Anteroposterior Skeletal Patterns Research Articles

Assessment of hyoid bone position among different skeletal patterns

PurposeTo determine the hyoid bone position in subjects with various skeletal patterns. Materials and methodsConventional pre-treatment lateral cephalograms of 100 subjects aged 18–25 years were selected from the files of orthodontic patients based on anteroposterior skeletal pattern and facial divergence pattern. Subjects with Class I skeletal pattern (ANB 1–4°) were categorized into group A and group B depending on the measurements of Frankfort Mandibular Plane Angle (FMA) of 22–30° (normo divergence) and greater than 30° (hyper divergence) respectively. Likewise subjects with Class II skeletal pattern (ANB >4°) were categorized into group C and D, based on the above same divergence. The angular and linear measurements were recorded and measured. Statistical assessments include unpaired Student t-test and one-way analysis of variance (ANOVA). ResultsThe vertical position of hyoid bone was not affected by nature of horizontal or vertical growth pattern of the face. The mean anteroposterior position of the hyoid bone among the 4 groups of subjects was statistically significant (p<0.05). The position of hyoid bone in group D was significantly backward compared with the subjects in group A (p<0.05) or group C (p<0.05). The mean hyoid axis angle among subjects in the hyper divergent group (group B and group D) was high but insignificant. ConclusionThe position of hyoid bone was most posterior in subjects with skeletal Class II malocclusion associated with mandibular retrognathism.

Buccolingual inclination of the mandibular second molars with different anteroposterior skeletal patterns in cone-beam computed tomography

PurposeThe purpose of this study was to evaluate the buccolingual inclination of second mandibular molars between groups with varying sagittal skeletal relationship of maxilla and mandible using cone-beam computed tomography (CBCT). Materials and methodsThe sample consisted of 90 adult non-orthodontic treatment patients' CBCT images. They were divided into 3 groups according to sagittal skeletal pattern using Wits appraisal, which were skeletal Class I (13 men and 17 women), skeletal Class II (17 men and 13 women) and skeletal Class III (13 men and 17 women) with an average age of 37.6 years. All subjects had a normal vertical skeletal pattern and had mandibular deviation less than 3mm. Buccolingual inclination was measured in a radiographic software as the angle between the long axis of lower second molars and a reference line tangent to the lower border of the mandibular body. ResultsThere was a statistically significant difference of second mandibular molar buccolingual inclination between the three groups (p=0.000), with a decreasing trend of the inclination angle from skeletal Class II to skeletal Class III. Wits appraisal had a moderate positive correlation with mandibular second molar buccolingual inclination (R=0.648). ConclusionPretreatment patients with different sagittal skeletal patterns have different buccolingual inclination of mandibular molars. These results might affect the preparation of orthodontic appliances or treatment technique.

Relationships among maxillofacial morphologies, bone properties, and bone metabolic markers in patients with jaw deformities

The aim of this study was to determine the relationships among bone properties, bone metabolic markers, and types of jaw deformity. The subjects were 55 female patients with jaw deformities. Skeletal morphology was examined using lateral cephalograms, and the patients were divided into three groups according to the type of anteroposterior skeletal pattern. Serum osteocalcin, bone alkaline phosphatase, and tartrate-resistant acid phosphatase isoform 5b, as well as deoxypyridinoline in urine, were measured as bone metabolic markers. Quantitative ultrasound (QUS) measurements were used to assess bone properties at the calcaneal bone. The bone volume and bone density of the condylar process were measured in 43 patients by computed tomography. There were no significant differences in bone metabolic markers and QUS parameters between the groups, although bone formation and resorption markers tended to be higher in patients with a protrusive mandible. On the other hand, patients with mandibular retrusion had a higher tendency to have small and dense condylar processes. In conclusion, the results suggest that growth depression or a degenerative change in the mandibular condyle is involved in the pathogenesis of mandibular retrusion, although risk factors for progressive condylar resorption were not determined.

Effects of orthognathic surgery on psychological status of patients with jaw deformities

The purpose of this study was to determine the effect of orthognathic surgery on psychological status. The subjects were 119 patients (38 males and 81 females, mean age 25.5±9.4 years) who underwent orthognathic surgery. They were divided into class III (84 patients), class II (20 patients), and class I (15 patients) groups according to the anteroposterior skeletal pattern, and they were also divided into an asymmetry group (51 patients) and a symmetry group (68 patients). We assessed psychological status using the Minnesota Multiphasic Personality Inventory (MMPI) before surgery and at more than 6 months after surgery. The MMPI scores for the depression, hysteria, psychasthenia, and social introversion scales were significantly higher than standard values before surgery, and the hypomania scale significantly lower. The cannot say scale, depression scale, and hysteria scale decreased significantly after surgery. A comparison of MMPI scores among the groups showed the depression scale in the class III group to be higher than those in the class I and II groups; there was no significant difference between the asymmetry and symmetry groups. In conclusion, orthognathic surgery has a positive influence on the psychological status of patients with jaw deformities, especially patients with skeletal class III malocclusion.

Proximal Segment Changes After Bilateral Sagittal Split Ramus Osteotomy in Facial Asymmetry Patients

To investigate the 3-dimensional postoperative changes in the proximal segments in patients with facial asymmetry according to the anteroposterior skeletal patterns. A total of 51 patients with facial asymmetry who had undergone Le Fort I osteotomy and sagittal split ramus osteotomy (SSRO) with rigid fixation were classified according to their anteroposterior skeletal patterns. Cone-beam computed tomography (CBCT) data were obtained before (T0) and 6 months (T1) after surgery. The position, angulation, and distance of the proximal segment were measured from the CBCT superimposition. Comparing the T0 and T1 CBCT data, almost no significant differences were found in the condylar head position in any of the groups (P > .05), except for the axial condylar head position on the deviated side in the skeletal Class I group (P < .05) and the sagittal condylar head position on the deviated side in the skeletal Class III group (P < .05). However, the changes in the coronoid process and ramus down varied (P < .05), and these movements were related to changes in the ramal plane. Comparing the deviated and nondeviated sides, significant differences were found only in the skeletal Class I group (P < .05). The most influential factors affecting differences between the deviated and nondeviated sides in patients with facial asymmetry after bilateral SSRO could be the direction of the surgical movement of the distal segment of the mandible rather than its extent.

A lateral cephalogram study for evaluation of pharyngeal airway space and its relation to neck circumference and body mass index to determine predictors of obstructive sleep apnea

Introduction: The airway is assumed to play a role in dentofacial development. So, several studies tried to correlate patients with normal nasorespiratory functions with different malocclusions and airway dimensions. A narrow upper airway is associated with obstructive sleep apnea (OSA). Currently neck size and obesity are considered to be the most important physical characteristics of patients with sleep apnea. Aim: To study the interaction between craniofacial structures and pharyngeal airway space along with soft palate and tongue in patients with different anteroposterior skeletal patterns using lateral cephalogram. The correlation of upper airway and soft-tissue measurements with neck circumference (NC) and body mass index (BMI) was elucidated to evaluate the predictors on lateral cephalogram, in order to determine the etiology of OSA. Materials and Methods: Lateral cephalograms of 45 subjects were used to measure the pharyngeal airway and were divided into three groups (each group included 15 subjects) according to ANB angle: Class I (ANB angle 2°-4°), Class II (ANB angle >4°), and Class III (ANB angle <2°). Velar morphology along with its length was also analyzed and categorized into different types. The NC and BMI of all the patients were also calculated. Student's t-test for paired samples was used to compare the mean values of the study variable vital parameters. Results: Significant reduction was found in pharyngeal airway in ANB group II. The soft palate and tongue size increased with increasing BMI and NC. Conclusion: Sagittal skeleton pattern had a close association with the dimensions of pharyngeal airway passage. The correlation of NC with increase in soft-tissue size (soft palate and tongue) suggested that obesity mediates its effects in OSA through fat deposition in the neck.

Three‐dimensional evaluation of upper airway in patients with different anteroposterior skeletal patterns

To investigate variability in the upper airway of subjects with different anteroposterior skeletal patterns by evaluating the volume and the most constricted cross-sectional area of the pharyngeal airway and defining correlations between the different variables. The study sample consisted of 60 patients (29 boys, 31 girls) divided into three groups: Class I (1 ≤ ANB ≤ 3), Class II (ANB>3), and Class III (ANB<1), to evaluate how the jaw relationship affects the airway volume and the most constricted cross-sectional area (Min-CSA). Differences between groups were determined using the Tukey-Kramer test. Correlations between variables were tested using Pearson's correlation coefficient. The volume and the Min-CSA of the pharyngeal airway (PA) were significantly related to anteroposterior skeletal patterns (p < 0.05). The nasopharyngeal airway (NA) volume of Class I and Class III subjects was significantly larger than that of Class II subjects (p < 0.05). The Min-CSA and the length of PA were significantly related to the volume of PA (p < 0.05). The site and the size of the Min-CSA varied among the three groups. The volume and the most constricted cross-sectional area of the airway varied with different anteroposterior skeletal patterns. The NA volume of Class I and Class III subjects was significantly larger than that of patients with a Class II skeletal pattern.

Three-dimensional condylar positions and forms associated with different anteroposterior skeletal patterns and facial asymmetry in Chinese adolescents

Objective. To evaluate the association of condylar asymmetry and chin position with different anteroposterior skeletal patterns using three-dimensional models reconstructed from cone-beam computed tomography (CBCT) images. Materials and methods. CBCT scans of 123 Chinese adolescents (aged 11–15 years, 68 girls and 55 boys) with 64 skeletal Class I, 46 Class II and 13 Class III were selected from scans of patients attending the orthodontic clinic. The condyles of the subjects were reconstructed bilaterally and 25 linear, angular and volumetric measurements were performed to evaluate the asymmetry of the condyles and position of the chin. The proportions of condylar asymmetry in the different skeletal groups were calculated by the absolute difference value between the left and right sides to the smaller side value. One-way analysis of variance and Pearson's correlations were used to analyse the data. Results. The values for RV, RCL, LCH, RCH, LCGM, RCGM, LCo-Me and RCo-Me were significantly different among the three skeletal groups (p < 0.05). There were significant positive correlations between Pog-Ss and Co-Sh, Co-Me in the Class I and II groups (p < 0.05). Asymmetries for Co-Ss, Co-Sh, CP and SP between the left and right condyles exceeded a ratio of 20% for more than 30% of the subjects. Conclusion. Condylar asymmetry varied significantly among the three skeletal groups, with the vertical position of the condyle (Co-Sh) and height of the mandibular ramus (Co-Me) being significantly and positively related to the chin position.

Evaluation of pharyngeal airway space amongst different skeletal patterns

The aim of the present study was to evaluate the dimensions of the pharyngeal airway space (PAS) in awake, upright children with different anteroposterior skeletal patterns using cone beam computed tomography (CBCT). The volume, area, minimum axial area and seven linear measurements of PAS were obtained from the CBCT images of 50 children (mean age 9.16 years). The patients were divided in two groups according to the ANB angle (group I 2°≤ANB≤5°; group II ANB>5°). Means and standard deviations of each variable were compared and correlated using independent t-test and Pearson's correlation test. There were statistically significant differences in the following parameters: angle formed by the intersection between NA and NB lines (p<0.001), angle formed by the intersection between SN and NB lines (p<0.05), Minimal pharyngeal airway space between the uvula and the posterior pharyngeal wall (p<0.05), airway volume (p<0.01), airway area (p<0.01) and minimum axial area (p<0.05). The anteroposterior cephalometric variable SNB had positive correlation with the variables PAS-UP (p<0.01), Minimal pharyngeal airway space between the uvula tip and the posterior pharyngeal wall (p<0.05), Pharyngeal airway space on mandibular line (p<0.05), Minimal pharyngeal airway space between the back of the tongue and the posterior pharyngeal wall (p<0.05), volume airway (p<0.05), airway area (p<0.05) and minimum axial area (p<0.05). The vertical cephalometric variables angle formed by the intersection between SN and GoGn lines (p<0.05) and angle formed by the intersection between FH and mandible plane (p<0.05) showed negative correlation with PAS-UT. These results showed that PAS was statistically larger in group I than group II, indicating that the dimensions of the PAS are affected by different anteroposterior skeletal patterns.

Mandibular third molar space in different antero-posterior skeletal patterns

Retromolar space has long been identified as a major factor in the aetiology of mandibular third molar impaction. The aims of this study were to compare mandibular third molar space between the different antero-posterior (A-P) skeletal patterns, between erupted and impacted third molars in the different A-P skeletal patterns, and to report on the status of third molar eruption/impaction among the studied subjects. A total of 432 mandibular third molars in 270 subjects (132 females and 138 males) were investigated from dental pantomograms (DPTs) and lateral cephalograms (LC). The average age for the total sample was 20.80 ± 2.03 years. The subjects were divided into three groups according to their ANB angle as follows: skeletal Class I (144 third molars in 90 subjects), skeletal Class II (145 third molars in 95 subjects), and skeletal Class III (143 third molars in 85 subjects). Each group was subdivided into impacted and erupted subgroups. DPT and LC were traced and the following variables were measured: retromolar space width, third molar width and angulation, β angle, second molar angulation, mandibular length, and gonial angle. Independent t-test, analysis of variance, and chi-square test were used for statistical analysis. Retromolar space width in the Class III subjects was smaller than in the Class I subjects (P < 0.05). Mandibular third molars were recorded as impacted in 26, 32, and 42 per cent of the Class I, II, and III subjects, respectively (P < 0.001). The impacted groups had a reduced retromolar space width, increased β angle, and reduced third molar angulation in all A-P skeletal patterns. Class III subjects showed increased mandibular third molar impaction with reduced retromolar space width.

Cervical vertebra morphology in different skeletal classes

To describe cervical vertebra morphology in subjects with different anteroposterior jaw relationships. 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. 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. The height of the atlas dorsal arch of cervical vertebrae is affected by the anteroposterior skeletal pattern.

Three-dimensional analysis of pharyngeal airway in preadolescent children with different anteroposterior skeletal patterns

In growing patients with skeletal discrepancies, early diagnosis, evidence-based explanations of etiology, and assessment of functional factors can be vital for the restoration of normal craniofacial growth and the stability of the treatment results. The aims of our study were to compare the 3-dimensional pharyngeal airway volumes in healthy children with a retrognathic mandible and those with normal craniofacial growth, and to investigate possible significant relationships and correlations among the studied cephalometric variables and the airway morphology in these children. Three-dimensional airway volume and cross-sectional areas of 27 healthy children (12 boys, 15 girls; mean age, 11 years) were measured by using cone-beam computed tomography volume scans, and 2-dimensional lateral cephalograms were created and analyzed. The subjects were divided into 2 groups based on their ANB angles (group I: 2 degrees < or = ANB < or = 5 degrees ; group II: ANB >5 degrees ), and cephalometric variables, airway volumes, and cross-sectional measurements were compared. There were statistically significant differences in the following parameters: height of the posterior nasal plane (P <0.05), pogonion to nasion perpendicular distance (P <0.01), ANB angle (P <0.01), mandibular body length (P <0.01), facial convexity (P <0.01), and total airway volume (P <0.05). No statistically significant differences between the 2 groups were found in the cross-sectional area and the volumetric measurements of the various sections of the airway except for total airway volume, which had larger values in group I (P <0.05). The mean total airway volume, extending from the anterior nasal cavity and the nasopharynx to the epiglottis, in retrognathic patients was significantly smaller than that of patients with a normal anteroposterior skeletal relationship. On the other hand, differences in volume measurements of the 4 subregions of the airway were not statistically significant between the 2 groups.

Editor's Summary and Q&A: Three-dimensional analysis of pharyngeal airway in preadolescent children with different anteroposterior skeletal patterns

Introduction In growing patients with skeletal discrepancies, early diagnosis, evidence-based explanations of etiology, and assessment of functional factors can be vital for the restoration of normal craniofacial growth and the stability of the treatment results. The aims of our study were to compare the 3-dimensional pharyngeal airway volumes in healthy children with a retrognathic mandible and those with normal craniofacial growth, and to investigate possible significant relationships and correlations among the studied cephalometric variables and the airway morphology in these children. Methods Three-dimensional airway volume and cross-sectional areas of 27 healthy children (12 boys, 15 girls; mean age, 11 years) were measured by using cone-beam computed tomography volume scans, and 2-dimensional lateral cephalograms were created and analyzed. The subjects were divided into 2 groups based on their ANB angles (group I: 2° ≤ ANB ≤ 5°; group II: ANB >5°), and cephalometric variables, airway volumes, and cross-sectional measurements were compared. Results There were statistically significant differences in the following parameters: height of the posterior nasal plane ( P P P P P P P Conclusions The mean total airway volume, extending from the anterior nasal cavity and the nasopharynx to the epiglottis, in retrognathic patients was significantly smaller than that of patients with a normal anteroposterior skeletal relationship. On the other hand, differences in volume measurements of the 4 subregions of the airway were not statistically significant between the 2 groups.

Uvulo-glosso-pharyngeal dimensions in different anteroposterior skeletal patterns.

The aim of this study was to investigate the uvulo-glosso-pharyngeal dimensions in subjects with different anteroposterior jaw relationship. Cephalometric radiograph of 90 subjects (45 females and 45 males, aged 14-17 years) were divided into three groups according to the ANB angle, ie, group 1, skeletal Class I (ANB angle 1-5); group 2, skeletal Class II (ANB angle >5); and group 3, skeletal Class III (ANB angle <1). In addition, each group was divided into two subgroups according to sex. Statistical analysis was undertaken using analysis of variance and least significant difference test. Pearson's Correlation test was also performed. Sex differences were found in Class I and III subjects. No sex differences were detected in Class II subjects. On average, tongue length was significantly shorter in Class III subjects (P < .05), tongue height was reduced in Class II female subjects, the soft palate was thicker in Class III females and the vertical airway length (VAL) was reduced in Class II male subjects (P < .01). In Class II subjects, the hyoid bone was closer to the mandible vertically and to C3 horizontally compared with Class I (P < .01) and Class III (P < .001) male subjects. Anteroposterior skeletal pattern showed a weak, but significant correlation with inferior pharyngeal airway space (R = -0.24, P = .024), vertical position of hyoid bone in relation to mandibular plane (R = -0.26, P = .014), and anteroposterior position of hyoid bone in relation to C3 (R = -0.561, P = .000). In conclusion, uvulo-glosso-pharyngeal dimensions are affected by anteroposterior skeletal pattern.

Antero-posterior skeletal patterning is not dependent on continuity of the apical ectodermal ridge in the chick wing bud.

The mechanism of antero-posterior specification of limb skeletal pattern is still controversial. If, as proposed by the ZPA model, a diffusible morphogen does exist, its route of passage across the limb field has not been resolved. To investigate the contribution of the apical ectodermal ridge (AER) to the control of antero-posterior pattern formation, we examined the consequences of small wounds made to the AER. The wound response was investigated by means of resin histology and scanning electron microscopy; subsequent limb development and cartilage pattern were examined in whole-mount preparations. Although regrowth of the bilaminate dorsal and ventral ectoderm over the wound occurred within 15 h, the more highly differentiated pseudostratified columnar epithelium of the AER did not reform, and there was subsequent retardation of limb outgrowth at the wound site. At 10-11 days of development, the appearance of the limbs allowed them to be placed into one of three categories; presence of supernumerary elements, accentuation of an inter-digital cleft, or normal. The first of these categories included limbs in which digit 3 had bifurcated such that the sum of the parts of the resultant digital skeleton was greater than that which forms in a normal limb. Since in all of the experimental limbs all skeletal elements were present, we propose that continuity of the AER is not a pre-requisite for antero-posterior skeletal pattern formation in the chick wing.