Evaluating cranial landmarks for yaw orientation in natural head position: a 3D study.

OBJECTIVES: To assess the symmetry of various cranial anthropometric points used as references for yaw orientation in the natural head position (NHP), relative to the mid-sagittal plane. MATERIALS AND METHODS: A prospective analysis using tomography data from 55 patients was conducted. Radiopaque markers, placed on patients in NHP, facilitated head position recording in three planes, with subsequent digital transfer for orientation analysis. Symmetry of eight points (zygomaxillare, zygion, ectoconchion, frontozygomatic suture, stephanion, porion, mastoidale, condylion laterale) was measured against the mid-sagittal plane. RESULTS: Significant asymmetry was observed in the stephanion, frontozygomatic suture, and ectoconchion points (p < 0.05). No significant differences were found in the symmetry of other points (p > 0.05). CONCLUSIONS: Findings suggest that stephanion, frontozygomatic suture, and ectoconchion are unreliable for yaw orientation in NHP. Other points, combined with clinical measurements, may offer better reliability.

Comparison of the performance of various virtual articulator mounting procedures: a self-controlled clinical study.

OBJECTIVES: This clinical study aimed to compare the performance of various virtual articulator (VA) mounting procedures in the participants' natural head position (NHP). MATERIALS AND METHODS: Fourteen participants with acceptable dentitions and jaw relationships were recruited in this study registered in the Clinical Trials Registry (#NCT05512455; August 2022). A virtual facebow was designed for virtual mounting and hinge axis measurement. Intraoral scans were obtained, and landmarks were placed on each participant's face to register the horizontal plane in NHP. Six virtual mounting procedures were performed for each participant. The average facebow group (AFG) used an indirect digital procedure by using the average facebow record. The average mounting group (AMG) aligned virtual arch models to VA's average occlusal plane. The smartphone facial scan group (SFG) and professional facial scan group (PFG) used facial scan images with Beyron points and horizontal landmarks, respectively. The cone-beam computed tomography (CBCT) scan group (CTG) used the condyle medial pole, and horizontal landmarks were applied. The kinematic facebow group (KFG) served as the control group, and a direct digital procedure was applied using a kinematic digital facebow and the 3D skull model. Deviations of the reference plane and the hinge axis between the KFG and other groups were calculated. The inter-observer variability in virtual mounting software operation was then evaluated using the interclass correlation coefficient (ICC) test. RESULTS: In virtual condylar center deviations, the CTG had the lowest condylar deviations. The AFG showed larger condylar deviations than PFG, SFG, and CTG. There was no statistically significant difference between the AFG and the AMG and between the PFG and the SFG. In reference plane deviations, the AMG showed the largest angular deviation (8.23 ± 3.29°), and the AFG was 3.89 ± 2.25°. The angular deviations of PFG, SFG, and CTG were very small (means of each group < 1.00°), and there was no significant difference among them. There was no significant difference between the researchers, and the ICC test showed moderate to excellent reliability for the virtual condylar center and good to excellent reliability for the reference plane in the operation of the virtual mounting software. CONCLUSIONS: CBCT scan provided the lowest hinge axis deviation in virtual mounting compared to average mounting, facebow record, and facial scans. The performance of the smartphone facial scanner in virtual mounting was similar to that of the professional facial scanner. Direct virtual mounting procedures using horizontal landmarks in NHP accurately recorded the horizontal plane. CLINICAL RELEVANCE: Direct digital procedures can be reliably used for virtual articulator mounting. The use of a smartphone facial scanner provides a suitable and radiation-free option for clinicians.

Digital to Analog Facially Generated Interchangeable Facebow Transfer: Capturing a Standardized Reference Position.

Although the evolution of digital technology continues to improve patient data acquisition, the ability to both standardize the recording of the maxillary occlusal plane and capture the necessary dynamic data for dento-facial analysis remains elusive. This article describes step-by-step techniques to position the maxilla on an articulator using the natural head position and a facial reference system (Kois Facial Reference Glasses) for both analog and digital workflows. A photographic technique will be presented that captures the natural head position and allows the clinician to align a 2D reference photograph with the maxillary intraoral digital scan and the virtual articulator. Using this reference photograph, the clinician can record and communicate to the technician the maxillary arch position in relationship with the facial references, as well as transfer the additively manufactured casts in the same facial orientation for mounting and analysis either virtually or on an analog articulator.

Reliability of Frankfort Horizontal Plane with True Horizontal Plane in Cephalometric Measurements.

INTRODUCTION: The purpose of the study is to determine reliability of true horizontal (TH) plane with Frankfort horizontal (FH) plane in cephalometric measurements. MATERIALS AND METHODS: One hundred lateral cephalograms were collected and traced using FACAD software, all cephalometric measurements which included FH plane as reference planes were used in this study. Cephalometric tracing was done with FH plane as reference plane and another set of measurements with TH plane as reference plane was done. Statistical tests were done using independent sample t-test (p <0.05). RESULTS: Results of an independent t-test revealed a statistically insignificant difference that was observed for all the parameters assessed (p <0.05). Both angular and linear measurements showed an insignificant difference between FH and TH. CONCLUSION: Within the limitations of the study, the results show that the FH plane is closest and as reliable as the TH plane. The variation of FH was least for all the parameters assessed.

Recording Natural Head Position Using Cone Beam Computerized Tomography.

The purpose of this study was to develop a technique to record the natural head position (NHP) of a subject using the scout images of cone beam computerized tomography (CBCT) scans. The first step was to align a hanging mirror with the vertical (XY) plane of the CBCT field-of-view (FOV) volume. Then, two scout CBCT images, at frontal and at sagittal planes, were taken when the subject exhibited a NHP. A normal CBCT scan on the subject was then taken separately. These scout images were used to correct the orientation of the normal CBCT scan. A phantom head was used for validation and performance analysis of the proposed method. It was found that the orientation detection error was within 0.88°. This enables easy and economic NHP recording for CBCT without additional hardware.

Reproducibility of Natural Head Position assessed with stereophotogrammetry.

OBJECTIVE: The aim of this study was to assess the stability of Natural Head Position (NHP) over time using the 3dMDface System. SETTING AND SAMPLE POPULATION: This was an experimental study. Three-dimensional facial images of 40 students were captured on two different occasions, with an interval of at least two weeks. MATERIALS AND METHODS: The images were taken using a stereophotogrammetric device (3dMD). The mirror positioned NHP was obtained in a standing position and then replicated in a sitting position for capturing. The self-balanced NHP was taken in a sitting position. Rapidform 3D software was used for position angle calculations. The angle changes between the positions were calculated for rotations around the x-, y- and z-axes. RESULTS: The differences between NHP in the self-balanced and mirror positions recorded on the first and second occasions were 2.43 and 1.75 degrees, respectively, around the x-axis. The average changes in NHP around the x-axis between the self-balanced and mirror balanced positions exceeded 3 degrees at the two-week interval. The differences were smaller for the rotations around the y- and z-axes. Some subjects consistently tended to hold their heads in a more extended position when self-balanced, while others did this when mirror balanced. There was no difference in the reproducibility of NHP between men and women. CONCLUSION: The reproducibility of NHP for consecutive stereophotogrammetric captures is generally acceptable. The reproducibility of NHP using the mirror position was slightly better compared with NHP in the sitting self-balanced position.

A modified Steiner's analysis that does not require radiographic exposure of the cranial base.

OBJECTIVE: To correlate traditional Steiner's skeletal and dental measurements to similar measurements that use the eyes and natural head position as references instead of the cranial base. SETTING AND SAMPLE: One hundred and fifty-two lateral cephalometric radiographs (66 female and 86 male) from the Harvard Forsyth twin sample were included in the study based on record availability. MATERIAL AND METHODS: This was an observational study in which all cephalometric radiographs were traced and analysed using Steiner's cephalometric analysis. Each cephalogram was then altered to perform a similar analysis that uses the maximum convexity of the cornea together with natural head position as references instead of the cranial base. A Pearson product-moment correlation coefficient was measured to determine the correlation between the conventional Steiner's analysis measurements and the novel measurements relying on the eyes and natural head position. RESULTS: Steiner's cephalometric measurements of the jaws to each other, the divergency and the orientation of the incisors had a strong positive correlation with their counterparts that relied on true horizontal and/or the eyes (P < 0.001). CONCLUSION: The eyes and true horizontal can be used as alternatives to the cranial base when diagnosing the relationship between the jaws and the position and orientation of the teeth. Since the eyes and natural head position are identifiable without ionizing radiation, future research should focus on the use of radiographic exposures limited to the upper and lower jaws for orthodontic diagnosis and outcome assessment.

A new method to orient a 3-dimensional facial model to natural head position: A preliminary report on accuracy and reproducibility.

OBJECTIVES: To establish and validate a novel method to orient a 3-dimensional (3D) facial model to natural head position (NHP) in a stereophotogrammetric system using a 2-dimensional frontal full-face photograph of NHP. MATERIAL AND METHODS: Specific technique procedure was reported for our method, and in vitro model experiment was performed for accuracy test. A preliminary volunteer study was then planned for reproducibility test. RESULTS: The accuracy on a 3D-printed test model was within 0.15°. Within an observational cohort of 22 dental students, the angular deviations of different maxillofacial regions (e.g., central forehead, left and right zygomatic regions, apex of nose and mental region) were no more than 2° between the 3D NHP models acquired with a shorter time-interval (1 h from baseline) or a longer time-interval (7 days from baseline), which were all considered clinically insignificant. In addition, the angular deviations were significantly larger with a 7d-interval than with a 1h-interval, indicting a decline in 3D NHP reproducibility over short time duration. CONCLUSION: The current method may represent a clinically useful protocol for recording and transferring 3D NHP in stereophotogrammetry. CLINICAL RELEVANCE: It may provide reliable and meaningful reference information for evaluating craniofacial morphology, and be of clinical use in the diagnosis, treatment and follow-ups of patients with aesthetic or deformed craniofacial problems.

Evaluation and Comparison of the Geometrical Relationship of Tooth and Lip Arcs and Their Correlation to Smile Arcs Between Males and Females in a North Indian Population.

Background With the increasing influence of social media, millennials and the generations that follow have increasingly pressing aesthetic concerns. Following this, there has been a sea change in treatment plans and procedures as well as the choice of material. Dentistry nowadays is dependent on digital data to compute and design prostheses; these technologies are often not readily available all over the world. The purpose of this research article is to measure the tooth arc (TA) and lip arc (LA) and their correlation to the smile arcs with a cohort consisting of males and females from a single center in northern India. The SA measurement, evaluation, and comparison of smile aesthetics in this young population may be used as a threshold to these smile variables so that prosthodontists can easily prevent or modify aesthetically displeasing features. This research article will be useful for cases requiring restorations and replacements of maxillary anterior teeth. Materials and methods In this research work, photographic analysis was used and photographs of hundred subjects were taken. The camera was fixed using a tripod, at an 11-inch distance from the face, so that a clear picture of the face could be taken from the tip of the nose to the chin. A digital single-lens reflex (DSLR) camera (Nikon D-60, with the Nikon DX AF-S Nikkor 18- 135mm lens, Tokyo, Japan) was used to take the facial photographs. As the posed smile is more predictable than the natural smile, subjects were asked to smile while keeping their natural head position (NHP). Parabolas were made with Math-GV software () and superimposed on the photographs to calculate the value. Results The mean LA shows greater curvature in the female population. There was no significant (p=0.92) relationship between TA curvature in the male (0.07±0.03) and female populations (0.08 ± 0.03), whereas the LA in males (0.10±0.03) and LA in females (0.12±0.04) showed a significant relationship (p=0.03) between both groups. The LA of the female population was found to be steeper than that of the male population. This study signifies that there is no significant difference (p=0.92) between the skeletal makeup of the male and female populations but the muscular activity and muscle function differ in the male and female populations. Regarding arc-wise comparisons in both male and female populations, the male population showed a statistically insignificant (p=0.27) correlation in lip and tooth arcs. But in the female population, the correlation between these arcs was statistically significant (p=0.01). Conclusion These study results provide useful guidance for evaluating anterior teeth and planning treatment for aesthetic restorative care. Clinicians should consider not only racial and gender differences when developing an aesthetic treatment plan but also the symmetry of the facial structure which should be in harmony with the dental arc. The harmony of each determinant of aesthetics, with each other, aids in promoting beauty as a whole.

Prosthetic Rehabilitation and Its Effect on Head Posture.

BACKGROUND: Edentulism is a debilitating and irreversible condition. It is often accompanied by compromises in the surrounding joint's range of motion and changes in the posture of the head. The natural head position is maintained by a balanced tension between cranio-cervical bones, myofacial structures and the dental occlusion. Loss of teeth may cause changes in the head posture that may disturb the patency of the spinal cord and lead to the loss of postural balance. Therefore, this study aimed at evaluating the head posture in the edentulous subjects before and after prosthetic rehabilitation. METHODS: A total of 16 completely edentulous subjects were selected for the study. Removable complete denture prosthesis was fabricated for all the subjects. Lateral photographs were taken at different time intervals i.e., pre-rehabilitation, 30 minutes, 2 days and 30 days post-rehabilitation. The cranio-vertical angle obtained was digitally calculated using Kinovea software and the results obtained were statistically analysed. RESULTS: The paired-sample t-test and repeated measures analysis of variance showed an increase in the cranio-vertical angulation of edentulous subjects after rehabilitation, indicating a mild extension of the head. CONCLUSION: The insertion of prosthesis leads to a mild extension of the head. Hence, rehabilitation with a removable prosthesis has a positive effect on the head posture and could therefore aid in maintaining a stable head posture.

Different Modalities to Record and Transfer Natural Head Position to Virtual Planning in Orthognathic Surgery: Case Reports of Asymmetric Patients.

AIM: To describe different modalities to record and transfer natural head position (NHP) to 3D facial imaging by using the virtual surgical planning software in three facial asymmetry patients. CASE REPORTS: Three patients with facial asymmetries (A, B, and C) were evaluated by means of dental and facial analysis, photographs, cone-beam computed tomography (CBCT) and digitized dental arches. Before starting the VSP workflow with Dolphin Imaging, NHP was recorded by three modalities and transferred to three-dimensional (3D) facial images as follows: (a) facial photographs taken with digital camera and the estimated NHP was transferred to 3D images by comparing lines and planes from both images; (b) cross-line level laser was used to place radiopaque markers on the face skin for recording the estimated NHP, which was transferred to 3D images by alignment of planes and markers in the software; and (c) photographs of the face were processed to generate facial surface mesh by using the Agisoft PhotoScan software, which maintained the same position of the estimated NHP in 3D for aligning the images of the soft tissue with the facial surface mesh by using superimposition. All the three patients underwent bi-maxillary orthognathic surgery. CONCLUSION: There are different modalities using simple and available technologies in the clinical routine, but whose reproducibility, reliability and validation could not be assessed nor compared to each other. There was no trend for better predictability, feasibility and efficiency because the postoperative outcomes were adequate regarding the patients' satisfaction and facial symmetry.

A Complete Digital Workflow for Planning, Simulation, and Evaluation in Orthognathic Surgery.

The purpose of this study was to develop a complete digital workflow for planning, simulation, and evaluation for orthognathic surgery based on 3D digital natural head position reproduction, a cloud-based collaboration platform, and 3D landmark-based evaluation. We included 24 patients who underwent bimaxillary orthognathic surgery. Surgeons and engineers could share the massive image data immediately and conveniently and collaborate closely in surgical planning and simulation using a cloud-based platform. The digital surgical splint could be optimized for a specific patient before or after the physical fabrication of 3D printing splints through close collaboration. The surgical accuracy was evaluated comprehensively via the translational (linear) and rotational (angular) discrepancies between identical 3D landmarks on the simulation and postoperative computed tomography (CT) models. The means of the absolute linear discrepancy at eight tooth landmarks were 0.61 ± 0.55, 0.86 ± 0.68, and 1.00 ± 0.79 mm in left-right, advance-setback, and impaction-elongation directions, respectively, and 1.67 mm in the root mean square direction. The linear discrepancy in the left-right direction was significantly different from the other two directions as shown by analysis of variance (ANOVA, p < 0.05). The means of the absolute angular discrepancies were 1.43 ± 1.06°, 0.50 ± 0.31°, and 0.58 ± 0.41° in the pitch, roll, and yaw orientations, respectively. The angular discrepancy in the pitch orientation was significantly different from the other two orientations (ANOVA, p < 0.05). The complete digital workflow that we developed for orthognathic patients provides efficient and streamlined procedures for orthognathic surgery and shows high surgical accuracy with efficient image data sharing and close collaboration.

Airway Analysis in Skeletal Class I and Class II Subjects with Different Growth Patterns: A 2D Cephalometric Study.

OBJECTIVE: A two-dimensional cephalometric study was carried out to assess the airway among individuals with Class I and Class II skeletal base. MATERIALS AND METHODS: Class II subjects were further categorized into horizontal and vertical growers and average growth patterns to check the possible relationship between the facial skeleton and pharyngeal airway. Lateral cephalograms of 150 subjects were obtained using standard protocol in natural head position (NHP). Nasopharyngeal and oropharyngeal linear, and angular and nasopharyngeal area measurements were obtained using standardized tracing technique. Analysis of variance (ANOVA), level of significance, and post hoc Turkey's test were performed to assess the correlation between skeletal pattern of the individual and airway dimension. Gender discrimination was assessed using independent sample t test. RESULTS: In linear measurements, significant differences were observed among upper pharynx (0.039), adenoid tissue 1 (0.036), and adenoid tissue 2 (0.01). In angular measurements, differences were observed with angle of nasopharynx (0.008). The nasopharyngeal area measurements were also associated with significant difference (0.038) with Class II vertical growers less than those with Class I average and Class II horizontal groups. CONCLUSION: Class II vertical growers had significantly reduced nasopharyngeal airways.

Are orthodontic landmarks and variables in digital cephalometric radiography taken in fixed and natural head positions reliable?

OBJECTIVE: The purpose of the study was to evaluate the reliability of the most common landmarks and variables in digital lateral cephalometric radiographies in fixed and natural head positions. MATERIALS AND METHODS: Twenty-one patients with anterior or distal displacement of the mandible treated in the Postgraduate Orthodontic Clinic of the Aristotle University of Thessaloniki had a digital lateral cephalometric radiography in fixed and in natural head position. The images where digitized. The main investigator and 6 examiners, digitized 61 landmarks and analysed 34 variables. We examined the intra-observer and inter-observer variability. RESULTS: There was a significant difference in X-axis in the distribution (hence the mean results) according to the reliability of the landmarks and in only 2 variables in digital lateral cephalograms between fixed and natural head position. CONCLUSIONS: Cephalometric landmarks and variables showed reliability in digital lateral cephalometric radiography in fixed and natural head position. In lateral cephalograms taken in fixed head position an anterior inclination of the head was noticed compared to those in natural head position.

Correlation study of increase of pharyngeal airway space after mandibular advancement, taking natural head position into consideration.

The increase in the pharyngeal airway space after mandibular advancement has not been well explained, and in this study we aimed to show whether there is a correlation in the increase of pharyngeal airway space as a consequence of the mandibular advancement or of the relative change between the mandibular position and the natural head position (NHP). Fifteen patients who had bilateral sagittal split osteotomy for mandibular advancement with or without genioplasty were studied retrospectively. The primary variables of mandibular position, NHP, and pharyngeal airway space were measured in three dimensions using preoperative and postoperative cone-beam computed tomographic datasets and were compared using the paired t test. The secondary variable of pharyngeal airway space was defined as the square root of the mean cross-sectional area (CSA1/2) of the pharyngeal airway space. Pearson's correlation coefficient was used to find out whether there was a correlation between the change in CSA1/2 and the change in mandibular position, or the relative change between the mandibular position and the NHP. Volumes and minimal cross-sectional areas were increased in the pharyngeal airway space, and lengths of airways decreased. Correlation existed only between the increase in CSA1/2 and the relative change between the mandibular position and NHP. The increase in pharyngeal airway space after mandibular advancement correlated with the relative changes between the mandibular position and the NHP.

Cephalometric Evaluation of Natural Head Position in Lingayat Population of Karnataka.

AIMS AND OBJECTIVES: To ascertain norms in cephalometry for 11- to 13-year-old Lingayat children in natural head position (NHP). MATERIALS AND METHODS: Lateral cephalograms of children were obtained by using fluid level device. We determined the variance in Frankfort horizontal plane (FHP) inclination to extracranial horizontal in NHP. The G*Power, version 20 for Windows was used for analysis. RESULTS: Reduced facial convexity was observed when the analysis was carried out in relation to true horizontal with significant difference of "t" value of 3.05 and percentage difference of 1.1 (P < 0.01) and for girls "t" value of 9.69 and percentage difference of 2.5 (P < 0.001). The highest correlation coefficient for Lingayat boys (r = 0.77) was seen between palatal plane and occlusal plane. We found least correlation coefficient among FHP and Sella-nasion plane (SNP). The coefficient was r = 0.62 and correlation coefficient of r = 0.70 was between FHP and determination coefficient r 2 = 0.38 or 38%. For girls, highest correlation coefficient of r = 0.70 was seen among FHP and palatal plane. CONCLUSION: Conventional study of craniofacial forms of Lingayat children showed the average skeletal pattern as Class II with retrognathic mandible in comparison to Caucasians. However, when seen in NHP by new method of analysis based on the true horizontal, the skeletal model was Class III in comparison to Caucasians.

The difference between registered natural head position and estimated natural head position in three dimensions.

This study determined the intra-rater and inter-rater reliability of re-orientating three-dimensional (3D) facial images into the estimated natural head position. Three-dimensional facial images of 15 pre-surgical class III orthognathic patients were obtained and automatically re-orientated into natural head position (RNHP) using a 3D stereophotogrammetry system and in-house software. Six clinicians were asked to estimate the NHP of these patients (ENHP); they re-estimated five randomly selected 3D images after a 2-week interval. The differences in yaw, roll, pitch, and chin position between RNHP and ENHP were measured. For intra-rater reliability, the intra-class correlation coefficient (ICC) values ranged from 0.55 to 0.77, representing moderate reliability for roll, yaw, pitch, and chin position, while for inter-rater reliability, the ICC values ranged from 0.38 to 0.58, indicating poor to moderate reliability. The median difference between ENHP and RNHP was small for roll and yaw, but larger for pitch. There was a tendency for the clinicians to estimate NHP with the chin tipped more posteriorly (6.3±5.2mm) compared to RNHP, reducing the severity of the skeletal deformity in the anterior-posterior direction.

A New Horizontal Plane of the Head.

AIM: This study aimed to attempt to introduce a new extracranial horizontal plane of the head (K plane that extends from SN to SAE bilaterally) that could act as a substitute to the Frankfurt horizontal intracranial reference plane; both clinically and radiographically. MATERIAL AND METHODS: The new K plane depended on three points of the head. The first was the soft tissue nasion (NS) on the interpupillary line when the subject looked forward at a distant point at eye level. The other two points were the superior attachments of the ears (SAE). RESULTS: The student "t" test comparing mean values of K/V and FH/V was not significant; -0.21. The coefficient of correlation between different variables was highly positively significant (r = 0.98 with probability = 0.001). CONCLUSION: Within the limitations of this prospective study, the new K plane was found to be both reliable and reproducible. It can be used as a reliable reference plane instead of Frankfort horizontal plane both clinically and radiographically; as it is an accurate tool for head orientation in the natural head position.

Accuracy of 3D reproduction of natural head position using three different manual reorientation methods compared to 3D software.

PURPOSE: The aim of this study was to analyze the positional differences of three-dimensional (3D) natural head positions (NHPs) reproduced by three different manual reorientation methods without special software by the Pose from Orthography and Scaling with ITerations (POSIT) method. METHODS: Five ceramic markers were attached to each of 12 patients' faces, and frontal and lateral photographs in the NHP and 3D computed tomography (CT) were taken. The 3D surface model was reoriented for the NHP reproduction by four different methods: the POSIT method (standard method), the location of the markers (A), the soft tissue landmarks (B) on the photographs, and manual correction without photographs (C). On each 3D surface model, the location of the skull was evaluated three-dimensionally. RESULTS: Differences between reproduced NHPs in each of the four different methods were statistically significant (p < 0.0001). Compared to the POSIT method, the accuracy of the other reproducing methods was lower. The A and B methods showed a similar accuracy to each other, while the C method presented the most inaccurate NHP. CONCLUSION: If 3D NHP reproduction using special software is impossible, reproducing NHP with photographs may be used as an alternative method, but its application should be clinically limited.

Relationships of vertical facial pattern, natural head position and craniocervical posture in young Chinese children.

OBJECTIVE: To investigate relationships of vertical facial patterns, natural head position (NHP), and craniocervical posture in young Chinese children with skeletal Class I relationship. METHODS: Ninety-four patients with skeletal Class I relationship were classified into low, average, and high angle groups according to their mandibular plane angle (NSL/ML). Cephalometric radiographs in NHP were taken. Variables representing vertical and sagittal craniofacial morphology, head posture, and craniocervical posture were measured and compared. RESULTS: Inclinations of the mandible to the true vertical and cervical column were smallest in the high angle group and largest in the low angle group. Other variables representing head posture and craniocervical posture were largest in the high angle group, smallest in the low angle group. Inclinations of ramus to cervical column were largest in the high angle group and smallest in the low angle group. DISCUSSION: Subjects with large NSL/ML angles showed extended head and craniocervical posture, while subjects with small NSL/ML angles exhibited flexed head and craniocervical posture.