The reproducibility of natural head posture: a methodological study

Evaluation of the reproducibility of facial profile photographic records taken in two different head positions

OBJECTIVE

This study aimed to evaluate the intra- and inter-examiner reproducibility of photographic records of the facial profile in Natural Head Position (NHP) and Oriented Position (OP) taken by four examiners (two orthodontists, one oral and maxillofacial surgeon, and one photography technician).

METHODS

Each professional captured two lateral photographs of 25 individuals during the first (T1) and second phases (T2), to assess the reproducibility of the technique and method error using angular measurements, based on the soft tissue Glabella and soft tissue Pogonion landmarks. The Shapiro-Wilk normality test and intraclass correlation coefficient (ICC) tests, using a two-way mixed model, were applied. To assess the agreement between the NHP and OP methods, Bland-Altman analysis was conducted, followed by regression analysis. The significance level for all statistical analyses was set at 5%.

RESULTS

The ICC analysis for the angular measurement in the NHP position demonstrated good inter-examiner reliability at T1 (ICC=0.706; p<0.001) and T2 (ICC=0.739; p<0.001). In the intra-examiner analysis, only examiner 1 (orthodontist) showed moderate reliability (ICC=0.504; p<0.001). For the OP position, the analysis revealed good inter-examiner reliability at T1 (ICC=0.708; p<0.001) and T2 (ICC=0.704; p<0.001). Again, only examiner 1 (orthodontist) exhibited moderate intra-examiner reliability (ICC=0.530; p=0.033). The Bland-Altman plots demonstrated agreement between NHP and OP for each examiner at T1 and T2.

CONCLUSION

The NHP and OP techniques were reliable when performed by technically proficient and calibrated professionals.

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.

Evaluation of head and cervical spine posture after functional therapy with Twin‑Block and Bionator appliances: A pilot randomized controlled trial

OBJECTIVE

Evaluation of head and cervical spine posture and estimation of sample size.

METHODS

Thirty eligible participants who required functional therapy were randomly assigned to the Control group (C), Twin Block group (TB), or the Bionator group (B). Randomization was accomplished by means of blocks of fixed size stratified by sex and age, with the allocations concealed in opaque and sealed envelopes.

RESULTS

Significant differences were identified between the pre -and post-functional SNB (p = 0.024) and ANB (p = 0.034) angles in the Twin Block group and SNA (p = 0. 019) and ANB (p = 0. 028) angles in the Bionator group. No statistically significant changes were seen in the head or cervical variables in the three groups.

CONCLUSION

The functional appliance did not cause any statistical change in head posture or cervical spinal column in comparison with the non-treatment group.

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.

The effect of observation angles on facial age perceptions: A case study of Japanese women

Most conventional aging research has limited its approach concerning the head and face shape and skin condition to the frontal face. However, in our daily lives, we observe facial features from various angles, which may reveal or obscure aging features that could only be identified under limited conditions in the past. This study systematically investigates the effect of facial observation angles-specifically, of horizontal and vertical angles-on age impression. A total of 112 Japanese women aged 20-49 years participated as observers who evaluated the age impressions of 280 Japanese women aged 20-69 years. A two-way analysis of the variance of the age impression score was conducted for two factors: observation angle (five angles with yaw and pitch directions) and age group (five ages, from the 20s to the 60s). The results reveal that, as compared with frontal observation, the perceived age tended to decrease with the facial observation angles and that the effect of the angle on perceived age decreased with increasing age, especially for the profile face. Understanding the effect of the facial observation angle on age impression and clarifying the characteristics of the face and skin not perceived in the frontal face will provide useful knowledge to make people look youthful, look more beautiful, and be happier in all aspects of their lives.

Midsagittal Plane First: Building a Strong Facial Reference Frame for Computer-Aided Surgical Simulation

PURPOSE

A facial reference frame is a 3-dimensional Cartesian coordinate system that includes 3 perpendicular planes: midsagittal, axial, and coronal. The order in which one defines the planes matters. The purposes of this study are to determine the following: 1) what sequence (axial-midsagittal-coronal vs midsagittal-axial-coronal) produced more appropriate reference frames and 2) whether orbital or auricular dystopia influenced the outcomes.

METHODS

This study is an ambispective cross-sectional study. Fifty-four subjects with facial asymmetry were included. The facial reference frames of each subject (outcome variable) were constructed using 2 methods (independent variable): axial plane first and midsagittal plane first. Two board-certified orthodontists together blindly evaluated the results using a 3-point categorical scale based on their careful inspection and expert intuition. The covariant for stratification was the existence of orbital or auricular dystopia. Finally, Wilcoxon signed rank tests were performed.

RESULTS

The facial reference frames defined by the midsagittal plane first method was statistically significantly different from ones defined by the axial plane first method (P = .001). Using the midsagittal plane first method, the reference frames were more appropriately defined in 22 (40.7%) subjects, equivalent in 26 (48.1%) and less appropriately defined in 6 (11.1%). After stratified by orbital or auricular dystopia, the results also showed that the reference frame computed using midsagittal plane first method was statistically significantly more appropriate in both subject groups regardless of the existence of orbital or auricular dystopia (27 with orbital or auricular dystopia and 27 without, both P < .05).

CONCLUSIONS

The midsagittal plane first sequence improves the facial reference frames compared with the traditional axial plane first approach. However, regardless of the sequence used, clinicians need to judge the correctness of the reference frame before diagnosis or surgical planning.

Restoring cervical lordosis by cervical extension traction methods in the treatment of cervical spine disorders: a systematic review of controlled trials

[Purpose] To systematically review the literature on the use of cervical extension traction methods for increasing cervical lordosis in those with hypolordosis and cervical spine disorders. [Methods] Literature searches for controlled clinical trials were performed in Pubmed, PEDro, Cochrane, and ICL databases. Search terms included iterations related to the cervical spine, neck pain and disorders, and extension traction rehabilitation. [Results] Of 1,001 initially located articles, 9 met the inclusion/exclusion criteria. The trials demonstrated increases in radiographically measured lordosis of 12-18°, over 5-15 weeks, after 15-60 treatment sessions. Untreated controls/comparison groups not receiving extension traction showed no increase in cervical lordosis. Several trials demonstrated that both traction and comparison treatment groups experienced immediate pain relief. Traction treatment groups maintained their pain and disability improvements up to 1.5 years later. Comparative groups not receiving lordosis improvement experienced regression of symptoms towards pre-treatment values by 1 years' follow-up. [Conclusion] There are several high-quality controlled clinical trials substantiating that increasing cervical lordosis by extension traction as part of a spinal rehabilitation program reduces pain and disability and improves functional measures, and that these improvements are maintained long-term. Comparative groups who receive multimodal rehabilitation but not extension traction experience temporary relief that regresses after treatment cessation.

Effect of positional errors on the accuracy of cervical vertebrae maturation assessment using CBCT and lateral cephalograms

BACKGROUND

The objective of this study was to evaluate the effects of single plane and multiplane rotational errors in yaw, pitch, and roll of the head while recording the lateral cephalogram on CVM (cervical vertebrae maturity) assessment.

METHODS

A total of 40 cone-beam computed tomography (CBCT) scans and 360 lateral cephalograms were analyzed for patients with different rotations: Controls (no rotation), Y5 (yaw 5° rotation), Y10 (yaw 10° rotation), R5 (roll 5° rotation), R10 (Roll 10° rotation), P5 (pitch 5° rotation), P10 (pitch 10° rotation), YRP5 (yaw, roll, and pitch 5° rotation), and YRP10 (yaw, roll, and pitch 10° rotation). The C2, C3, and C4 concavity and their base-anterior ratio and posterior-anterior ratio were measured. In addition, maxillomandibular linear parameters, such as effective mandibular length and height, mandibular body length, effective midface length, and maxillomandibular differential, were also evaluated.

RESULTS

Y5, Y10, R5, and R10 led to overestimation of CVM in comparison with controls. Multiplane rotations (YRP5 and YRP10) led to more inaccuracies in CVM measurements than single plane rotations; 10° of rotation led to more inaccuracies than 5° of rotation while recording the lateral cephalogram, irrespective of the plane. Yaw rotational errors led to an underestimation of maxillomandibular linear measurements, whereas roll rotational errors led to an overestimation of the measurements; however, there were wide individual variations in the measurements between the different rotations and controls.

CONCLUSIONS

Rotational errors lead to overestimation of CVM assessment. Multiplane rotations cause higher inaccuracies than single plane rotations. Increased degree of rotations while capturing the lateral cephalograms lead to more inaccuracies in CVM assessment.

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.

Comparison of three midsagittal planes for three-dimensional cone beam computed tomography head reorientation

Objective

This study compared three prominent midsagittal planes (MSPs) to identify the MSP that best approximates the true symmetrical MSP.

Methods

Forty-three patients (mean age, 23.0 ± 8.20 years) were grouped as follows: group 1 consisted of 10 patients with skeletal Class I and a menton (Me) deviation of < 2 mm; group 2, 11 patients with skeletal Class III and a Me deviation < 2 mm; group 3, nine patients with skeletal Class III and a Me deviation of 2 to less than 4 mm; and group 4, 13 patients with skeletal Class III and an Me deviation ≥ 4 mm. The candidate MSPs were established by three-dimensional (3D) cone beam computed tomography (CBCT) reorientation methods (RMs): (1) the MSP perpendicular to the Frankfort horizontal (FH) plane while passing through the crista galli and basion; (2) the MSP including the nasion, incisive foramen, and basion; (3) the MSP including the nasion, anterior nasal spine, and posterior nasal spine. The mean absolute distances (MADs) to the MSPs were calculated from the coordinates of 1,548 points on 129 CBCT images. The differences in the values of the 3D coordinates among RMs were compared.

Results

The MADs of the three RMs showed significant differences (p < 0.05). Most of the differences in values of the coordinates were not significant among RMs.

Conclusions

Although the differences in distance among the three MSPs were minor, the MSP perpendicular to the FH plane while passing through the crista galli and basion best approximated the true symmetrical MSP.

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.

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.

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 (CSA^1/2) of the pharyngeal airway space. Pearson's correlation coefficient was used to find out whether there was a correlation between the change in CSA^1/2 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 CSA^1/2 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.

Virtual facebow technique using standardized background images

The procedure described provides a novel and accessible virtual facebow transfer based on standardized photographs loaded in the virtual articulator module of a computer-assisted design and computer-assisted manufacturing (CAD-CAM) software program for dental applications. The practical application of the technique in a digital workflow is the correct alignment of the digital maxillary cast to the virtual articulator with respect to the patient's planes and the skin markings of the condylar axis.

Test-retest reliability of posture measurements in adolescents with idiopathic scoliosis

BACKGROUND CONTEXT

Posture changes are a major consequence of idiopathic scoliosis (IS). Posture changes can lead to psychosocial and physical impairments in adolescents with IS. Therefore, it is important to assess posture, but the test-retest reliability of posture measurements still remains unknown in this population.

PURPOSE

The primary objective of the present study was to determine the test-retest reliability of 25 head and trunk posture indices using the Clinical Photographic Postural Assessment Tool (CPPAT) in adolescents with IS. The secondary objective was to determine the standard error of measurement and the minimal detectable change.

STUDY DESIGN/SETTING

This is a prospective test-retest reliability study carried out at two tertiary university hospital centers.

PATIENTS SAMPLE

Forty-one adolescents with IS, aged 10-16 years old with curves 10°-45° and treated by medical intervention, were recruited.

METHODS

Two posture assessments were done using the CPPAT 5-10 days apart following a standardized procedure. Photographs were analyzed with the CPPAT software by digitizing reference landmarks placed on the participant by a physiotherapist evaluator. Generalizability theory was used to obtain a coefficient of dependability, standard error of measurement, and the minimal detectable change at 90% confidence interval.

RESULTS

Fourteen of 25 posture indices had a good reliability (ϕ≥0.78), 10 had moderate reliability (ϕ=0.55-0.74), and 1 had poor reliability (ϕ=0.45). The most reliable posture indices were waist angle asymmetry (ϕ=0.93), right waist angle (ϕ=0.91), and frontal trunk list (ϕ=0.92). Right sagittal trunk list was the least reliable posture index (ϕ=0.45). The MDC₉₀ values ranged from 2.6 to 10.3° for angular measurements and from 8.4 to 35.1 mm for linear measurements.

CONCLUSIONS

The present study demonstrates that most posture indices, especially the trunk posture indices, are reproducible in time among adolescents with IS and provides reference values. Clinicians and researchers can use these reference values to assess change in posture over time attributable to treatment effectiveness.

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.

[Natural head position's reproducibility on photographs]

INTRODUCTION

The purpose of this study is to evaluate the reproducibility of natural head position with time on profile photographs.

MATERIALS AND METHODS

Our sample is composed of 96 students (20-30 years old) at the department of dentistry of Saint Joseph University in Beirut. Two profile photographs were taken in natural head position about a week apart.

RESULTS

No significant differences were found between T0 and T1 (E = 1.065°).

DISCUSSION

Many studies confirmed this reproducibility with time. Natural head position can be adopted as an orientation for profile photographs in orthodontics.

Facial profile esthetics in operated children with bilateral cleft lip and palate

OBJECTIVE:

The aim of this study was to evaluate the facial profile esthetics of rehabilitated children with complete bilateral cleft lip and palate (BCLP), comparing the judgment of professionals related and not related to cleft rehabilitation and laypersons.

METHODS:

Thirty children in the mixed dentition (24 male; 6 female) with a mean age of 7.8 years were evaluated using facial profile photographs by 25 examiners: 5 orthodontists and 5 plastic surgeons with experience in cleft care, 5 orthodontists and 5 plastic surgeons without experience in oral cleft rehabilitation and 5 graduated laymen. Their facial profiles were classified into esthetically unpleasant (grade 1 to 3), esthetically acceptable (grade 4 to 6), and esthetically pleasant (grade 7 to 9). Intraexaminer and interexaminer errors were evaluated using Spearman correlation coefficient and Kendall's test, respectively. Inter-rater differences were analyzed using Friedman test and Student-Newman-Keuls test for multiple comparisons.

RESULTS:

Orthodontists dealing with oral clefts rehabilitation considered the majority of the sample as esthetically pleasant. Plastic surgeons of the cleft team and laypersons classified most of the sample as esthetically acceptable. Most of the orthodontists and plastic surgeons not related to cleft care evaluated the facial profile as esthetically unpleasant. The structures associated to unpleasant profiles were the nose, the midface and the upper lip.

CONCLUSIONS:

The facial profile of children with BCLP was classified as esthetically acceptable by laypersons. Professionals related to cleft rehabilitation were more lenient and those not related to cleft care were stricter to facial esthetics than laypersons.

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.

Skeletal and dento-alveolar norms: Conventional and based on true vertical in a Lebanese population

OBJECTIVE

The aims of this study were to determine the cephalometric norms in a Lebanese population of young adults, to find the differences in cranio-facial morphology between males and females and to establish the equivalency between conventional measurements and those based on the true horizontal.

MATERIALS AND METHOD

Ninety subjects divided into 43 women and 47 men, aged from 18 to 30years, were selected based on specific criteria. The lateral cephalograms were taken in the natural head position. Downs, Steiner, Tweed, Ricketts, Epker and Fish, Coben, McNamara and Jacobson analyses were applied by orienting radiographs according to the Frankfurt anatomic plane, and Scheideman, Cooke, Arnett, and Viazis analyses were performed by orienting the radiographs according to the true vertical.

RESULTS AND CONCLUSION

The specific skeletal and dento-alveolar measurements from this sample are reported in nine grids. Differences between males and females were found especially at the B and Pog points, which were more posterior in men, who also presented a greater lower facial height in relation to total facial height. Women had more protrusive upper incisors when measured in the maxillary plane.

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.

Airway compartments volume and oxygen saturation changes after rapid maxillary expansion: a longitudinal correlation study

OBJECTIVE

To evaluate changes in airway volumes and respiratory performance in patients undergoing rapid maxillary expansion and determine whether any correlations exist between the morphological and respiratory functional modifications induced by rapid maxillary expansion and pretreatment airway stenosis.

MATERIALS AND METHODS

Fifteen patients (11 females and 4 males; mean age, 7.5 ± 0.3 years) were enrolled in the study. Each patient underwent cone beam computed tomography and polysomnography examination before rapid maxillary expansion and after the removal of the maxillary expander 12 months later. The airway regions were segmented and the volumes were computed.

RESULTS

The upper, middle, and lower airway volumes were significantly increased 2305 mm(3), 1144 mm(3), and 1915 mm(3), respectively. Similarly, oxygen saturation was increased (+5.3%) and the apnea/hypopnea index was improved (-4.2 events). All the observed modifications were statistically significant (P < .05). Baseline middle and lower airway volume showed a significant negative correlation with the oxygen saturation modification.

CONCLUSIONS

The results of this study showed that when rapid maxillary expansion is performed in subjects having posterior crossbite, oxygen saturation is improved. The improvement is greater in subjects having more reduced middle and lower airway volumes.

Cephalometric analysis for functional occlusion

Background

Various elements contributing to good functional occlusion have not been clearly assessed with cephalometrics for the diagnosis of functional problems and their application in clinical practice. The aim of this study, therefore, was to analyze different components of functional occlusion to formulate concise functional cephalometric analysis.

Materials and Methods

Eighty-two cases (38 males and 44 females), with class I occlusion and balanced facial profile, were examined based on the selection criteria, and cephalograms were taken in natural head position. All the radiographs were then analyzed using various functional parameters.

Results

The mean values of condylar path angle and incisal path angle were 55.83° and 65.67°, respectively, with large deviations. However, both showed positive correlation. The value of the angle of long axis of mandibular incisor with respect to the line joining center of condyle and lower incisor tip was 88.04°. Moreover, the angle between the occlusal plane and horizontal plane was 12.88°. In vertical plane, lower face height (LFH) was found to be slightly less than the upper face height. Maxilla contributed around 45% of the LFH while mandible formed about 60%. Furthermore, upper alveolar component (maxillary alveolar height) formed more than half of the maxilla (53.79%) whereas lower alveolar component (mandibular alveolar height) was 74.8% of the mandible.

Conclusion

This study has analyzed various components of functional occlusion and formulated a concise functional cephalometric analysis for diagnosis, treatment planning, and assessment of treatment results.

Three-dimensional Analysis of Normal Facial Morphologies of Asians and Whites: A Novel Method of Quantitative Analysis

The purpose of this study is to compare 3-dimensional facial averages of Asians (Koreans and Chinese) and Houstonian white faces using a (3-dimensional) surface imaging system.

Soft tissue norms: Conventional and based on true vertical in a Lebanese population

INTRODUCTION

The aim of this study was to establish cephalometric soft tissue norms in a Lebanese population of young adults and profile differences between males and females.

MATERIALS AND METHODS

Ninety subjects divided into 43 women and 47 men, aged from 18 to 30 years, were selected based on specific criteria. The lateral cephalograms were taken in the natural head position. Holdaway, Steiner, Merrifield, Ricketts, Epker and Fish analyses were applied as conventional analyses. Scheideman, Spradley, Cooke, Arnett, Bergman, Farkas and Viazis analyses were applied as analyses based on the true vertical.

RESULTS AND CONCLUSION

The specific soft tissue measurements of this sample are reported in six grids. The differences between males and females related especially to the lower facial height and lip thickness, which had higher values in males, who also presented a more retruded lower lip and more protruded nasal tip. Women had higher values for mentolabial and frontonasal angles.

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.

Age-related changes in the Brazilian woman's smile

The aim of this research was to evaluate age-related changes in the smile of Brazilian women. The sample consisted of 249 Brazilian women who had not undergone previous orthodontic treatment or facial surgery. They were divided into four groups, according to age: G1 (20-29), G2 (30-39), G3 (40-49) and G4 (50 or older). Standardized front view photographs were taken while smiling and at rest. Measurements were evaluated by ANOVA and post-hoc Tukey. The Chi-square test was applied for qualitative variables. Upper lip thickness at rest and exposure of upper incisors on smiling decreased with age. Most individuals (60.9%) exhibited a medium smile. High smiles were more often seen in G1 (45%) and less frequently in G4 (18.8%), whereas the opposite occurred with the low smile, i.e., G4 (21.9%) and G1 (6.7%). Variations among the groups were observed in the transverse exposure of the teeth on smiling. In G1 and G3, there was a balance between tooth exposures, so that the teeth were exposed as far as the premolars and/or molars. Most of the women (56.3%) in G2 exposed their teeth as far as the first molars on smiling, whereas most of those (40.6%) in G4 exposed their teeth only as far as the first premolars on smiling. As age increased, there was decreased exposure of the upper incisors, decreased upper lip thickness and lower exposure of teeth vertically and transversely.

Natural position of the head: review of two-dimensional and three-dimensional methods of recording

Both the correct position of the patient's head and a standard system for the acquisition of images are essential for objective evaluation of the facial profile and the skull, and for longitudinal superimposition. The natural position of the head was introduced into orthodontics in the late 1950s, and is used as a postural basis for craniocervical and craniofacial morphological analysis. It can also have a role in the planning of the surgical correction of craniomaxillofacial deformities. The relatively recent transition in orthodontics from 2-dimensional to 3-dimensional imaging, and from analogue to digital technology, has renewed attention in finding a versatile method for the establishment of an accurate and reliable head position during the acquisition of serial records. In this review we discuss definition, clinical applications, and procedures to establish the natural head position and their reproducibility. We also consider methods to reproduce and record the position in two and three planes.

Natural head position: An overview

Cephalometrics has given us a different perspective of interpreting various skeletal problems in the dentofacial complex. Natural head position (NHP) is a reproducible, physiologically determined aspect of function. To determine NHP, a horizontal or vertical reference line outside the crania was used, but preference was given generally to the horizontal. Various intra and extracranial cephalometric horizontal reference planes have been used to formulate diagnosis and plan individualized treatment for an integrated correction of the malocclusion cephalometrics is constantly undergoing refinements in its techniques and analyses to improve the clinical applications. Even though various methods for establishing NHP have been proposed, still it remains a challenge to the clinicians to implement the concept of NHP thoroughly in all the stages of treatment because of practical difficulties in the clinical scenario.

Frontal facial proportions of 12-year-old southern Chinese: a photogrammetric study

This study aimed to establish norm values for facial proportion indices among 12-year-old southern Chinese children, to determine lower facial proportion, and to identify gender differences in facial proportions.

A random population sample of 514 children was recruited. Fifteen facial landmarks were plotted with ImageJ (V1.45) on standardized photos and 22 Facial proportion index values were obtained. Gender differences were analyzed by 2-sample t-test with 95 % confidence interval. Repeated measurements were conducted on approximately 10 % of the cases.

The rate of adopted subjects was 52.5 % (270/514). Intraclass correlation coefficient values (ICC) for intra- examiner reliability were >0.87. Population facial proportion index values were derived. Gender differences in 11 of the facial proportion indices were evident (P < 0.05).

Upper face-face height (N- Sto/ N- Gn), vermilion height (Ls-Sto/Sto-Li), upper face height-biocular width (N-Sto/ExR-ExL) and nose -face height (N-Sn/N-Gn) indices were found to be larger among girls (P < 0.01). Males had larger lower face-face height (Sn -Gn/ N-Gn), mandibulo-face height (Sto-Gn/N-Gn), mandibulo-upper face height (Sto-Gn/N-Sto), nasal (AlR-AlL/N-Sn), upper lip height-mouth width (Sn-Sto/ChR-ChL), upper lip-upper face height (Sn-Sto/N-Sto) and upper lip-nose height (Sn-Sto/N-Sn) indices (P < 0.05).

Population norm of facial proportion indices for 12-year-old Southern Chinese were derived and mean lower facial proportion were obtained. Sexual dimorphism is apparent.

Comparison of the Kois Dento-Facial Analyzer System with an earbow for mounting a maxillary cast

STATEMENT OF PROBLEM

The Kois Dento-Facial Analyzer System (KDFA) is used by clinicians to mount maxillary casts and evaluate and treat patients. Limited information is available for understanding whether the KDFA should be considered as an alternative to an earbow.

PURPOSE

The purpose of this study was to evaluate maxillary casts mounted using the KDFA with casts mounted using Panadent's Pana-Mount Facebow (PMF). Both articulation methods were compared against a lateral cephalometric radiograph.

MATERIAL AND METHODS

Fifteen dried human skulls were used. Lateral cephalometric radiographs and 2 maxillary impressions were made of each skull. One cast from each skull was mounted on an articulator by means of the KDFA and the other by using the PMF. A standardized photograph of each articulation was made, and the distance from the articular center to the incisal edge position and the occlusal plane angle were measured. The distance from condylar center to the incisal edge and the occlusal plane angle were measured from cephalometric radiographs. Finally, the 3-dimensional position of each articulation was determined with a Panadent CPI-III. A randomized complete block design analysis of variance (RCBD) and post hoc tests (Tukey-Kramer HSD) (α=.05) were used to evaluate the occlusal plane angle and axis-central incisor distance. A paired 2-sample t test for means (α=.05) was used to compare the X, Y, and Z distance at the right and left condyle.

RESULTS

The KDFA and PMF mounted the maxillary cast in a position that was not statistically different from the skull when comparing the occlusal plane angle (P=.165). Both the KDFA and the PMF located the maxillary central incisor edge position in a significantly different position compared with the skull (P=.001) but were not significantly different from each other. The 3-dimensional location of the maxillary casts varied at the condyles by approximately 9 to 10.3 mm.

CONCLUSION

The KDFA mounted the maxillary cast in a position that was not statistically different from the PMF when comparing the incisal edge position and the occlusal plane angle. Both the KDFA and the PMF located the maxillary incisal edge position in a significantly different position compared with the anatomic position on dried human skulls.

Natural head position: key position for radiographic and photographic analysis and research of craniofacial complex

The Frankfort horizontal is a useful compromise for studying skulls but not for orienting the natural head position (NHP) in the living because it is normally distributed around a true extracranial horizontal. Nonetheless, orthodontists dealing with living subjects, rather than inert crania, have used this Frankfort horizontal faithfully in cephalometry. Because the cant or inclination of all intracranial reference lines is subjected to biologic variation, they are unsuitable for meaningful cephalometric analysis. Registration of head posture in its natural position has the advantage that an extracranial vertical or a horizontal perpendicular to that vertical can be used as reference line for cephalometric analysis. Purpose of this paper is to provide an updated review of various methods to reproduce and record the NHP.

Variability of the inclination of anatomic horizontal reference planes of the craniofacial complex in relation to the true horizontal line in orthognathic patients

INTRODUCTION

The purpose of this study was to assess the reliability of the Frankfort horizontal (FH), sella-nasion horizontal, and optic planes in terms of their variabilities in relation to a true horizontal line in orthognathic surgery patients.

METHODS

Thirty-six consecutive presurgical orthognathic patients (13 male, 23 female; age range, 16-35 years; 30 white, 6 African Caribbean) had lateral cephalometric radiographs taken in natural head position, with a plumb line orientating the true vertical line, and the true horizontal line perpendicular to the true vertical. The inclinations of the anatomic reference planes were compared with the true horizontal.

RESULTS

The FH plane was found to be on average closest to the true horizontal, with a mean of -1.6° (SD, 3.4°), whereas the sella-nasion horizontal and the optic plane had means of 2.1° (SD, 5.1°) and 3.2° (SD, 4.7°), respectively. The FH showed the least variability of the 3 anatomic planes. The ranges of variability were high for all anatomic planes: -8° to 8° for the FH, -8° to 15° for the sella-nasion horizontal, and -6° to 13° for the optic plane. No significant differences were found in relation to patients' sex, skeletal patterns, or ethnic backgrounds.

CONCLUSIONS

The clinically significant variability in the inclinations of anatomic reference planes in relation to the true horizontal plane makes their use unreliable in orthognathic patients.

Angular photogrammetric analysis of the soft tissue profile in 12-year-old southern Chinese

Introduction

To quantify average angular measurements that define the soft tissue profiles of 12-year-old southern Chinese and to determine gender differences.

Materials and methods

A random population sample of 514 12-year-old children was recruited (about 10% of a Hong Kong Chinese birth cohort). Photographs were taken in natural head posture and 12 soft tissue landmarks were located on the photos to measure 12 angular measurements using ImageJ (V1.45s) for Windows. Approximately 10% of photographs were reanalyzed and method error was calculated. Angular norm values for the 12 parameters were determined and gender differences were assessed using 2 sample T-test with 95% confidence interval.

Results

The response rate was 54.1% (278/514). Norm values for the 12 angular measurements were generated. The greatest variability was found for the nasolabial (Cm-Sn-Ls) and labiomental (Li-Sm-Pg) angles. Gender differences were found in 4 angular parameters: vertical nasal angle (N-Prn/TV) (p < 0.05), cervicomental angle (G-Pg/C-Me) (p < 0.001), facial convexity angle (G-Sn-Pg) (p < 0.01) and total facial convexity angle (G-Prn-Pg)(p < 0.01).

Conclusion

Norm values for 12 angular measurements among 12-year-old southern Chinese children were provided and some variability noted. Gender differences were apparent in several angular measurements. This study has implications in developing norm values for southern Chinese and for comparison with other ethnic groups.

Esthetic evaluation of the facial profile in rehabilitated adults with complete bilateral cleft lip and palate

PURPOSE

To assess the facial esthetics of patients with complete bilateral cleft lip and palate, and to compare the judgment of raters related and unrelated to cleft care.

MATERIALS AND METHODS

The sample comprised 23 adult patients (7 women and 16 men) with a mean age of 26.1 years, rehabilitated at a single center. Standardized photographs of the right and left facial profile were taken of each patient and subjectively evaluated by 25 examiners: 5 orthodontists and 5 plastic surgeons with expertise in oral cleft rehabilitation, 5 orthodontists and 5 plastic surgeons without expertise in oral cleft rehabilitation, and 5 laypersons. The facial profiles were classified into 3 categories: esthetically unpleasant, esthetically acceptable, and esthetically pleasant. Intraexaminer and interexaminer agreements were evaluated with the Spearman correlation coefficient and Kendall coefficient of concordance. The differences between rater categories were analyzed using the Student-Newman-Keuls test (with P < .05 indicating a statistically significant difference).

RESULTS

Most of the sample was classified as esthetically acceptable. Orthodontists and plastic surgeons related to oral cleft rehabilitation gave the best scores to the facial profiles, followed by layperson examiners and by orthodontists and plastic surgeons unrelated to oral cleft rehabilitation. The middle third of the face, the nose, and the upper lip were frequently pointed out as contributors to the esthetic impairment.

CONCLUSIONS

The facial profile of rehabilitated adult patients with complete bilateral cleft lip and palate was considered esthetically acceptable because of morphologic limitations in the structures affected by the cleft. Laypersons and professionals unrelated to oral cleft rehabilitation seem to be more critical regarding facial esthetics than professionals involved with cleft rehabilitation.

Variation in natural head position and establishing corrected head position

Corrected head position (CHP) has been simulated by using the Frankfurt horizontal (FH) for over 100 years but FH varies between individuals. Because CHP is biologically relevant for orthodontic diagnosis and treatment planning, orthognathic surgical planning, and art, this study examined relationships between head position and selected cephalometric planes. Natural head position cephalograms of Aboriginal Australians and two contemporary samples from private orthodontic practices were analysed. Each sample comprised 40 individuals (20 males and 20 females). The Aboriginal Australian sample comprised longitudinal data (T1 early adolescent, T2 late adolescent, and T3 adult), enabling examination of natural head position (NHP) reproducibility over a period of approximately 8 years. Results of reproducibility differences revealed an absolute mean=2.9°, range=-7.9° to 8.2°, and standard deviation=3.6°. Stable basicranial line (SBL), neutral horizontal axis (NHA), FH, palatal plane (P plane), and Krogman-Walker plane (KW plane) demonstrated near parallelism and their mean angulations from the true horizontal (HOR) ranged between -4.6° and 2.4°. While NHP is not consistently reproducible at the individual level, the combined use of multiple planes such as SBL, P plane, and KW plane enables a more consistent CHP to be achieved.

New way to achieve frontal facial photographs of the head in its natural position

Frontal photographs of the head in its natural position are not as easy to achieve as lateral ones. We describe a new way to obtain standard 2-dimensional images of its natural position in full-face frontal view using a customised photographic system, which may provide supplementary information for traditional lateral facial imaging, and be helpful for standard assessment of 3-dimensional facial images.

Soft tissue cephalometric analysis applied to regional Indian population

Introduction:

Importance of soft tissue consideration in establishing treatment goals for orthodontics and orthognathic surgery has been recognized and various cephalometric analysis incorporating soft tissue parameters have evolved. The great variance in soft tissue drape of the human face and perception of esthetics exists and normative data based on one population group cannot be applied to all. The study was conducted to compare the standard soft tissue cephalometric analysis (STCA) norms with norms derived for population of western Uttar Pradesh region of India.

Materials and Methods:

The sample consisted of lateral cephalograms taken in natural head position of 33 normal subjects (16 males, 17 females). The cephalograms were analyzed with soft tissue cephalometric analysis for orthodontic diagnosis and treatment planning, and the Student's t test was used to compare the difference in means between study population and standard STCA norms.

Results:

Compared with established STCA norms, females in our study had steeper maxillary occlusal plane, more proclined mandibular incisors, and less protrusive lips. Both males and females showed an overall decrease in facial lengths, less prominent midface and mandibular structures and more convex profile compared with established norms for the White population.

Conclusions:

Statistically significant differences were found in certain key parameters of STCA for western Uttar Pradesh population when compared with established norms.

[New developments in cephalometrics]

Recently l recalled the error in the principle which makes cephalometric analysis unsuitable for orthodontic diagnosis. Now, three methods of analysis have been published precisely conceived in order to avoid this error. Will cephalometric analysis succeed in its search for the truth?

Arch coordination does not affect the stability in class III orthognathic surgery patients

The purpose of this study was to evaluate if the arch coordination manifested by preorthodontics had an effect on the short-term stability after orthognathic surgery by evaluating the B point, menton, overjet, and overbite. The subjects were 10 healthy adult female and male Koreans (mean age, 24.9 years) with insufficient arch coordination and 10 healthy adult female and male Koreans (mean age, 22 years) with sufficient arch coordination. All subjects had sagittal split ramus osteotomy with 1-piece maxillary Le Fort I surgery with/without genioplasty done from the same practitioner at Kyung Hee University Hospital at Gangdong from 2009 to 2011. All arch widths of the maxilla and mandible were measured. Cephalometric tracings of the subjects were made of the presurgical and postsurgical period with a follow-up at 3 months. Relapse was measured according to cephalometric tracing changes using the V-ceph Cephalometric Analysis Software version 5.5(Osstem, Seoul, South Korea). Insufficient arch coordination did not definitively affect the overall treatment outcome. There was significant difference in the horizontal dimensions of the mandible (vertical plane to point B, overjet) in the study group. The study group showed instability in orthodontic factors, whereas skeletal factors were stable. Vertical dimensions (horizontal plane to point B, horizontal plane to menton, overbite) were not statistically significant.