Cephalometric assessment of sagittal relationship between maxilla and mandible

Correlation Between Horizontal and Vertical Skeletal Components in Dental Malocclusions Among the Jazan Population

INTRODUCTION

The dentoskeletal morphology of various malocclusions has been analyzed in cephalometric studies. It is important to understand the vertical and horizontal components of orthodontic treatment. To provide accurate treatment, an orthodontist needs to understand the facial types of an individual. This study aims to evaluate a correlation between vertical and horizontal components of skeletal and dental malocclusion by assessing cephalometric radiographs of the population of Jazan province.

METHODS

The cephalometric radiographs of 267 eligible participants were assessed digitally. Fourteen skeletal and dental parameters were used to evaluate the association. Reliability was checked with the intra-class coefficient. Statistical analyses included descriptive statistics and Spearman's rho test. Statistical significance was set at P ≤ 0.05.

RESULTS

Correlations were found between anterior facial height (AFH), posterior facial height (PFH), FH ratio (Jarabak ratio), upper incisor to NA (U1-NA), lower incisor to NB (L1-NB), and upper incisor to the palatal plane (U1/PP). In dental class I, AFH (N-Me) had a strong positive correlation with L1-NB (0.300), U1/PP (0.164), and L1/MP (0.215). In dental class II, AFH negatively correlated with U1-NA (-0.735) and positively correlated with L1-NB (0.292), L1/MP (0.085), and U1-NA. PFH (S-Go) positively correlated with L1-NB (0.525) in class I but negatively correlated in class II. However, a negative relation was observed between all the vertical and horizontal components in class III.

CONCLUSION

This study suggests potential associations between vertical and horizontal components in developing skeletal and dental discrepancies.

Definition of New Three-Dimensional Cephalometric Analysis of Maxillomandibular Sagittal Relationship for Orthodontics and Orthognathic Surgery: Normative Data Based on 700 CBCT Scans

The objective of the study was to define the norm of new 3-dimensional cephalometric analysis of maxillomandibular sagittal relationship with the patient in Natural Head Position. A cross-sectional study was performed using 700 consecutives cone beam computed tomography datasets of pre-orthodontic patients received for three-dimensional craniofacial analysis. To stablish the clinical norm of the new sagittal reference (linear distance A-B), the correlation with the gold standard (ANB angle) was estimated with the Pearson's correlation coefficient. Subsequently, the prognostic values of the linear distance A-B was calculated to define the clinical norm. The sample was composed by 463 women (66.1%) and 237 men (33.9%). The mean age was 30 ± 14,5 years old (range 6-71 y old). According to the skeletal class classification (ANB), 46.1% (323) were class I, 42% (294) class II, and 11.9% (83) class III. The regression model found that each additional grade of the ANB angle imply a mean increase of 1.24 mm of the distance A-B ( P <0.001). The normative value of the linear distance A-B was obtained through the prognostic values of the distance for the limits of the ANB norm 0 to 4. These values were on the range of 0.52 to 5.48 mm. Therefore, the clinical norm for cephalometric maxillomandibular sagittal relationship using linear distance from point A-B is: 3±2.48 mm. With this new approach, we can define the skeletal sagittal relationship of the patient in natural head position overcoming the limitations of using intracranial or occlusal plane references improving the diagnosis and orthognathic surgical planning process.

Eruption Pattern of Third Molars in Orthodontic Patients Treated with First Permanent Molar Extraction: A Longitudinal Retrospective Evaluation

The aim of this study was to evaluate angular and positional changes in the second (M2) and third molars (M3) of orthodontically treated patients undergoing a first molar (M1) extraction. A retrospective longitudinal study with a sample of 152 pre- and post-treatment panoramic radiographs was conducted. Thirty-nine patients (51.3%) were orthodontically treated with M1 extraction and thirty-seven (48.7%) were treated without extraction. Angulations of M2 and M3 relative to the infraorbital (IOP) and the palatal planes (PP) were measured and compared between the groups before orthodontic treatment (T1) and after the completion of orthodontic space closure (T2). The prognosis of M3 eruptions was evaluated by assessing their horizontal and vertical position (inclination) using different classification systems. The angular (p < 0.001) and inclination improvement (p < 0.01) of the maxillary M3 was significant for the M1 extraction group. The mandibular M3 inclination significantly improved (p < 0.01), whereas the groups' angulation and vertical position were not significantly different. These findings suggest that extraction therapy has a favorable effect on the maxillary M2 and M3 angulation, but not on the mandibular. M1 extraction showed a signi- ficant effect on the horizontal position of M3 and thus may improve the eruption space and prognosis.

Geometrical Approaches for the Accurate Identification of Normal Vertical Positions of Sella and Nasion Points in Cephalograms

OBJECTIVE

The aim of the study is to identify the normal vertical positions of sella (S) and nasion (N) points in subjects with a normal inclination of anterior cranial bases.

MATERIALS AND METHODS

Lateral cephalograms of 117 subjects who had a normal ∠SN-FH plane (7° ± 1°), ∠SN-palatal plane (9° ± 2°), ∠FH-palatal plane (1° ± 1°), and cranial base angles (131° ± 4°) were included in the study. Various linear and angular parameters and ratios were evaluated to determine the normal vertical positions of S and N points. An unpaired t-test was used to identify any significant differences between males and females. The P value of 0.05 was considered as the level of significance.

RESULTS

Among subjects with the normal inclinations of SN, FH, and palatal planes and cranial base angle, the mean values of ∠Ar-S-Ptm, ∠S-Ptm-Ar, and ∠S-Ar-Ptm were 59.38° ± 3.52°, 59.70° ± 3.21°, and 60.84° ± 3.56°, respectively, forming an almost equilateral triangle between S, Ar, and Ptm points. The mean values of ∠Ba-S-PNS, ∠S-PNS-Ba, and ∠S-Ba-PNS were 59.56° ± 3.17°, 59.72° ± 3.47°, and 60.76° ± 3.11°, respectively, forming another approximate equilateral triangle between S, Ba, and PNS points. The mean S-FH to N-FH ratio was 0.67 ± 0.06% for the whole sample, but it was significantly greater in males (0.69 ± 0.07%) compared to females (0.65 ± 0.06%) (P=0.002).

CONCLUSIONS

Two approximate equilateral triangles were formed between S, Ar, and Ptm points; and S, Ba, and PNS points in subjects with normal inclinations of SN, FH, and palatal planes and cranial base angle. The S-FH to N-FH ratio was an excellent guide to locating the normal vertical position of S and N points.

New Sagittal and Vertical Cephalometric Analysis Methods: A Systematic Review

Cephalometric analysis is an essential tool used in orthodontic diagnosis and treatment planning. The main objectives of correct cephalometric analysis include resolving anteroposterior and vertical maxillary and mandibular base discrepancies. For a diagnostic tool to be of value, it should be precise, reliable and reproducible. Unfortunately, according to some studies, the accuracy of input and, therefore, the diagnostic reliability of some of the points and measurements may not be satisfactory. To this end, new cephalometric measurements are being developed with increased precision. In order to properly and definitively determine the usefulness of a given measurement in cephalometric diagnosis, it is necessary to carry out a critical evaluation of available studies. The aim of this systematic review was to evaluate the available scientific literature describing new landmarks and reference linear and angular measurements of 2D cephalometric analyses assessing the sagittal and vertical discrepancy in the position of jaw bases since the last systematic review in 2013. The secondary aim was to assess the accuracy and reliability of new anthropometric landmarks and reference planes in relation to those used previously, and their instability in relation to growth and orthodontic tooth movements. To carry out the intended plan, electronic databases such as PubMed, Scholar Google, Web of Science and Pro Quest were searched using specific keywords. Initially, a total of 1451 articles were retrieved. Then, duplicate articles in all databases were excluded from the resulting publications. The results showed that despite such a high number of articles published in peer-reviewed scientific journals, only 12 studies on new cephalometric analyses in the sagittal plane and 4 studies on new cephalometric analyses in the horizontal plane met the criteria and, as a result, were included in the review.

Volumetric Analysis of the Jaws in Skeletal Class I and III Patients with Different Facial Divergence Using CBCT Imaging

Aim

The main objective was to evaluate any possible maxillary or mandibular volumetric difference between hyperdivergent skeletal Class III (CIII), normodivergent skeletal CIII, hypodivergent skeletal CIII, and normodivergent skeletal Class I (CI) patients using cone-beam computed tomography (CBCT) images. Also, the secondary objective was to investigate any possible correlation between CBCT-derived lateral cephalometric variables and the mandibular and maxillary volumes (MdV and MxV, respectively).

Materials and Methods

80 CBCT images of patients between 18 and 32 years of age were taken with one CBCT imaging device (Scanora 3D®, Soredex, Tuusula, Finland). The sample consisted of four groups: 20 hypodivergent skeletal CIII (11 males and 9 females), 20 normodivergent skeletal CIII (7 males and 13 females), 20 hyperdivergent skeletal CIII (8 males and 12 females), and 20 normodivergent skeletal CI (5 males and 15 females). The volumes of both jaws and the ratio of MxV/MdV were obtained using Mimics™ 19 software (Materialise, NV, Belgium), and 2D variables were obtained from CBCT-derived lateral cephalogram using AudaxCeph™ software (Orthodontic software suite, Ljubljana, Slovenia). One-way ANOVA test and Kruskal–Wallis analysis were employed to detect any possible significant difference between the volumetric variables, whereas Pearson's and Spearman's correlation coefficients were calculated to detect any possible relationship between the 2D variables and the volumetric measurements.

Results

There were no statistically significant differences in the maxillary volume or maxillary/mandibular ratio between the four groups (p=0.081 and 0.432, respectively). There was a significant difference in MdV between CIII hypodivergent (higher mean) and CIII hyperdivergent (p=0.039). There were some correlations between the MdV and 2D variables in the four studied groups especially in the posterior facial height (S-Go) and the facial depth (N-Go). There were some weaker correlations between the MxV and some 2D variables in the CIII hypodivergent and hyperdivergent groups.

Conclusions

The mandibular volume of the Class III hypodivergent patient was significantly greater than that of the Class III hyperdivergent patients. Correlations between the maxillary or mandibular volumes were found with some of the 2D variables. The volume of both jaws increased when the maxillofacial complex moved toward a horizontal growth pattern.

A heuristic model for cephalometric diagnosis of sagittal dysplasia

OBJECTIVE

To identify the best-suited cephalometric parameter for assessing the sagittal skeletal discrepancy in the Indian population.

DESIGN

An in vitro, observational, single-blinded, retrospective study.

SETTING

Department of Orthodontics and Dentofacial Orthopaedics.

METHODS

A total of 94 lateral cephalograms were used in this study. The study involved one key person and two examiners. The key person collected the radiographs, coded, analysed and classified them into three groups (skeletal classes I, II and III). Subsequently, the coded radiographs were independently analysed by the two examiners. They classified the cases by matching a minimum of 6 out of 11 parameters. On completion of diagnosis by the examiners, the samples were decoded and matched with the original diagnosis given by the key person. The samples in which identification of a particular cephalometric parameter matched the original evaluation as given by the key person was regarded as correctly diagnosed. The number of correctly assessed cases was used to judge the diagnostic performance of all the parameters in all the cases. Cross-validation of the method was performed, and a diagnostic algorithm was developed for diagnosis.

RESULTS

β angle and Pi angle showed a positive predictive value of 1 in both skeletal class I and II cases. ANB angle, W angle and HBN angle showed a positive predictive value of 1 in skeletal class III cases.

CONCLUSION

No single cephalometric parameter can independently be used to diagnose sagittal skeletal discrepancy in all cases. However, a conclusive diagnosis on the type of sagittal skeletal malocclusion can be made by using a simple and easy to use diagnostic algorithmic process having a combination of cephalometric parameters.

MKG Angle: A True Marker for Maxillomandibular Discrepancy

Aim: To evolve a new cephalometric estimation called the MKG angle using three skeletal landmarks—point key ridge (KR), point M, and point G to evaluate the sagittal relationship between the maxilla and mandible.

Materials and methods: A total of 60 pretreatment lateral cephalograms were selected and segregated into classes I, II, and III groups on the basis of ANB angle, Wits appraisal, and W angle. The MKG angle was constructed between the lines drawn from point M to point KR and point KR to point G. The MKG angle was measured to calculate the mean and the standard deviation.

Results: After using the one-way analysis of variance and the Newman–Keuls test and running ROC curves, the results showed that an MKG angle in the range 51º–59º can be considered to have a class I skeletal pattern. The MKG angle more than 59º indicates a class II skeletal pattern and less than 51º indicates class III skeletal pattern.

Conclusion: The MKG angle can be used as a dependable marker to assess sagittal jaw discrepancy.

Relationship between skeletal Class II and Class III malocclusions with vertical skeletal pattern

OBJECTIVE

The purpose of this study was to establish the association between sagittal and vertical skeletal patterns and assess which cephalometric variables contribute to the possibility of developing skeletal Class II or Class III malocclusion.

METHODS

Cross-sectional study. The sample included pre-treatment lateral cephalogram radiographs from 548 subjects (325 female, 223 male) aged 18 to 66 years. Sagittal skeletal pattern was established by three different classification parameters (ANB angle, Wits and App-Bpp) and vertical skeletal pattern by SN-Mandibular plane angle. Cephalometric variables were measured using Dolphin software (Imaging and Management Solutions, Chatsworth, Calif, USA) by a previously calibrated operator. The statistical analysis was carried out with Chi-square test, ANOVA/Kruskal-Wallis test, and an ordinal multinomial regression model.

RESULTS

Evidence of association (p< 0.05) between sagittal and vertical skeletal patterns was found with a greater proportion of hyperdivergent skeletal pattern in Class II malocclusion using three parameters to assess the vertical pattern, and there was more prevalent hypodivergence in Class III malocclusion, considering ANB and App-Bpp measurements. Subjects with hyperdivergent skeletal pattern (odds ratio [OR]=1.85-3.65), maxillary prognathism (OR=2.67-24.88) and mandibular retrognathism (OR=2.57-22.65) had a significantly (p< 0.05) greater chance of developing skeletal Class II malocclusion. Meanwhile, subjects with maxillary retrognathism (OR=2.76-100.59) and mandibular prognathism (OR=5.92-21.50) had a significantly (p< 0.05) greater chance of developing skeletal Class III malocclusion.

CONCLUSIONS

A relationship was found between Class II and Class III malocclusion with the vertical skeletal pattern. There is a tendency toward skeletal compensation with both vertical and sagittal malocclusions.

Sagittal discrepancies of the jaw in a Bangladeshi cohort: three-dimensional computed tomography analysis

Objectives

In orthodontic diagnosis and treatment planning, the assessment of skeletal jaw relationships is an essential step. This study aimed to evaluate skeletal jaw relationships in a Bangladeshi cohort by using traditional (ANB angle and Wits appraisal) and newly described (Beta angle, W angle, and Yen angle) sagittal measurements in three-dimensional (3D) computed tomography (CT).

Methods

The radiology department conducted CT scans of Bangladeshi patients. Mimics 3D imaging software (Materialise) was used to process the CT images and evaluate 3D sagittal measurements. SPSS software (IBM) was used to assess significant differences in the data at a confidence level of 5%. Independent-samples t-tests were used to evaluate sexual dimorphism for the measured values.

Results

In total, 85 men and 32 women were included in this study. All measurements were equivalent to the existing standards. There were no significant differences in the acquired values between men and women. Measurements were consistent with Class I normal classification.

Conclusions

This study established 3D CT standards for ANB, Wits appraisal, Beta angle, W angle, and Yen angle in Bangladeshi patients.

Challenges in measuring angles between craniofacial structures

Objective:

Three-dimensional (3D) angular measurements between craniofacial planes pose challenges to quantify maxillary and mandibular skeletal discrepancies in surgical treatment planning. This study aims to compare the reproducibility and reliability of two modules to measure angles between planes or lines in 3D virtual surface models.

Methodology:

Twenty oriented 3D virtual surface models de-identified and constructed from CBCT scans were randomly selected. Three observers placed landmarks and oriented planes to determine angular measurements of pitch, roll and yaw using (1) 3D pre-existing planes, (2) 3D planes created from landmarks and (3) lines created from landmarks. Inter- and intra-observer reproducibility and repeatability were examined using the Intra-Class Correlation (ICC) test. One observer repeated the measurements with an interval of 15 days. ANOVA was applied to compare the 3 methods.

Results:

The three methods tested provided statistically similar, reproducible and reliable angular measurements of the facial structures. A strong ICC varying from 0.92 to 1.00 was found for the intra-observer agreement. The inter-observer ICC varied from 0.84 to 1.00.

Conclusion:

Measurements of 3D angles between facial planes in a common coordinate system are reproducible and repeatable either using 3D pre-existing planes, created based on landmarks or angles between lines created from landmarks.

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.

Three-Dimensional Analysis of Maxillary and Mandibular Growth Increments

Objective

To analyze changes in the facial, maxillary, and mandibular skeleton in the vertical, sagittal, and transverse dimensions during an orthodontically relevant period of dentofacial development (i.e., between 7 and 15 years of age).

Subjects and Method

This longitudinal study comprised posteroanterior (PA) and lateral cephalograms at 7, 9, 11, 13, and 15 years of 18 untreated Class I subjects with good occlusion. Transverse growth (width) was analyzed on the basis of PA cephalograms and sagittal (depth) and vertical (height) growth by means of lateral cephalograms. For each linear measurement, mean percentage increases were calculated relative to the size at 7 years of age.

Results and Conclusions

Between 7 and 15 years of age, in the whole facial skeleton and the maxilla, percentage increases were most pronounced in the vertical dimension when compared with the sagittal and transverse dimensions. In the mandible, the largest percentage increases were found in both sexes for vertical growth of the ramus, followed by sagittal growth (body length) and then mandibular width. In the sagittal dimension, development was more pronounced in the mandible (at pogonion more than at B point) than in the maxilla (A point). With respect to vertical growth, percentage increases in posterior face height exceeded the increases in anterior face height. When facial shape changes were analyzed between 7 and 15 years of age in both sexes, the ratio facial height/facial width increased and the ratio facial depth/ facial height decreased, which points toward an age-related increasing influence of vertical development.

Correlation of Beta Angle with Antero-Posterior Dysplasia Indicators and FMA: An Institution Based Cephalometric Study

INTRODUCTION

Beta angle utilizes three skeletal landmarks - point A, point B, and point C (the apparent axis of the condyle). It is formed between A-B line and point A perpendicular to C-B line. Further this angle indicates the severity and the type of skeletal dysplasia in the sagittal dimension and it changes with the growth pattern of the patient. Hence, it is important to study the dependence of beta angle on the growth pattern.

AIM

The present study was designed to evaluate the correlation of Beta angle with point A-Nasion-point B (ANB) angle, points A and B to palatal plane (App-Bpp), Wit's appraisal and Maxillary-Mandibular plane angle Bisector (MMB) and Frankfort-Mandibular plane Angle (FMA) in Skeletal Class I, Class II and Class III malocclusion groups.

MATERIALS AND METHODS

Pre-treatment lateral head cephalo-grams of 120 subjects in age group of 15-25 years were obtained. Three skeletal Class I, Class II and Class III malocclusion groups (40 each) were assorted on the basis of ANB, MMB, App-Bpp, Wit's appraisal and FMA. Analysis of variance (ANOVA) and mean differences were calculated to compare the study groups. Bivariate correlations among different parameters of these groups were obtained.

RESULTS

Normal values of beta angle in skeletal Class I group, skeletal Class II group and skeletal Class III group was 31.33±3.25, 25.28±4.28 and 40.93±4.55 respectively. Overall beta angle showed a strong correlation with all parameters of anterio-posterior dysplasia indicators except FMA.

CONCLUSION

Beta angle shows weak correlation with FMA and is not affected by growth pattern/jaw rotation. The normal values are in same range irrespective of the differences in craniofacial morphology.

A cephalometric evaluation of the effect of glenoid fossa location on craniofacial morphology

AIM

The purpose of this study was to assess the effect of glenoid fossa location in various skeletal malocclusions on craniofacial morphology.

METHODS

Cephalometric data of 84 subjects were analyzed for four linear and two angular variables for assessing glenoid fossa location in cranial base and eight linear and eight angular variables for evaluating the corresponding effect on craniofacial morphology using statistical software STATA 12 for windows. Regression analysis was done to see the effect of glenoid fossa location on the parameters measuring craniofacial morphology.

RESULTS

Significant association between glenoid fossa location and craniofacial morphology was demonstrated in skeletal class I, class II, and class III malocclusion subjects by the regression analysis.

CONCLUSIONS

Glenoid fossa location varies significantly among skeletal malocclusions and glenoid fossa location has a profound effect on craniofacial morphology of skeletal class I, class II, and class III malocclusions.

Evaluation and Comparison of Anatomical Landmark Detection Methods for Cephalometric X-Ray Images: A Grand Challenge

Cephalometric analysis is an essential clinical and research tool in orthodontics for the orthodontic analysis and treatment planning. This paper presents the evaluation of the methods submitted to the Automatic Cephalometric X-Ray Landmark Detection Challenge, held at the IEEE International Symposium on Biomedical Imaging 2014 with an on-site competition. The challenge was set to explore and compare automatic landmark detection methods in application to cephalometric X-ray images. Methods were evaluated on a common database including cephalograms of 300 patients aged six to 60 years, collected from the Dental Department, Tri-Service General Hospital, Taiwan, and manually marked anatomical landmarks as the ground truth data, generated by two experienced medical doctors. Quantitative evaluation was performed to compare the results of a representative selection of current methods submitted to the challenge. Experimental results show that three methods are able to achieve detection rates greater than 80% using the 4 mm precision range, but only one method achieves a detection rate greater than 70% using the 2 mm precision range, which is the acceptable precision range in clinical practice. The study provides insights into the performance of different landmark detection approaches under real-world conditions and highlights achievements and limitations of current image analysis techniques.

A “new vista” in the assessment of antero-posterior jaw relationship

Aim

The purpose of this investigation was to (1) compare the credibility of four recently introduced cephalometric measurements in assessing the antero-posterior jaw relationship; (2) To assess the correlation between various measurements used for assessment of antero-posterior discrepancy, including Yen linear, Yen angle, W angle and Pi angle.

Materials and Methods

The sample size for the study consisted of 45 subjects with age group of 15-19 years (mean age 17 ± 2.1) and was subdivided into Skeletal Class I, II and III groups of 15 each based upon the ANB angle derived from the pre treatment lateral cephalogram. Landmarks were located and Yen angle, Yen linear, W angle and Pi angle were assessed for each group. All the lateral cephalograms were traced by a single examiner. Intra examiner reliability was assessed by Intraclass co-efficient correlation (ICC) test. Correlation coefficients were obtained for each of parameters to compare their relationship with other parameters in Class I group. Receiver operating characteristics (ROC) curves were run to examine sensitivity and specificity of all the angles.

Results

The results showed that ICC for all the groups were ≥0.90 showing good repeatability of the measurements. There was statistically significant correlation between Yen angle and ANB angle, Yen linear and Yen angle for Class I group, between W angle and Yen angle for Class II group, between Yen angle, Yen linear and ANB for Class III group. ROC curves showed that Pi angle had 100% sensitivity and specificity to discriminate a Class II and a Class III group from a Class I and a Class III group from a Class II. Yen linear and W angle showed very low specificity to differentiate a Class II from a Class I group.

Interpretation and Conclusion

The new parameters considered in the study were found to be equally reliable and are not affected much by local remodeling due to tooth movements or by occlusal or Frankfurt horizontal plane. These parameters measure the antero-posterior discrepancy more consistently and accurately, with Pi angle being the most accurate.

DK, Prasad M, Shamnur N, G. AK, K.R. S, B.R. GK, Gupta N. 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.

Cephalometric study to test the reliability of anteroposterior skeletal discrepancy indicators using the twin block appliance

Background

The objectives of this study were to check the reliability of the five angular and two linear parameters for sagittal maxillo-mandibular discrepancy and to compare and correlate angular parameters with the ANB angle, and the linear parameter with Wits analysis.

Methods

The pre-treatment and post-functional lateral cephalograms of 25 subjects (17 males, 8 females) with class II division 1 malocclusion treated with twin block functional appliance were selected. Five angular (ANB, β angle, APDI, YEN angle, W angle) and two linear (Wits analysis, App-Bpp) parameters were traced on both sets of cephalograms. Paired Student’s t-test, one-way ANOVA, post hoc test, and Karl Pearson correlation statistical analysis were performed.

Results

All the parameters considered in our study showed highly significant difference in pre-treatment and post-functional values, suggesting their reliability (p < 0.0001). When ANB angle was compared with the other angular parameters, a highly significant change in the mean value of the difference in pre-treatment (T1) and post-functional (T2) values was noted (p < 0.001). No significant change was seen when comparing the mean value of the difference in T1 and T2 between linear parameters (p = 0.949).

Conclusions

All the parameters used in the study can be reliably used to assess anteroposterior skeletal discrepancy. Whenever limitations of the ANB angle and Wits analysis are foreseen, the W angle and App-Bpp, respectively, can be reliably used. The YEN angle may reliably predict the post-functional change with the use of twin block appliance.

A reflection on radiographic cephalometry: the evaluation of sagittal discrepancy

A critical review is presented of the basic properties and applications of cephalometry as a clinical tool with a focus on the evaluation of sagittal discrepancy. Diagnostic cephalometric assessments are subjective and not based on evidence. To assess individual skeletal and/or facial soft tissue form subjectively, selected norms are used. Norms have been developed for various ethnical groups to improve clinical applicability, but subjectivity remains. That subjectivity precludes application of a modern review system, making the present review a personal account. The cephalometric evaluation of sagittal discrepancy finds its historic origin in the Angle classification. Recent publications try to improve accuracy in classifying sagittal discrepancy. It remains unclear in what sense such efforts influence treatment decisions and/or treatment effect. Almost all selected landmarks are located on or dependent upon periosteal/endosteal bone image contours. Their homology is based on circumstantial reasoning and stability over time, which is implicitly assumed. However, implant growth studies and histological investigations show most landmarks to be unstable, as they are involved in displacement and bone remodelling. These landmarks are therefore heterologous when used for individual evaluation of change over time. Notwithstanding the above-indicated limitations, diagnostic cephalometric assessments are clinically useful and help to develop perceptions of balance and harmony and communication between colleagues and patients. There is no evidence-based method to prefer one particular diagnostic method. Landmark location accuracy and geometric issues do not play a decisive role. The subjective characteristic of diagnostic evaluations limits their power to size/shape comparisons. Structural superimposition is the valid biologically evidence-based method to provide advanced insight in individual growth and/or treatment changes and their variations.

Establishment of norms of the beta angle to assess the sagittal discrepancy for Nellore district population

BACKGROUND AND OBJECTIVES

In orthodontic diagnosis and treatment planning, assessment of anteroposterior discrepancy is of importance to the orthodontist. Both angular and linear measurements have been incorporated into various cephalometric analyses to help the clinician diagnose anteroposterior discrepancies and establish the most appropriate treatment plan. Hence the present study is designed to establish the norms of Beta angle to assess the sagittal discrepancy for Nellore district population.

MATERIALS AND METHODS

The sample was screened from the old records of the Orthodontic department of Narayana Dental College and Hospital. One hundred and fifty pretreatment cephalometric radiographs (50 each of Class I, II, and III) were subdivided based on ANB, Wits appraisal, and Beta angle into skeletal Class I, II, III. The same cephalograms were again classified into skeletal Class I, II, and III based purely on Beta angle. Each group was again divided into 2 subgroups consisting of 25 male and 25 female subjects with a mean age limit between 15 and 45 years old.

RESULTS

The Newman-keuls post hoc test and ANOVA showed that the 3 groups were significantly different (P ≤ 0.001). The Newman-keuls post hoc test also found the groups to be significantly different.

CONCLUSIONS

There was statistically significant difference for, the mean values and the standard deviation for Beta angle within the three skeletal patterns (Class I, Class II and Class III skeletal patterns). There was no statistically significant difference among the mean values of beta angle between Nellore district population and Caucasian norms and between male and female sex groups.

An evaluation of the Pi analysis in the assessment of anteroposterior jaw relationship

OBJECTIVE

This study has investigated two new cephalometric variables, the Pi angle and Pi linear in the evaluation of anteroposterior skeletal discrepancy.

DESIGN

Retrospective cross-sectional study.

SETTING

Manipal College of Dental Sciences, Manipal, India

SUBJECTS AND METHOD

A sample of 155 subjects (mean age 19·7 years) were subdivided into skeletal class I, II and III groups based upon ANB angle. Descriptive data were calculated for each variable and group. Receiver operating characteristics curves were used to examine sensitivity and specificity of the Pi angle in the discrimination between different skeletal groups. Correlation coefficients were obtained for each of the parameters to compare their relationship with other parameters in the class I group. Coefficient of determination, regression coefficient, regression equation and standard error of estimate were also calculated from the parameters showing significant correlation with the Pi angle.

RESULTS

Mean values for the Pi angle in skeletal class I, II and III subjects were 3·40 (±2·04), 8·94 (±3·16) and -3·57 (±1·61) degrees, respectively. For the Pi linear they were 3·40 (±2·20), 8·90 (±3·56) and -3·30 (±2·30) mm for class I, II and III subjects, respectively. Receiver operating characteristic curves showed that a Pi angle greater than 5 degrees had 89% sensitivity and 82% specificity for discriminating a skeletal class II group from class I. A Pi angle of less than 1·3 degrees had 100% sensitivity and 84% specificity in discriminating skeletal class III groups from class I. The overall accuracy for discriminating class II groups from class I was 85% and for class III from class I, 90%. Thus, a cut-off point between class I and II groups could be considered a Pi angle of approximately 5 degrees and between class I and class III, approximately 1·3 degrees. There were no statistically significant correlations found between Pi angle and ANB (0·07), Beta angle (-0·04) and WITS analysis (0·19). The highest level of correlation was obtained for the Pi angle and Pi linear (0·96).

CONCLUSION

The anglar and linear components of the Pi analysis are a suitable method for assessing anteroposterior jaw discrepancy in daily clinical practice.

Craniofacial and upper airway morphology in pediatric sleep-disordered breathing: Systematic review and meta-analysis

INTRODUCTION

Pediatric sleep-disordered breathing is a continuum, with primary snoring at one end, and complete upper airway obstruction, hypoxemia, and obstructive hypoventilation at the other. The latter gives rise to obstructive sleep apnea. An important predisposing factor in the development and progression of pediatric sleep-disordered breathing might be craniofacial disharmony. The purpose of this systematic review and meta-analysis was to elucidate the association between craniofacial disharmony and pediatric sleep-disordered breathing.

METHODS

Citations to potentially relevant published trials were located by searching PubMed, Embase, Scopus, and the Cochrane Central Register of Controlled Trials. The MetaRegister of controlled trials database was also searched to identify potentially relevant unpublished trials. Additionally, hand-searching, Google Scholar searches, and contact with experts in the area were undertaken to identify potentially relevant published and unpublished studies. Inclusion criteria were (1) randomized controlled trials, case-control trials, or cohort studies with controls; (2) studies in nonsyndromic children 0 to 18 years of age with a diagnosis of sleep-disordered breathing or obstructive sleep apnea by either a sleep disorders unit, screening questionnaire, or polysomnography; and (3) principal outcome measures of craniofacial or upper airway dimensions or proportions with various modalities of imaging for the craniofacial and neck regions. The quality of the studies selected was evaluated by assessing their methodologies. Treatment effects were combined by meta-analysis with the random-effects method.

RESULTS

Children with obstructive sleep apnea and primary snoring show increased weighted mean differences in the ANB angle of 1.64° (P <0.0001) and 1.54° (P <0.00001), respectively, compared with the controls. An increased ANB angle was primarily due to a decreased SNB angle in children with primary snoring by 1.4° (P = 0.02). Children with obstructive sleep apnea had a distance from the posterior nasal spine to the nearest adenoid tissue measured along the PNS-basion line reduced by 4.17 mm (weighted mean difference) (P <0.00001) and a distance from the posterior nasal spine to the nearest adenoid tissue measured along the line perpendicular to the sella-basion line reduced by 3.12 mm (weighted mean difference) (P <0.0001) compared with the controls.

CONCLUSIONS

There is statistical support for an association between craniofacial disharmony and pediatric sleep-disordered breathing. However, an increased ANB angle of less than 2° in children with obstructive sleep apnea and primary snoring, compared with the controls, could be regarded as having marginal clinical significance. Therefore, evidence for a direct causal relationship between craniofacial structure and pediatric sleep-disordered breathing is unsupported by this meta-analysis. There is strong support for reduced upper airway width in children with obstructive sleep apnea. Larger well-controlled trials are required to address the relationship of craniofacial and upper airway morphology to pediatric sleep-disordered breathing in all 3 dimensions.

Effects of sagittal maxillary growth hypoplasia severity on mandibular asymmetry in unilateral cleft lip and palate subjects

OBJECTIVE

To test the hypothesis that sagittal maxillary growth hypoplasia has no effect on mandibular asymmetry among subjects with complete unilateral cleft lip and palate (UCLP).

DESIGN

A total of 86 subjects (normal noncleft, 42; UCLP, 44) in the age range of 15 to 25 years were chosen. Normal noncleft subjects were included in Group I. Based on the severity of sagittal maxillary growth hypoplasia, subjects with UCLP were divided into two groups. Subjects with UCLP in whom the SNM angle was ≥71 degrees and the M-point to Nasion perpendicular distance was ≤-10 mm were included in Group II. Group III consisted of subjects with UCLP in whom the SNM angle was <71 degrees and the M-point to Nasion perpendicular distance was >-10 mm. The mandibular asymmetry index (condylar, ramal, and condylar+ramal), gonial angle, and depth of the antigonial notch of three groups of subjects were examined on orthopantomograms (OPGs).

RESULTS

Among Group II subjects in whom sagittal maxillary growth was near normal, ramal and condylar+ramal heights were significantly less on the cleft side than on the normal side (P < .01). Condylar, ramal, and condylar+ramal asymmetry indices were significantly greater among Group II subjects. Mandibular asymmetry indices among Group III subjects were comparable with those in Group I subjects.

CONCLUSION

The hypothesis was rejected. The mandible was significantly asymmetrical among subjects with UCLP in whom sagittal maxillary growth was near normal, whereas the mandible was nearly symmetrical among subjects with UCLP in whom sagittal maxillary growth hypoplasia was very severe.

A new approach of assessing sagittal dysplasia: the W angle

In orthodontic diagnosis and treatment planning, an accurate antero-posterior measurement of jaw relationships is critically important. Previously described angular and linear measurements can be inaccurate because of their dependency on various factors. The purpose of this study was to introduce a new cephalometric measurement, named the W angle, to assess the sagittal relationship between maxilla and mandible with accuracy and reproducibility. This angle uses three skeletal landmarks--point S, point M, and point G--to measure an angle that indicates the severity and the type of skeletal dysplasia in the sagittal dimension. One hundred and forty-two pre-treatment cephalometric radiographs of patients between the age of 15 and 25 years were selected. They were again subdivided into Classes I, II, and III groups on the basis of Beta angle, Wits appraisal, and ANB angle. The W angle was measured between the perpendicular from point M on S-G line and the M-G line. The mean and the standard deviation for the W angle were calculated. After using the one-way analysis of variance and the Newman-Keuls test, receiver operating characteristics curves were obtained. Results showed that a patient with a W angle between 51 and 56 degrees can be considered to have a Class I skeletal pattern. With an angle less than 51 degrees, patients are considered to have a skeletal Class II relationship and with an angle greater than 56 degrees, patients have a skeletal Class III relationship.

Maxillary incisor proclination effect on the position of point A in Class II division 2 malocclusion

OBJECTIVE

To test the hypothesis that the magnitude of alteration in the position of point A is not associated with proclination of the upper incisors in Class II division 2 malocclusion.

MATERIALS AND METHODS

Cephalometric films were taken for 30 Class II division 2 patients (8 males and 22 females; average age, 18.3 years) before and after upper incisor proclination. The total change in the position of point A was measured by superimposing the pretreatment and postproclination lateral cephalograms on the sella-nasion line at the sella. To determine the local effect of alveolar bone remodeling associated with upper incisor proclination on the position of point A, postproclination tracing of the maxilla was superimposed on the pretreatment tracing according to the Bolton template of maxillary superimposition.

RESULTS

The total vertical displacement in Point A position was downward by 0.84 mm (P = .002), and the total horizontal displacement was forward by 0.45 mm (P = .054). Assessment of local changes in point A revealed that the position of point A had moved backward by 0.60 mm (P = .001). No significant change was observed in the value of the sella-nasion-point A angle (SNA).

CONCLUSION

The hypothesis is rejected. The position of point A is affected by local bone remodeling associated with proclination of the upper incisor in Class II division 2 malocclusion, but this minor change does not significantly affect the SNA angle.

Improving the concordance between various anteroposterior cephalometric measurements using Procrustes analysis

The aim of this study was to investigate a method which minimizes the effects of geometric distortion on various cephalometric measurements used to determine sagittal discrepancy, such as ANB angle, Wits appraisal, AB plane angle, projections on the palatal plane, Frankfort horizontal (FH) plane, the mandibulomaxillary bisector, and the SN line, in an attempt to optimize the correlation between them. This was accomplished by superimposing the Bolton 12-year male-female averaged template on a patient's tracing using Procrustes analysis and performing measurements while exchanging the patient's reference landmarks/planes (point N, the mandibulomaxillary bisector, FH plane, occlusal plane, palatal plane, and SN line) with those of the template. The normalized measurements were then compared with their classic counterparts using correlation coefficients. The above cephalometric analyses, classic and normalized, were applied to 71 patients [26 males: mean age 13.1 years, standard deviation (SD) 1.1 years and 45 females: mean age of 14.6 years, SD 8.2 years]. Spearman's rank correlation coefficient was calculated between the classic measurements and their normalized counterparts, resulting in a consistent increase in the correlation between the normalized measurements in comparison with the classic ones. This increase varied in absolute value from 0.052 to 0.405. All normalized measurements were highly correlated (P > 0.742, absolute value). Although correlation calculations do not represent a true measure of diagnostic performance, it is hoped that improving their correspondence heightens the possibility of the different tests agreeing on the patient's sagittal discrepancy, decreasing the possibility of differing, or even totally opposing diagnostic outcomes resulting from their application to (clear-cut) Class I, II, and III patients.

Occlusal outcomes and efficiency of 1- and 2-phase protocols in the treatment of Class II Division 1 malocclusion

INTRODUCTION

The purpose of this study was to compare the occlusal outcomes and the efficiency of 1-phase and 2-phase treatment protocols in Class II Division 1 malocclusions. Treatment efficiency was defined as a change in the occlusal characteristics in a shorter treatment time.

METHODS

Class II Division 1 subjects (n = 139) were divided into 2 groups according to the treatment protocol for Class II correction. Group 1 comprised 78 patients treated with a 1-phase treatment protocol at initial and final mean ages of 12.51 and 14.68 years. Group 2 comprised 61 patients treated with a 2-phase treatment protocol at initial and final mean ages of 11.21 and 14.70 years. Lateral cephalometric radiographs were taken at the pretreatment stage to evaluate morphological differences in the groups. The initial and final study models of the patients were evaluated by using the peer assessment rating index. Chi-square tests were used to test for differences between the 2 groups for categorical variables. Variables regarding occlusal results were compared by using independent t tests. A linear regression analysis was completed, with total treatment time as the dependent variable, to identify clinical factors that predict treatment length for patients with Class II malocclusions.

RESULTS

Similar occlusal outcomes were obtained between the 1-phase and the 2-phase treatment protocols, but the duration of treatment was significantly shorter in the 1-phase treatment protocol group.

CONCLUSIONS

Treatment of Class II Division 1 malocclusions is more efficient with the 1-phase than the 2-phase treatment protocol.

Dental arch widths and mandibular-maxillary base widths in Class III malocclusions from ages 10 to 14

INTRODUCTION

Evaluations of the dental arch widths and mandibular-maxillary base are needed for a comprehensive dentofacial analysis in subjects with Class III malocclusion. The aim of this study was to analyze the development of the dental arches and the skeletal mandibular-maxillary bases in untreated subjects with Class III malocclusions.

METHODS

Two groups of subjects, 1 with Class III malocclusion and the other with Class I malocclusion, were examined. Maxillary skeletal base width, biantegonial widths, and maxillary and mandibular intermolar widths were determined on posteroanterior cephalograms at annual intervals between the ages of 10 and 14 years.

RESULTS

Maxillary skeletal base widths and intermolar widths in the Class III subjects were significantly smaller than those in the Class I subjects (P <.05). No statistically significant differences were found among the groups for skeletal mandibular width or intermolar width for the total observation period. The deviations in molar differences increased from ages 10 to 14 in the Class III group.

CONCLUSIONS

The main transverse deficiencies in the Class III group were maxillary deficiencies in both skeletal and dental widths. The deviations in molar differences appear to become larger from age 10 to age 14.

Long-term anteroposterior and vertical maxillary changes in skeletal class II patients treated with slow and rapid maxillary expansion

OBJECTIVE

To evaluate a 10-year follow-up of anteroposterior and vertical maxillary changes in skeletal Class II patients treated with slow and rapid maxillary expansion methods.

MATERIALS AND METHODS

The sample consisted of 70 patients divided into two groups: (1) treated with a cervical headgear with expansion of the inner bow (CHG) and (2) using a Haas-type rapid maxillary expansion appliance in conjunction with cervical headgear (RME-CHG). The CHG group consisted of 40 patients (18 males and 22 females; average age 10.6 years at pretreatment [T1], 13.6 years at posttreatment [T2], and 23.6 years at postretention [T3]). The RME-CHG group consisted of 30 patients (14 males and 16 females; average age 10.4 years at T1, 14.0 years at T2, and 24.6 years at T3). The profiles of SNA and SN-PP angles showed no significant differences in either group at T1, T2, and T3 phases.

RESULTS

For the entire sample, the profile analysis between the phases showed reduction in the SNA angle from T1-T2 and an increase from T2-T3. The SN-PP angle showed an increase from T1-T2 and a decrease from T2-T3. Treatment of skeletal Class II patients with slow and rapid maxillary expansions was efficient and stable over the long-term.

CONCLUSIONS

The profiles of SNA and SN-PP at T1, T2, and T3 achieved with slow and rapid maxillary expansions were clinically equivalent.

Longitudinal intermaxillary relationships in class III malocclusions with low and high mandibular plane angles

OBJECTIVE

To analyze the sagittal, vertical, and transverse relationships of the maxilla and mandible in Japanese girls with Class III malocclusions with different inclination of mandibular plane.

MATERIALS AND METHODS

This longitudinal study utilized serial posteroanterior and lateral cephalograms of 56 untreated subjects from the age of 8 years until the age of 14 years (low mandibular plane angle group: n = 20; average mandibular plane angle group: n = 15; high mandibular plane angle group: n = 21). Sagittal and vertical growth was analyzed on the basis of lateral cephalograms, and transverse growth was analyzed on the basis of posteroanterior cephalograms.

RESULTS

There was no significant difference in intermaxillary sagittal relationships among the three groups from age 8 until 14. On the other hand, there were significant changes in the vertical and transverse intermaxillary relationships during this period. When comparing the three groups at the same age, there were significant differences in vertical and transverse intermaxillary relationships in some ages, whereas no significant difference was found in sagittal relationships in any ages.

CONCLUSIONS

The inclination of mandibular plane might play a role in anticipating changes in vertical and transverse intermaxillary relationships from 8 until 14 years of age.

Dental Arch Widths and Mandibular-Maxillary Base Width in Class III Malocclusions with Low, Average and High MP-SN Angles

Objective: To analyze the development of the dental arches and skeletal mandibular-maxillary bases in untreated Class III malocclusions with low averages and high mandibular plane angles in subjects aged 10 to 14.

Materials and Methods: The records of 50 untreated Japanese girls with Class III malocclusions at age 10 were selected from the files of patients pending orthodontic surgery. The patients included those with low (≤27°), average (27° through 37°) and high (&gt;37°) mandibular plane angles. The maxillary skeletal base width, biantegonial width, and maxillary and mandibular intermolar width were determined on posteroanterior cephalograms obtained at annual intervals when subjects were between 10 and 14 years of age. The difference between the maxillary and mandibular intermolar width was also calculated and reported.

Results: All skeletal and dental transverse widths in the high-angle group were significantly smaller than those in the low-angle group (P &lt; .05) from ages 10 to 14. On the other hand, the maxillary to mandibular molar difference was the same for the three groups (P &gt; .05) at each age. The deviations in molar differences did increase from age 10 to age 14 in all three groups.

Conclusion: Mandibular plane angles might play a stronger role in the transverse skeletal growth of the maxilla and the mandible than the transverse dental growth of the maxilla and the mandible.

Longitudinal Evaluation of the Intermaxillary Relationship in Class III Malocclusions

Objective: To analyze the sagittal, vertical, and transverse relationship of the maxilla and mandible in Japanese girls with Class III malocclusions.

Materials and Methods: This longitudinal study utilized biannual posteroanterior and lateral cephalograms of 44 untreated subjects from age 8 to 14 years (Class I, 23 girls; Class III, 21 girls). Sagittal and vertical growths were analyzed on the basis of lateral cephalograms, and transverse growth was analyzed on the basis of posteroanterior cephalograms.

Results: There was no significant difference in sagittal intermaxillary relationships in Class III malocclusion from age 8 to 14 years, whereas significant difference in vertical and transverse intermaxillary relationships appeared with ages during this period. When comparing Class III to Class I malocclusions at the same age point, there were significant differences in sagittal and transverse intermaxillary relationships, whereas significant difference in vertical intermaxillary relationship appeared after 12 years of age.

Conclusion: The results suggest that the sagittal intermaxillary relationships in Class III malocclusions were established before 8 years of age and remained through puberty and that the vertical and transverse intermaxillary relationships in Class III malocclusions changed with ages from 8 to 14 years.

Influence of occlusal plane inclination on ANB and Wits assessments of anteroposterior jaw relationships

INTRODUCTION

Although assessments of anteroposterior relationships are vital for orthodontic treatment planning, they cannot be precisely achieved by current cephalometric and noncephalometric resources. ANB angle and the Wits appraisal are the most popular cephalometric measurements applied in clinical orthodontics, although they have drawbacks. Facial vertical features, especially the occlusal plane angle, play an important role in their assessment, contributing to their unreliability.

METHODS

To further understand the influence of occlusal plane inclination, ANB angle and the Wits appraisal were analyzed in cephalo-lateral radiographs of 122 finished orthodontic patients in 2 groups: high occlusal plane angle and low occlusal plane angle.

RESULTS

There was a tendency for inconsistency between ANB and Wits assessments in the high occlusal plane angle group and a tendency for consistency in the low occlusal plane angle group. Cranial base influences on ANB and Wits assessments were investigated by subdividing the groups. Any of the considered cranial base factors was decisive for lack or presence of consistency between ANB and Wits assessments.

CONCLUSIONS

The clinician should beware of possible misinterpretations when using ANB and Wits to assess the anteroposterior relationship of the jaws, especially in high occlusal plane angle patients.

Age-related changes in sagittal relationship between the maxilla and mandible

The aim of the study was to assess age-related changes in sagittal jaw relationship during pre-pubertal and pubertal development on the basis of angular [ANB, anteroposterior dysplasia indicator (APDI) and A-B plane angle] and linear (Wits, AF-BF, App-Bpp, and App-Pgpp) measurements. Lateral cephalograms of orthodontically untreated subjects were evaluated at 7, 9, 11, 13 and 15 years of age. Cephalometric standards and age-related changes were determined on the basis of Class I subjects with a good occlusion (n = 18, 10 males and 8 females). With respect to changes related to growth, the main findings were, in both genders, a statistically significant age-related decrease in ANB angle, App-Bpp and App-Pgpp, a significant increase in APDI, but no age-related change in Wits. A reduction of sagittal jaw distance during pre-pubertal and pubertal development was observed arising from a relative dominance of sagittal mandibular growth. For an evaluation of differences concerning jaw relationship in Class II subjects, a group with Class II division 1 malocclusions (n = 17) and a group with Class II division 2 malocclusions (n = 12 were compared with two control groups, i.e. the good occlusion group and a Class I group (n = 37). Conclusions about the sagittal discrepancy in Class II division 1 and Class II division 2 subjects depended on the geometric reference used in the various parameters, and further research is called for with respect to the diagnostic performance of the various measurements. Differences between Class II subjects and controls present at 15 years of age were already established at 7 years of age, but were less pronounced.

A new approach of assessing sagittal discrepancies: the Beta angle

An accurate anteroposterior measurement of jaw relationships is critically important in orthodontic diagnosis and treatment planning. The angular and linear measurements that have been proposed can be inaccurate because they depend on various factors. The purpose of this study was to establish a new cephalometric measurement, named the Beta angle, to assess the sagittal jaw relationship with accuracy and reproducibility. This angle uses 3 skeletal landmarks-point A, point B, and the apparent axis of the condyle-to measure an angle that indicates the severity and the type of skeletal dysplasia in the sagittal dimension. Seventy-six pretreatment cephalometric radiographs of white patients were selected on the basis of 4 criteria that indicate a normal Class I skeletal pattern; the mean and the SD for the Beta angle were calculated. This group was compared with Class II and Class III skeletal pattern groups. After using the 1-way analysis of variance and the Newman-Keuls test and running receiver-operating-characteristics curves, we obtained results that showed that a patient with a Beta angle between 27 degrees and 35 degrees can be considered to have a Class I skeletal pattern. A more acute Beta angle indicates a Class II skeletal pattern, and a more obtuse Beta angle indicates a Class III skeletal pattern.

Extraoral appliances: a twenty-first century update

With the locations of the centers of resistance of the dentomaxillary complex having recently been defined, and with the newly acquired knowledge of the critical interplay between part-time extraoral and full-time intraoral force systems, the basic designs of all types of extraoral appliances are discussed in depth. Armed with this information, the clinician can improve the efficiency of all extraoral appliances to obtain better dentomaxillary-complex growth control and negate or enhance appliance-induced intraoral force systems.

Comparison of maxillary and mandibular growth

In this longitudinal study, serial lateral cephalometric radiographs were used to compare growth patterns of the maxilla and mandible, with hand-wrist radiographs used to assess skeletal maturity. The sample comprised 28 untreated subjects (15 female, 13 male) who were followed from ages 6 to 20 years. All subjects had Class I malocclusions without anterior crossbites. Absolute values and incremental changes for linear and angular cephalometric measurements were recorded and analyzed, and the relative growth-rate formula was used to provide an accurate index of acceleration and deceleration of growth. The SNA angle did not change significantly with age, but the SNB angle increased significantly in the male subjects. The ANB angle decreased continuously until age 14. The palatal plane descended significantly from the horizontal plane. The anterior and posterior nasal spines moved at about the same rate. The mandible grew in length twice as much as the maxilla from ages 6 to 20. With growth, the facial profiles of the male subjects became straighter as the chin became more prominent. The female subjects had less incremental growth and duration of growth of the mandible, so that the profiles remained more convex. Overall, skeletal and chronologic ages did not differ significantly, except at ages 10 and 16 in the female subjects. Individual variability pointed to the need for assessing each patient's pattern in the general guidelines of the group pattern.

Stability of anterior open bite nonextraction treatment in the permanent dentition

This study cephalometrically evaluated the long-term stability of anterior open bite nonextraction treatment in the permanent dentition after a mean period of 5 years. The experimental group consisted of 21 patients who had undergone orthodontic treatment with fixed appliances from whom cephalometric headfilms were obtained at the pretreatment, posttreatment, and postretention stages. Two control groups were used. The first, with ages comparable with the experimental group before treatment, was used only to characterize it. The second control group, with normal occlusion, was longitudinally followed for a period comparable with the posttretention period and was used to compare the changes between groups during this period. The differences between the observation stages in the experimental group were analyzed with paired t tests, and the postretention changes were compared with the changes of the second control group with independent t tests. A statistically significant decrease of the obtained anterior overbite was demonstrated at the end of the postretention period. The primary factor that contributed to the overbite decrease was the smaller vertical development of the maxillary and mandibular incisors in the postretention period. Neither the pretreatment anterior open bite amount nor the magnitude of correction was associated with the long-term overbite decrease. However, 61.9% of the sample had a clinically stable open bite correction.

Bialveolar protrusion in a Zimbabwean sample

This study was undertaken to assess dentoalveolar relationships in a well-balanced sample of adult black Zimbabweans. Lateral cephalograms of 25 men and 25 women 18 to 38 years of age with Class I occlusions were obtained from the University of Zimbabwe. Twelve angular and 6 linear measurements were analyzed, and men and women were compared with the Student t test. No statistically significant difference was noted between the 2 sexes. The Zimbabwean sample had a low Frankfort-mandibular plane angle (19.6 degrees +/- 5.5 degrees ) with a receding chin as shown by the negative Pog-NB measurement (-0.7 +/- 1.5 mm). Both the maxilla (SNA = 88.5 degrees +/- 4.7 degrees ) and the mandible (SNB = 83.3 degrees +/- 4.4 degrees ) were prognathic, and the ANB difference was large (5.3 degrees +/- 2.7 degrees ). The maxillary incisors were more upright compared with those of white people as measured by the angle of the maxillary incisor to NA line (20.6 degrees +/- 7.7 degrees ), while the mandibular incisors were severely proclined (IMPA = 105.8 degrees +/- 6.0 degrees, L1-Apog = 6.9 degrees +/- 2.7 degrees, L1-NB = 37.6 degrees +/- 4.9 degrees ), and this proclination was considered to be compensatory to the prognathic maxilla.

Transition of molar relationships in different skeletal growth patterns

This study investigated maxillary and mandibular growth differences and their effect on the changes in molar relationships from early transitional dentition to adult permanent dentition. Various landmarks were identified and measurements made on the longitudinal cephalometric radiographs of 40 people. The subjects were classified into 3 groups based on the amount of sagittal skeletal growth difference between the jaws. In group A, the mandible grew more than did the maxilla; in Group B, growth was about the same; and in group C, the maxilla grew more than did the mandible. The results revealed that skeletal growth differences between the jaws significantly influenced the changes in molar relationship during the transitional dentition, not only by translating basal bones but also by altering the amount of physiologic mesial shift in the dentition. However, the skeletal growth difference during the permanent dentition did not influence the changes in molar relationship. The sagittal growth difference between the jaws was largely absorbed by a dentoalveolar compensation. Tooth movement showed different characteristic features depending on the amount of the skeletal growth difference: (1) If the mandible grew more than did the maxilla, the growth difference was mostly absorbed by mesial displacement of the maxillary first molars and counterclockwise rotation of the occlusal plane. Anterior occlusion was adjusted by mesial displacement and labial inclination of the maxillary incisors and lingual inclination of the mandibular incisors. (2) If the maxilla grew more than did the mandible, the growth difference was mainly absorbed by mesial displacement of the mandibular molars. Then the maxillary molars showed minimal mesial displacement. The occlusal plane also showed minimal rotational change. Anterior occlusion was adjusted by lingual tipping of the maxillary incisors and mesial displacement and labial tipping of the mandibular incisors.

The reliability of 3 sagittal reference planes in the assessment of Class I and Class III treatment

The objective of this study was to test the reproducibility and validity of 3 sagittal reference planes with the use of the Wits analysis. Measurements made to the functional occlusal plane, the bisected occlusal plane, and the maxillomandibular bisector were compared with each other and with the angular measurement of the ANB angle. The angular relationship of these reference planes to the postmaxillary vertical reference plane was also studied. The data were collected from pretreatment (T1), posttreatment (T2), and 2-year postretention (T3) lateral cephalograms of 35 Class I and 10 Class III subjects. Nonextraction treatment for these patients was performed with full fixed orthodontic appliances in the permanent dentition. Cephalometric data were compared with 39 Class I and 9 Class III control subjects. The serial lateral cephalograms of untreated control subjects that were analyzed were taken at ages approximating those of the treated groups at T1, T2, and T3. The maxillomandibular bisector was determined to be an easily identifiable and reproducible reference plane that exhibited greater stability over time with both growth and treatment than either the functional occlusal plane or bisected occlusal plane. The mean values for the maxillomandibular bisector Wits result for Class I and III populations were distinct and, when combined with previous Class II data, yielded a triphasic distribution that may be a useful clinical tool for patient assessment.

Morphologic determinants in the etiology of class III malocclusions: a review

Morphospatial disharmony of the craniomaxillary and mandibular complexes may yield apparent mandibular prognathism, but Class III malocclusions can exist with any number of aberrations of the craniofacial complex. Deficient orthocephalization of the cranial base allied with a smaller anterior cranial base component has been implicated in the etiology of Class III malocclusions. Whereas the more acute cranial base angle may affect the articulation of the condyles resulting in their forward displacement, the reduction in anterior cranial size may affect the position of the maxilla. As well, intrinsic skeletal elements of the maxillary complex may be responsible for maxillary hypoplasia that may exacerbate the anterior crossbite seen in the Class III condition. Conversely, with an orthognathic maxilla, condylar hyperplasia and anterior positioning of the condyles at the temporo-mandibular joint may produce an anterior crossbite. Aside from the skeletal components, soft tissue matrices, particularly labial pressure from the circumoral musculature, may influence the final outcome of craniofacial growth of a child skeletally predisposed to Class III conditions. Indeed, as some Asian ethnic groups demonstrate an increased prevalence of Class III malocclusions, it is likely that the skeletal components and soft tissues matrices are genetically determined. Presumably, the co-morphologies of the craniomaxillary and mandibular complexes are likely dependent upon candidate genes that undergo gene-environmental interactions to yield Class III malocclusions. The identification of such genes is a desirable step in unraveling the complexity of Class III malocclusions. With this knowledge, the clinician may elect an early course of dentofacial orthopedic and orthodontic treatments aimed at preventing the development of Class III malocclusions.

Comparative study of diagnostic measures in borderline surgical cases of unilateral cleft lip and palate and noncleft Class III malocclusions

Patients with complete unilateral cleft lip and palate present difficult growth problems. Their anteroposterior discrepancies in jaw and dentition are frequently so severe that some epidemiologic studies report the necessity of orthognathic surgery in 25% of their sample. The aims of this study were three-fold: (1) to delineate diagnostic measures in borderline surgical cases of unilateral cleft lip and palate, (2) to verify the significance of negative overjet as a measure of anteroposterior discrepancy, and (3) to compare these diagnostic measures with those of borderline surgical cases of noncleft Class III malocclusions. The sample consisted of 29 patients with unilateral cleft lip and palate and 25 noncleft Class III Korean patients (mean age, 18.69 years); all had crossbites of all four incisors. Each of their pretreatment study casts and cephalograms were analyzed. The group with unilateral cleft lip and palate was divided into two subgroups on the basis of the method of their anterior crossbite resolution; 18 subjects were treated with orthodontics alone (Cleft-NS) and 11 subjects with orthognathic surgery (Cleft-Surg). The noncleft Class III group was divided into two subgroups; 6 of the subjects were orthodontically treated (Cl III-NS), and 19 were surgically treated (Cl III-Surg). The group with unilateral cleft lip and palate showed smaller SNA and SNB angles than the noncleft Class III group, but the ANB angles and the amount of anterior crossbites showed no statistical differences. When the Cleft-NS and the Cleft-Surg groups were compared, the ANB angle and the Wits measurements were significantly different. When the Cl III-NS and Cl III-Surg groups were compared, the SNB, ANB, L1GoGn, Wits, and the crossbite showed significant differences. For borderline surgical Class III unilateral cleft lip and palate cases, ANB angle, Wits appraisal, and ABGoGn angle were critical diagnostic parameters. On the other hand, the magnitude of anterior crossbite, the negative overjet, was shown not to be a significant measure of anteroposterior discrepancy.

The reliability of three sagittal reference planes in the assessment of Class II treatment

This investigation evaluated the reliability and validity of three anteroposterior skeletal measurements using the maxillary-mandibular (MM) Bisector, the functional occlusal plane (FOP), and the bisected occlusal plane (BOP) as reference planes in the assessment of anteroposterior discrepancies. Comparisons were made between these measurements in both treated and control samples of Class II Division 1 patients. The data were collected from pretreatment, posttreatment, and 2 years posttreatment lateral cephalograms of 36 Class II Division 1 subjects whose treatment was nonextraction with low or straight pull headgears. Comparisons were made to an untreated control group of 15 Class II Division 1 subjects. The MM Bisector was found to be a highly reproducible reference plane whose greater stability was demonstrated by a lack of change in its cant during growth or during growth and treatment, compared with the BOP or FOP. With the ANB angle used as a standard, and MM Bisector anteroposterior measure was a more reliable and valid indicator of the skeletal anteroposterior relationship of the jaws, especially longitudinally during growth and treatment, than the Wits appraisals made with either the FOP or BOP.