Natural head position and natural head orientation: basic considerations in cephalometric analysis and research

Sagittal cranial projections dataset extracted from CBCT volumes corrected to natural head position in a mixed ethnicity population

This dataset features 200 sagittal projection images derived from Cone Beam Computed Tomography (CBCT) scans, corrected according to the Natural Head Position (NHP) guidelines proposed by Fredrik Lundström and Anders Lundström. The images originate from orthodontic patients in Cali, Valle del Cauca, Colombia, encompassing both initial phases and ongoing treatments. The dataset is divided into two groups: 100 images from female subjects (CoF) and 100 from male subjects (CoM), facilitating gender-specific studies. The dataset is accompanied by an Excel file ``Data info.xlsx'' that details the rotation angles in the axial (Yaw), coronal (Roll), and sagittal (Pitch) planes, along with the pixel size and image dimensions. This detailed documentation supports the replication of studies and aids in the interpretation of cephalometric analyses. Corrections made to align the images with NHP standards involve adjustments in the three main anatomical planes using points from the frontozygomatic suture (Fz) in the axial and coronal planes, and sella (S) and nasion (N) for the sagittal plane.

Scan body system to translate natural head position and virtual mounting into a 3-dimensional virtual patient: A dental technique

Various techniques have been developed for a 3-dimensional (3D) virtual patient. However, those techniques do not enable the registration of the alignment of the facial and intraoral digital scans, the registration for the mounting on the virtual articulator, and the integration of the natural head position (NHP) together. In the present manuscript, a scan body system is described that assists with the translation of the horizon orientation within the NHP of the patient into a computer-aided design software program. Additionally, the scan body system facilitates the facial and intraoral alignment, as well as the mounting of the maxillary virtual cast on the virtual articulator. This scan body system facilitates the integration of the 3D virtual patient and reduces chair and laboratory time.

Using an additively manufactured natural head position reference device to transfer the horizon orientation plane and integrate it with a 3-dimensional virtual patient: A dental technique

A virtual patient is obtained by aligning a patient's digital information, including facial and intraoral digital scans with or without hard tissue information from a cone beam computed tomography scan. However, while computer-aided design programs facilitate virtual patient integration, they do not provide a way to relate the horizon orientation with the patient's horizontal and vertical facial references. The present technique describes a way of relating the horizon orientation plane to the natural head position of the patient. An additively manufactured natural head position reference device was used to transfer the horizon orientation plane to the 3-dimensional virtual patient.

Definition of New Three-Dimensional Cephalometric Analysis of Maxillomandibular Sagittal Relationship for Orthodontics and Orthognathic Surgery: Normative Data Based on 700 CBCT Scans

The objective of the study was to define the norm of new 3-dimensional cephalometric analysis of maxillomandibular sagittal relationship with the patient in Natural Head Position. A cross-sectional study was performed using 700 consecutives cone beam computed tomography datasets of pre-orthodontic patients received for three-dimensional craniofacial analysis. To stablish the clinical norm of the new sagittal reference (linear distance A-B), the correlation with the gold standard (ANB angle) was estimated with the Pearson's correlation coefficient. Subsequently, the prognostic values of the linear distance A-B was calculated to define the clinical norm. The sample was composed by 463 women (66.1%) and 237 men (33.9%). The mean age was 30 ± 14,5 years old (range 6-71 y old). According to the skeletal class classification (ANB), 46.1% (323) were class I, 42% (294) class II, and 11.9% (83) class III. The regression model found that each additional grade of the ANB angle imply a mean increase of 1.24 mm of the distance A-B ( P <0.001). The normative value of the linear distance A-B was obtained through the prognostic values of the distance for the limits of the ANB norm 0 to 4. These values were on the range of 0.52 to 5.48 mm. Therefore, the clinical norm for cephalometric maxillomandibular sagittal relationship using linear distance from point A-B is: 3±2.48 mm. With this new approach, we can define the skeletal sagittal relationship of the patient in natural head position overcoming the limitations of using intracranial or occlusal plane references improving the diagnosis and orthognathic surgical planning process.

Analysis of select esthetic nasal parameters in virtually planned orthognathic patients

PURPOSE

Bony changes after orthognathic surgery are always followed by changes of the overlying soft tissues. Therefore, morphologic changes of the nose may be expected after procedures involving the maxilla. The purpose of this study was to evaluate the changes in the nasal region due to orthognathic surgery using computed tomography (CT) images of virtually planned patients.

METHODS

35 patients who underwent Le Fort I osteotomy, with or without bilateral sagittal split osteotomy, were included. 3D measurements on preoperative and postoperative images were performed and analyzed.

RESULTS

The results revealed that aesthetically acceptable results can be achieved by orthognathic surgery alone.

CONCLUSIONS

According to the results of this study, it can be concluded that it is best to reserve decisions on rhinoplasty to the post-orthognathic period.

The reliability of analytical reference lines for determining esthetically pleasing lip position: An assessment of consistency, sensitivity, and specificity

INTRODUCTION

This study aimed to identify a simple yet reliable soft-tissue parameter for the clinical determination of esthetic lip position by investigating the most consistent reference lines and assessing their sensitivity and specificity.

METHODS

A total of 5745 records from Chinese patients aged >18 years were screened. In part I of the study, lateral view photographs of 96 subjects (33 males, 63 females) with esthetic facial profiles were selected. The profile esthetics of each photograph was first scored by 52 dental students, followed by 97 laypeople on a 5-point attractiveness scale. For the top 25% of photographs with the highest score for each sex (8 males, 16 females), the consistency of 6 commonly used reference lines were assessed to determine the esthetic lip position. In part II of the study, lip positions relative to Steiner's (S) and Ricketts' (E) lines in the profile photographs of 86 patients (43 males, 43 females) deemed to have an esthetically unpleasing profile were compared with those in 86 Chinese movie star idols (43 males, 43 females).

RESULTS

In part I of the study, the S, E, and Burstone's (B) lines exhibited the lowest standard deviations for the upper and lower lips. B line was excluded from further analysis because of its higher mean absolute values, and S and E lines were used for the subjective assessment in part II of the study. In part II, the S line showed a sensitivity of 86.0% and 86.0% and a specificity of 81.4% and 83.7% for males and females, respectively. In contrast, the E line presented a sensitivity of 88.4% and 93.0% and a specificity of 79.1% and 74.4% for males and females, respectively.

CONCLUSIONS

S, E, and B lines were the most consistent soft-tissue parameters among both sexes; however, because of the smaller absolute values, the S line would be more convenient among the 3 for a quick clinical assessment of lip position. Moreover, the performance of both S and E lines was similar among both sexes, which supports using these lines in assessing the esthetic lip position.

Validation of Andrews Analysis in the Virtual Environment

BACKGROUND

Andrews analysis is a tool to establish the aesthetic anteroposterior position of the maxilla. Andrews analysis has not been evaluated through computer-aided surgical simulation (CASS).

PURPOSE

The purpose of this study was to evaluate the accuracy of Andrews profile analysis when performed in the virtual environment.

STUDY DESIGN, SETTING, SAMPLE

A retrospective cohort study was implemented with consecutive patients undergoing orthognathic surgery between February 2020 and February 2022 at the University of Alabama, Birmingham. Traditional Andrews analysis with lateral smiling photographs were taken during the presurgical appointment in adjusted natural head position (aNHP). The standard cone-beam CT obtained for CASS and archived on the KLS Martin (Jacksonville, Florida) database was accessed for retrospective measurement. Lateral facial photographs in aNHP were imported into the virtual environment and the three dimensional (3D) composite model was then oriented into aNHP. The software engineer, blinded to the traditional measurements, then performed the Andrews analysis in the virtual environment by placing a vertical glabella line on the 3D composite model in aNHP. The linear horizontal distance of the maxillary central incisor perpendicular to the vertical glabella line was recorded.

PREDICTOR/EXPOSURE/INDEPENDENT VARIABLE

Method of Andrews analysis measurement (traditional photographic evaluation vs CASS) MAIN OUTCOME VARIABLE: Linear Andrews analysis measurement.

COVARIATES

Additional covariates evaluated were sex, age at surgery, and dentofacial deformity diagnosis.

ANALYSES

Descriptive statistics were computed to compare photographic analysis versus CASS analysis. A P value of <.05 was considered statistically significant.

RESULTS

The average age was 25.7 years old and 54% of patients were female. For the photographic analysis, the mean incisor-goal anterior limit line distance was -0.44 ± 7.12 mm (95% CI, -1.13 to 0.37 mm; P = .46). For the virtual analysis, the mean incisor-goal anterior limit line distance was 0.13 ± 7.21 (95% CI, -0.004 to 0.30; P = .89). The Pearson correlation coefficients between the photograph and 3D analysis were very strong (0.93). The root mean square deviation between the photographic and 3D analysis cohorts was 2.7 mm.

CONCLUSION AND RELEVANCE

Given the high correlation coefficients between all demographics, CASS can be utilized for Andrews analysis to determine ideal anteroposterior maxillary position to streamline data collection and the planning process.

Mandibular asymmetry: Is there a difference in the bone and soft tissue thickness between both sides?

OBJECTIVE

The asymmetric mandible presents the clinician with unique anatomic challenges in orthognathic surgery correction. This study aims to investigate these characteristics of the asymmetric mandible: mandible bone thickness, soft tissue thickness, and the proximity of the bone cortex to the inferior alveolar nerve (IAN) canal.

STUDY DESIGN

Three-dimensional virtual models were created of 35 participants of Asian descent with mandibular asymmetry. Mandibular bone thicknesses and soft tissue thicknesses were measured at certain landmarks. Statistical analysis of the thicknesses of both sides of the mandible was performed. Comparison of thicknesses between patients with minor and major asymmetry were also performed.

RESULTS

The bone was significantly thinner at the longer side at all 4 mandible landmarks (P < .001). The bone lateral to the IAN was significantly thinner at the longer side, as well (P < .001). The soft tissue thickness did not differ significantly across sides, except at 1 landmark. These findings were even more exaggerated in the major asymmetry group.

CONCLUSIONS

The longer side of the asymmetric mandible bone was thinner, and the bone lateral to the IAN was also thinner as a result. This asymmetric thinness was exaggerated in patients with severe asymmetry, which may predispose the longer side to IAN injury and unfavorable fractures. The differences in bone thickness in the asymmetric mandible may also result in residual postoperative asymmetry.

Automated analysis of three-dimensional CBCT images taken in natural head position that combines facial profile processing and multiple deep-learning models

BACKGROUND AND OBJECTIVES

Analyzing three-dimensional cone beam computed tomography (CBCT) images has become an indispensable procedure for diagnosis and treatment planning of orthodontic patients. Artificial intelligence, especially deep-learning techniques for analyzing image data, shows great potential for medical and dental image analysis and diagnosis. To explore the feasibility of automating measurement of 13 geometric parameters from three-dimensional cone beam computed tomography images taken in natural head position (NHP), this study proposed a smart system that combined a facial profile analysis algorithm with deep-learning models.

MATERIALS AND METHODS

Using multiple views extracted from the cone beam computed tomography data of 170 cases as a dataset, our proposed method automatically calculated 13 dental parameters by partitioning, detecting regions of interest, and extracting the facial profile. Subsequently, Mask-RCNN, a trained decentralized convolutional neural network was applied to detect 23 landmarks. All the techniques were integrated into a software application with a graphical user interface designed for user convenience. To demonstrate the system's ability to replace human experts, 30 CBCT data were selected for validation. Two orthodontists and one advanced general dentist located required landmarks by using a commercial dental program. The differences between manual and developed methods were calculated and reported as the errors.

RESULTS

The intraclass correlation coefficients (ICCs) and 95% confidence interval (95% CI) for intra-observer reliability were 0.98 (0.97-0.99) for observer 1; 0.95 (0.93-0.97) for observer 2; 0.98 (0.97-0.99) for observer 3 after measuring 13 parameters two times at two weeks interval. The combined ICC for intra-observer reliability was 0.97. The ICCs and 95% CI for inter-observer reliability were 0.94 (0.91-0.97). The mean absolute value of deviation was around 1 mm for the length parameters, and smaller than 2° for angle parameters. Furthermore, ANOVA test demonstrated the consistency between the measurements of the proposed method and those of human experts statistically (F_dis=2.68, ɑ=0.05).

CONCLUSIONS

The proposed system demonstrated the high consistency with the manual measurements of human experts and its applicability. This method aimed to help human experts save time and efforts for analyzing three-dimensional CBCT images of orthodontic patients.

Characteristics and Dynamics of Smile in Patients With Skeletal Class II Malocclusion Versus Class I Malocclusion Using Still Digital Video Captures: A Three-Group, Cross-Sectional, Comparative Study

Background Smiling is one of the effective ways for people to express their feelings. It is an integral part of the diagnosis and planning and a key point of the treatment objectives in orthodontic care. Many factors are associated with a pleasant smile, such as correct anatomy, gingival health, and teeth proportion. Therefore, different malocclusion classes can affect the characteristics of smile esthetics. This study aimed to evaluate the effect of skeletal class II malocclusion on the characteristics and dynamics of the smile in the sagittal and frontal planes. Methodology The study sample included 60 patients comprising three groups of malocclusion classes, namely, Class I, Class II division 1, and Class II division 2. A video recording was taken for 5-10 seconds for each patient using a specific camera mounted at a fixed distance from the imaged face. Two facial expressions were captured for each patient, one representing the lips at rest and the second representing the unrestricted natural smile. The facial still images were derived from the streaming video recording, and two images were chosen for each plane (the frontal plane and the sagittal plane) for each patient. In total, 12 variables were assessed on these captured images. One-way analysis of variance (ANOVA) was used to detect significant differences between the three groups. Results There were statistically significant differences in some of the measured variables. The mean values of thickness of the upper lip, commissure height, gum width, maxillary incisor display, and interlabial gap were greater in the Class II division 1 group than in the other two groups. The proclined incisors were evident in the Class II division 1 group, while the retroclined incisors were evident in the Class II division 2 group. Conclusions The skeletal Class II malocclusion influences the characteristics of the smile, either assessed on the anterior or lateral imaging angles, in addition to its influence on the resting position of the lips. Orthodontists should always analyze patients' facial expressions, including those related to the upper and lower lips at rest and when patients smile naturally. Depending on the results of this analysis, treatment planning could be built to improve the characteristics of the natural smile in patients with Class I and Class II malocclusions.

Effect of Orthognathic Surgery on Movement of the Cheilion

The cheilion (Ch), corner of the mouth, is the soft-tissue landmark where the upper and lower lips intersect. Orthognathic surgery can modify Ch position, which can affect facial esthetics. The aims were to evaluate Ch movements resulting from Le Fort I maxillary advancement with maxillary impaction or downgrafting, and with mandibular advancement or setback, and to investigate relationships between surgical movements and Ch movements. The 45 patients had undergone bilateral sagittal split ramus osteotomy with Le Fort I advancement surgery. They were divided into 4 groups according to surgical movement direction. Preoperative and postoperative photographs were calibrated. Standardized methods were used to identify and measure preoperative and postoperative Ch positions. Significant correlations were detected between extent of maxillary downgrafting and inferior movement of the Ch in group 1 (r=0.988, P=0.001) and group 3 (r=0.915, P=0.001). Also, significant correlations were detected between extent of mandibular advancement and anterior movement of the Ch in group 3 (r=0.561, P=0.046) and group 4 (r=0.661, P=0.005). The findings indicate that, in patients who undergo bilateral sagittal split ramus osteotomy/Le Fort I surgeries, mandibular advancement moves Ch anteriorly and maxillary downgrafting moves Ch inferiorly.

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.

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.

Variation between natural head orientation and Frankfort horizontal planes in orthognathic surgery patients: 187 consecutive cases

The purpose of this study was to assess the relationship between the Frankfort horizontal (FH) and natural head orientation (NHO), their correlation between patients' malocclusion, and the impact of counterclockwise rotation (CCW) on the FH-NHO angle variation after orthognathic surgery. An evaluation of 187 consecutive patients was performed at the Maxillofacial Institute (Teknon Medical Center, Barcelona). FH-NHO° was measured pre- and postoperatively at 1 and 12 months, after three-dimensional (3D) superimposition using a software (Dolphin®). Patients were classified as follows: 3.2%, 48.7% and 48.1%, class I, II and III, respectively. Baseline FH-NHO° was significantly positive for patients with dentofacial deformities (2.73°±4.19 (2.12-3.33°, P<0.001). The impact of orthognathic surgery in FH-NHO° was greater in class II when compared with class III patients, with a variation of 2.04°±4.79 (P<0.001) and -1.20°±3.03 (P<0.001), respectively. FH-NHO° increased when CCW rotational movements were performed (P=0.006). The results of this study suggest that pre- and postoperative NHO differs from FH in orthognathic patients. The angle between FH and NHO is significantly larger in class III than in class II patients at baseline, which converges after orthognathic surgery when CCW rotation is performed. Therefore, NHO should be used as the real horizontal plane when planning for orthognathic surgery.

Three-dimensional virtual surgical planning (3D-VSP) in orthognathic surgery: Advantages, disadvantages and pitfalls

In this article, the advantages, disadvantages and pitfalls of three-dimensional virtual surgical planning (3D-VSP) compared to traditional two-dimensional (2D) planning methods in orthognathic surgery are discussed, alongside a standardised protocol that can be utilised. A skeletal Class II, skeletal Class III and an anterior open bite clinical case along with their 3D-VSP management are presented, highlighting modifications that can be made to computer-aided design/computer-aided manufacture (CAD/CAM) cutting guide and plate designs.

Use of the orbito-occipital line as an alternative to the Frankfort line

Frankfort horizontal line, the line passing through the orbitale and porion, is one of the most widely used intracranial landmarks in cephalometric analysis. This study investigated the use of the orbito-occipital line extending from the orbitale to the external occipital protuberance as a novel horizontal line of the skull for substituting the Frankfort horizontal line. We evaluated the reproducibility of the new landmark and measured the angle between the orbito-occipital line and the Frankfort line. This study was conducted on 170 facial computed tomography (CT) scans of living adults from the Department of Plastic Surgery. After three-dimensionally reconstructed images were obtained from facial CT, the porion, orbitale, and external occipital protuberance were indicated by two observers twice. The angles between the orbito-meatal line (inferior orbital rim to porion; the Frankfort line) and the orbito-occipital line (inferior orbital rim to external occipital protuberance) were measured. There was no significant intraobserver or interobserver bias. The overall angle between the Frankfort line and orbito-occipital line was −0.5°±2.2° (mean±standard deviation). There was no statistically significant difference among side and sex. This study demonstrated good reproducibility of a new landmark—the external occipital protuberance—tested to replace the porion. The orbito-occipital line is a reliable, reproducible, and easily identifiable line, and has potential as a novel standard horizontal line to replace or at least supplement the Frankfort line in anthropological studies and certain clinical applications.

Selected Orthodontic Principles for Management of Cranio-Maxillofacial Deformities

An understanding of fundamental orthodontic principles involving diagnosis, treatment planning, and clinical strategies is essential for achieving successful outcomes in the treatment of craniofacial patients, particularly cleft lip/palate. This article focuses on: customizing a mandibular dental arch form using the WALA ridge; accurately diagnosing the maxillary skeletal transverse dimension (cusp to cusp/fossa to fossa); coordinating the upper dental arch with the lower; using a smiling profile and glabella vertical to assess anteroposterior jaw position; and leveling the mandibular curve of Spee while considering the lower one-third of the face. These concepts influence treatment outcomes to the extent they are used.

The relationship between 3D dentofacial photogrammetry measurements and traditional cephalometric measurements

OBJECTIVES

To determine the relationship between traditional cephalometric measurements and corresponding nonradiographic three-dimensional (3D) photogrammetry measurements.

MATERIALS AND METHODS

This was a cross-sectional study of 20 orthodontic patients (10 male and 10 female) who received lateral cephalometric radiographs and 3D dentofacial photogrammetric records with each subject serving as his or her own control for a total sample size of 40 images (20 per method). A 3D analysis that resembled a traditional cephalometric analysis was established using the eyes and natural head orientation as substitutes for the cranial base. Pearson correlation coefficients and multivariable linear regression plots were calculated to evaluate the relationship between the photogrammetry measurements and the cephalometric measurements.

RESULTS

The ANB angle, mandibular plane angle, lower anterior face height, upper incisor angle to SN, upper incisor angle to NA, and all measurements of lower incisor position and inclination had strong positive Pearson correlation coefficients with the corresponding 3D photogrammetry measurements ( P < .004). Statistically significant regression plots demonstrated that cephalometric relationships between the jaws and incisor orientation can be predicted from corresponding 3D photogrammetry measurements.

CONCLUSIONS

3D photogrammetry measurements relating the jaws to each other and incisor orientation has a strong positive correlation with corresponding traditional cephalometric measurements and can serve as cephalometric predictors. Capturing the eyes using 3D photogrammetry can obviate the need to expose the cranial base and allow limiting the radiographic field to the area of interest.

Facial Versus Skeletal Landmarks for Anterior-Posterior Diagnosis in Orthognathic Surgery and Orthodontics: Are They the Same?

PURPOSE

The purpose of this investigation was to evaluate diagnostic agreement in anterior-posterior (AP) categorization of the maxilla and mandible between a skeletal-landmark analysis and a facial-landmark analysis for treatment planning of orthognathic surgery and orthodontics.

MATERIALS AND METHODS

This retrospective, consecutive case series of adult patients who presented to the Mayo Clinic orthodontic department compared maxillary and mandibular AP diagnoses. Steiner's analysis of the sella-nasion-A point angle and sella-nasion-B point angle was used for a skeletal-landmark diagnosis. Element II of Andrews' 6 elements of orofacial harmony was used for a facial-landmark diagnosis. Both diagnoses were categorized as either deficient, optimal, or excessive for each jaw. Categorization of the skeletal landmark was determined by normative data, whereas the facial landmark provides a customized categorization unique to each individual.

RESULTS

Weighted κ statistics were completed to test agreement between the categories determined by the skeletal and facial landmarks. The maxilla showed poor agreement, and the mandible showed slight agreement.

CONCLUSIONS

No agreement was found for AP categorization of the maxilla and mandible between skeletal-landmark and facial-landmark analyses. Most mandibles were diagnosed as retrognathic by the facial landmark, whereas most were diagnosed as optimal by the skeletal landmark. When the 2 landmarks disagreed, the facial landmark defined the optimal position farther anterior. The landmark chosen for diagnosis will impact the optimal jaw position and can affect orthognathic and orthodontic outcomes.

Are pediatricians and otolaryngologists well prepared to identify early signs of vertical facial growth?

BACKGROUND

The prevalence of vertical facial growth is very high in the developed world. Most authors agree that mouth breathing is its main cause. Even though care is mainly conducted by odontologists, the professionals who first see these patients are pediatricians and otolaryngologists. The objective of this study is to analyze the ability of pediatricians and otolaryngologists to identify early signs of vertical facial growth among children.

METHODS

60 participant aged 4.1-13.7 years were analyzed subjectively by 9 otolaryngologists, 9 pediatricians and two specialists in dentofacial orthopedics. They were also assessed objectively with cephalometric analysis.

RESULTS

Otolaryngologists showed 34.78% sensitivity, 92.86% specificity and 48.33% efficiency. Pediatricians showed 13.04% sensitivity, 100% specificity and 33.33% efficiency. Using a linear regression model compared against the objective measurements we found a weak positive correlation both for otolaryngologists and pediatricians.

CONCLUSION

The sensitivity was very low for both groups. We believe it is of paramount importance to increase the awareness and the ability of otolaryngologists and pediatricians to recognize signs of disrupt facial growth.

Effects of Different Head Positioning Methods on Facial Soft Tissue Analysis Using Stereophotogrammetry

PURPOSE

The purpose of this study was to compare the sagittal tilt of the head in different head positioning techniques using an inclinometer and facial stereophotogrammetric measurements.

MATERIALS AND METHODS

The study was carried out in 45 participants (26 female, 19 male). Participants' head positioning was obtained with dynamic walking, Frankfort horizontal plane (FHP'), self-balance plus mirror, and subjective photographic positioning methods. All pitch values were recorded by an inclinometer and stereophotogrammetric images were obtained. Facial analysis included distances of the glabella (G'), pronasale (Pn), soft tissue A point (A'), upper lip (Ls), lower lip (Li), soft tissue B point (B)', and soft tissue pogonion (Pog') to the true vertical line (TVL) and face height and lip length measurements.

RESULTS

Participants' head positions were observed to be more forward in the FHP' head positioning technique compared with other methods, whereas a more backward head position was recorded with subjective head positioning, and the difference was significant (P < .001). There were no relevant differences in pitch values between the self-balance plus mirror and dynamic walking methods. G'-TVL (P < .000), Pn-TVL (P < .029), A'-TVL (P < .039), Ls-TVL (P < .001), Li-TVL (P < .037), B'-TVL (P < .003), and Pog'-TVL (P < .000) in the profile view and face height, lower face height, and lower lip length values in the frontal view (P < .001) differed significantly by head positioning method.

CONCLUSIONS

The dynamic walking and self-balance plus mirror head positioning methods offered similar and advisable natural head position results, whereas FHP' head positioning was questionable for an accurate determination of natural head position. Facial soft tissue measurements, such as face height, lower face height, lower lip length, and projection of structures such as the G', Pn, lips, and chin, varied based on head positioning method.

Skeletal-versus soft-tissue-based cephalometric analyses: is the correlation reproducible?

OBJECTIVES

Dentofacial deformities can be analyzed by skeletal and soft tissue cephalometric analysis (CA). The aim was to evaluate the difference in reproducibility between both methods.

MATERIALS AND METHODS

Lateral cephalograms of 112 patients (65 females and 47 males, 27.7 ± 9.0 years) were oriented in natural head position (NHP) and digitized. The distances of skeletal (SNA, SNB, SnPog) and soft tissue (A', B' and Pog') landmarks relative to the respective norm values and the angles between the Nasion Sella line (NSL) and Frankfurt horizontal (FH) to NHP were measured for statistical evaluation and compared with respective data of an adult control group (CG) with class I occlusion and harmonic facial balance.

RESULTS

The mean differences (mm ± SD) of skeletal and soft tissue landmarks were -2.4 ± 4.4 (A), -7.0 ± 9.3 (B), -6.3 ± 11.2 (Pog), -0.9 ± 1.8 (A'), -4.7 ± 6.2 (B'), and -6.1 ± 7.8 (Pog'), respectively. Pearsons's correlation (r) between the measurements of SNA/A', SNB/B' and SNPog/Pog' were r = .158 (p = .092), r = .662 (p < .001) and r = .655 (p < .001), respectively. The mean (±SD) angles between NSL and FH to NHP were -9.8° ± 5 and 0.0° ± 3.9, respectively.

CONCLUSION

Variability of cranial-based measurements could give a possible explanation for the high variation and the low reproducibility of skeletal cephalometric analysis with soft tissue measurements. Soft-tissue cephalometric analysis would probably improve facial analysis and treatment planning.

Reliability and diagnostic accuracy of cervicothoracic differentiation testing and regional unloading for identifying improvement after thoracic manipulation in individuals with neck pain

BACKGROUND & PURPOSE

The cervicothoracic differentiation test (CTDT), cervical and thoracic unloading are used clinically to guide treatment. This study sought to determine the reliability and diagnostic accuracy of these tests.

METHODS

A prospective diagnostic accuracy study was performed at two outpatient clinics and one university research center. A convenience sample of 48 individuals with neck pain was recruited. Cervical and thoracic unloading tests and CTDT were performed with symptom relief considered a positive test. Pain was assessed using a visual analog pain scale (VAS) at rest and during provocative movements. The reference standard was pain relief following thoracic manipulation. Change in pain was used to identify improvement at the MCID (15 mm) and 50% improvement thresholds.

RESULTS

All three tests demonstrated high levels of inter-rater reliability, K = 0.90[0.77-1.00]. Of 48 individuals who completed the study, 39 (81.3%) were improved ≥ MCID; compared to 34 (70.8%) at the 50% threshold. As a single test, the CTDT yielded the strongest diagnostic utility (at MCID threshold) based on ROC curve: AUC 0.791 s.e. 0.078; with high specificity (0.89[51.75-99.72]); LR+ 6.23 [0.97-40]; LR- 0.35 [0.20-0.58]; and PPV 96.43. Unloading tests demonstrated high sensitivity, but poor specificity and likelihood ratios. Composite tests improved specificity, but with lower accuracy and minimal changes in ROC area compared to the CTDT in isolation.

CONCLUSIONS

The CTDT is a specific test with significant diagnostic utility to identify individuals who will experience immediate pain relief following thoracic manipulation. The CTDT should be considered during the clinical decision making process when treating individuals with neck pain.

Facial analysis using a new clinical device: The Kattan Facio-meter

BACKGROUND

The aim of the study was to attempt to set average faciometric standards for Egyptians using the Kattan Facio-meter.

MATERIAL AND METHODS

The sample consisted of 180 faculty students with age range 17-25 years. It was divided into three groups; Angle Class I, II and III. Class II was further subdivided into divisions 1 and 2. Linear and angular facial measurements in relation to K plane were taken using the Kattan facio-meter. The measurements were correlated to Angle's classification and between genders.

RESULTS

On comparing the different classes, Class II division 1 showed the statistically highest mean value for Orbitale-soft tissue A; p=0.042, Class II divisions 1 and 2 for Orbitale- Labrale superius; p=0.002 and soft tissue ANB; p<0.001. Females showed significantly higher mean value than males for the upper incisor/K plane; p=0.031. Males showed significantly higher mean value for the inter-incisal angle than females; p=0.001.

CONCLUSIONS

Within the limitations of the current study, it was found that both linear and angular soft tissue measurements conformed to the antroposterior skeletal relation of the jaws and that Class II division 1 was due to protruded maxilla. Males had more prominent lips and deeper mentolabial sulcus. Egyptians had less prominent noses than Caucasians. The Kattan Facio-meter was a valuable tool for clinical analysis without the hazards of irradiation. Key words:Kattan Facio-meter, Angle Class I, II and III.

Using the zygomatic arch as a reference line for clinical applications and anthropological studies

PURPOSE

The Frankfurt line is the most frequently and widely used reference line in cephalometric analysis, but has shortcomings including the difficulty of landmark identification. This study investigated using the superior border of the zygomatic arch as a new external bony landmark, including measuring the angle between the new reference line and the Frankfurt line.

METHODS

Facial computed tomography scans were obtained from 170 patients (100 males and 70 females) hospitalized at Konkuk University Chungju Hospital. After three-dimensional reconstruction, the locations of the porion and the inferior orbital rim and the superior border of the zygomatic arch were identified twice by two observers using software. A horizontal line parallel to the superior border of the zygomatic arch was established. The angle between the Frankfurt line and new reference line was then measured on each side.

RESULTS

There was no significant intraobserver or interobserver bias. The angle between the Frankfurt line and the superior border of the zygomatic arch was 4.5° ± 2.5° (mean ± SD), and it was somewhat larger in females than males, but the difference was not statistically significant.

CONCLUSIONS

This study demonstrated the good reproducibility of the location of the superior border of the zygomatic arch and found that the angle between the new reference line and the Frankfurt line is relatively constant. The superior border of the zygomatic arch therefore has potential as an alternative reference line to the Frankfurt line in specific clinical applications and anthropological studies, since it is a more accessible bony landmark on the external skull.

Injectable profiloplasty: Forehead, nose, lips, and chin filler treatment

INTRODUCTION

We propose a medical filler treatment algorithm of the profile which includes forehead, nose, and chin and to evaluate profilometric results and complications.

MATERIALS AND METHODS

83 case reviews of associated liquid forehead, nose, and chin plasty performed consecutively from 2014 to 2016. We monitored the horizontal and vertical sagittal stability into two age group: <40 y.o. and >40 y.o. using profilometric Arnett analysis measurements on the F, Gb, Na, Nd, Nt, Sn, ULA, LLA, B, Pg, and Gn soft-tissue points.

RESULTS

The results at both 3 and 6 months were consistent with the normal ranges indicated by Arnett, with a 0.8 mm maximum of defect/excess. Forehead treatment was performed in 51 (61.4%) patient. Patients >40 y.o. always needed a global correction of the forehead profile. We performed nasal treatment in 83 (100%) patient, acute nasolabial angles was the more frequent nasal defect. The lips were injected in 59 patients (71.1) more frequently >40 y.o. In 83 (100%) patients we perform a chin augmentation. The average advancement of the chin was 3 mm.

CONCLUSIONS

The correction of the projection of the forehead, of the profile and shape of the nose, of the lips and chin as well as an overall improvement in face aesthetics and harmony gives a good solution in patients avoiding the need for a surgical intervention, scars and cost of general anesthesia, thus providing the optimum in patient satisfaction.

Both the Observer's Expertise and the Subject's Facial Symmetry Can Affect Anatomical Position of the Head

PURPOSE

It is easier to judge facial deformity when the patient's head is in anatomic position. The purposes of this study were to determine 1) whether a group of expert observers would agree more than a group of nonexperts on what is the correct anatomic position of the head, 2) whether there would be more variation in the alignment of an asymmetrical face compared with a symmetrical one, and 3) whether the alignments of experts would be more repeatable than those of nonexperts.

MATERIALS AND METHODS

Thirty-one orthodontists (experts) and 31 dental students (nonexperts) were recruited for this mixed-model study. They were shown randomly oriented 3-dimensional head photographs of an adult with a symmetrical face and an adolescent with an asymmetrical face. In viewing software, the observers oriented the images into anatomic position. They repeated the orientations 4 weeks later. Data were analyzed using a generalized linear model and Bland-Altman plots. The primary predictor variables were experience and symmetry status. The outcome variable was the anatomic position of the head. The other variables of interest included time and orientation direction.

RESULTS

There was a statistically significant difference between measurements completed by experts and nonexperts (F_1,60 = 14.83; P < .01). The interaction between expertise and symmetrical status showed a statistically significant difference between symmetrical and asymmetrical faces in the expert and nonexpert groups (F_1,60 = 9.93; P = .003). The interaction between expertise and time showed a statistically significant difference in measurement over time in the expert and nonexpert groups (F_1,60 = 4.66; P = .03).

CONCLUSIONS

The study shows that experts can set a head into anatomic position better than nonexperts. In addition, facial asymmetry has a profound effect on the ability of an observer to align a head in the correct anatomic position. Moreover, observer-guided alignment is not reproducible.

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.

Optimal antero-posterior position of the maxillary central incisors and its relationship to the forehead in adult African American females

OBJECTIVES

To determine an optimal anteroposterior (AP) position of the maxillary central incisors and their relationship to the forehead in adult African American (AA) females.

MATERIALS AND METHODS

Smile profile photographs of 150 AA females were acquired and divided into an optimal control group (N = 48) and a study group (N = 102) based on the position of the maxillary central incisors, as judged by a panel of orthodontists and orthodontic residents. The AP position of the maxillary central incisors and the forehead inclination (FI) were measured relative to Glabella vertical (GV). A two-sample t-test was used to compare the incisor AP position and the FI between the two groups. Linear regression was used to quantify the relationship between the incisor AP position and the FI.

RESULTS

In all groups, the maxillary incisors were anterior to GV. However, a significant difference was found in the incisor AP position between the groups (8.58 ± 3.96 mm for the control group and 11.2 ± 4.48 mm for the study group; P = .001). Furthermore, the control group demonstrated a positive association between the optimal AP position of the maxillary central incisors and FI ( P < .0001).

CONCLUSIONS

GV is a reliable landmark with which to access the AP maxillary incisor position in AA females. The optimal AP position of the maxillary central incisors is significantly associated with FI; the greater the FI, the more anterior the optimal maxillary incisor position. A prediction equation to determine the optimal position of the maxillary incisors relative to GV for AA females is proposed.

Ready to Use Norms for Arnett Bergman Soft-Tissue Cephalometric Analysis for South Indian Population

CONTEXT

Variability of the soft-tissue drape in humans has complicated the accuracy of evaluating soft tissue profiles in diagnosis and treatment planning.

AIMS

The objective of the present study is to establish soft-tissue cephalometric norms for South Indian population using Arnett Bergman Soft tissue analysis.

SETTINGS AND DESIGN

This study was conducted at the Department of Orthodontics and Dentofacial Orthopaedics.

SUBJECTS AND METHODS

Lateral cephalograms of 60 individuals (30 males and 30 females), age ranging between 18 and 25 years, with orthognathic facial profiles were obtained in natural head position. True vertical line was drawn through subnasale parallel to the vertical reference plane. Measurements were done according to soft-tissue cephalometric analysis.

STATISTICAL ANALYSIS USED

Student's t-test was used to compare the means between two groups.

RESULTS

The results of the study showed significant gender dimorphism, with men having thicker soft-tissue structures, larger vertical dimensions, deep-set midface structures, more upright incisors, and deeper inferior labial sulci than women. When compared with the standard norms, the South Indian population had significantly protruded dentition, thinner soft-tissue drape, shorter vertical face heights, prominent forehead and midface with retusive lower facial thirds and convex profiles as compared to Caucasians.

CONCLUSIONS

Significant gender dimorphism was evident in the local population suggesting the need for separate set of norms for males and females. Distinct ethnic differences were found between Caucasians and the Indian population that were statistically significant, highlighting the importance of defining separate set of norms for ethnic groups. The norms obtained should be used as reference when planning treatment of a specific ethnic group.

CBCT and MRT imaging in patients clinically diagnosed with temporomandibular joint arthralgia

OBJECTIVES

To compare cone beam computed tomography (CBCT) and magnetic resonance tomography (MRT) in patients with temporomandibular joint (TMJ) arthralgia in respect of the evaluation of bony structures, and to correlate joint space distances measured in CBCT with the morphology and the position of the disc visualized in MRT.

MATERIALS & METHODS

26 temporomandibular joints (TMJs) in 13 patients clinically diagnosed with TMJ arthralgia were examined by both CBCT and MRT. All images were evaluated by use of a form. The results were compared in regard of conformability of the diagnoses of osseous structures established by each imaging method. Anterior, superior and posterior joint space distances measured in CBCT-images were related to disc morphology and position visualized in MRT.

RESULTS

Conformability of CBCT and MRT in the evaluation of bony TMJ structures ranged from 69.3 to 96.6 %. Osseous alterations such as erosions, osteophytes and cysts detected by CBCT could partly not be discerned by MRT. The correlation of joint space distances with disc morphology (biconcave or not biconcave) was not statistically significant. The correlation of joint space distances and disc position was statistically significant only for the superior joint distance.

CONCLUSION

CBCT outclasses MRT in the visualization of osseous alterations, which are diacritic in the differentiation of simple arthralgia from osteoarthritis. Therefore, CBCT imaging is appropriate in patients clinically diagnosed with TMJ arthralgia.Superior joint space distance not being the highest joint space in sagittal CBCT indicates an anterior disc displacement.For the visualization of structural changes or displacement of the disc frequently associated with osseous changes, MRT is the optimal tool. Thus, the combination of the two imaging methods allows a comprehensive diagnosis in TMJ arthralgia patients.

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.

The slant of the forehead as a craniofacial feature of impulsiveness

Objective:

Impulsiveness has been the subject of much research, but little is known about the possible relationship between craniofacial anatomy and impulsiveness. The present study was designed to investigate the relationship between one aspect of craniofacial structure (the angle of inclination of the forehead) and impulsiveness.

Method:

Photographs in profile were obtained from 131 volunteers who had been fined for driving at high speed and were undergoing a court-mandated driving license point-recovery course. They completed the Barratt Impulsiveness Scale (BIS-11), the Impulsive Behavior Scale (UPPS-P), and Zuckerman’s Sensation Seeking Scale (V). The angle of the slant of the forehead was measured with a photographic support and a protractor.

Results:

High positive concordance was found between forehead inclination and 14 out of the 15 impulsiveness factors studied.

Conclusions:

The angle of inclination of the forehead was significantly associated with self-reported impulsiveness in this sample of traffic violators.

Computer Image-Guided Template for Horizontal Advancement Genioplasty

BACKGROUND

Horizontal advancement genioplasty can be extremely rewarding for microgenia. However, it is challenging for even very experienced surgeon to determine the three-dimensional position of the distant bone fragment during the operation. This study aimed to apply and evaluate computer-aided design (CAD) and computer-aided manufacturing techniques for horizontal advancement genioplasty to improve surgical accuracy.

METHODS

Seven patients with microgenia were prospectively enrolled in the study. Preoperative and postoperative computed tomography (CT), photographs, and lateral cephalograms were performed. Computer-aided design was done based on preoperative CT data, and then surgical templates (cutting guide templates and fixation templates) were designed accordingly to guide horizontal advancement genioplasty. All surgeries were performed by junior surgeons. The accuracy of the authors' method was evaluated by the relative error (the mean value of discrepancy between postoperative CT and preoperative design at 6 points selected randomly/preoperative design movement × 100%), Pg position error (postoperative Pg Advancement - preoperative CAD Pg Advancement)/preoperative CAD Pg Advancement × 100%), and Me position error (postoperative Me downward movement - preoperative CAD Me downward movement)/preoperative CAD Me downward movement × 100%). They are all calculated by Geomagic automatically.

RESULTS

All 7 patients were satisfied with their aesthetic outcomes. The average absolute relative error is 1.8%. The average absolute Pg position error is 1.9% and the average absolute Me position error value is 1.3%.

CONCLUSIONS

The authors' study showed that applying computer-assisted techniques for horizontal advancement genioplasty provided accurate surgical result. With this technique, best result for horizontal advancement genioplasty could be achieved by even inexperienced surgeons.

Enhanced Surgical Outcomes in Patients With Skeletal Class III Facial Asymmetry by 3-Dimensional Surgical Simulation

PURPOSE

With the advance of image fusion techniques, the creation of 3-dimensional (3D) virtual head and 3D surgical simulations has provided previews of surgical procedures. The aim of this study was to investigate the surgical outcomes in patients receiving orthognathic surgery (OGS) with the guidance of 3D computer-assisted surgical simulation.

PATIENTS AND METHODS

The study included 34 consecutive patients (15 men and 19 women; age, 18.1 to 33.0 yr) with skeletal Class III facial asymmetry who underwent bimaxillary OGS. One-week postoperative cone-beam computed tomographic craniofacial images (Ta) were constructed and superimposed on preoperative simulated virtual images (Ts) at the cranial base and surfaces of the frontal and periorbital regions. The 3D cephalometric landmarks were measured relative to 3 reference planes. The outcomes among different experience levels of surgeons also were compared.

RESULTS

Although the mean values between Ta and Ts were small, statistical differences were observed in the center of maxillary and mandibular incisors and the B point relative to the midline and in the maxillary first molar in vertical distances, sagittal dentoskeletal dimensions, and pitch angles. The root mean square deviations (RMSD_L) of measurement variables relative to center landmark accuracy were 1.5 and less than 2 mm at the maxilla and mandible, respectively. RMSD_L greater than 2 mm was located at the maxillary first molar in the vertical distance and in the sagittal dimension at the anterior nasal spine and B point. Variables related to centering the midline structures were highly inter-related. The roll angle deviation was associated with centering the midline landmarks. The yaw angle deviation was not associated with midline correction.

CONCLUSION

With guidance from 3D surgical simulation, surgeons could achieve similar outcomes to correct facial asymmetry regardless of their years of practice.

3D dentofacial photogrammetry reference values: a novel approach to orthodontic diagnosis

Background

Orthodontic diagnostic standards generally use the cranial base as a reference and rely on samples selected by orthodontists.

Objective

The purpose of this study was to provide male and female standards for a novel non-radiographic approach for orthodontic diagnosis that utilizes 3D dentofacial photogrammetry using the eyes and natural head orientation as references instead of the cranial base.

Methods

One hundred and eighty females and 200 males between the ages of 18 and 35 years from 2 modeling agencies were orthodontically screened for near ideal occlusion. Subjects that met the inclusion criteria were rated by a sample of 40 lay people for attractiveness on a visual analogue scale. The final sample that had 3D facial and dental imaging included 49 subjects 25 males and 24 females with near ideal occlusion and considered attractive by the public.

Results

Inter and Intra-examiner ICC were greater than 0.8 for both landmarking and indexing. Relative to a coronal plane contacting the pupils (MC), the mean sagittal position of the alar curvature (representing the nasomaxillary complex) was 14.36 ± 3.08 mm in males and 12.4 ± 3.58 mm in females. The sagittal position of soft tissue pogonion relative to the pupils was 14.84 ± 3.63 mm in males and 12.78 ± 5.68 mm in females. The angle between the alar curvature and pogonion relative to the pupils was 9° in males and 10° in females. With the exception of the occlusal plane which was steeper in females, no ratios or angular facial measurements showed a significant gender difference. Relative to MC, males had more proclined upper incisors (20° vs 16°) and more retroclined Lower incisors (27° vs 31°; P > 0.05). A Procrustes ANOVA and permutation test showed that the shapes of males and females are different enough to be considered two distinct populations.

Conclusions

1. When using the proposed method for orthodontic diagnosis, male and female patients should be compared to their respective dentofacial standards. 2. Validation of the proposed method and standards on an orthodontic population is underway to determine the scope its use.

Photographic Assessment of Cephalometric Measurements in Skeletal Class II Cases: A Comparative Study

INTRODUCTION

Cephalometry has many limitations of which radiation exposure is most important. Hence, there is a need to resort to other safer methods which could give equal if not better results.

AIM

The purpose of this study was to compare and correlate the craniofacial measurements obtained from cephalometric radiographs and analogous measurements from standardized facial profile photographs in skeletal class II cases.

MATERIALS AND METHODS

A total of 30 lateral cephalograms and profile photographs of patients exhibiting skeletal class II malocclusion, in the age group of 19-25 years of age, were examined in this study using Dolphin software (version 11.8). A standardized protocol was followed for all the lateral cephalograms and photographs. A total of 15 parameters were studied in this study out of which seven were angular and eight were linear parameters. Angular parameters included Frankfort Mandibular Plane Angle (FMA), Mandibular Plane-Occlusal Plane (MP-OP) angle, Occlusal Plane (OP) angle, gonial angle, ANB angle, facial angle and convexity whereas linear parameters included Anterior Facial Height (AFH), Ramal height, Posterior Facial Height: Anterior Facial Height (PFH/ AFH), convexity (in mm), Nasion perpendicular- Point A, Nasion perpendicular- Pogonion, Witts and Mandibular body length. All these parameters were digitised on both the cephalogram and photographs and were compared using one sample-2 tailed t-test, Pearson correlation coefficient. Bland-Altman Plot was considered to find comparison between the measurements from photographs and cephalograms in skeletal class II patients.

RESULTS

On comparing the angular cephalometric and photographic variables for the skeletal class II subjects we found the cephalometric parameters like FMA, MP-OP angle, OP, gonial angle, convexity (in degrees) to have an insignificant difference compared to the analogous photographic measurements. On comparing the linear cephalometric and photographic variables, it was found that all the cephalometric parameters like AFH, ramal height, PFH/AFH, N perp-Point A, N perp-Poghad a good relationship with the analogous photographic measurements.

CONCLUSION

The photographic method can be considered as a repeatable and reproducible method if a homogeneous protocol is followed. Thus, photographic measurements may reflect to be a rational and practical diagnostic substitute to measurements obtained from cephalograms in Class II malocclusion subjects.

Diagnosis and treatment planning of orthodontic patients with 3-dimensional dentofacial records

INTRODUCTION

Cephalometrics has been the foundation of orthodontic diagnosis for many years. However, for many orthodontic patients, a lateral cephalogram might not be necessary. The aim of this study was to compare the diagnosis and treatment planning agreement between standard records and nonradiographic 3-dimensional (3D) dentofacial photogrammetry records.

METHODS

Twenty patients had standard orthodontic records taken for their treatment as well as extraoral and intraoral 3D images. Twelve evaluators examined the standard records and then completed diagnosis and treatment planning questionnaires. They repeated the process 4 to 6 weeks later by using 3D photographic images along with the panoramic radiographs. Each evaluator also evaluated 2 random orthodontic cases twice with each method to evaluate consistency within each method. At the end of study, each evaluator was asked to complete a survey to document his or her experiences with the 3D photogrammetry method. Descriptive and kappa statistics were used to determine the agreement.

RESULTS

Most diagnosis parameters had fair agreement between the methods and within each method. Skeletal and dental relationships had excellent agreement between and within the methods as well as most treatment decisions such as the need for extractions and surgery. Most evaluators (91.7%) thought that cephalometric x-rays would be needed only some of the time in diagnosis and treatment planning. Most evaluators (83.33%) thought that cephalometric radiographs are not needed in patients with a Class I ± a quarter cusp with crowding or spacing.

CONCLUSIONS

Most diagnostic decisions had fair agreement within and between the 2 methods. The decision to extract and the need for orthognathic surgery had excellent agreement between the cephalometric and photogrammetric methods. The majority of examiners agreed that patients with Class I malocclusions ± a quarter cusp with no obvious skeletal discrepancy can be diagnosed and planned without a cephalometric radiograph.

There is variability in our perception of the standard head orientation

The purposes of this study were to determine: (1) whether an observer's perception of the correct anatomical alignment of the head changes with time, and (2) whether different observers agree on the correct anatomical alignment. To determine whether the perception of the correct anatomical alignment changes with time (intra-observer comparison), a group of 30 observers were asked to orient, into anatomical alignment, the three-dimensional (3D) head photograph of a normal man, on two separate occasions. To determine whether different observers agree on the correct anatomical alignment (inter-observer comparison), the observed orientations were compared. The results of intra-observer comparisons showed substantial variability between the first and second anatomical alignments. Bland-Altman coefficients of repeatability for pitch, yaw, and roll, were 6.9°, 4.4°, and 2.4°, respectively. The results of inter-observer comparisons showed that the agreement for roll was good (sample variance 0.4, standard deviation (SD) 0.7°), the agreement for yaw was moderate (sample variance 2.0, SD 1.4°), and the agreement for pitch was poor (sample variance 15.5, SD 3.9°). In conclusion, the perception of correct anatomical alignment changes considerably with time. Different observers disagree on the correct anatomical alignment. Agreement among multiple observers was bad for pitch, moderate for yaw, and good for roll.

Precision of manual landmark identification between as-received and oriented volume-rendered cone-beam computed tomography images

INTRODUCTION

The objective of this study was to evaluate the effect of the orientation of cone-beam computed tomography (CBCT) images on the precision and reliability of 3-dimensional cephalometric landmark identification.

METHODS

Ten CBCT scans were used for manual landmark identification. Volume-rendered images were oriented by aligning the Frankfort horizontal and transorbital planes horizontally, and the midsagittal plane vertically. A total of 20 CBCT images (10 as-received and 10 oriented) were anonymized, and 3 random sets were generated for manual landmark plotting by 3 expert orthodontists. Twenty-five landmarks were identified for plotting on each anonymized image independently. Hence, a total of 60 images were marked by the orthodontists. After landmark plotting, the randomized samples were decoded and regrouped into as-received and oriented data sets for analysis and comparison. Means and standard deviations of the x-, y-, and z-axis coordinates were calculated for each landmark to measure the central tendency. Intraclass correlation coefficients were calculated to analyze the interobserver reliability of landmark plotting in the 3 axes in both situations. Paired t tests were applied on the mean Euclidean distance computed separately for each landmark to evaluate the effect of 3-dimensional image orientation.

RESULTS

Interobserver reliability (intraclass correlation coefficient, >0.9) was excellent for all 25 landmarks for the x-, y-, and z-axes on both before and after orientation of the images. Paired t test results showed insignificant differences for the orientation of volume-rendered images for all landmarks except 3: R1 left (P = 0.0138), sella (P = 0.0490), and frontozygomatic left (P = 0.0493). Also midline structures such as Bolton and nasion were plotted more consistently or precisely than bilateral structures.

CONCLUSIONS

Orientation of the CBCT image does not enhance the precision of landmark plotting if each landmark is defined properly on multiplanar reconstruction slices and rendered images, and the clinician has sufficient training. The consistency of landmark identification is influenced by their anatomic locations on the midline, bilateral, and curved structures.

Systematic Analysis of Clinical Outcomes of Bilateral Sagittal Split Ramus Osteotomy With Preoperative Modeling and Postoperative Orthodontic in the Treatment of Mandibular Protrusion

The purpose of this study was to determine the changes in hard tissues, soft tissues, and teeth after bilateral sagittal split ramus osteotomy and orthodontic treatment for the treatment of mandibular protrusion. Cephalometric analysis was used to evaluate the aesthetic effects and occlusal relationships obtained. The subjects included 11 women and 9 men (aged 18-27 years; average, 20 years) with mandibular protrusion who underwent bilateral sagittal split ramus osteotomy. Based on a preoperative computer-aided manufacturing/design-assisted, model surgical design and an occlusal guide plate, new occlusal relationships were established for the patients. In addition, the preoperative and the end of postoperative orthodontic treatment cephalometric radiographs were systematically analyzed. In all patients, the surgical incisions underwent primary healing, with no infection or osteonecrosis. Significant differences were observed in the preoperative and the end of postoperative orthodontic treatment values of all hard tissue and teeth parameters, except for SNA°, ANB°, GoGn-SN°, SE (mm), NP-FH°, SGn-FH°, OP-FH°, 1-MP°, Li-E (mm). The most obvious significant differences were seen in SNB°, SND°, 1_-NA°, 1_-NA (mm), 1-NB (mm), 1-NB°, Po-NB (mm), NA-PA°, AB-NP°, 1-OP°, Ui-E (mm), and S-N'-B'° (P < 0.001). Postoperative follow-up lasted for 10 to 12 months. All patients eventually achieved normal downjaw relationship, tooth arch forms, and spee curves. There were no evident irregularities of teeth arrangement or abnormal occlusal relationships were observed. All patients were satisfied with their facial appearance and occlusal relationships at the end of postoperative orthodontic treatment. The authors found a precise preoperative model surgical design combined with postoperative orthodontic treatment is a simple and time-saving technique. It can be used to correct mandibular protrusion with satisfactory occlusal relationship, facial appearance, and minimal postoperative complications.

Varied Definitions of Nasolabial Angle: Searching for Consensus Among Rhinoplasty Surgeons and an Algorithm for Selecting the Ideal Method

Background:

The nasolabial angle (NLA) is an important aesthetic metric for nasal assessment and correction. Although the literature offers many definitions, none has garnered universal acceptance.

Methods:

To gauge the consensus level among practitioners, surveys were administered to a convenience sample of rhinoplasty surgeons soliciting practice characteristics, self-assessment of rhinoplasty experience and expertise, and preferred NLA definition. Choices of NLA definition included the angle between: (A) columella and line intersecting subnasale and labrale superius; (B) columella and line tangent to philtrum; (C) nostril long axis and Frankfort perpendicular; and (D) nostril long axis and vertical facial plane.

Results:

Of the 82 total respondents, mean age was 50 years (range, 30–80years), and mean professional experience was 17 years (range, 0–67 years). Nineteen described themselves as novice rhinoplasty surgeons, 27 as intermediates, and 36 as experts. Mean number of lifetime rhinoplasties performed was 966 (range, 0–10,000). Twenty respondents (24%) agreed with definition A, 27 (33%) with B, 16 (20%) with C, and 13 (16%) with D. Six chose “other,” offering their own explanations of NLA. Self-identified novices were more likely to prefer definition D than were experts (P = 0.009).

Conclusions:

No majority consensus was reached regarding the definition of NLA. Each method has its benefits and drawbacks, and establishing a single one may be unnecessary and even counterproductive in some cases. Having options available means that surgeons can tailor to each encounter, as long as they adopt a systematic methodology. We submit an algorithm to facilitate this effort.

Correlation Assessment between Three-Dimensional Facial Soft Tissue Scan and Lateral Cephalometric Radiography in Orthodontic Diagnosis

Purpose. The aim of the present prospective study was to investigate correlations between 3D facial soft tissue scan and lateral cephalometric radiography measurements. Materials and Methods. The study sample comprised 312 subjects of Caucasian ethnic origin. Exclusion criteria were all the craniofacial anomalies, noticeable asymmetries, and previous or current orthodontic treatment. A cephalometric analysis was developed employing 11 soft tissue landmarks and 14 sagittal and 14 vertical angular measurements corresponding to skeletal cephalometric variables. Cephalometric analyses on lateral cephalometric radiographies were performed for all subjects. The measurements were analysed in terms of their reliability and gender-age specific differences. Then, the soft tissue values were analysed for any correlations with lateral cephalometric radiography variables using Pearson correlation coefficient analysis. Results. Low, medium, and high correlations were found for sagittal and vertical measurements. Sagittal measurements seemed to be more reliable in providing a soft tissue diagnosis than vertical measurements. Conclusions. Sagittal parameters seemed to be more reliable in providing a soft tissue diagnosis similar to lateral cephalometric radiography. Vertical soft tissue measurements meanwhile showed a little less correlation with the corresponding cephalometric values perhaps due to the low reproducibility of cranial base and mandibular landmarks.

Assessment of anterior-posterior jaw relationships in Korean adults using the nasion true vertical plane in cone-beam computed tomography images

Objective

The aims of this study were to investigate a simple method for assessing anterior-posterior jaw relationships via cone-beam computed tomography (CBCT) images taken in the natural head position (NHP) relative to the nasion true vertical plane (NTVP), and measure normative data in Korean adults with normal profiles.

Methods

Subjects were selected from patients presenting for third molar extraction and evaluated as having normal profiles by three examiners. The CBCT images of 80 subjects (39 males, 41 females) were taken in the NHP according to Solow and Tallgren's method. Linear measurements of the A-point, B-point, and Pog were calculated relative to the NTVP. Student's t-test was used to assess sexual differences in these measurements.

Results

The mean linear measurements of the A-point, B-point, and Pog relative to the NTVP were 0.18 mm (standard deviation [SD], 4.77 mm), −4.00 mm (SD, 6.62 mm), and −2.49 mm (SD, 7.14 mm) respectively in Korean males, and 1.48 mm (SD, 4.21 mm), −4.07 mm (SD, 6.70 mm) and −2.91 mm (SD, 7.25 mm) in Korean females respectively. There were no statistically significant differences between Korean males and females (p < 0.05).

Conclusions

Three-dimensional CBCT analysis using the NTVP is a simple and reliable method for assessing anterior-posterior skeletal relationships.