Natural cervical inclination and craniofacial structure

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.

A radiologic parameter that could be applied in the development of sleep apnea in rheumatoid arthritis patients undergoing occipitocervical fusion

BACKGROUND

The prevalence of sleep apnea in rheumatoid arthritis (RA) patients with occipitocervical lesions was 79%. Occipitocervical fusion (OCF) could incur sleep apnea or worsen this condition. Recent studies reported that this complication is caused by stenosis of the oropharyngeal airway accompanying a decrease in the occipitoaxial angle (O-C2a). However, there are several limitations to the application of the O-C2a, which decreases its effectiveness. Therefore, we aimed to evaluate the association between a new radiologic parameter, the CVT/NSL angle (CVT: craniocervical inclination in the second and fourth vertebrae; NSL: Nasion-Sella line), and sleep apnea in RA patients accepting OCF.

METHODS

A total of 35 patients who underwent OCF due to upper cervical lesions secondary to RA and had sleep apnea before surgery were analyzed. Those who have a postoperative apnea-hypopnea index (AHI) < 15 and a ΔAHI ≥50% were considered "responders"; patients were otherwise considered "non-responders." They were analyzed whether pre- and postoperative radiologic parameters and their differences in plain lateral radiographs were correlated to the parameter related to sleep apnea.

RESULTS

The included patients have a mean AHI of 21.9 (range, 10 to 52) before surgery. The mean postoperative CVT/NSLa, ΔCVT/NSLa, andΔO-C2a in complete responders were significantly greater compared with non-responders (p < 0.05). Both the changes in the CVT/NSLa and O-C2a were linearly correlated within patients. However, the R² value for the CVT/NSLa was greater compared with the O-C2a (0.403 vs. 0.203).

CONCLUSIONS

The usefulness of the new craniovertebral angle, CVT/NSLa, as an intraoperative indicator during OCF, is more valuable in comparison with the conventional method of measuring the O-C2a. Measuring the craniovertebral angle is extremely important in the planning of surgical treatment for the development of sleep apnea in rheumatoid arthritis patients undergoing occipitocervical fusion.

Morphometric characteristics of cervical vertebrae in subjects with short, normal, and long faces

PURPOSE

The prolonged change in the head posture alters the morphological characteristics of cervical vertebrae. The difference in the head posture among subjects with short, normal, and long anterior facial heights might have a significant influence on the morphological characteristics of cervical vertebrae. Thus, the present study was conducted to evaluate the morphometric characteristics of cervical vertebrae in subjects with short, normal, and long faces.

METHODS

Based on Frankfort mandibular plane angle (FMA) on lateral cephalograms, 135 subjects were equally divided into three groups, i.e. Group I [Short face], II [Normal face], and III [Long face]. The angular variables like Atlas-dens angle (ADA), Pars interarticularis-dens angle (PDA), Pars interarticularis-vertebrae angle of C3 vertebrae (PVA3), Pars interarticularis-vertebrae angle of C4 vertebrae (PVA4), Lamina-Pars interarticularis angle of C2 vertebrae (LP2), Lamina-Pars interarticularis angle of C3 vertebrae (LP3), and Lamina-Pars interarticularis angle of C4 vertebrae (LP4) in the first four cervical vertebrae were measured, analyzed, and compared. Descriptive statistics, analysis of variance, Bonferroni, and Pearson's correlation coefficient tests were used. The P value of 0.05 was considered as the level of significance.

RESULTS

All parameters except PDA and PVA3 were comparable among the groups. The PDA was 54.35⁰ ± 1.87⁰, 57.89⁰ ± 1.55⁰, and 60.29⁰ ± 2.83⁰ in Group I, II, and III, respectively; these differences were statistically significant [P < 0.001]. The PVA3 was 42.70⁰ ± 5.64⁰ in Group I, 45.85⁰ ± 3.82⁰ in Group II, and 45.59⁰ ± 5.53⁰ in Group III subjects that were also statistically significant [P < 0.01]. A fairly strong positive correlation was observed between FMA and PDA.

CONCLUSION

A significant difference was found in the PDA among subjects with short, normal, and long faces. The vertical height of the face had a strong correlation with the morphology of axis vertebra.

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.

The relationship between lateral displacement of the mandible and scoliosis

OBJECTIVES

Idiopathic scoliosis is an orthopaedic disease of childhood, with onset and progress occurring until adolescence. Here, the relationship between lateral displacement of the mandible and scoliosis was analysed quantitatively.

METHODS

Seventy-nine non-syndromic Japanese patients (18 men, 61 women), who were diagnosed with jaw deformities and underwent surgical orthognathic treatment at Kyushu University Hospital from January 2011 to August 2014, were enrolled. Their mean age at the time of radiography was 25.3 ± 8.7 years. Postero-anterior cephalometric radiographs and chest radiographs were examined. In postero-anterior cephalometric radiographs, a horizontal baseline (X-axis) was drawn as a straight line that intersects both the zygomatic bases, and a vertical line (Y-axis) was marked perpendicular to the X-axis, with an intersection at the anterior nasal spine (ANS). Point A was defined as the intersection of the X- and Y-axes, and line A was defined as the line connecting point A to the menton. The angle made by the X-axis and line A (i.e., lateral displacement of the mandible) was measured. We designated an absolute value even if the mandibular menton was located on the right or left side. In chest radiographs, Cobb's method was used to measure scoliosis curves; the direction of the curve was designated similarly.

RESULTS

Nine (11.4%) individuals had a Cobb angle >10°. There was a positive correlation between the Cobb angle and the degree of mandibular deviation (p < 0.05).

CONCLUSION

Lateral displacement of the mandible and scoliosis are related.

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.

The relation between idiopathic scoliosis and the frontal and lateral facial form

OBJECTIVE

The purpose of this study was to evaluate the relation between idiopathic scoliosis and facial deformity in the horizontal, vertical, and anteroposterior planes.

METHODS

A total of 123 female patients aged 14 years or older, who visited the Spine Clinic at the Department of Orthopedics, Korea University Guro Hospital for treatment of idiopathic scoliosis, were enrolled. Whole-spine anteroposterior and lateral radiographs were taken with the patient in a naturally erect position, and frontal and lateral cephalograms were taken in an erect position with the Frankfort horizontal line parallel to the floor. Scoliosis was classified according to the Cobb angle and Lenke classification of six curve types. Cephalometric tracing in all cases was carried out with V-Ceph 5.5 by the same orthodontist. The Kruskal-Wallis test was performed to determine whether any relation existed between each group of the idiopathic scoliosis classification and the cephalometric measurements of frontal and lateral cephalograms.

RESULTS

The measurements did not reveal any significant association between the Cobb angle and cephalometric measurements and between the curve type based on the Lenke classification and cephalometric measurements.

CONCLUSIONS

Based on the results of this study, no apparent relation was observed between the severity of scoliosis and facial form variations in idiopathic scoliosis patients.

Cephalometric investigation of first cervical vertebrae morphology and hyoid position in young adults with different sagittal skeletal patterns

The aim of this retrospective study was to examine hyoid bone position and C1 (atlas) morphology in males and females and analyze these parameters with respect to different sagittal skeletal patterns via cephalometry, with the goal of identifying cephalometric norms. Lateral cephalometric radiographs from 120 individuals (average age: 21.1 ± 2.9 years) were classified according to their ANB angle (Class I, II, or III) and used to assess 14 parameters. Class I and II patients showed significant differences in Hy-NSL, Hy-PD, Hy-CVT, Lum, and a-p measurements. These parameters were consistently larger in males than in females. Intergroup comparisons among males showed significant differences in the SNA, ANB, Hy-CVT, X, and Z measurements. The hyoid was positioned more inferiorly and anteriorly and was more prominent in males than in females in all groups. Among participants exhibiting a Class I skeletal pattern, C1 was also larger in the anterior-posterior direction in males than in females. In the sagittal plane, the hyoid was positioned similarly in males with either Class I or III skeletal patterns but was positioned posteriorly in males with a Class II skeletal pattern. In addition, the vertical position of C1 varied with sagittal skeletal pattern in males.

Natural head position and growth of the facial part of the skull

The aim of this study was to determine any correlation between natural head position and cranio-cervical growth direction and if natural head position influences facial growth direction. One hundred sixty (160) cephalometric radiographs were examined and cranio-cervical inclinations determined (angles: NS-Ver, NS-OPT, NS-CVT). On the basis of the NS-ML angle, radiographs were divided into two groups: mandibular anteriorotation and posteriorotation. On the basis of the SGo/NMe index, two groups were formed: short-faced and long-faced subjects. The angles NS-Ver, NS-OPT, and NS-CVT describe cranio-cervical inclination. Subjects with anterior mandible growth do position their heads more vertically and have a shorter face, and those with posterior mandible growth tilt their heads more backwards and have a longer face. An adaptive head position can be a factor in altering the direction of facial growth. Determination of head position and mandible growth direction can be an important indicator in patients with TMD treatment.

Three-dimensional changes of the hyoid bone and airway volumes related to its relationship with horizontal anatomic planes after bimaxillary surgery in skeletal Class III patients

OBJECTIVE

To evaluate longitudinal changes of the hyoid bone position and pharyngeal airway space after bimaxillary surgery in mandibular prognathism patients.

MATERIALS AND METHODS

Cone-beam computed tomography scans were taken for 25 mandibular prognathism patients before surgery (T0), 2 months after surgery (T1), and 6 months after surgery (T2). The positional displacement of the hyoid bone was assessed using the coordinates at T0, T1, and T2. Additionally, the volume of each subject's pharyngeal airway was measured.

RESULTS

The mean amount of posterior maxilla impaction was 3.76 ± 1.33 mm as the palatal plane rotated 2.04° ± 2.28° in a clockwise direction as a result of bimaxillary surgery. The hyoid bone moved backward (P < .05, P < .001) and downward (P > .05, P < .05) at 2 months and 6 months after surgery, while the total volume of the pharyngeal airway significantly decreased at the same time points (P < .001, P < .001). There was significant relationship between the changes of the hyoid bone position and airway volume at 2 months after surgery (P < .05). The change of the palatal plane angle was positively correlated to the decrease in the total airway volume (P < .001).

CONCLUSIONS

The null hypothesis was rejected. The hyoid bone moved inferoposteriorly, and the pharyngeal airway volume decreased for up to 6 months after bimaxillary surgery. The decrease in the pharyngeal airway volume was correlated to the changes in the palatal plane inclination and the positional change of the hyoid bone.

A correlational study of scoliosis and trunk balance in adult patients with mandibular deviation

Previous studies have confirmed that patients with mandibular deviation often have abnormal morphology of their cervical vertebrae. However, the relationship between mandibular deviation, scoliosis, and trunk balance has not been studied. Currently, mandibular deviation is usually treated as a single pathology, which leads to poor clinical efficiency. We investigated the relationship of spine coronal morphology and trunk balance in adult patients with mandibular deviation, and compared the finding to those in healthy volunteers. 35 adult patients with skeletal mandibular deviation and 10 healthy volunteers underwent anterior X-ray films of the head and posteroanterior X-ray films of the spine. Landmarks and lines were drawn and measured on these films. The axis distance method was used to measure the degree of scoliosis and the balance angle method was used to measure trunk balance. The relationship of mandibular deviation, spine coronal morphology and trunk balance was evaluated with the Pearson correlation method. The spine coronal morphology of patients with mandibular deviation demonstrated an "S" type curve, while a straight line parallel with the gravity line was found in the control group (significant difference, p<0.01). The trunk balance of patients with mandibular deviation was disturbed (imbalance angle >1°), while the control group had a normal trunk balance (imbalance angle <1°). There was a significant difference between the two groups (p<0.01). The degree of scoliosis and shoulder imbalance correlated with the degree of mandibular deviation, and presented a linear trend. The direction of mandibular deviation was the same as that of the lateral bending of thoracolumbar vertebrae, which was opposite to the direction of lateral bending of cervical vertebrae. Our study shows the degree of mandibular deviation has a high correlation with the degree of scoliosis and trunk imbalance, all the three deformities should be clinically evaluated in the management of mandibular deviation.

Cervical vertebra morphology in different skeletal classes. A three-dimensional computed tomography evaluation

OBJECTIVE

To describe cervical vertebra morphology in subjects with different anteroposterior jaw relationships.

MATERIALS AND METHODS

Cone-beam computed tomography images of 31 female subjects aged 19 to 41 years were evaluated. Subjects constituted two groups according to the ANB angle: group 1, skeletal Class II (ANB angle >5); and group 2, skeletal Class III (ANB angle <1). Nine linear measurements and one angular measurement were used to assess the vertebral morphology. The Mann-Whitney U-test was used for statistical analysis.

RESULTS

The mean atlas dorsal arch height was significantly shorter in Class II subjects compared with those in Class III (P < .05). The cervical vertebra morphological analysis by cone-beam computed tomography was of comparable precision to three-dimensional computed tomography evaluations. This study confirmed previous findings that Class II subjects have significantly lower atlas dorsal arch heights.

CONCLUSION

The height of the atlas dorsal arch of cervical vertebrae is affected by the anteroposterior skeletal pattern.

Asymmetric muscle function in patients with developmental mandibular asymmetry

The aim was to test the hypothesis that developmental mandibular asymmetry is associated with increased asymmetry in muscle activity. Patients with mandibular condylar and/or ramus hyperplasia having unilateral cross-bite were compared with healthy subjects with normal occlusion. Muscle activity was recorded with surface electrodes in the masseter, suprahyoid, sternocleidomastoid muscle (SCM) and upper trapezius areas during jaw opening-closing-clenching, head-neck flexion-extension, and elevation-lowering of shoulders. Root mean square (RMS) and mean power frequency (MPF) values were calculated and analysed using anova and t-tests with P < 0.05 chosen as significance level. The SCM and masseter muscles showed co-activation during jaw and head movements, significantly more asymmetric in the patients than in the healthy subjects. The RMS and MPF values were higher in the patients than in the controls in the SCM and suprahyoid areas on both sides during jaw opening-closing movement. The results indicate that the ability to perform symmetric jaw and neck muscle activities is disturbed in patients with developmental mandibular asymmetry. This is of clinical interest because asymmetric activity may be an etiologic factor in temporomandibular joint and cervical pain. The results support that co-activation occurs between jaw and neck muscles during voluntary jaw opening and indicate that postural antigravity reflex activity occurs in the masseter area during head extension. Further studies, where EMG recordings are made from the DMA patients at early stages are motivated to verify activity sources and test if the asymmetric activity is associated with muscle and joint pain in the jaw and cervical areas.

Relationship between head posture and hyoid position in adult females and males

AIM

The aim of this study was to investigate head posture and hyoid bone position using cephalometric radiographs of adults.

MATERIAL AND METHODS

The material consisted of 76 cephalometric films (38 each male/female) taken at the natural head posture. The individuals were over 18 years of age, had parents of Turkish origin, an acceptable face structure, ideal dental occlusion, and an ANB angle of 1-5 degrees; the dentitions were complete except the third molars and there were no visual, hearing, breathing or swallowing disorders. In addition, the subjects had not undergone orthodontic treatment or orthognathic surgery, had no burns, injuries, or scars in the head and neck regions. In order to determine the natural head position, the subjects were asked to stand in a relaxed manner (the self-balance position), and this position was transferred to the cephalostat by means of a fluid level device. The differences among sexes were investigated by means of Student's t-test, carried out using SPSS (Windows 7.5).

RESULTS

It was found that there were no sex variations in head position. The linear measurements regarding the position of hyoid bone showed statistically significant differences with respect to sex. However, hyoid bone position was higher and more posterior in females, while natural head position was not affected by sex.

Evaluation of cervical posture of children in skeletal class I, II, and III

Previous studies on the relationship between morphological structure of the face and cervical posture have predominantly focused on vertical dimensions of the face. The aim of this study was to investigate whether there are significant differences in cervical posture in subjects with a different sagittal morphology of the face, i.e., a different skeletal class. One hundred twenty (120) children (60 males and 60 females, average age 9.5 yrs., SD+/-0.5) were admitted for orthodontic treatment. Selection criteria was: European ethnic origin, date of birth, considerable skeletal growth potential remaining and an absence of temporomandibular joint dysfunction (TMD). Lateral skull radiographs were taken in mirror position. Subjects were divided into three groups based on their skeletal class. The cephalometric tracings included postural variables. The most interesting findings were: 1. children in skeletal class III showed a significantly lower cervical lordosis angle (p<0.001) than the children in skeletal class I and skeletal class II; 2. children in skeletal class II showed a significantly higher extension of the head upon the spinal column compared to children in skeletal class I and skeletal class III (p<0.001 and p<0.01, respectively). This is probably because the lower part of their spinal column was straighter than those of subjects in skeletal class I and II (p<0.01 and p<0.001, respectively). Significant differences among the three groups were also observed in the inclination of maxillary and mandibular bases to the spinal column. The posture of the neck seems to be strongly associated with the sagittal as well as the vertical structure of the face.

Investigation of natural head posture in different head types

The aim of this study was to investigate natural head posture (NHP) in different head types. Lateral cephalograms of 99 adults (Mean age, 21.8 years +/- SD, 2.2 yrs, range between 19 and 29 yrs) were examined. Head types were determined as Hyperbrachycephal, Brachycephal, Mesocephal or Dolichocephal according to the cephalic index. Analysis of variance and the Duncan's test were performed to assess inter-group differences for the parameters. The findings revealed that, NHP was statistically not different between the head type groups. Thus, it was suggested that environmental factors during growth may alter NHP, as well as craniofacial morphology but in a different manner (i.e. degree and direction) in each head type.

Cervical lordosis angle measured on lateral cephalograms; findings in skeletal class II female subjects with and without TMD: a cross sectional study

The literature reports evidence of various types of correlations between cervical alterations and cervical pain, and the existence of cervical pain in subjects with temporomandibular joint internal derangement (TMD). The hypothesis of this study is that cervical lordosis angle (CVT/EVT angle) alteration on cephalometrics could be correlated to the presence of TMD. The cephalometric records of 50 females with documented TMD were compared with those of a control group of 50 females. The subjects in the sample were 25-35 years of age, average 28.9 years (SD, 3.2). Radiographs were taken in mirror position, and seventeen variables, including the CVT/EVT angle, were traced. Double measurements were made to evaluate method error using Dahlberg's formula. Pearson's correlation coefficient and Mann-Whitney's t-test were used to evaluate the data. Intra-group analysis showed significant correlations between the CVT/EVT angle and mandibular length (p<0.01), mandibular position (p<0.05), mandibular divergence (p<0.01), and overjet (p<0.01) in both groups. Between groups, the analysis showed significant differences in CVT/EVT angle (p<0.05), maxillary protrusion (p<0.01), mandibular protrusion (p<0.01), mandibular length (p<0.01), mandibular divergence (p<0.05), and overbite (p<0.05).

The effect of head posture on the pharyngeal airway space (PAS)

The purpose of this study was to investigate the relationship between cranio-cervical inclination and pharyngeal airway space (PAS) by measuring these parameters at different head postures in the same subjects and to obtain a regression equation to correct the values measured. Fifty lateral cephalometric radiographs taken at five different head postures per individual were obtained from ten adults (seven males and three females) aged from 25 to 30 years with nose breathers and Class I occlusion. The changes in cranio-cervical inclination produced by head extension were correlated with changes in the variables describing the PAS. The OPT/NSL (cranio-cervical inclination in the second vertebrae) and C3-Me (distance between the third vertebrae and the Menton) correlated strongly with PAS-TP (the most proximal distance measured between the posterior pharyngeal wall and the tongue base) in the pharyngeal airway space (r = 0.807 and 0.854 respectively). The regression equations were Y = - 27.177+0.39X (Y = PAS-TP, X = OPT/NSL), and Y = -21.105+0.402X (Y = PAS-TP, X = C3-Me), respectively. From these equations we could conclude that an increase of 10 degrees in OPT/NSL or 10 mm in C3-Me increased the pharyngeal airway space (PAS-TP) by about 4 mm.

Relationship of natural head position to craniofacial morphology

This investigation aimed at discussing the utility of natural head position-based cephalometric variables and to evaluate the relationship between natural head position and craniofacial morphology. Lateral facial photographs and cephalograms of 284 young adult males taken in a natural head position were analyzed. The average inclination of the intracranial reference planes, Frankfurt horizontal, and palatal plane, in relation to the true horizontal were nearly similar and smaller than 1 degrees. Variables based on the true vertical to describe mandibular sagittal position like B-N(vert) and Pg-N(vert) had very high variances. To study the topographic error, flexors and extenders were identified on basis of four positional variables: NSL/VER; FH/VER; PP/VER; and PMvert/VER. Only 15 measurements were different, according to at least 2 of the 4 positional variables. The 3 that were different in all categories were: facial axis (NBa/PmGn), lower face height (ANS-Me), and the facial ratio (N-ANS/ANS-Me). The "extenders" had higher values for the facial axis and lower face height, and smaller for the face height ratio. Besides these 3 measurements, there was a tendency for the extenders to have increased anterior vertical height, distal sagittal relations, and smaller and retrognathic mandibles. Correlation coefficients between postural and morphologic variables tended to confirm these observations.