Studies on the relationship between body posture and craniofacial parameters often focus on the cervical spine. Thus, less attention has been paid to the morphology of the vertebra C2 that serves as both a structural and functional link between the craniofacial area and the other part of the spine. The objective of this study was to assess the relation of craniofacial features to certain morphological and positional characteristics of the cervical vertebrae and the spine during growth. We determined body posture indices for 69 children and adolescents by means of a radiation-free method (rasterstereography). The morphological and positional analysis of the craniofacial area and the cervical vertebrae was based on standardized lateral X-ray cephalograms. Medium to strong correlations were found between body posture, C2 morphology, and craniofacial parameters. We found significant correlations between the C2 dens axis height and maxillary indices as well as between the C2 dens axis inclination and cephalometrical values of the mandibular area. Similarly the correlation between the C2 dens axis inclination and the postural index flèche cervicale was highly significant (
Abnormal body posture has long been known to be a potential cause of various craniofacial orthopedic and orthodontic conditions [
As the first cervical vertebra to form a single joint with the next vertebra (C3), the
In this study, we investigated the relationship between sagittal postural parameters and the results of a cephalometrical examination involving a wide range of cephalometrical indices. We were particularly interested in how the morphological and positional properties of the cervical part of the spine are related to the various cephalometrical parameters. We also paid special attention to the morphological and positional parameters of C2.
Participants had been retrospectively recruited from a group of initially 100 patients classified as requiring orthodontic treatment within a period of 3 months. Exclusion criteria were presence of orthopedic illness (e.g., idiopathic scoliosis or
The mean patient age was 11 years and 10 months (range: 7 years and 11 months to 16 years and 11 months; SD: 2 years and 2 months). The male to female ratio was 21 : 48. Parents had been informed about the exclusion criteria, the aims, and the procedures of the study in both oral and written form. Underage children and adolescents participated in the study with their parents’ informed consent. The study conformed in all respects to the tenets of the Declaration of Helsinki and was approved by the local Ethics Committee.
Cephalometrical analyses in this study were carried out on the basis of standardized initial orthodontic treatment records. We used lateral skull radiographs for planning the orthodontic treatment of individual patients. In this way, patients were not exposed to additional X-rays for study purposes. All cephalograms were taken digitally by the same operator with a Sirona© Orthophos XGPlus cephalometrical device (Sirona© Dental Systems GmbH, Bensheim, Germany) and set to the program C3F with an image field of 24 × 27 cm. The X-ray source had a focus of 0.5 mm, and the exposure data were 73 kV and 15 mA for 14.9 s. We achieved a total enlargement rate of 11.7% by using a fixed focal plane length of 171.4 cm and a fixed midsagittal plane length of 20 cm and used a reference ruler for exact calibration. Cephalograms were taken in the morning in a natural body position, the so-called orthoposition [
Cephalograms were analyzed with the Planmeca Romexis Cephalometrical Analysis software 3.0 according to the Ricketts norms [
Cephalometric drawing: reference points and measurements.
The morphology of the cervical vertebrae was described by the following parameters (Figure C2p_C2a: the lower P-A width of the body of C2; C2m_C2m′—the lower concavity of the body of C2; C2s_C2i: the distance of the apex of C2 from the C2p_C2a line that determines the lower edge of the body of the vertebra; C2i_C2p: the posterior distance of the apex of C2 from C2p; C2p_C2i: the anterior distance of the apex of C2 from C2p; C3p_C3a: the lower P-A width of the body of C3; C3m_C3m′: the lower concavity of the body of C3; C4p_C4a: the lower P-A width of the body of C4; C4m_C4m′: the lower concavity of the body of C4. C2a_tGo: the vertical distance between the lowermost frontal point of the body of C2 and a plotted point representing the mandibular angle (Gonion, tGo) as measured perpendicularly to the Frankfurt horizontal.
The vertical position of the second cervical vertebra related to the mandibular angle was described by the following parameter (Figure
Inclination of the dens axis: (a) posterior inclination; (b) anterior inclination.
Vertical position of the second vertebra (C2): (a) above tGo; (b) below tGo.
Rasterstereographical images of the backs of the patients were obtained in the same examination session as the lateral skull radiographs with the Formetric II 3D/4D device (Diers International GmbH©, Schlangenbad, Germany), which has been designed to generate a three-dimensional photographical image of a person’s back in standing position. Images are generated with the help of a fine line grid projected onto the back of the subject. This grid provides information about the surface of the back at an error level of <0.1 mm [
Rasterstereographical back surface reconstruction: an optical line grid is projected onto the back of the patient, while a separate camera compiles optical measurement data from a different direction.
In the lateral view, sagittal curvatures can be characterized by the indices flèche cervicale and flèche lombaire. These values give the distance of the apex of the cervical and lumbar lordosis from a virtual vertical plumb line [
Rasterstereographical measurements (sagittal plane): (a) flèche cervicale or flèche lombaire: sagittal distance between the lowest point of the cervical or lumbar spine and the virtual vertical plumb line; (b) trunk inclination: angle between the connection line of the vertebral point (VP) and the midline of the right (DR) and left (DL) dimple points, representing the
The cephalometrical and rasterstereographical data of patients were blinded before measurements and statistical analysis. To determine the method error of the cephalometrical measurements, we used the Dahlberg’s formula: mean square error
All analyses were carried out using the Statistical Package for Social Sciences 17.0 (SPSS Inc., Chicago, Illinois, USA). Descriptive statistics were calculated with regard to mean, standard deviation, and range. Assumptions for parametrical tests were verified prior to significance testing. Correlations between the craniofacial, cervical, and posture parameters were assessed by Pearson’s correlation coefficient
The method error calculated by Dahlberg’s formula was below the acceptable reference error levels of 0.5° and 0.5 mm [
A correlation analysis of the cephalometrical craniofacial parameters (Table Trunk inclination was significantly correlated with +1/A-Pg ( Flèche cervicale was not significantly correlated with any of the variables. Flèche lombaire was significantly correlated with the interincisal angle (
Descriptive statistics of the cephalometrical analysis of the craniofacial parameters. SD: standard deviation.
Craniofacial parameters | Mean | SD | Minimum | Maximum |
---|---|---|---|---|
Craniofacial Morphology | ||||
Cranial deflection (°) | 27.79 | 2.53 | 20.77 | 36.22 |
Facial depth (°) | 85.86 | 3.08 | 79.63 | 92.26 |
Facial axis (°) | 88.54 | 4.31 | 76.41 | 96.52 |
Facial taper (°) | 68.72 | 4.16 | 58.58 | 80.61 |
Anterior cranial length (mm) | 54.28 | 2.87 | 48.38 | 62.40 |
Maxillomandibular Complex | ||||
Lower facial height (°) | 46.46 | 4.91 | 33.51 | 59.58 |
Xi-PM/Occ. (°) | 25.27 | 3.83 | 17.01 | 33.65 |
Xi-Occ. (mm) | 0.75 | 2.92 | −5.86 | 7.55 |
+1/A-Pg (°) | 28.04 | 7.54 | 13.99 | 46.20 |
−1/A-Pg (°) | 21.59 | 5.65 | 9.73 | 32.50 |
Interincisal angle (°) | 130.37 | 9.89 | 112.91 | 151.76 |
Overjet (mm) | 4.68 | 2.38 | 0.30 | 13.14 |
Overbite (mm) | 2.81 | 2.17 | −2.01 | 8.21 |
Maxilla | ||||
Landes angle (°) | 60.91 | 3.20 | 52.24 | 67.25 |
Maxillary height (°) | 56.37 | 3.36 | 48.32 | 66.21 |
Palatal plane to FH (°) | −1.37 | 3.85 | −11.76 | 10.74 |
Mandible | ||||
Ramus Xi position (°) | 70.11 | 6.03 | 39.07 | 84.01 |
Ramus height (mm) | 57.25 | 6.06 | 46.23 | 70.76 |
Mandibular arc (°) | 152.19 | 7.96 | 128.65 | 170.40 |
Esthetic relations | ||||
Lip protrusion (mm) | −0.71 | 2.74 | −9.10 | 4.83 |
Upper lip length (mm) | 20.21 | 2.06 | 17.01 | 26.65 |
Nasolabial angle (°) | 115.11 | 10.35 | 79.58 | 133.31 |
After correlating the cephalometrical cervical parameters (Table Trunk inclination was significantly correlated with the lower concavities of the vertebrae C2 ( Flèche cervicale was significantly correlated with the lower concavities of the same vertebrae: C2 ( Flèche lombaire values were not correlated with any of the cervical vertebrae indices.
Descriptive statistics of the cephalometrical analysis of the cervical parameters. SD: standard deviation.
Cervical parameters | Mean | SD | Minimum | Maximum |
---|---|---|---|---|
Cervical vertebra morphology | ||||
C2a_tGo (mm) | 4.41 | 4.43 | −4.02 | 14.77 |
C2p_C2a (mm) | 12.42 | 1.33 | 8.68 | 15.26 |
C2m_C2m′ (mm) | 0.71 | 0.59 | 0.00 | 2.42 |
C2s_C2i (mm) | 30.20 | 2.40 | 24.25 | 36.66 |
C2i_C2p (mm) | 3.95 | 2.38 | 0.00 | 12.34 |
C2p_C2i (mm) | 2.07 | 1.79 | 0.19 | 5.86 |
C3p_C3a (mm) | 12.65 | 1.26 | 8.75 | 17.06 |
C3m_C3m′ (mm) | 0.62 | 0.54 | 0.00 | 2.21 |
C4p_C4a (mm) | 12.66 | 1.24 | 8.69 | 16.62 |
C4m_C4m′ (mm) | 0.43 | 0.46 | 0.00 | 1.99 |
Descriptive statistics of the rasterstereographical analysis. SD: standard deviation.
Rasterstereographical sagittal values | Mean | SD | Minimum | Maximum |
---|---|---|---|---|
Flèche cervicale (mm) | 48.58 | 23.71 | 0.00 | 102.80 |
Flèche lombaire (mm) | 29.32 | 12.87 | 5.31 | 54.80 |
Trunk inclination (°) | 2.82 | 3.37 | −3.96 | 11.09 |
Correlation between dens axis inclination and flèche cervicale. The dashed curves denote the 95% confidence interval.
An important aim of this study was to determine whether the projection of the
A graphical representation of the results of the regression analysis between dens axis inclination and trunk inclination. The dashed curves denote the 95% confidence interval.
Of the cervical vertebrae indices (Table
The P-A width of the base of C2 (C2p_C2a) was significantly correlated with upper lip length (
The lower concavity of C2 (C2m_C2m′) was significantly correlated with lip protrusion (
The height of the dens axis of C2 (C2s_C2i) was significantly correlated with the following cephalometrical indices: upper lip length (
Of the variables characterizing the projection of the
The P-A width of the base of C3 (C3p_C3a) (Table
The P-A width of the body of C4 (C4p_C4a) (Table
Unlike earlier publications on the subject, we compared the results of rasterstereographical back surface analysis to those of a larger cephalometrical database [
The influence of body balance should be discussed regarding the position of the patient positioned meanwhile the examination of the head position and the body balance. The examinations in the lateral cephalographs were done in natural head position. No flexion or extension of the head was performed. The rasterstereographic images of the patients back surface were performed in natural standing position. This results in a normal patient individual body posture and the results of the lateral head cephalographs and the patients data showing kyphosis or lordosis could be analysed.
First of all, our data support the results of earlier craniofacial analyses by providing associated soft tissue and dental indices [
Although earlier research concentrated primarily on the structures of the dentofacial area, some of the significant but previously not described correlations found in this study may indicate new directions for further research. For instance, the correlation between trunk inclination and anterior cranial length may indicate a link between body posture and the formation of the craniobasal configuration during growth.
None of the cephalometrical indices were significantly correlated with flèche cervicale, and parameters of the cervical vertebrae did not show any significant correlation with flèche lombaire. At the same time, a strong positive correlation was found between the concavity of the bases of C2, C3, and C4, trunk inclination, and flèche cervicale. This correlation verifies that the sagittal curvatures of the spine become accentuated during skeletal maturation.
Beyond the concavity indices, flèche cervicale was also significantly correlated with the posterior projection of the
The strong correlation between the height of the dens axis with the dentoskeletal parameters of the mandible (e.g., inner gonial angle, lower incisor protrusion) deserves special attention. At the same time, indicators of the inclination of the dens axis show a strong correlation with maxillary parameters, such as the nasolabial angle, the upper incisor inclination, and the interincisal angle.
Therefore, the examined parameters of the cervical vertebrae are primarily correlated with structures of growth during this period.
Earlier studies involving all seven cervical vertebrae failed to find a correlation between cervical curvature and craniofacial morphology in adults [
Some significant correlations are difficult to explain. These include the correlation between trunk inclination and lip protrusion or the correlation between dens axis height and upper lip length. We propose that these are not real, generalizable correlations but rather result from the characteristics of our sample.
We also evaluated possible gender differences for the parameters studied, but none were found. Given that the age ranges included the pubertal growth period, this is a counterintuitive result. However, it must be noted that our sample used was not balanced in terms of gender (more than twice as many girls as boys) and that this could account for the gender indifference observed.
Our measurements of children and adolescents showed new associations between sagittal back surface parameters and a large number of craniofacial indices. Since these measurements were made in children and adolescents during the growth phase, the repetition of such measurements in adults, whose skeletal development is completed, seems to be indicated. Our results suggest that the morphological parameters of the vertebra C2 that is situated at the border of the craniofacial area in a position distinguished in both a structural and functional respect could be efficiently used in interdisciplinary orthopedic-orthodontic diagnostics.
The authors declare that there is no conflict of interests regarding the publication of this paper.