRP was established using two different methods on each patient's CT image. The x-coordinates of four midfacial landmarks (the menton, nasion, upper incisor, and lower incisor) were obtained by measuring the distance and direction of the landmarks from the MRP, and the two methods were compared statistically. The direction of deviation and the severity of asymmetry found using each method were also compared.ResultsThe x-coordinates of the four anatomic landmarks all showed a statistically significant difference between the two methods of establishing the MRP. For the nasion and lower incisor, six patients (25.0%) showed a change in the direction of deviation. The severity of asymmetry also changed in 16 patients (66.7%).ConclusionThe results of this study suggest that the locations of midfacial landmarks change significantly according to the method used to establish the MRP.

Construction and Validation of the Midsagittal Reference Plane Based on the Skull Base Symmetry for Three-Dimensional Cephalometric Craniofacial Analysis

The objective of this study was to determine the reliable midsagittal (MS) reference plane in practical ways for the three-dimensional craniofacial analysis on three-dimensional computed tomography images. Five normal human dry skulls and 20 normal subjects without any dysmorphoses or asymmetries were used. The accuracies and stability on repeated plane construction for almost every possible candidate MS plane based on the skull base structures were examined by comparing the discrepancies in distances and orientations from the reference points and planes of the skull base and facial bones on three-dimensional computed tomography images. The following reference points of these planes were stable, and their distribution was balanced: nasion and foramen cecum at the anterior part of the skull base, sella at the middle part, and basion and opisthion at the posterior part. The candidate reference planes constructed using the aforementioned reference points were thought to be reliable for use as an MS reference plane for the three-dimensional analysis of maxillofacial dysmorphosis.

Deviation of landmarks in accordance with methods of establishing reference planes in three-dimensional facial CT evaluation.

PurposeThis study aimed to investigate the deviation of landmarks from horizontal or midsagittal reference planes according to the methods of establishing reference planes.Materials and MethodsComputed tomography (CT) scans of 18 patients who received orthodontic and orthognathic surgical treatment were reviewed. Each CT scan was reconstructed by three methods for establishing three orthogonal reference planes (namely, the horizontal, midsagittal, and coronal reference planes). The horizontal (bilateral porions and bilateral orbitales) and midsagittal (crista galli, nasion, prechiasmatic point, opisthion, and anterior nasal spine) landmarks were identified on each CT scan. Vertical deviation of the horizontal landmarks and horizontal deviation of the midsagittal landmarks were measured.ResultsThe porion and orbitale, which were not involved in establishing the horizontal reference plane, were found to deviate vertically from the horizontal reference plane in the three methods. The midsagittal landmarks, which were not used for the midsagittal reference plane, deviated horizontally from the midsagittal reference plane in the three methods.ConclusionIn a three-dimensional facial analysis, the vertical and horizontal deviations of the landmarks from the horizontal and midsagittal reference planes could vary depending on the methods of establishing reference planes.

A novel approach for craniofacial symmetry evaluation: Using the midsagittal Reference line drawn from "Crista Gali" with NHP technique

Background & Objective: The purpose of this study was the determination of midsagittal reference line (MSL) for craniofacial asymmetry assessment by drawing a line from Crista gali parallel to the true vertical line in PA cephalometry, using Natural Head Position (NHP) technique. Method and Materials: 60 Iranian subjects within the age range of 9-13 years old were selected for this prospective study. Patients referred for orthodontic treatment and ghad no supernumerary or missing teeth, no skeletal anomaly, or any history of orthodontic and jaw surgery with normal occlusion. Posteroanterior cephalometric radiographs (PA Ceph) were taken of all subjects with NHP technique. The midsagittal line was also traced parallel to the hanging chain from Crista gali. True horizontal line (THL) and true vertical line (TVL) were also traced from Crista gali (Cg). Using Cartesian system based upon Cg point (0~0), the craniofacial symmetry was assessed with linear, angular and proportional measurements in PA cephalogam, related to TVL and THL lines, for 10 bilateral (R&L) anatomical landmarks. The mean differences of the above measurements in left and right sides were analyzed by T- test. Results: The proportional ratios for all left and right measurements were not statistically significant. This was true for both vertical and horizontal distances. The significant level for MSL drawn from Cg as referred to ANS (0±0.255) and Me points (0.007±0.527) was 0.002 and 0.004, respectively. Conclusion: In posteroanterior cephalometry radiographs taken with NHP method, the MSL drawn from Crista gali is reproducible and reliable up to 96% of the times for facial symmetry diagnosis.

Three-dimensional evaluation of midfacial asymmetry in patients with nonsyndromic unilateral cleft lip and palate by cone-beam computed tomography

ObjectiveTo compare three-dimensionally the midfacial hard- and soft-tissue asymmetries between the affected and the unaffected sides and determine the relationship between the hard tissue and the overlying soft tissue in patients with nonsyndromic complete unilateral cleft lip and palate (UCLP) by cone-beam computed tomography (CBCT) analysis.MethodsThe maxillofacial regions of 26 adults (18 men, 8 women) with nonsyndromic UCLP were scanned by CBCT and reconstructed by three-dimensional dental imaging. The frontal-view midfacial analysis was based on a 3 × 3 grid of vertical and horizontal lines and their intersecting points. Two additional points were used for assessing the dentoalveolar area. Linear and surface measurements from three reference planes (Basion-perpendicular, midsagittal reference, and Frankfurt horizontal planes) to the intersecting points were used to evaluate the anteroposterior, transverse, and vertical asymmetries as well as convexity or concavity.ResultsAnteroposteriorly, the soft tissue in the nasolabial and dentoalveolar regions was significantly thicker and positioned more anteriorly on the affected side than on the unaffected side (p < 0.05). The hard tissue in the dentoalveolar region was significantly retruded on the affected side compared with the unaffected side (p < 0.05). The other midfacial regions showed no significant differences.ConclusionsWith the exception of the nasolabial and dentoalveolar regions, no distinctive midfacial hard- and soft-tissue asymmetries exist between the affected and the unaffected sides in patients with nonsyndromic UCLP.

The reliability of cone-beam computed tomography (CBCT) – Generated frontal cephalograms

BackgroundThe purpose of this study was to evaluate the reliability of measurements from cone-beam computed tomography (CBCT)-generated frontal cephalogram. Materials and methodsCBCT and conventional posteroanterior (PA) cephalograms were taken from 30 adult patients. CBCT image was set according to the Frankfurt-Horizontal (FH) plane as the horizontal plane and the midsagittal reference (MSR) plane. The CBCT frontal cephalograms were generated using the orthogonal Raycast method (group CTraycast), the orthogonal maximum intensity projection (MIP) method (group CTMIP) after the head reorientation according to the reference planes, and the generator tool provided by the employed 3-dimensional (3D) imaging software (group CTgenerator), respectively. The differences between the CBCT-generated frontal cephalograms and conventional PA cephalograms (group PAceph) were compared by paired t-test (p<0.05). ResultsThe significant differences were shown in two measurements for group CTraycast, in 12 measurements for group CTMIP, and in eight measurements for group CTgenerator. It was confirmed that the CBCT frontal cephalograms, generated by means of the Raycast method (Group CTraycast), were more comparable to the conventional PA cephalograms in their measurements than were the others (Groups CTMIP, CTgenerator). ConclusionThis study may well suggest that frontal cephalograms derived by 3D CBCT reorientation can be effectively employed in clinical applications.

Midfacial soft tissue changes after leveling Le Fort I osteotomy with differential reduction

To compare the short- and long-side soft tissue changes in the midfacial areas of patients who have undergone superior repositioning Le Fort I osteotomies for the correction of occlusal cant. The null hypothesis was that there were no significant differences in the midfacial soft tissue changes between the greater- and lesser-reduction sides. The subjects included 25 patients who had undergone Le Fort I osteotomy with superior repositioning and mandibular setback sagittal split ramus osteotomy. Using the cone-beam computed tomography volume superimposition method, the soft tissue changes were measured and determined both preoperatively and postoperatively. A 10 × 27 grid at 4.5-mm (vertical) and 5-mm (horizontal) intervals was used for the hard to soft tissue response. The mean difference in the reduction from leveling Le Fort I osteotomy was 3.2 ± 1.2 mm between the short and long sides (P < .05). The mandibular setback movement averaged 5.4 ± 3.3 mm on the long side and 5.0 ± 3.6 mm on the short side (P > .05). The soft tissue areas below the Frankfort horizontal (FH) plane to 13.5 mm showed different changes after the differential leveling Le Fort I osteotomies. The distinctly changed areas, which showed differences between the greater- and lesser-reduction sides beyond the 2.5-mm average for the soft tissue response, were below the FH plane to 13.5 mm and lateral to the midsagittal reference plane to 30 mm. In light of this, oral surgeons and orthodontists should be concerned about the volumetric midfacial difference after leveling the maxillary occlusal plane at the preoperative stage and thus should take appropriate measures to improve it.

Poster 55: Evaluation of the Novel Midsagittal Line for Diagnosis of Craniofacial Asymmetry

The purpose of this Diagnostic study was determination of midsagittal reference line ( MSL ) for craniofacial asymmetries assessment by drawing a line from crista gali parallel to the true vertical line in PA cephalometry, using NHP technique.

Comparison of midsagittal reference plane in PA cephalogram and 3D CT

Comparison of midsagittal reference plane in PA cephalogram and 3D CT

Safe zone for anterior cortical perforation of the ulna during tension-band wire fixation: A magnetic resonance imaging analysis

Placing K-wires obliquely through the anterior ulnar cortex is a common modification of traditional olecranon tension-band wiring. Wire tip protrusion, however, risks injury to adjacent neurovascular structures and may impede forearm rotation. This study examines the proximity of neurovascular structures to the anterior proximal ulnar cortex. The anatomy of 47 adult elbows was examined through magnetic resonance imaging. A radiologist measured the spatial relationship of 6 neurovascular structures to a mid-sagittal reference point 1.5 cm distal to the coronoid on the anterior surface of the ulna. Distance and angular measurements were made in the transverse plane of the reference point. Within a reasonable arc of K-wire placement, the ulnar artery and median nerve were at greatest risk yet were still beyond 10 mm from the anterior ulnar cortex. To avoid iatrogenic neurovascular injury during tension-band wiring of the olecranon, protrusion of wire tips beyond the anterior ulnar cortex should be no more than 1 cm at a distance of 1.5 cm distal to the coronoid.

Effects of the size and form of the orofacial structure on vowel production

Individual difference of the orofacial structure and its articulatory and acoustic influences have been studied based on the University of Wisconsin x-ray microbeam database [Honda and Wu, J. Acoust. Soc. Am. 100, 2598(A) (1996)]. This work describes a subsequent statistical analysis on the same datasets. The outlines of the orofacial structure of 20 subjects (10 Japanese and 10 English speakers) were extracted from lateral x-ray scan images and mapped onto a midsagittal reference space defined by the palatal plane and anterior nasal spine. Vowel records in the microbeam data were analyzed to reveal the effect of orofacial morphological difference on vowel articulation and acoustic parameters. In the main results, the size parameters were commonly correlated with the three formant frequencies. In particular, the lower facial height or the size of the mandibular symphysis showed a clear tendency to inversely correlate with the first formant. Among the parameters of form, oral cavity aspect ratio and mandibular symphysis shape thought to be possible factors affecting vowel gestures, which were reflected in the spread of the second formant in all the vowels analyzed. A multiple regression model of speaker characteristics will be discussed.