The relationship between ortho head posture and head posture measured during walking

The Effect of Bimaxillary Surgery on the Airway Morphology in Class III Patients: Taking Into Account the Head Posture During Walking

OBJECTIVES

To assess changes in head and neck posture, airway, hyoid, tongue, and soft palate in skeletal class III individuals whose cephalograms were taken using dynamic natural head positioning method with an inclinometer.

MATERIALS AND METHODS

This study was conducted on 20 class III patients operated with double jaw surgery. Natural head positions were determined before and 6 months after the surgery. Craniocervical, pharyngeal airway, tongue, and hyoid positions were measured. In the analysis of the data, paired t test, independent sample t test and correlation tests were used.

RESULTS

There was a statistically significant change in the craniocervical measurements with the operation and the head position was further extended (P < 0.05). Significant changes were observed in the soft palate angles upon surgery (P < 0.026) and the increase in oropharyngeal airway area was statistically significant (P < 0.001). There was a statistically significant increase in tongue length (TL) and distance from vertical reference plane to tongue tip (TTi/VRP) measurements (P < 0.001 and P < 0.012, respectively). There was a statistically significant decrease in distance from horizontal reference plane to tongue tip (TTi/HRP) and tongue dorsum (TD/HRP) measurements (P < 0.033 and P < 0.003, respectively). The only significant change among the hyoid bone position-related measurements was distance between hyoidale and epiglottis (P < 0.013).

CONCLUSIONS

Hyoid bone location, tongue measurements, and posterior pharyngeal airway were found to be related to each other and they have been found to be effective on the head and neck posture. Head position will be affected by possible surgical alternatives.

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.

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.

Reliability of forward head posture evaluation while sitting, standing, walking and running

Forward head posture has been evaluated mostly by visual observation or simple non-invasive measurements without a standardized evaluation method or protocol. In this experimental study, the reliability of existing forward head-posture measurement methods was evaluated by computing the intra-class correlation coefficients of three different head-position variables (two horizontal gap variables and one head-orientation variable) in seven different posture conditions from 20 asymptomatic participants. The position variables of the head were measured three times using a three-dimensional motion capture system while sitting comfortably, sitting with the back straight, standing comfortably, standing with the back straight, walking at 4 and 6km/h on a treadmill, and running at 8km/h on a treadmill. Intra-class correlation coefficients between repetitive measures ranged from 0.81 to 0.96, and high correlation coefficient values (>0.9) were produced when the head-position variables were measured during straight sitting, straight standing, and walking at 6km/h. Among the three head-position variables, a horizontal gap between the tragus and the 7th cervical vertebra was recorded more consistently than other variables. Results of this study highlight the importance of a standardized evaluation protocol for more reliable assessment of the forward head posture.

Accuracy of Different Modalities to Record Natural Head Position in 3 Dimensions: A Systematic Review

PURPOSE

Three-dimensional (3D) images are taken with positioning devices to ensure a patient's stability, which, however, place the patient's head into a random orientation. Reorientation of images to the natural head position (NHP) is necessary for appropriate assessment of dentofacial deformities before any surgical planning. The aim of this study was to review the literature systematically to identify and evaluate the various modalities available to record the NHP in 3 dimensions and to compare their accuracy.

MATERIALS AND METHODS

A systematic literature search of the PubMed, Cochrane Library and Embase databases, with no limitations on publication time or language, was performed in July 2015. The search and evaluations of articles were performed in 4 rounds. The methodologies, accuracies, advantages, and limitations of various modalities to record NHP were examined.

RESULTS

Eight articles were included in the final review. Six modalities to record NHP were identified, namely 1) stereophotogrammetry, 2) facial markings along laser lines, 3) clinical photographs and the pose from orthography and scaling with iterations (POSIT) algorithm, 4) digital orientation sensing, 5) handheld 3D camera measuring system, and 6) laser scanning. Digital orientation sensing had good accuracy, with mean angular differences from the reference within 1° (0.07 ± 0.49° and 0.12 ± 0.54°, respectively). Laser scanning was shown to be comparable to digital orientation sensing. The method involving clinical photographs and the POSIT algorithm was reported to have good accuracy, with mean angular differences for pitch, roll, and yaw within 1° (-0.17 ± 0.50°). Stereophotogrammetry was reported to have the highest reliability, with mean angular deviations in pitch, roll, and yaw for active and passive stereophotogrammetric devices within 0.1° (0.004771 ± 0.045645° and 0.007572 ± 0.079088°, respectively).

CONCLUSIONS

This systematic review showed that recording the NHP in 3 dimensions with a digital orientation sensor has good accuracy. Laser scanning was found to have comparable accuracy to digital orientation sensing, but routine clinical use was limited by its high cost and low portability. Stereophotogrammetry and the method using a single clinical photograph and the POSIT algorithm were potential alternatives. Nevertheless, clinical trials are needed to verify their applications in patients. Preferably, digital orientation sensor should be used as a reference for comparison with new proposed methods of recording the NHP in future research.

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.

Natural head position and lower incisor irregularity: Is there a relationship?

OBJECTIVE

The aim of this study was to assess the relationship between dynamic measurements of natural head position (NHP) and lower incisor irregularity to identify potential gender differences.

MATERIALS AND METHODS

A total of 103 plaster models and dynamic NHP measurements were taken from 51 male (mean age: 14.20 ± 2.51 years) and 52 female (mean age: 15.02 ± 2.67 years) subjects. The dynamic NHP data were gathered by using an inclinometer device and a portable data logger. Lower incisor irregularity was measured with Little's irregularity index. The Mann-Whitney U and Kruskal-Wallis rank tests were used at a significance level of p < 0.05. To evaluate the correlation between NHP and lower incisor irregularity, Spearman correlation coefficients (r) were calculated.

RESULTS

There were significant gender differences in the sagittal measurements of NHP (p = 0.031) and incisor irregularity (p = 0.023). A Kruskal-Wallis test revealed no significant difference in NHP measurements between subjects presenting different levels of irregularity. Females displayed no significant correlation between incisor irregularity and any NHP measurement. However, in the males high correlation coefficients between incisor irregularity and sagittal NHP measurements (r = 0.369; p = 0.008) were noted.

CONCLUSION

Significant correlations between lower incisor irregularity and sagittal NHP measurements in males were observed. Females had a more forwardly inclined NHP than males. Moreover, male subjects displayed greater incisor irregularity than female subjects.

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.

Rapid maxillary expansion effects on dynamic measurement of natural head position

OBJECTIVE

To identify the effect of rapid maxillary expansion (RME) procedure on dynamic measurement of natural head position (NHP).

MATERIALS AND METHODS

The treatment group comprised 23 patients, 12 girls and 11 boys (mean age: 10.1 ± 1.1 years), and the control group comprised 15 subjects, 8 girls and 7 boys (mean age: 9.7 ± 1.4 years). The test subjects underwent RME treatment using full cap acrylic device, and the mean amount of expansion was 5.48 mm. An inclinometer and a portable data logger were used to collect the NHP data. Intragroup changes were evaluated by using nonparametric Wilcoxon test, and intergroup changes were analyzed with Mann-Whitney U-test. P values less than .05 were considered statistically significant.

RESULTS

The mean difference between initial and final NHP was 0.31°, and this difference was not statistically significant. Also, there were no statistically significant differences between the RME and control groups before and after treatment.

CONCLUSION

Treatment with the RME procedure showed no statistically significant effects on dynamic measurement of NHP when compared with initial values or untreated control.

Relationship between static natural head position and head position measured during walking

INTRODUCTION

The aim of this project was to determine whether there is a statistically significant difference between the means of static and dynamic (measured during walking) measurements of head posture.

METHODS

The sample consisted of 50 subjects, 25 women and 25 men, 20 to 25 years of age. None had a history of orthodontic treatment, head or neck injury, or nasal breathing problems, and none wore eyeglasses to correct vision. Static measurement of head position was recorded by using the self-balance position. Dynamic measurements of head position were made with an inclinometer device with the subject walking in a relaxed manner for 5 minutes. The data, measured in degrees, were stored in a pocket data logger. Recorded static and dynamic head posture data were transferred to a computer for analysis. The means of the measurements were statistically compared with the t test (alpha = .05). The mean walking head position was tipped forward relative to the mean static head position.

RESULTS

The mean value of static position minus walking head position measurements was +4.60 degrees . The differences between the 2 recordings were statistically significant (P < .001).

CONCLUSIONS

Static and walking head position measurements are not interchangeable. Therefore, it might be advisable to use the mean dynamic measurement of head position to represent natural head position for positioning when taking case records such as lateral and posteroanterior cephalograms, clinical extraoral photography, or 3-dimensional imaging.

Effect of complete dentures on dynamic measurement of changing head position: A pilot study

STATEMENT OF PROBLEM

Complete dentures contribute significantly to the facial esthetics of edentulous patients. However, information as to the effect of complete dentures on the natural position of the head is limited.

PURPOSE

The purpose of this pilot study was to evaluate the immediate and 30-day effect of wearing complete dentures on the dynamic natural head position measured during walking.

MATERIALS AND METHODS

The sample consisted of a volunteer group of 16 patients, 8 women and 8 men, who received new complete dentures. The ages of the subjects ranged from 45 to 64 years (mean=52 years). Dynamic measurement of head posture was carried out by a specially constructed inclinometer device. Each subject in turn was fitted with the inclinometer system and instructed to walk in a relaxed manner for 5 minutes. The data, measured as degrees, were stored in a pocket data logger. This procedure was repeated before insertion of dentures (T1), immediately after insertion of dentures (T2), and 30 days after insertion of dentures (T3). Stored dynamic head posture data were transferred to computer for analysis. The means of the measurements were statistically compared with Friedman and following Wilcoxon tests (alpha =.05).

RESULTS

Twelve of 16 (75%) subjects showed an average of 4.6 degrees of cranial extension immediately after insertion of dentures. Six (37.5%) subjects showed an average of 6.4 degrees of cranial flexion, and 8 (50%) subjects showed an average of 5.2 degrees of cranial extension at T3 relative to the T1 measurement. Dynamic head posture measurements of the other 2 subjects remained unchanged. There were significant differences between different measurements of dynamic head posture positions (P<.025). However, only the T1 and T2 measurements were significantly different (P<.015).

CONCLUSION

The findings indicate that the statistically significant average extension 4.6 degrees in subjects immediately after insertion of complete dentures was not stable after a 30-day evaluation period and did not produce any statistically significant change. The overall effect of wearing dentures was an irregular flexion or extension pattern on dynamic head posture.

Inclinometer method for recording and transferring natural head position in cephalometrics

The purposes of this study were (1) to construct a device to record natural head position and transfer it to the cephalostat, (2) to assess its clinical use, and (3) to evaluate the reproducibility of lateral cephalograms taken with the device. The device, incorporated into a pair of eyeglass frames, included 2 tilt sensors to measure pitch and roll of the head. The natural head positions of 20 subjects were established 10 times by self balance and mirror position, recorded with the device, and reproduced in the cephalostat by using the average of these 10 measurements. Three lateral cephalograms were obtained in this manner at 30-minute intervals. The first 2 films were made with the subject wearing the device to assess the reproducibility of the recorded position in the cephalostat by the inclinometer. During exposure of the third film, the device was not worn, and this film was used to determine the stability of the established position when the inclinometer was removed. The results revealed method errors of 0.6 degrees (SD, 0.9) between the first 2 sets of radiographs with a correlation coefficient of 0.985. Method errors between the first and third and the second and third sets were 0.6 degrees (SD, 0.8) and 0.7 degrees (SD, 1), respectively, with correlation coefficients of 0.989 and 0.982. The reproducibility of the method was high, and the system was clinically practical for both recording and transferring natural head position in cephalometrics. This technique should make it possible to measure and reproduce head position accurately. Minimizing the size of the device, making it radiolucent, and integrating it into the radiographic device will make it more versatile and decrease error.