Skeletal Landmarks Research Articles

Three-dimensional cone beam computed tomographic image reorientation using soft tissues as reference for facial asymmetry diagnosis

To investigate discrepancies in results of facial asymmetry analysis using different cone beam computed tomography (CBCT) image reorientation methods and the effectiveness of soft tissue as a reorientation reference for analysis of facial asymmetry. An asymmetric group of 30 patients with 4 mm or more of chin point (menton [Me]) deviation and a symmetric group of 30 patients with less than 4 mm of deviation of Me were chosen as study subjects. Three orientation methods were used to calculate and compare Me deviation values of the 60 subjects. Two methods used only skeletal landmarks for reference, and one method included the soft tissue landmarks around the eye. Preferences of an expert group for the facial midline as determined by each reorientation method were also examined. The examinations showed significant discrepancies in Me deviation values between the three reorientation methods. The expert group showed the greatest preference for the facial midline reorientation method that incorporated soft tissue landmarks of the eye. These study findings suggest that the inclusion of soft tissue landmarks, especially those around the eyes, is effective for three-dimensional CBCT image reorientation for facial asymmetry analysis.

Three-Dimensional Cephalometry

The aims of this work were (1) to describe a method to identify new skeletal landmarks useful to define the reference system to orient the skull in a new position after cone-bean computed tomographic scan and (2) to demonstrate the reliability of this new method.Ten orthognathic patients (5 male, 5 female; mean [SD] age, 18.9 [1.2] years) underwent the cone-bean computed tomographic scan before surgery. Seven 3-dimensional skeletal measurements derived from 4 skeletal point of construction (C) (right, left, and median orbital C, and sella C) have been used for this study. Reliability has been calculated using Pearson correlation coefficient tests.Intraobserver reliability was 0.9999 for operator A (T1-T2) and 0.9999 for operator B (T1-T2); interobserver reliability was 0.9999 between the first (T1-T1) measurement and 0.9999 between the second (T2-T2).The original method is able to reduce the variability of landmark identification due to the variability of the human anatomy and the influence of the human error in cephalometric analysis. The innovation of this new method is the real possibility to use the anatomical structures in a 3-dimensional way, enhancing the reliability of the reference points.

Orthodontic camouflage versus orthognathic surgery: A comparative analysis of long-term stability and satisfaction in moderate skeletal Class III

Objective: The purpose of this study was to compare long-term stability and satisfaction between orthodontic camouflage and orthognathic surgery in treatment of moderate skeletal Class III adults. Materials and Methods: A total of 25 adults females who had been treated with orthodontic camouflage for Class III malocclusions were recalled at least 3 years post-treatment to evaluate stability and satisfaction with treatment outcomes. The data were compared with similar data for long-term outcomes in 21 patients with the same Class III problems who had bimaxillary surgical correction. Results: In the camouflage patients, small mean changes in skeletal landmark positions occurred over the long term, although the changes were generally much smaller than in the surgery patients. Dental changes in the surgery group were more severe than those in the camouflage group. The camouflage patients reported fewer functional or temporomandibular joint problems than did the surgery patients. Both groups reported similar levels of overall satisfaction with treatment. Conclusion: The results suggest that both camouflage and surgical treatment in moderate skeletal Class III adults can achieve satisfactory outcomes and provide long-term stability. If patients do not readily accept surgery because of potential surgical complications or financial difficulties, camouflage treatment may be an effective alternative treatment.

Reproducibility of three-dimensional coordinate systems based on craniofacial landmarks

To propose a method for evaluating the reproducibility of anatomical coordinate systems based on craniofacial skeletal landmarks and to tentatively evaluate four systems created on preoperative cone-beam computed tomography (CBCT) data obtained from mandibular prognathism patients in order to confirm the utility for actual patients' data. In three-dimensional images of 10 patients obtained by a CBCT with a large field of view, six dentists set four coordinate systems that were created in different ways, twice by plotting some landmarks situated in the superior portion of the maxillofacial skeletons. The 95% confidence ellipse of six objective landmarks related to the jaw and teeth (upper incisor, left upper first molar, lower incisor, left lower first molar, menton, and left gonion) were three-dimensionally drawn for each coordinate system. The ellipsoid volume was calculated to evaluate the reproducibility of the coordinate systems. The reproducibility could be evaluated for each coordinate system using the method proposed. The coordinate systems that were created by landmarks situated at greater distances from each other showed relatively small ellipsoid volume in comparison to those with shorter distances between landmarks. Anatomical coordinate systems with larger distances between the landmarks used were stable when landmarks related to the jaw and teeth were assigned as objective landmarks. The method proposed here was effective in terms of the reproducibility evaluation of a coordinate system.

Kinetics of the cervical spine in pediatric and adult volunteers during low speed frontal impacts

Previous research has quantified differences in head and spinal kinematics between children and adults restrained in an automotive-like configuration subjected to low speed dynamic loading. The forces and moments that the cervical spine imposes on the head contribute directly to these age-based kinematic variations. To provide further explanation of the kinematic results, this study compared the upper neck kinetics – including the relative contribution of shear and tension as well as flexion moment – between children (n=20, 6–14yr) and adults (n=10, 18–30yr) during low-speed (<4g, 2.5m/s) frontal sled tests. The subjects were restrained by a lap and shoulder belt and photo-reflective targets were attached to skeletal landmarks on the head, spine, shoulders, sternum, and legs. A 3D infrared tracking system quantified the position of the targets. Shear force (Fx), axial force (Fz), bending moment (My), and head angular acceleration (θ̈head) were computed using inverse dynamics. The method was validated against ATD measured loads. Peak Fz and θ̈head significantly decreased with increasing age while My significantly increased with increasing age. Fx significantly increased with age when age was considered as a univariate variable; however when variations in head-to-neck girth ratio and change in velocity were accounted for, this difference as a function of age was not significant. These results provide insight into the relationship between age-based differences in head kinematics and the kinetics of the cervical spine. Such information is valuable for pediatric cervical spine models and when scaling adult-based upper cervical spine tolerance and injury metrics to children.

Skeleto-Dental Changes After Camouflage Treatment in Class II division 1 Adult Patients with Average Mandibular Plane Angle

Objective: To assess the skeleto-dental changes in adult Class II Division 1 patients with average mandibular plane angle after camouflage orthodontic treatment by premolars extraction.&#x0D; Materials and Method: Total 30 adult female patients, aged between 20-40 years with Class II Division 1 malocclusion with average mandibular plane angle (Mp-SN: 30-38) were selected for the study. Pre-treatment and post-treatment cephalographs were traced and different measurements are derived from skeletal and dental landmarks. Statistical analysis was done by paired t-test using SPSS software version 16.00.&#x0D; Results: SNA, SNB and ANB angles were reduced significantly. The maxillary length was also decreased significantly. However mandibular dimension was not changed significantly after camouflage treatment. The upper and lower incisors were significantly intruded whereas upper molar was slightly intruded and lower molar was significantly extruded. Antero-posteriorly, incisors were retracted significantly. Upper molars had negligible mesial movement however lower molars had moved mesially with statistical significance.&#x0D; Conclusion: During camouflage treatment care should be taken on incisor retraction. The vertical control of the molar teeth is important during the treatment period to avoid worsening of the facial proportion.

Interfractional Reproducibility of Gastro-Esophageal Junction (GEJ) Location for Patients with Esophageal Cancer

To assess the inter-fractional reproducibility of GEJ location based on radiation treatment setup utilizing skeletal landmarks and weekly 4D-CT scans in patients with mostly distal esophageal tumors undergoing chemoradiation.

A More Reliable Method to Assess Acetabular Component Position

Acetabular component position is associated with joint function and bearing wear. Current techniques for determining acetabular component version on standard radiographs lack reliability. Other, more consistent techniques are time-consuming and require additional equipment or software. We compared three methods of acetabular component position assessment: (1) Einzel-Bild-Roentgen-Analyse (EBRA), (2) Woo and Morrey, and (3) the new ischiolateral method. We assessed axial component position for 52 hips, with at least three radiographic series, using EBRA, and on true lateral radiographs using the Woo and Morrey method and a new method that uses the ischium as a skeletal landmark, the ischiolateral method. The mean SDs of the ischiolateral (2.15°) and EBRA (2.06°) methods were lower than that of the Woo and Morrey method (3.65°) but were not different from one another. We observed a SD of greater than 4° in 19 (36.5%) hip series using the Woo and Morrey method, compared to six series (11.5%) for both the ischiolateral and EBRA methods. Twenty-four (12.6%) Woo and Morrey measurements were greater than 4° from the mean for the hip series, compared to seven (3.8%) for ischiolateral and nine (4.7%) for EBRA. The intraclass correlation coefficients for intra- and interobserver reliability for the ischiolateral method and EBRA were the same (0.9). Referencing the ischium standardizes pelvic position on each lateral radiograph and provides a simple and reliable means to assess axial component position, which is a surrogate for the planar anteversion measured by EBRA.

Evaluating craniofacial asymmetry with digital cephalometric images and cone-beam computed tomography

The aim of this study was to evaluate craniofacial asymmetry by using 2-dimensional (2D) posteroanterior cephalometric images, 3-dimensional cone-beam computed tomography (CBCT), and physical measurements (gold standard). Ten dry human skulls were assessed, and radiopaque markers were placed on 17 skeletal landmarks. Twenty linear measurements were taken on each side to compare the right and left sides and to compare these measurements with the physical measurements made with a digital caliper. To acquire the 2D posteroanterior radiographs, an Extraoral Phosphor Storage Plate (Air Techniques, Chicago, Ill) was used as the image receptor with a Eureka x-ray-Duocon Machlett unit (Machlett Laboratores, Chicago, Ill). Three-dimensional imaging data were acquired from a CB MercuRay (Hitachi Medical, Tokyo, Japan). On average, the right side was larger than the left for most of the 20 distances evaluated in the digital 2D and the CBCT images, and there was poor agreement between the digital 2D images and the physical measurements (kappa= 0.0609) and almost perfect agreement (kappa= 0.92) between the CBCT and physical measurements when individual measurements were considered. Human skulls, with no apparent asymmetry, had some differences between the right and left sides, with dominance for the right side but with no clinical significance. CBCT can better evaluate craniofacial morphology when compared with digital 2D images.

A new approach of assessing sagittal dysplasia: the W angle

In orthodontic diagnosis and treatment planning, an accurate antero-posterior measurement of jaw relationships is critically important. Previously described angular and linear measurements can be inaccurate because of their dependency on various factors. The purpose of this study was to introduce a new cephalometric measurement, named the W angle, to assess the sagittal relationship between maxilla and mandible with accuracy and reproducibility. This angle uses three skeletal landmarks--point S, point M, and point G--to measure an angle that indicates the severity and the type of skeletal dysplasia in the sagittal dimension. One hundred and forty-two pre-treatment cephalometric radiographs of patients between the age of 15 and 25 years were selected. They were again subdivided into Classes I, II, and III groups on the basis of Beta angle, Wits appraisal, and ANB angle. The W angle was measured between the perpendicular from point M on S-G line and the M-G line. The mean and the standard deviation for the W angle were calculated. After using the one-way analysis of variance and the Newman-Keuls test, receiver operating characteristics curves were obtained. Results showed that a patient with a W angle between 51 and 56 degrees can be considered to have a Class I skeletal pattern. With an angle less than 51 degrees, patients are considered to have a skeletal Class II relationship and with an angle greater than 56 degrees, patients have a skeletal Class III relationship.

The use of the T1 sagittal angle in predicting overall sagittal balance of the spine

Background context A balanced sagittal alignment of the spine has been shown to strongly correlate with less pain, less disability, and greater health status scores. To restore proper sagittal balance, one must assess the position of the occiput relative to the sacrum. The assessment of spinal balance preoperatively can be challenging, whereas predicting postoperative balance is even more difficult. Purpose This study was designed to evaluate and quantify multiple factors that influence sagittal balance. Study design Retrospective analysis of existing spinal radiographs. Methods A retrospective review of 52 adult spine patient records was performed. All patients had full-column digital radiographs that showed all the important skeletal landmarks necessary for accurate measurement. The average age of the patient was 53 years. Both genders were equally represented. The radiographs were measured using standard techniques to obtain the following parameters: scoliosis in the coronal plane; lordosis or kyphosis of the cervical, thoracic, and lumbar spine; the T1 sagittal angle (angle between a horizontal line and the superior end plate of T1); the angle of the dens in the sagittal plane; the angle of the dens in relation to the occiput; the sacral slope; the pelvic incidence; the femoral-sacral angle; and finally, the sagittal vertical axis (SVA) measured from both the dens of C2 and from C7. Results It was found that the SVA when measured from the dens was on average 16 mm farther forward than the SVA measured from C7 (p<.0001). The dens plumb line (SVA dens) was then used in the study. An analysis was done to examine the relationship between SVA dens and each of the other measurements. The T1 sagittal angle was found to have a moderate positive correlation (r=0.65) with SVA dens, p<.0001, indicating that the amount of sagittal T1 tilt can be used as a good predictor of overall sagittal balance. When examining the other variables, it was found that cervical lordosis had a weak correlation (r=0.37) with SVA dens that was unexpected, given that cervical lordosis determines head position. Thoracic kyphosis also had a weak correlation (r=0.26) with SVA C1, which was equally surprising. Lumbar lordosis had a slightly higher correlation (r=0.38), p=.006, than the cervical or thoracic spine. A multiple regression was run on the data to examine the relationship that all these independent variables have on SVA dens. SPSS (SPSS, Inc., Chicago, IL, USA) was used to create a regression equation using the independent variables of T1 sagittal angle, cervical lordosis, thoracic kyphosis, lumbar lordosis, sacral slope, pelvic incidence, and femoral-sacral angle and the dependent variable of SVA dens. The model had a strong correlation (r=0.80, r 2=0.64) and was statistically significant (p<.0001). The T1 sagittal angle was the variable that had the strongest correlation with the SVA dens Spearman r=0.65, p<.0001, followed by pelvic incidence, p=.002, and lumbar lordosis, p=.006. We also observed that when the T1 tilt was higher than 25°, all patients had at least 10 cm of positive sagittal imbalance. In addition, patients with negative sagittal balance had mostly low T1 tilt values, usually lower than 13°. The other variables were not shown to have a statically significant influence on SVA. Conclusions This analysis shows that many factors influence the overall sagittal balance of the patient, but it may be the position of the pelvis and lower spine that have a stronger influence than the position of the upper back and neck. Unfortunately, to our knowledge, there are no studies to date that have established a normal sagittal T1 tilt angle. However, our analysis has shown that when the T1 tilt was higher than 25°, all patients had at least 10 cm of positive sagittal imbalance. It also showed that patients with negative sagittal balance had mostly low T1 tilt values, usually below 13° of angulation. The T1 sagittal angle is a measurement that may be very useful in evaluating sagittal balance, as it was the measure that most strongly correlated with SVA dens. It has its great utility where long films cannot be obtained. Patients whose T1 tilt falls outside the range 13° to 25° should be sent for full-column radiographs for a complete evaluation of their sagittal balance. On the other hand, a T1 tilt within the above range does not guarantee a normal sagittal balance, and further investigation should be performed at the surgeon’s discretion.

Curvilinear Mandibular Distraction Results and Long-Term Stability Effects in a Group of 40 Patients

The mandibular internal curvilinear distractor design produces a curvilinear vector to provide ideal three-dimensional curvilinear movements compared with the limited straight unidirectional predecessor devices. In this manner, it corrects craniofacial deformities as anatomically as possible, allowing simultaneous bidirectional (rotational and translational) mandibular movement and multidirectional distraction. The aim of this study was to quantify the sagittal and vertical mandibular changes achieved through curvilinear distraction and to assess the long-term effect of this generated bone. Forty patients (20 male and 20 female), with ages ranging from 5 to 55 years, who underwent mandibular distraction from December of 1999 to August of 2007 at Lucile Packard Children's Hospital in Stanford, California, were included. Preoperatively, postoperatively, and at follow-up (at least 2 years following distraction), panoramic and lateral cephalometric radiographs were traced by plotting different skeletal landmark points and were then analyzed. All patients tolerated the curvilinear distraction process well through completion. The average of the mandibular body elongation recorded was 8 to 9 mm and 6 to 8 mm in the panoramic and cephalometric radiographs, respectively; whereas the vertical change of the mandibular ramus achieved was 10 to 12 mm and 10 to 11 mm, respectively. The curvilinear distraction effect on the mandible was found to be significantly stable when the long-term follow-up measurements were compared with the postoperative data revealed in the panoramic and lateral cephalometric radiographs for the two dimensions. The internal curvilinear device is an effective tool that achieves a stable mandibular distraction, resulting in the correction of craniofacial deformities.

Repeatability and reproducibility of OSSCA, a functional approach for assessing the kinematics of the lower limb

Marker-based gait analysis of the lower limb that uses assumptions of generic anatomical morphology can be susceptible to errors, particularly in subjects with high levels of soft tissue coverage. We hypothesize that a functional approach for assessing skeletal kinematics, based on the application of techniques to reduce soft tissue artefact and functionally identify joint centres and axes, can more reliably (repeatably and reproducibly) assess the skeletal kinematics than a standard generic regression approach. Six healthy adults each performed 100 repetitions of a standardized motion, measured on four different days and by five different observers. Using OSSCA, a combination of functional approaches to reduce soft tissue artefact and identify joint centres and axes, the lengths of the femora and tibiae were determined to assess the inter-day and inter-observer reliability, and compared against a standard generic regression approach. The results indicate that the OSSCA was repeatable and reproducible (ICC lowest bound 0.87), but also provided an improvement over the regression approach (ICC lowest bound 0.69). Furthermore, the analysis of variance revealed a statistically significant variance for the factor “observers” ( p < 0.01; low-reproducibility) when using the regression approach for determining the femoral lengths. Here, this non-invasive, rapid and robust approach has been demonstrated to allow the repeatable and reproducible identification of skeletal landmarks, which is insensitive to marker placement and measurement session. The reliability of the OSSCA thus allows its application in clinical studies for reducing the uncertainty of approach-induced systematic errors.

Analysis of Facial Skeletal Characteristics in Patients With Chin Deviation

This study was undertaken to investigate the facial skeletal features associated with chin deviation. Twenty-five patients (14 males and 11 females) diagnosed with chin deviations of more than 2 mm were recruited. Fifteen skeletal landmarks, including median and lateral points, were located on posteroanterior cephalograms. The CG-ANS (crista-galli of the ethmoid-anterior nasal spine) line and the perpendicular line through the CG were used as references. The differences between the distances from paired lateral points to reference lines were examined with intraclass correlation coefficients to analyze the symmetry of facial skeletal tissue. The factors associated with the amount or direction of chin deviation were analyzed by multiple regression analysis or by logistic regression analysis. Seventeen subjects (68%) showed chin deviation to the left side and 8 subjects (32%) to the right side. Sixty-eight percent of subjects presented with Angle Class III malocclusion. Horizontal distances of all paired lateral points to the y-axis, in mandibular body length and effective length, showed a low grade of symmetry. Only vertical distances of paired zygomaticofrontal sutures and zygonion points to the x-axis were asymmetric. However, there were no significant asymmetries of the gonial angle, ramus height, and vertical distances from other paired lateral points to the x-axis. The amount of chin deviation was associated with the absolute differences of the left and right antegonion to the y-axis and zygomaticofrontal suture to the x-axis. The direction of chin deviation was significantly associated with the difference in the effective length of bilateral mandibular halves. Facial skeletal asymmetry exists in patients with chin deviation. This should be considered when planning treatment for both the nonsurgical and surgico-orthodontic cases with chin deviation.

Transmission of whole body vibration in children while standing

Background Whole body vibration has recently been used as a therapeutic intervention for the treatment of children with disabling conditions. Researchers of these studies observed encouraging results; however, children may not be capable of attenuating high vibration accelerations to the head because of low mass. The purpose of this study was to determine if children transmit vibration differently than adults while standing on a vibration platform. Methods The experimental protocol required 11 children and 10 adults to stand on a commercially available vibration platform at progressively greater frequencies (28, 33, and 42 Hz). Transmissibility of vibration to various skeletal landmarks was assessed with a high speed motion analysis system. Findings Transmissibility in children was 42% and 62% greater than adults for the ankle and hip, respectively ( P = 0.03; effect size = 0.84–1.29). The values at the head were not different between groups ( P = 0.92) and remained 86% and 50% lower than values at the ankle and knee, respectively (effect size = 4.75–19.1). Interpretation Transmissibility of whole body vibration while standing is not markedly different between children and adults. In fact, the only differences are the transmissibility to the ankle and hip which are greater in children when the vibration platform is set at 33 Hz. More importantly, transmissibility to the head is not different between groups. These results do not suggest vibration therapy is safe as the biological response of children to acute or chronic acceleration impacts during whole body vibration is unknown.

High-speed X-ray video demonstrates significant skin movement errors with standard optical kinematics during rat locomotion

The sophistication of current rodent injury and disease models outpaces that of the most commonly used behavioral assays. The first objective of this study was to measure rat locomotion using high-speed X-ray video to establish an accurate baseline for rat hindlimb kinematics. The second objective was to quantify the kinematics errors due to skin movement artefacts by simultaneously recording and comparing hindlimb kinematics derived from skin markers and from direct visualization of skeletal landmarks. Joint angle calculations from skin-derived kinematics yielded errors as high as 39° in the knee and 31° in the hip around paw contact with respect to the X-ray data. Triangulation of knee position from the ankle and hip skin markers provided closer, albeit still inaccurate, approximations of bone-derived, X-ray kinematics. We found that soft tissue movement errors are the result of multiple factors, the most impressive of which is overall limb posture. Treadmill speed had surprisingly little effect on kinematics errors. These findings illustrate the significance and context of skin movement error in rodent kinematics.

Evaluation of Treatment Modality for Skeletal Class III Malocclusion With Labioversed Upper Incisors and/or Protrusive Maxilla

The purpose of this study was to evaluate the range of surgical movement and stability of rotational maxillary setback (MXS) procedure as treatment modality for skeletal class III malocclusion with labioversed upper incisors and/or protrusive maxilla (CIII/LUI-PM). The samples consisted of 20 adult patients (mean [SD] age, 23.55 [4.30] y) who had CIII/LUI-PM and were treated with rotational MXS and mandibular setback using LeFort I osteotomy and bilateral sagittal split ramus osteotomy. The lateral cephalograms were obtained 1 week before (T0), 1 week after (T1), and 1 year after surgery (T2). The amounts of surgical movement, relapse, and stability rate of the upper central incisor (UIE), upper first molar (U6MBC), point A (A), incisive canal point, and posterior nasal spine (PNS) in relation to the reference planes were statistically analyzed. During T1 - T0, there were backward and downward movements of UIE and A, backward and upward movements of U6MBC, and upward and slight forward movements of PNS due to rotational MXS. The center of rotation of the maxilla was placed between A and the upper premolar area. During T2 - T1, skeletal landmarks showed clinically insignificant counterclockwise rotational relapse (<0.5 mm). The anteroposterior (AP) and vertical positions of skeletal landmarks were more stable than dental landmarks. The U6MBC was more stable in the vertical aspect than UIE (P < 0.01). Posterior nasal spine showed significantly higher stability rate in both vertical and AP aspects (P < 0.01, respectively), whereas UIE showed a lower value in the vertical aspect (P < 0.05). Rotational MXS procedure in cases with CIII/LUI-PM can be regarded as a stable one, especially in the vertical and AP positions of PNS. Vertical relapse in UIE should be managed with postoperative orthodontic treatment.

Characteristics and Corrective Outcome of Face Asymmetry by Orthognathic Surgery

This study was conducted to identify the characteristics of facial asymmetry before surgery and to evaluate the facial skeletal changes and stability after 2-jaw orthognathic surgery. The ideal "double-cross grid" as fitting the key landmarks to the reference planes on posteroanterior cephalograms was set as the treatment goal. Twenty-seven adult patients, 18 female and 9 male subjects, were evaluated before and after surgery and at completion of orthodontic treatment. Cephalometric measurements of posteroanterior and lateral cephalograms were obtained at 3 timings. Measurements of frontal facial photographs were recorded before and after treatment. Data from each time set were compared to evaluate surgical achievement and postsurgical stability. All patients had original malocclusion of Class III in at least 1 side of the dentition except 1 patient. Total treatment duration was 15 +/- 3.5 months on average. Laterality of the patients demonstrated left-side dominance in 18 patients and right-side dominance in 9 patients. After surgery, face symmetry was improved by correction of the occlusal plane cant, incisal dental axis, and chin deviation. Symmetry of bilateral gonial width was also improved significantly with good stability. Intergonial width was reduced by 3.4 mm during treatment. Soft tissue presented similar correction by leveling oral commissures and correcting chin deviation. The maxilla was moved forward 1.25 mm and upward 1.20 mm, and the mandible was setback 4.3 mm and upward 1.5 mm as measured from lateral cephalograms. All sagittal changes remained stable after surgery. Fitting skeletal landmarks into a double-cross grid on posteroanterior cephalogram is an attainable guide and goal for 2-jaw orthognathic correction of facial asymmetry. Symmetry was achieved and facial profile was improved after surgery and remained stable afterward. The decrease of intergonial width indicated considerable remodeling of the bilateral gonial angle after surgery.

Novel 3-D CT Craniomaxillofacial Skeletal Landmarks for Treatment Planning and Outcomes Assessment

Novel 3-D CT Craniomaxillofacial Skeletal Landmarks for Treatment Planning and Outcomes Assessment

Relationship of nasal and skeletal landmarks in lateral cephalograms of preschool children

The purpose of this study was to investigate the relationship between cephalometric nasal and skeletal landmarks in preschool children. Lateral cephalograms of 80 Japanese preschool children (40 boys, mean age 5.4 ± 0.3 years; 40 girls, mean age 5.2 ± 0.1 years; total mean age 5.3 ± 0.3 years) were traced, and 22 skeletal and 3 soft-tissue nasal points were digitized. The coordinates from each subject were transformed to a standardized plane using a custom-made program written in Microsoft Visual C++ ®. In this standard plane, sella was the origin, Frankfort Horizontal (FH) plane was parallel to the X-axis, and all 25 points were rotated to match this reference plane. The three nasal landmarks used in this investigation were: (1) rhi’, the intersection point of a line parallel to the FH plane at rhinion and the facial line; (2) pronasale (Prn), the most anterior point on the nose; and (3) subnasale (Sn), the most posterior–superior point where the columella met the upper lip. An independent-groups t-test was used to test for sex differences of coordinates of the nasal landmarks and their related skeletal landmarks. Significance was set at p < 0.05. A stepwise regression analysis determined how combinations of skeletal landmarks explained the location of the nasal landmarks. Only one skeletal coordinate (N X) and no nasal coordinates showed a significant difference between boys and girls. The coordinates of rhi contributed significantly to the location of rhi’ and Prn (except for the Y-coordinate of girls). Moreover A-point and ANS contributed to the location of Prn and Sn. For Sn, the X- and Y-coordinates of girls and the Y-coordinate of boys were related to lower incisor or dentoalveolar structure of the mandible. It appears that the nasal landmarks in preschool children can be predicted from selected skeletal landmarks, and there are no sex differences for the nasal landmarks in children.