The use of linear and angular measurements of maxillo-mandibular anteroposterior discrepancies

Craniofacial Morphology of Temporomandibular Disorder Patients with Different Disc Positions: Stratifying Features Based on Sex and Sagittal Skeletal Pattern

Disc displacement (DD) appears in the majority of temporomandibular disorder (TMD) patients. The correlation between craniofacial morphology and different disc positions has been underlined, while the craniofacial morphological differences based on sex and sagittal skeletal pattern stratification have been insufficiently studied. In this study, 304 patients with TMD complaints were included and classified into normal position, disc displacement with reduction (DDwR) and disc displacement without reduction (DDwoR) groups according to magnetic resonance imaging. A total of 24 cephalometric measurements, covering the cranial base, vertical relationship, sagittal relationship, mandible position and morphology, and dental relationship, were assessed using lateral cephalograms. A stratified analysis was performed based on the sex and sagittal skeletal pattern. Overall, DD patients had distinctive craniofacial morphological features. The posterior cranial base length and mandibular arc angle were statistically different only in females, while the Y-axis angle, occlusal plane angle and sella nasion point A angle (SNA) might be unique features in males. Skeletal class II had the most statistically different measurements compared to the others. Differences in the Frankfort mandibular incisor angle (FMIA) and saddle angle were especially displayed in skeletal class III patients. The sex and skeletal sagittal pattern could affect the morphological differences in TMD patients with different disc positions.

Assessment of Dentofacial Characteristics and Pharyngeal Airway in Children with Class II Malocclusion and Mouth Breathing

Background In growing patients with skeletal discrepancies, early diagnosis, evidence-based explanation of etiology, and assessment of functional factors can be vital for the restoration of normal craniofacial growth and the stability of treatment needs.

Aims The aim of the study was to assess dentofacial characteristics as well as upper and lower pharyngeal airway in children with skeletal class II malocclusion with mouth breathing, and to investigate possible significant relationships and correlations among the studied cephalometric variables and the airway morphology in these children.

Materials and Methods Sixty untreated children, aged 9 to 13 years, were divided into three groups according to clinical findings and cephalometric analysis of dentofacial characteristics as well as the presence of mouth breathing habit: Group I (20 children with normal jaw relation/class I), Group II (20 children with skeletal class II), and Group III (20 children with skeletal class II with confirmed mouth breathing habit). Cephalometric variables and upper/lower airway widths were recorded. Intergroup comparison of all measurements was performed by post hoc Tukey test, and Pearson's correlation was used to determine the correlation among the variables.

Results Significant changes existed in more than half of the dentofacial measurements among the three groups. Significantly greater skeletal anteroposterior jaw discrepancy and mandibular retrognathism were found in both groups II and III as determined by specific anteroposterior determinants. Children in group III showed significantly increased angle between Sella-Nasion and mandibular plane (SN-MP) angle, y-axis, and a vertical growth pattern. Significant increases in dental measurements, namely upper incisor to Nasion- point A (NA), lower incisor to Nasion - point B (NB), and overjet, were found in group II and group III, while overbite showed a significant decrease. Upper pharyngeal airway width was found to be significantly decreased in group III followed by a smaller though significant decrease in group II. No significant differences were found in lower pharyngeal airway width between the groups. There were statistically significant dentofacial characteristics that showed fair to good correlation with the upper airway width.

Conclusion Children with skeletal class II malocclusion with and without mouth breathing showed significant differences in dentofacial measurements and a significantly narrower upper pharyngeal airway as compared with children with normal jaw/class I relation.

Three dimensional reliability analyses of currently used methods for assessment of sagittal jaw discrepancy

Background

The objective of this study was to analyse three dimensionally the reliability and correlation of angular and linear measurements in assessment of anteroposterior skeletal discrepancy.

Material and Methods

In this retrospective cross sectional study, a sample of 213 subjects were three-dimensionally analysed from cone-beam computed tomography scans. The sample was divided according to three dimensional measurement of anteroposterior relation (ANB angle) into three groups (skeletal Class I, Class II and Class III). The anterior-posterior cephalometric indicators were measured on volumetric images using Anatomage software (InVivo5.2). These measurements included three angular and seven linear measurements. Cross tabulations were performed to correlate the ANB angle with each method. Intra-class Correlation Coefficient (ICC) test was applied for the difference between the two reliability measurements. P value of < 0.05 was considered significant.

Results

There was a statistically significant (P<0.05) agreement between all methods used with variability in assessment of different anteroposterior relations. The highest correlation was between ANB and DSOJ (0.913), strong correlation with AB/FH, AB/SN/, MM bisector, AB/PP, Wits appraisal (0.896, 0.890, 0.878, 0.867,and 0.858, respectively), moderate with AD/SN and Beta angle (0.787 and 0.760), and weak correlation with corrected ANB angle (0.550).

Conclusions

Conjunctive usage of ANB angle with DSOJ, AB/FH, AB/SN/, MM bisector, AB/PP and Wits appraisal in 3D cephalometric analysis provide a more reliable and valid indicator of the skeletal anteroposterior relationship. Clinical relevance: Most of orthodontic literature depends on single method (ANB) with its drawbacks in assessment of skeletal discrepancy which is a cardinal factors for proper treatment planning, this study assessed three dimensionally the degree of correlation between all available methods to make clinical judgement more accurate based on more than one method of assessment. Key words:Anteroposterior relationships, ANB angle, Three-dimension, CBCT.

Upper airway asymmetry in skeletal Class III malocclusions with mandibular deviation

The purpose of this study was to investigate the relationship between bilateral differences of upper airway and mandibular morphologic patterns in subjects with skeletal Class III mandibular deviation. 47 skeletal Class III (ANB < 0°) adult patients with and without mandibular deviation were divided into 2 groups. Bilateral differences of minimum cross-sectional area, mean cross-sectional area, volume of subdivisions (nasopharynx, palatopharynx, glossopharynx, hypopharynx) were assessed paired t test. Stepwise linear regression analysis and Pearson correlation coefficients were computed between a significant pair of upper airway variables and a pair of mandibular deviation variables to examine the quantitative relationship between the upper airway asymmetry and mandibular deviation. The mean cross-sectional area and the volume of palatopharynx on the deviated side in mandibular deviated group was significantly smaller than non-deviated side. The asymmetry index of the palatopharyngeal volume showed significant correlations with CRA asymmetry (r = 0.49) and Ramus asymmetry (r = 0.54). However, in the glossopharyngeal and hypopharyngeal segment, the mandibular deviated group showed significant asymmetry, characterized by larger mean cross-sectional area and volume in deviated side. The asymmetry index of the glossopharyngeal volume and hypopharyngeal volume showed significant correlations with CRA asymmetry (r = 0.42), Me-s (r = 0.72) and Me-s (r = 0.67) respectively.

Airway in Class I and Class II skeletal pattern: A computed tomography study

BACKGROUND AND OBJECTIVES

A normal airway is required for the normal growth of the craniofacial structures. The present study was designed to evaluate and compare the airway in Class I and Class II skeletal pattern and to see if there is any association between the airway and maxillomandibular relationship.

MATERIALS AND METHODS

Peripheral nervous system computed tomography scans of 30 patients were divided into two groups as Class I (ANB ≤ 4.5°), Class II (ANB ≥ 4.5°). The Dolphin three-dimensional version 11 was used to assess the airway.

STATISTICAL ANALYSIS

Correlations between the variables were tested with the Pearson correlation coefficient. Independent sample t-test was performed to compare the averages between the two groups. P < 0.05 was considered as statistically significant.

RESULTS

The ANB angle was negatively correlated with all the airway parameters. The airway area and volume was significantly reduced in Class II subjects compared to Class I.

CONCLUSION

The results suggest a strong association between the airway and skeletal pattern showing a reduced airway in Class II patients with a high ANB angle.

Comparative assessment of sagittal skeletal discrepancy: a cephalometric study

BACKGROUND AND OBJECTIVES

Evaluating the sagittal apical base relationship during orthodontic diagnosis and treatment planning is an important step. This study was aimed at comparison of Beta angle, ANB angle and Wit's appraisal for assessment of sagittal skeletal discrepancy.

MATERIALS AND METHODS

Eighty six young adults (43 female and 43 male) were selected from the patient's reporting to Department of Orthodontics, College of Dental Sciences, Davangere, India. Family lineage was studied to know the nativity of Davangere. The standardized pre-treatment lateral cephalogram of the chosen sample was traced. The sample was divided into three skeletal pattern groups: Class I, Class II and Class III, based on the ANB angle and profile, Beta angle was assessed in each group.

STATISTICAL ANALYSIS

The data was subjected to statistical analysis student's t-test, ANOVA test and correlation and regression analysis, using the software namely SPSS Software version 13. Microsoft word and Excel were used to generate graphs and tables.

RESULTS

In the local Davangere population, Class I skeletal pattern group exhibited Beta angle between 26°-34°, Beta angle less than 27° was found in Class II skeletal pattern, and Beta angle greater than 32° was seen Class III skeletal pattern. The coefficient of variation of Beta angle in all the three groups was significantly homogenous compared to ANB angle and Wits appraisal. The correlation and regression analysis of the total sample indicated a highly significant correlation between Beta angle and ANB angle (p<.001), and between Beta angle and Wits appraisal (p<.01).

CONCLUSION

Beta angle can be used to classify subjects into different skeletal patterns. The Correlation and regression analysis for the total sample suggests a highly significant relation between Beta angle and ANB angle and, between Beta angle and Wits appraisal. It can be more reliably used to assess sagittal jaw discrepancies than ANB angle and Wits appraisal.

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 degrees < or = ANB < or = 5 degrees ; group II: ANB >5 degrees ), 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 <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).

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.