Prediction of mandibular growth rotation

Informational content of two-dimensional panoramic radiographs and lateral cephalometric radiographs with respect to the bone volume of intraoral donor regions considering CBCT imaging

BACKGROUND

To test the hypothesis that cephalometric parameters in two-dimensional routine dental radiographs correlate with the bone volume of intraoral bone donor sites.

METHODS

One-hundred and eight radiographs [36 panoramic radiographs (PRs), 36 lateral cephalometric radiographs (LCRs), and 36 cone-beam computed tomography scans (CBCT)] of 36 patients (all three imaging techniques applied according to the needs of treatment planning), were analyzed individually. Cephalometric parameters (PR and LCR) were correlated with the bone volume measurement in three-dimensional CBCT scans in three intraoral donor sites (chin, mandibular retromolar region, and zygomatic alveolar crest).

RESULTS

The mean bone volumes measured for the chin were (3.10 ± 1.11 cm³ SD), the mandibular retromolar region (1.66 ± 0.54 cm³ SD), and the zygomatic alveolar crest (0.17 ± 0.04 cm³ SD). Cephalometric parameters were significantly correlated (all p-values < 0.05) with the bone volume in the chin and the mandibular retromolar region. The bone volume of the zygomatic alveolar crest exhibited no correlations (p > 0.05) with cephalometric parameters. However, it was significantly correlated (p < 0.01) with the mandibular retromolar bone volume. No gender-specific differences (p > 0.05) were observed concerning bone volumes in all bone harvesting regions. Nevertheless, the male population's interforaminal distance in the chin region was significantly higher (p = 0.001).

CONCLUSIONS

PRs and LCRs can be used at the initial stage of peri-implant augmentation planning to deduce conclusions about the bone volume in different intraoral bone donor sites. It can help describe indications and justify additional diagnostic options, such as three-dimensional radiologic techniques.

Redirecting mandibular growth through orthodontic dentoalveolar height development in growing patients with Class III malocclusion undergoing maxillary orthopedic protraction

INTRODUCTION

To control mandibular growth could be the determining factor for any growing patients with Class III malocclusion undergoing maxillary orthopedics. It has been reported that orthodontic dentoalveolar height development (ODHD) through orthodontic total arch extrusion might redirect mandibular growth backward and downward in growing patients with Class III malocclusion. We hypothesized bimaxillary-ODHD (bimax-ODHD) should be equal to or exceed the mandibular condylar growth to redirect the mandible to grow downward and backward in growing patients with Class III malocclusion.

METHODS

Twenty-seven consecutive growing patients with Class III malocclusion who underwent maxillary orthopedics (MO) were recruited in this study, including 13 control patients (aged 12.70 ± 2.09 years) who underwent treatment of MO with no ODHD and another 14 patients who underwent MO and ODHD (ODHD group; aged 12.75 ± 1.40 years). The pretreatment (T1) and posttreatment (T2) CBCT images were superimposed and measured for the amount of ODHD and maxillary downward growth (ODHD-Mx), ODHD in the mandible (ODHD-Mn), T2 - T1 changes on facial convexity, y-axis, maxillary and condylar growth, and mandibular posture. The data were analyzed statistically.

RESULTS

The T2 - T1 treatment duration was 7.5 months, significantly (P = 0.028) shorter in the ODHD group. The maxillary and condylar growth were similar among the groups. The mandible grew forward and downward in the control group, the ODHD-Mx and ODHD-Mn were significantly (P = 0.011) more in the ODHD group, and the mandible significantly (P = 0.001) grew backward and downward. The mandible grew backward and downward when the bimax-ODHD (ODHD-Mx + ODHD-Mn) exceeded the condylar growth (r = 0.715; P <0.001).

CONCLUSIONS

The bimax-ODHD, including the downward growth of the maxilla, should be equal to or exceed the mandibular condylar growth to redirect the mandible to grow downward and backward and improve the skeletal facial convexity in growing patients with Class III malocclusion.

Cranial base measurements in different anteroposterior skeletal relationships using Bjork-Jarabak analysis

OBJECTIVES

To assess the linear and angular cranial base measurements (Bjork polygon) in different anteroposterior (AP) skeletal relationships using Bjork-Jarabak analysis.

MATERIALS AND METHODS

Pretreatment lateral cephalograms of 288 (146 women, 142 men, mean ages 21.24 ± 2.72 years and 22.94 ± 3.28 years, respectively) adult patients were divided into Class I, II, and III skeletal relationships according to their ANB angle. Linear and angular measurements of Bjork polygon were measured and compared among different skeletal relationships. Analysis of variance was performed to detect the differences among groups. Independent-sample t-test was used to detect differences between men and women.

RESULTS

The Class II skeletal relationship has a significantly larger saddle angle than Class III does (P < .05), whereas Class III has a significantly larger gonial angle than Class II does (P < .05). The articular angle and sum of Bjork polygon angles were not significantly different among groups (P > .05). Anterior (N-S) and posterior (S-Ar) cranial base lengths were similar in the different AP skeletal relationships (P > .05). The ramal height and body of the mandible length were significantly larger in Class III compared with Class I and II (P < .05). Women had a significantly larger articular angle than men did (P < .05), although men had significantly larger linear measurements of Bjork polygon than women did (P < .05).

CONCLUSIONS

The Class III skeletal relationship has a smaller saddle angle and larger mandibular length and gonial angle. Men have a larger cranial base and mandibular linear measurements and a smaller articular angle compared with women.

Mandibular antegonial notch depth in postpubertal individuals: A longitudinal cohort study

Objectives

To perform an epidemiological analysis of the antegonial notch depth in postpubertal individuals and to analyze the development of deep antegonial notches longitudinally in growing individuals.

Material and Methods

Lateral cephalograms of 302 untreated 17/18‐year‐old subjects (171 males; 131 females), from the craniofacial growth legacy collection, were analysed to measure antegonial notch depth along the mandibular plane. Sex and sagittal malocclusion were investigated as possible factors influencing notch depth. In subjects with deep antegonial notches (>1.5 standard deviation) at the age of 17/18 years, earlier lateral cephalograms at 7/8 and 13/14 years were obtained, and the magnitude of notch depth analyzed longitudinally. Linear regression analyses were used to assess correlations between antegonial notch depth and other recorded variables.

Results

Antegonial notch depth ranged from 0 to 5.3 mm (mean 2.0 ± 1.0 mm). Antegonial notches were significantly deeper in males (2.3 ± 1.1 mm) than females (1.5 ± 0.7 mm) (p < .001). Notch depth was on average 0.3 mm deeper in Class I than in Class II or III individuals (p = .019). Twenty‐one subjects (all male) were judged to have deep antegonial notches at the age of 17/18. In these subjects, notch depth deepened from 13/14 to 17/18 years (p < .001), whereas no change was observed between 7/8 and 13/14 years.

Conclusions

Antegonial notch depth shows important variation in postpubertal individuals, with males having deeper notches than females on average. In those with deep antegonial notches (all males in the present sample), notch depth increases not during prepubertal growth but during the pubertal growth spurt.

Accuracy of 3 Soft Tissue Prediction Methods After Double-Jaw Orthognathic Surgery in Class III Patients

PURPOSE

We aimed to evaluate the accuracy and validity of conventional manual prediction method (CM) and 2-dimensional and 3-dimensional (3D) soft tissue prediction methods for Class III bimaxillary orthognathic surgery patients.

METHODS

Twenty skeletal Class III patients were included in this study. Soft tissue prediction was achieved with a traditional manual technique, 2-dimensional software (Dolphin Imaging, version 11.5), and 3-dimensional software (SimPlant Master, version 16.0) on preoperative lateral cephalometric radiographs and cone beam computurized tomography (CBCT) images and then compared with postoperative lateral cephalometric radiographs obtained at least 6 months after surgery (mean, 11.5 ± 6.77 months). Forty-eight measurements were done to determine the reliability of the methods.

RESULTS

All prediction methods have limited postsurgery prediction accuracy for the subnasal upper lip area. Most of the differences were not more than 3 mm for all study groups, except the 3D software, which predicted the upper lip area to be, on average, 3.08 ± 1.38 mm further back (P < 0.001). Although the conventional method predicted 20 of 48 measurements similar to the final results, the poorest predictions were found at the nasal and labiomental areas (P < 0.001). Two-dimensional software predicted 23 of 48 measurements very close to the final results but made significantly different predictions for the nasolabial and labiomental angles, labrale superius point, and the chin area.

CONCLUSIONS

The 3D method predicted, especially the upper lip area, to be significantly and clinically incorrect, and its soft tissue prediction was insufficient compared with the other 2 methods. The 3D software needs to be updated, especially in evaluating soft tissue A point and upper lip changes after surgery.

Early extractions of premolars reduce age-related crowding of lower incisors: 50 years of follow-up

Objectives

To study the effects of extraction of four premolars, without subsequent orthodontic treatment, on the crowding of lower incisors in subjects between early adolescence and late adulthood, as compared to untreated subjects.

Materials and methods

A total of 45 subjects were included in this study. The extraction group comprised 24 subjects who had all the first premolars removed at a mean age of 11.5 years, to relieve crowding in a class I malocclusion without subsequent orthodontic treatment. The control group had 21 untreated subjects, having a normal occlusion at a mean age of 13.0 years. The participants were documented with dental casts and cephalograms at mean ages of 11.4 and 13.0 years, for the two groups respectively (T1), and at mean ages of 30.9 years (T2) and 61.7 years (T3). Changes in lower incisor crowding were described as changes in “irregularity” and “space deficiency.”

Results

The extraction group showed no changes in the irregularity of the lower incisors and significant improvement of the space deficiency of the lower teeth into late adulthood. While in the control group, both irregularity of the lower incisors and space deficiency of the lower teeth increased significantly into late adulthood.

Conclusion

Lower incisor alignment remains mainly unchanged into late adulthood in subjects who have all their first premolars removed in childhood, as the only treatment to relieve teeth crowding.

Clinical relevance

Severe crowding in a class I occlusion can be solved solely with premolar extraction, allowing for spontaneous adjustments with more stable incisor alignment up to late adulthood.

Maxillo-Facial Morphology in Beckwith-Wiedemann Syndrome: A Preliminary Study on (epi)Genotype-Phenotype Association in Caucasians

Beckwith–Wiedemann syndrome (BWS) is a congenital overgrowth disorder caused by various (epi)genetic alterations affecting the expression of genes on chromosome 11p15. Cardinal features include abdominal wall defects, macroglossia, and cancer predisposition. Several (epi)genotype–phenotype associations were described so far, but specific studies on the evolution over time of maxillo-facial phenotype in the molecular subtypes still are scanty. The aim of this cross-sectional study was to associate maxillo-facial morphology and growth pattern with genoype in 25 Caucasian children with BWS and macroglossia. Twelve patients experienced a loss of metilation at imprinting center 2 (IC2-LoM), five had mosaic paternal uniparental isodisomy of chromosome 11 (UPD(11)pat), and eight were negative. A more marked tongue enlargement was detected in patients with IC2-LoM and negative genotype, while UPD(11)pat children showed mild macroglossia (p = 0.048). A cluster analysis did not demonstrate any specific relationship between (epi)genotype and maxillo-facial phenotype, but separated BWS patients based on their cephalometric characteristics. Children with IC2-LoM or negative genotype displayed hyperdivergence values > 30°, clockwise growth tendency, and skeletal class II into the same cluster. They had a negative prognostic score. These preliminary data suggest the need for developing individualized protocols for early monitoring of the craniofacial growth in such patients.

Diagnostic validity of different gonial angle segmentation for the assessment of mandibular growth direction: a retrospective study

BACKGROUND

The development of the mandible largely determines the sagittal and vertical lateral appearance. The gonial angle (Articulare-Gonion-Menton, Ar-Go'-Me), as a composite indicator, representes the growth direction of the mandible. We proposed a method based on the Frankfort horizontal (FH) plane and its vertical plane (VFH) to divide the gonial angle into sagittal and vertical components (Articulare-Gonion-VFH / Menton-Gonion-FH, Ar-Go'-VFH / Me-Go'-FH) and to compare the accuracy of diagnosing the development of the mandible and maxillofacial structures with other methods.

METHODS

Lateral cephalometric films from 736 volunteers aged 6-30 years were collected and analyzed for cephalometric measurements. Four groups of segmentation-based angle, including the FH-based segmentation (Ar-Go'-VFH / Me-Go'-FH), the SN-based segmentation (Articulare-Gonion- Sellion-Nasion plane' vertical plane/ Menton-Gonion- Sellion-Nasion plane, Ar-Go'-VSN / Me-Go'-SN), the Go'-S based segmentation(Articulare-Gonion-Sellion / Menton-Gonion-Sellion, Ar-Go'-S / Me-Go'-S), and the Go'-N based segmentation (Articulare-Gonion-Nasion / Menton-Gonion-Nasion, Ar-Go'-N / Me-Go'-N), as well as commonly used sagittal and vertical indices were measured. Pearson correlation analysis was used to show the representativeness of different segmentation methods on the mandibular growth direction.

RESULTS

As the gonial angle decreased with age, all the segmentation-based metrics decreased. The plane-based segmentation metrics, including Ar-Go'-VFH / Me-Go'-FH, Ar-Go'-VSN / Me-Go'-SN, were superior to the point-based segmentation metrics (Ar-Go'-S / Me-Go'-S, and Ar-Go'-N / Me-Go '-N) in evaluating vertical and sagittal development of the mandible. The sagittal indicators displayed alteration of ramus and condyle, while these vertical indicators responded to the alteration of the mandibular corpus and gonial angle.

CONCLUSIONS

The gonial angle should be clinically segmented with planes (including SN plane and FH plane) rather than points (including Go'-S and Go'-N) to assess mandibular development. The FH plane-based segmentation method facilitated chair-side diagnosis of the mandibular growth direction.

Comparison of surface- and voxel-based registration on the mandibular ramus for long-term three-dimensional assessment of condylar remodelling following orthognathic surgery

OBJECTIVES

The purpose of the present study was to validate and compare the accuracy and reliability of surface- and voxel-based registration on the mandibular rami for long-term three-dimensional (3D) evaluation of condylar remodelling following Orthognathic Surgery.

METHODS

The mandible was 3D reconstructed from a pair of superimposed pre- and postoperative (two years) cone-beam computerized tomography scans and divided into the condyle, and 21 ramal regions. The accuracy of surface- and voxel-based registration was measured by the absolute mean surface distance of each region after alignment of the pre- and postoperative rami. To evaluate the reliability, mean absolute differences and intra class correlation coefficients (ICC) were calculated at a 95% confidence interval on volumetric and surface distance measurements of two observers. Paired t-tests were applied to statistically evaluate whether the accuracy and reliability of surface- and voxel-based registration were significantly different (p < 0.05).

RESULTS

A total of twenty subjects (sixteen female; four male; mean age 27.6 years) with class II malocclusion and maxillomandibular retrognathia, who underwent bimaxillary surgery, were included. Surface-based registration was more accurate and reliable than voxel-based registration on the mandibular ramus two years post-surgery (p < 0.05). The inter observer reliability of using surface-based registration was excellent, ICC range [0.82-1.00]. For voxel-based registration, the inter observer reliability ranged from poor to excellent [0.00-0.98]. The measurement error introduced by applying surface-based registration for assessment of condylar remodelling was considered clinical irrelevant (1.83% and 0.18 mm), while the measurement error introduced by voxel-based registration was considered clinical relevant (5.44% and 0.52 mm).

CONCLUSIONS

Surface-based registration was proven more accurate and reliable compared to voxel-based registration on the mandibular ramus for long-term 3D assessment of condylar remodelling following Orthognathic Surgery. However, importantly, the performance difference may be caused by an inappropriate reference structure, proposed in the literature, and applied in this study.

Skeletal and Dentoalveolar Effects Induced by the Paolone- Kaitsas Appliance in the Treatment of Class II Malocclusion: A Controlled Retrospective Study on Lateral Cephalograms

The aim of this study was to assess the skeletal and dentoalveolar effects induced by the Paolone-Kaitsas functional appliance (PK appliance) in the treatment of growing patients affected by Class II malocclusion. A group of 25 Class II patients, treated with the PK appliance followed by fixed appliances, was evaluated with lateral cephalograms at the start (9.6 ± 1.6 years) and at the end of treatment (13.0 ± 1.5 years), and was compared with a matched untreated Class II control group of 23 subjects selected from the web archive of the American Association of Orthodontists Foundation Craniofacial Growth Legacy. Statistical comparisons were performed with the Student’s t-tests. The treated group showed a significant decrease in SNA (−2.2°), ANB (−2.2°), and Wits appraisal (−3.4 mm), a significant increase in the SN-palatal plane angle (1.1°), and a significant improvement in overjet (−2.9 mm), overbite (−2.5 mm), and molar relationship (3.6 mm). The PK appliance produced favorable dentoalveolar and skeletal effects: it inhibited maxillary growth without effects on the mandible and it also induced a downward inclination of the palatal plane.

Non-surgical adult class II high-angle treatment with an invisible appliance: A case report

This case report describes the complex situation of a young adult Class II hyperdivergent patient treated by premolar extraction with a straight wire lingual appliance. Despite the patient's refusal to undergo surgical treatment, the dual goals of ideal occlusal relationship and profile improvement were achieved through a well thought-out biomechanical strategy with appropriate extraction choice and anchorage control during space closure. This case report demonstrates the possibility of successfully resolving severe sagittal and vertical discrepancies in an adult patient without surgical treatment using a completely invisible technique. This report also highlights the need for careful planning during the diagnostic and treatment phases.

Relationship of maxillary and mandibular effective base length, arch length and dental crowding in different vertical growth pattern

Objectives:

The objectives of the study were to assess, measure, and correlate the maxillary and mandibular effective base length, arch length to the amount of dental crowding in different vertical growth pattern patients.

Materials and Methods:

Sample comprising 100 pre-treatment lateral cephalograms and study models (age group – 16–25 years) was randomly selected. The sample was divided into two groups, that is, clockwise (50) and anticlockwise (50) rotation based on the measurement of the gonial angle. The gonial angle and maxillary and mandibular effective lengths were measured on pre-treatment lateral cephalograms. Dental crowding and arch length were measured on the pre-treatment dental casts. Intergroup comparisons of effective base length, arch length, and crowding were performed with unpaired t-tests. Correlations between effective base length, arch length, and dental crowding were examined by means of Pearson’s correlation coefficient (P < 0.05).

Results:

Subjects with clockwise rotation significantly had more mandibular dental crowding and significantly decreased mandibular arch length compared to the anticlockwise group. An inverse correlation was found between maxillary and mandibular effective base length, arch length, and dental crowding while a positive correlation was found between maxillary and mandibular base length and arch length in both the groups.

Conclusion:

Clockwise rotation of the mandible along with skeletal and dental factors such as decreased effective base lengths and arch length, respectively, constitutes an important factor leading to dental crowding.

The influence of 3x3 bonded retainer on anterior crowding relapse in mandibular incisor extraction cases

Objective:

To evaluate the 3x3 bonded retainer influence on the mandibular anterior crowding in cases treated with mandibular incisor extraction

Methods:

The sample comprised pretreatment, posttreatment and follow-up orthodontic records of 16 subjects (10 females and 6 males) with Class I malocclusion treated with extraction of a single mandibular incisor. The mean ages (± SD) at pretreatment, posttreatment and follow-up evaluation were 23.45 ± 9.14 years, 25.50 ± 8.95 years and 30.11 ± 8.59 years, respectively. The mean (± SD) treatment time and posttreatment evaluation time were 2.05 ± 0.45 years and 4.60 ± 1.85 years , respectively. Little irregularity index and interdental widths were evaluated using dental casts. The sample was divided into two subgroups, according to the presence of the 3x3 bonded retainer at follow-up.

Results:

The subgroup without 3x3 bonded retainer presented a greater relapse at the follow-up, when compared to 3x3 bonded retainer subgroup.

Conclusion:

There was a significant relapse in cases treated with mandibular incisor extraction at follow-up. The subgroup without 3x3 bonded retainer showed a significant relapse at the follow-up when compared to the retainer group.

Severe transverse discrepancy in adult Class III patient: Parallel rapid palatal expansion with a bone-borne tandem expansion screws (TSE) followed by lingual fixed appliance for a non-surgical treatment: A case report

INTRODUCTION

Midpalatal suture opening in young adults is often difficult to achieve, depending on the suture maturation stage. It has been suggested that it is possible to avoid surgery and still achieve a successful pure skeletal expansion if a bone-borne Miniscrew-Assisted Rapid Palatal Expander is chosen (MARPE).

CASE PRESENTATION

The following case report describes the use of a pure bone-borne miniscrew-assisted rapid palatal expander followed by lingual fixed appliance to correct a severe transversal discrepancy in an adult patient characterized by a hyperdivergent mandibular skeletal pattern.

MANAGEMENT AND OUTCOMES

All treatment phases were digitally planned, starting with the miniscrews' insertion with a three-dimensionally printed surgical guided (Miniscrew Assisted Palatal Application: MAPA system) and Tandem Skeletal Expander (TSE) appliance, to the lingual indirect bonding. The final outcomes confirmed that this orthodontic approach represented a valid alternative to orthognathic surgery, with a significant improvement of the patient's occlusion and facial appearance.

DISCUSSION

The Tandem Skeletal Expander (TSE) design and the expansion protocol applied allowed to obtain a significant and stable skeletal increase of transversal diameters by digital planning of the insertion of miniscrews, with lower risks and costs than other surgical approaches.

Maxillofacial morphological characteristics in growing orthodontic patients with non-syndromic oligodontia

OBJECTIVE

Patients with oligodontia frequently show different types of malocclusions. However, how oligodontia affects the maxillofacial growth remains uncertain. This study aimed to investigate the maxillofacial morphological characteristics in growing patients with oligodontia.

SETTING AND SAMPLE POPULATION

The study subjects included 33 Japanese children with non-syndromic oligodontia (14 boys and 19 girls; mean age: 10.2 years) who visited the orthodontic clinic of Fukuoka Dental College Medical and Dental Hospital from 1999 to 2019.

MATERIALS AND METHODS

Cephalometric analyses were performed, and the variables measured in each subject were converted into Z scores in relation to the mean and standard deviation of the Japanese norms matched for growth stage. The one-sample t-test or Wilcoxon signed-rank test was performed to compare the mean scores in the patients with oligodontia with those of the Japanese norms.

RESULTS

Compared with the Japanese norms, patients with oligodontia showed a smaller convexity and larger A-B plane and SNB angles. The Frankfort-mandibular plane and gonial angles were smaller, whereas the height of the ramus was larger. The vertical height of the alveolar bone in the maxillary and mandibular incisors and molar areas was smaller in patients with oligodontia.

CONCLUSIONS

Patients with oligodontia showed Class III skeletal tendency with mandibular prognathism and flattened mandibular plane with a smaller gonial angle. These maxillofacial morphological features can be induced by a deficiency in the vertical growth of the alveolar bone in the maxillary and mandibular molar areas due to the lack of tooth germs.

Comparison of 3-D mandibular surfaces generated by MRI and CT

OBJECTIVE

The purpose of this study was to evaluate the errors of three-dimensional mandibular surfaces generated using magnetic resonance imaging (MRI) when computed tomography (CT) was set as the gold standard.

SETTINGS AND SAMPLE POPULATION

Seven patients with orthognathic deformities who had undergone CT and MRI scans were included in the study.

MATERIALS AND METHODS

Mandibular surfaces were generated on each CT and MR image by the surface-rendering method. Intra-individual reliability between CT and MRI was statistically tested by the confidence limits of agreement (LOA) for systematic error, 95% confidence interval minimal detectable change (MDC₉₅ ) for random error and intra-class correlation coefficient (ICC).

RESULTS

The average total error was 1.6 mm. The greatest MDC₉₅ was observed in the coronoid region in all directions. The other regions showed MDC₉₅ values of < 1.8 mm (transvers direction), 3.5 mm (vertical direction) and 1.7 mm (antero-posterior direction). ICCs showed 'almost perfect' agreement with respect to all regions.

CONCLUSION

Random errors were quantified for 3-D rendering of the mandible from MRI data. Although the coronoid region showed the greatest errors, the other regions of the mandibular surfaces generated using MRI were able to be evaluated.

A predictive model of "favorable" and "unfavorable" anteroposterior skeletal relations among Class Is and Class IIs

OBJECTIVES

To validate the use of the sagittal distance between ANS and Pg (ANSPg) as a measure of favorable and unfavorable anteroposterior skeletal relations and to identify multivariate cephalometric measures that could be used to predict favorable and unfavorable relations at 15 years of age.

MATERIALS AND METHODS

This longitudinal study included 226 untreated adolescents evaluated at 10 and 15 years of age. Patients were grouped as "favorable" or "unfavorable" based on the ANSPg (measured parallel to S-N -7°) at 15 years of age (ANSPg15). ANSPg15 was validated based on its correlation with changes in ANSPg between 10 and 15 years of age, as well as its relationships with established measures of growth potential. Multiple regression and discriminant analyses were performed to predict ANSPg15 from measures at 10 years of age.

RESULTS

ANSPg15 and the change in ANSPg between 10 and 15 years of age were significantly correlated (R= -0.661; P ≤ .001), with 77% of patients in whom relationships improved (ie, distance decreased) exhibiting favorable relationships at 15 years of age. Established measures of growth potential were significantly (P < .001) correlated with ANSPg15 and showed significant differences between patients with favorable and unfavorable relations. Multiple regression showed that the Y-axis, ANS-N-Pg, and symphyseal angle measured at 10 years explained approximately 60% (R = 0.78) of the variation in ANSPg15. Based on these three variables, discriminant function correctly predicted favorable or unfavorable relations of ANSPg15 77% of the time.

CONCLUSIONS

ANSPg15 was a valid measure for determining favorable and unfavorable anteroposterior skeletal relationships that could be predicted with moderately high levels of accuracy.

Safe sites for orthodontic miniscrew insertion in the infrazygomatic crest area in different facial types: A tomographic study

INTRODUCTION

Temporary skeletal anchorage devices (TSADs) are used to obtain skeletal anchorage for orthodontic treatment. Their insertion in the infrazygomatic crest (IZC) allows efficient orthodontic mechanics. Different facial types have different bone configurations. We aimed to evaluate the differences in bone thicknesses in the IZC area among patients of each facial type to determine a safe zone for TSAD insertion.

METHODS

For this retrospective study, 86 cone-beam computed tomography (CBCT) scans were divided into 3 groups according to the facial type: group I, 24 CBCT scans of hyperdivergent patients; group II, 30 scans of neutral patients; and group III, 32 scans of hypodivergent patients. The buccal alveolar bone thickness was measured in 6 zones between the second premolar and distal root of the second molar, 5, 7, 9, and 11 mm apical to the alveolar crest.

RESULTS

The IZC areas with minimum thickness for TSAD insertion follows: group I, between first and second molars at 11 mm from the alveolar crest, mesial root of the second molar at 9 mm from the crest, and distal root of the second molar at 11 mm from the crest; groups II and III, between first and second molars at 11 mm from the crest and mesial root of the second molar at 11 mm from the crest.

CONCLUSIONS

The safe zones for IZC miniscrew insertion are located 11 mm from the alveolar crest between the maxillary first and second molars and on the mesial root of the second molar for all the 3 facial types.

Comparison of Roll and Pitch Among Patients with Vertical and Horizontal Skeletal Patterns Using Cant-O-Meter: A New Gyroscopic Device for Measuring Occlusal Cant

In Orthodontics, initial classification of malocclusions was based on planar malocclusions in the anteroposterior, transverse and vertical planes that were based only on translation of the jaws in space. In 2007, Ackermann and Proffit introduced rotational components—roll, pitch, and yaw—analogous to the position of the airplane in space. These rotations can result in canting of the occlusal plane.

There are no quantitative methods available in the literature for a precise estimation of the occlusal cant.

Qualitative evaluation of occlusal cant is subjective and is associated with inter-individual variations. This article describes an indigenously devised simple chairside device that can quantify cant of the occlusal plane in terms of the roll and pitch in degrees. There is accurate quantification of cant, which can be used effectively in many clinical scenarios.

Deep learning for cephalometric landmark detection: systematic review and meta-analysis

OBJECTIVES

Deep learning (DL) has been increasingly employed for automated landmark detection, e.g., for cephalometric purposes. We performed a systematic review and meta-analysis to assess the accuracy and underlying evidence for DL for cephalometric landmark detection on 2-D and 3-D radiographs.

METHODS

Diagnostic accuracy studies published in 2015-2020 in Medline/Embase/IEEE/arXiv and employing DL for cephalometric landmark detection were identified and extracted by two independent reviewers. Random-effects meta-analysis, subgroup, and meta-regression were performed, and study quality was assessed using QUADAS-2. The review was registered (PROSPERO no. 227498).

DATA

From 321 identified records, 19 studies (published 2017-2020), all employing convolutional neural networks, mainly on 2-D lateral radiographs (n=15), using data from publicly available datasets (n=12) and testing the detection of a mean of 30 (SD: 25; range.: 7-93) landmarks, were included. The reference test was established by two experts (n=11), 1 expert (n=4), 3 experts (n=3), and a set of annotators (n=1). Risk of bias was high, and applicability concerns were detected for most studies, mainly regarding the data selection and reference test conduct. Landmark prediction error centered around a 2-mm error threshold (mean; 95% confidence interval: (-0.581; 95 CI: -1.264 to 0.102 mm)). The proportion of landmarks detected within this 2-mm threshold was 0.799 (0.770 to 0.824).

CONCLUSIONS

DL shows relatively high accuracy for detecting landmarks on cephalometric imagery. The overall body of evidence is consistent but suffers from high risk of bias. Demonstrating robustness and generalizability of DL for landmark detection is needed.

CLINICAL SIGNIFICANCE

Existing DL models show consistent and largely high accuracy for automated detection of cephalometric landmarks. The majority of studies so far focused on 2-D imagery; data on 3-D imagery are sparse, but promising. Future studies should focus on demonstrating generalizability, robustness, and clinical usefulness of DL for this objective.

How did modern morphology evolve in the human mandible? The relationship between static adult allometry and mandibular variability in Homo sapiens

Key to understanding human origins are early Homo sapiens fossils from Jebel Irhoud, as well as from the early Late Pleistocene sites Tabun, Border Cave, Klasies River Mouth, Skhul, and Qafzeh. While their upper facial shape falls within the recent human range of variation, their mandibles display a mosaic morphology. Here we quantify how mandibular shape covaries with mandible size and how static allometry differs between Neanderthals, early H. sapiens, and modern humans from the Upper Paleolithic/Later Stone Age and Holocene (= later H. sapiens). We use 3D (semi)landmark geometric morphometric methods to visualize allometric trends and to explore how gracilization affects the expression of diagnostic shape features. Early H. sapiens were highly variable in mandible size, exhibiting a unique allometric trajectory that explains aspects of their 'archaic' appearance. At the same time, early H. sapiens share a suite of diagnostic features with later H. sapiens that are not related to mandibular sizes, such as an incipient chin and an anteroposteriorly decreasing corpus height. The mandibular morphology, often referred to as 'modern', can partly be explained by gracilization owing to size reduction. Despite distinct static allometric shape changes in each group studied, bicondylar and bigonial breadth represent important structural constraints for the expression of shape features in most Middle to Late Pleistocene hominin mandibles.

Evaluation of Vitamin D (25OHD), Bone Alkaline Phosphatase (BALP), Serum Calcium, Serum Phosphorus, Ionized Calcium in Patients with Mandibular Third Molar Impaction. An Observational Study

The aim of this study was to evaluate the levels of vitamin D (25OHD) and other bone biomarkers in patients with third molar impaction (TMI). Thirty males and 30 females with unilateral or bilateral impacted mandibular third molar, and 15 males and 15 females as a control group (CG) were recruited. Rx-OPT was used to evaluate dental position and Pederson index to measure the difficulty of the intervention. Bone biomarkers were measured through blood venous sample in TMI group and CG. Mann-Whitney test, Pearson’s correlation coefficient, linear regression model were used to compare the different parameters in the two groups. 25OHD showed lower values in TMI group than in CG (p < 0.05) with values significantly lower in bilateral impaction (p < 0.05). Pearson’s coefficient for 25OHD presented a negative correlation with the Pederson index (ρ = −0.75). Bone alkaline phosphatase (BALP) showed significantly lower dosage in TMI group than CG (p = 0.02), Pearson’s coefficient for BALP presented a negative correlation with the Pederson index. Serum calcium, serum phosphorus, ionized calcium levels in TMI and CG groups were similar and Mann-Whitney test did not significantly differ between TMI and CG. TMI could be a sign of vitamin D deficiency and of low BALP levels that should be investigated.

A comparison of voxel- and surface-based cone-beam computed tomography mandibular superimposition in adult orthodontic patients

OBJECTIVE

To evaluate the accuracy, reliability, and efficiency of voxel- and surface-based registrations for cone-beam computed tomography (CBCT) mandibular superimposition in adult orthodontic patients.

METHODS

Pre- and post-orthodontic treatment CBCT scans of 27 adult patients were obtained. Voxel- and surface-based CBCT mandibular superimpositions were performed using the mandibular basal bone as a reference. The accuracy of the two methods was evaluated using the absolute mean distance measured. The time that was required to perform the measurements using these methods was also compared. Statistical differences were determined using paired t-tests, and inter-observer reliability was assessed by intraclass correlation coefficients (ICCs).

RESULTS

The absolute mean distance on seven mandible surface areas between voxel- and surface-based registrations was similar but not significantly different. ICC values of the surface-based registration were 0.918 to 0.990, which were slightly lower than those of voxel-based registration that ranged from 0.984 to 0.996. The time required for voxel-based registration and surface-based registration was 44.6 ± 2.5 s and 252.3 ± 7.1 s, respectively.

CONCLUSIONS

Both methods are accurate and reliable and not significantly different from each other. However, voxel-based registration is more efficient than surface-based registration for CBCT mandibular superimposition.

Are chin and symphysis morphology facial type-dependent? A computed tomography-based study

INTRODUCTION

The chin is a major determinant of the facial profile; hence, it plays a major role in orthodontics and orthognathic surgery. It is thus essential to follow and better understand its expression in different facial types. The major objectives of the current study were to characterize morphometrically the chin and symphysis and reveal their association with different facial types.

METHODS

Computed tomography scans of the head and neck of 311 adults (163 males, 148 females; age range, 18-95 years) were classified into 3 facial types: short, average, and long. Height, width, projection, inclination, thickness, and area were measured on the chin and symphysis.

RESULTS

The majority of the population (70%) manifested an average facial type; the other 30% were almost equally distributed between short and long facial types. The long facial type was more common among females and the short facial type among males. Chin projection, area, and size were significantly greater in short-faced patients. Chin width in males was similar for all facial types, whereas, in females, chin width was the widest in the short facial type and the narrowest in the long facial type. Symphysis height was significantly greater in long-faced patients in both sexes. The mandibular incisors' inclination relative to the mandibular plane was not significantly associated with the chin or symphysis morphology.

CONCLUSIONS

Chin and symphysis morphology is facial type-dependent. Orthodontists and maxillofacial surgeons should be aware of the complex relationship between facial types and chin/symphysis size and shape when planning treatment.

Treatment effects of functional appliances in children with Class II malocclusion with and without morphologic deviations in the upper spine

INTRODUCTION

This research aimed to compare treatment effects of functional appliances between children with and without morphologic deviations in the upper spine and analyze associations between Atlas dimensions and the short- and long-term treatment effects.

METHODS

Sixty-eight prepubertal or pubertal children (35 boys and 33 girls; mean age, 11.47 ± 1.39 years) treated with Class II functional appliances were included. Lateral cephalograms were taken at pretreatment (T1), postfunctional appliance treatment (T2), and after retention at postpuberty (T3). Upper spine morphology and Atlas dimensions were evaluated at T1. T1-T2 and T1-T3 lateral cephalograms were superimposed using a structural method. Changes in the jaws were compared with multiple linear regression analysis between children with and without deviations in the upper spine. Associations between the changes and Atlas dimensions were analyzed by partial correlation.

RESULTS

Children with morphologic deviations in the upper spine showed significantly more backward rotation of the mandible (P <0.01) and increased inclination of the jaws (P <0.05, P <0.01) from T1-T2 and significantly smaller condylar growth (P <0.01) from T1-T3 compared with children without the deviations. Atlas height was significantly associated with vertical and rotational changes in the mandible (P <0.01) from T1-T2 and condylar growth (P <0.05) from T1-T2 and T1-T3.

CONCLUSIONS

Morphologic deviations in the upper spine and low Atlas height were significantly associated with smaller condylar growth induced by functional appliances in the long term. Upper spine morphology and the Atlas dimension may be valuable in phenotypic differentiation in children with Class II malocclusion for optimal treatment outcome.

Differences in mandibular condyle and glenoid fossa morphology in relation to vertical and sagittal skeletal patterns: A cone-beam computed tomography study

Objective

This study aimed to evaluate the following null hypothesis: there are no differences in the morphology of the temporomandibular joint (TMJ) structures in relation to vertical and sagittal cephalometric patterns.

Methods

This retrospective study was performed with 131 participants showing no TMJ symptoms. The participants were divided into Class I, II, and III groups on the basis of their sagittal cephalometric relationships and into hyperdivergent, normodivergent, and hypodivergent groups on the basis of their vertical cephalometric relationships. The following measurements were performed using cone-beam computed tomography images and compared among the groups: condylar volume, condylar size (width, length, and height), fossa size (length and height), and condyle-to-fossa joint spaces at the anterior, superior, and posterior condylar poles.

Results

The null hypothesis was rejected. The Class III group showed larger values for condylar width, condylar height, and fossa height than the Class II group (p < 0.05). Condylar volume and superior joint space in the hyperdivergent group were significantly smaller than those in the other two vertical groups (p < 0.001), whereas fossa length and height were significantly larger in the hyperdivergent group than in the other groups (p < 0.01). The hypodivergent group showed a greater condylar width than the hyperdivergent group (p < 0.01). The sagittal and vertical cephalometric patterns showed statistically significant interactions for fossa length and height.

Conclusions

TMJ morphology differed across diverse skeletal cephalometric patterns. The fossa length and height were affected by the interactions of the vertical and sagittal skeletal patterns.

Maxillary width and hard palate thickness in men and women with different vertical and sagittal skeletal patterns

INTRODUCTION

The objective of this research was to compare maxillary width and hard palate thickness in men and women with different vertical and sagittal skeletal patterns.

METHODS

A total of 241 adults (93 men and 148 women aged from 18 to 25 years) were divided into male and female groups. Subjects were then separately divided into 3 sagittal skeletal groups and 3 vertical skeletal groups. A lateral cephalogram and a cone-beam computed tomography were taken for each subject. We measured the parameters to make statistical analyses and compared them between the different groups.

RESULTS

Women had smaller craniomaxillofacial bone width and palatal thickness than men. In sagittal groups, maxillary width, maxillary alveolar width, and external temporomandibular joint fossa width in Class II and Class III malocclusion groups were smaller than in the Class I group for both women and men. The internal temporomandibular joint fossa width was the same results in men and women. In vertical groups, palate thickness, maxillary width, and maxillary alveolar width of the high-angle group were smaller than those of the low-angle group, regardless of sex.

CONCLUSIONS

To an extent, maxillary width is correlated with vertical and sagittal skeletal patterns, and insufficient maxillary width would lead to unfavorable skeletal patterns. Differences exist in the morphology of craniomaxillofacial bone between men and women. Therefore, these findings can provide clinicians with references for differential diagnosis and treatment plans.

Growth and sexual dimorphism of the hyoid bone and its relationship to the mandible from birth to 19 years: A three-dimensional computed tomography study

The hyoid bone and the hyomandibular complex subserve the functions of respiration, deglutition, and speech. This study quantified the growth of the hyoid bone and the hyomandibular relationships in males and females from birth to 19 years. Using 97 computed tomography (CT) scans, from a previous study (Kelly et al., 2017) on mandibular growth from 49 individuals (16 with longitudinal scans), landmarks were placed on 3D CT models and used to calculate four distance, and three angular measurements. A general increase in growth trend was observed in hyoid bone linear measurements-length, width, and depth-as well as relational mandible-to-hyoid distance, throughout the developmental ages examined in both males and females, with most variables having larger measurements for females up to age 10 years. A general decrease in all three angular measurements was observed in both males and females up to approximately age 12 years, at which time male angular measurements gradually increased with significant sexual dimorphism emerging after age 15 years. As expected, postpubertal males had greater hyoid angle than females; they also had greater hyoid angle of inclination than mandible body inclination (with inclination relative to the anterior-posterior nasal plane), likely related to hyo-laryngeal descent. This study contributes to normative data on hyoid bone and hyomandibular relational growth in typically developing individuals and provides a baseline against which structural and functional influences on anatomic growth may be examined by clinical disciplines that address the aerodigestive and speech functions, as well as the fields of anatomy, forensics, and anthropology.

A comparison of 2- and 3-dimensional mandibular superimposition techniques against Björk's structural superimposition method

INTRODUCTION

The purpose of this research was to compare mandibular growth rotation relative to the cranial base in different vertical facial patterns on the basis of multiple 2-dimensional (2D) and 3-dimensional (3D) superimposition methods.

METHODS

Cone-beam computed tomography (CBCT) images taken at a mean interval of 54.8 ± 16.8 months were assessed from a sample of 70 growing patients. Three mandibular superimposition methods were compared against Björk's structural method: (1) a 2D landmark method (2D-M1), (2) a voxel-based 3D method based on a previously reported method (3D-M1), and (3) a voxel-based 3D method incorporating symphyseal structures as references (3D-M2). After superimposition, the relative change in cranial base lines as depicted in sagittal views were measured for true mandibular rotation. Agreement between methods was assessed with Lin's concordance correlation coefficient, Bland-Altman's limits of agreement, and the Bradley-Blackwood test.

RESULTS

Lin's concordance correlation coefficients ranged between 0.924 for the 2D-M1 method, 0.695 for the 3D-M1 method, and 0.965 for the 3D-M2 method. Bland-Altman limits of agreement were wide for all but the 3D-M2 method. Finally, the Bradley-Blackwood test of equality of means and variances was significant in all except the 3D-M2 method.

CONCLUSIONS

For time intervals between CBCT volume acquisitions >3 years, the use of the 2D-M1 and 3D-M1 methods is not recommended. There was a high concordance between the 3D-M2 method and Björk's structural method when assessing mandibular growth rotation using relative changes in cranial base lines. The high concordance was displayed across all vertical facial types and for all time differences between first and second CBCT data acquisitions.

Keys to Class II correction: A comparison of 2 extraction protocols

INTRODUCTION

The purpose of this study was to evaluate the effects of 2 extraction patterns on incisor and molar movements in patients with growing Class II Division 1.

METHODS

The sample included 54 patients 10-17 years of age treated by 2 private practice orthodontists using Tweed directional force mechanics, 4 premolar extractions, J-hook headgears, and Class II elastics or Saif springs. The sample was divided on the basis of having maxillary and mandibular first premolars (4/4) or maxillary first and mandibular second premolars (4/5) extracted. Each group included 27 patients. Treatment lasted 2.8 ± 0.60 years and 2.6 ± 0.54 years for the 4/4 and 4/5 groups, respectively. Pretreatment (T1) and posttreatment lateral cephalograms and dental casts were evaluated. Cranial base, mandibular, and maxillary superimpositions were performed to quantify tooth movements and displacements.

RESULTS

There were no statistically significant T1 between-group differences in crowding or in the SNA, SNB, ANB, and MPA angles. Analyses of covariance, controlling for statistically significant (P <0.05) differences in T1 mandibular incisor position, showed that mandibular first premolars extractions produced greater (1.6 mm) mandibular incisor retraction than second premolar extractions. The mandibular first molars were protracted significantly more (0.7 mm) after the second premolar than the first premolar extractions. Within-group changes of the MPA, between-group differences in the changes in MPA, and the amount of vertical eruption of the maxillary and mandibular molars were not significantly different between the 2 extraction patterns.

CONCLUSIONS

Extraction of mandibular second premolars enhances Class II molar correction, with greater mesial first molar movement and less distal incisor movement. Neither extraction pattern has an effect on the MPA or the vertical dimension (ie, there was no "wedge effect").

Mandibular symphysis dimensions in different sagittal and vertical skeletal relationships

Background

The aim of this cross-sectional study was to compare the dimensions of mandibular symphysis (MS) between gender and the different sagittal and vertical skeletal relationships.

Material and Methods

Pre-treatment records of orthodontic patients were divided according to gender, sagittal (Class I, II and III) and vertical (decreased, average and increased mandibular plane [MP] angle) skeletal relationships. Measurements of MS parameters were performed on lateral cephalograms using IMAGEJ software. Comparisons between MS parameters and gender and the different skeletal relationships was performed using multifactorial and one-way ANOVA, and independent sample t-tests.

Results

A total of 104 records (25 males and 79 females) fulfilled the inclusion criteria. Males had significantly greater MS surface area, dentoalveolar length, skeletal symphysis length, total symphysis length, vertical symphysis dimension and symphysis convexity (p < 0.05). Skeletal Class II patients had significantly greater dentoalveolar and skeletal symphysis lengths while Class III had greater chin length, vertical symphysis dimension and symphysis convexity (p < 0.05). Patients with decreased vertical dimension had greater skeletal symphysis length (p = 0.026) and those with an average vertical relationship had greater chin length (p < 0.001).

Conclusions

The morphology of the mandibular symphysis is affected by gender, sagittal and vertical skeletal patterns. Males had increased mandibular symphysis surface area and linear dimensions. Class II patients had greater dentoalveolar length. Chin length was greater in patients with an average MP angle.

Twin study-genetic comparison of matrix versus intramatrix rotation in the mandible and three different occlusal planes

BACKGROUND

The purpose of this study is to investigate the heritability of total rotation, matrix rotation, and intramatrix rotation of the mandible in Korean monozygotic (MZ) twins, dizygotic (DZ) twins, and their siblings.

MATERIALS AND METHODS

The samples consisted of 75 pairs of Korean twins (39.7 + 9.26 years; MZ group, 36 pairs; DZ group, 13 pairs; sibling group, 26 pairs). Lateral cephalograms were taken, and 13 variables related to internal and external mandible rotation were measured. Three types of occlusal planes (bisected occlusal plane, functional occlusal plane, and the MM bisector occlusal plane) were used to evaluate genetic influence on the occlusal plane. Heritability (h²) was calculated by using the intraclass correlation coefficient (ICC) and Falconer's method.

RESULTS

With regard to mandibular rotation, the MZ twin group showed significantly higher ICC values compared to the DZ twin and sibling groups. The ICC mean values for 13 cephalometric measurements were 0.85 (MZ), 0.62 (DZ), and 0.52 (siblings) respectively. The heritability of the total rotation (0.48) and matrix rotation (0.5) between the MZ and DZ groups was higher than that of the intramatrix rotation (- 0.14). All of the three types of occlusal plane showed high heritability, and among the three types, the functional occlusal plane showed the highest heritability (h² = 0.76).

CONCLUSION

Based on these findings that showed a strong genetic effect on total rotation and matrix rotation, maintaining these rotations should be carefully considered in the orthodontic treatment plan, while the lower border of the mandible may be responsive to various treatments. Occlusal plane change, especially with regard to the functional occlusal plane, may not be stable due to strong genetic influences.

Occlusal Plane and Skeletal Changes After Cervical Headgear Treatment With and Without Lower Utility Arch in Class II Growing Patients

The purpose of this study was to investigate skeletal and dental changes affecting occlusal plane inclination after cervical headgear treatment with and without lower utility arch. In order to distinguish the orthodontic changes from natural growth a control group was employed.The sample of this study consisted by 20 Class II subjects (10 males, 10 females; mean age 8.54) treated by using cervical headgear, 19 class II children (19 males, 9 females; mean age 8.64) treated with cervical headgear and utility arch, and 21 Class II patients (11 males, 10 females; mean age 8.41) who had no therapy.Lateral head films were studied for all the patients before treatment (T1) and after therapy (T2) for all the treated groups and at the beginning and at the end of observational period for the control group; cephalometric analysis was carried out in order to seek for the modifications between time points and between groups.Means and standard deviation have been analyzed for all the groups. In order to compare the modification between the time points within the same group the ANOVA test was applied. The ANOVA test was used to compare the mean differences (T2-T1) of 3 groups.The study revealed that there were significant changes in occlusal plane inclination after the different treatment modalities employed instead control group. The treatment with cervical headgear and utility arch is more effective than cervical headgear alone in lowering occlusal plane posteriorly when it is compared with controls.

Comprehensive 3D analysis of condylar morphology in adults with different skeletal patterns - a cross-sectional study

Background

The correlation between individuals’ condylar morphology and their skeletal pattern is of great interest for treatment strategies ranging from orthodontic orthopaedics to orthognathic surgery. The objective of the present study was to investigate this relationship three-dimensionally.

Methods

A total of 111 adult patients (mean age = 27.0 ± 10.2 years) who underwent head computed tomography or cone beam computed tomography scans were included. Based on these data, 3D models of the skull and the condyles were calculated. The craniofacial skeleton was evaluated (1) transversally regarding skeletal symmetry (menton deviation), (2) sagittally regarding skeletal classes (Wits appraisal) and vertically regarding the inclination of the jaws (maxillomandibular plane angle). The condylar morphology was assessed (a) linearly by the condylar width, height and depth; (b) angularly by the antero-posterior and medio-lateral condylar inclination; and (c) volumetrically by the ratio of the condylar volume/mandibular volume (C/Mand).

Results

(1) Transversal: Asymmetric patients showed significantly higher discrepancies in the volumetric ratio C/Mand on the deviation and non-deviation side compared to symmetric patients. (2) Sagittal: Class III subjects demonstrated longer, more voluminous condyles with higher antero-posterior and medio-lateral inclination angles compared to Class II participants. (3) Vertical: Hyperdivergent subjects had smaller condyles with higher antero-posterior inclination angles than those of hypodivergent subjects. No interactions of skeletal class and vertical relationships regarding condylar morphology were observed.

Conclusions

This study demonstrates a clear correlation between pronounced skeletal patterns and condylar morphology in an adult population. The description of radiographic condyle characteristics in relation to the craniofacial morphology improves orthodontic treatment planning and could be helpful in the diagnosis of temporomandibular joint pathologies.

Effect of piezocision on molar intrusion in open-bite treatment using a modified MEAW technique

PURPOSE

The aim of this retrospective study was to investigate whether a piezocision technique influences molar intrusion in open-bite cases.

METHODS

In all, 30 patients with open-bite malocclusion were assigned to one of two groups: the piezocision group comprised 15 patients who were treated using curved arches and anterior elastics with the simultaneous combination of piezocision which was performed interdentally in the upper posterior region, while the control group comprised 15 patients who were treated with the same treatment mechanics without piezocision. In both groups, after leveling and aligning, upper 0.017 × 0.025 accentuated curve and lower 0.017 × 0.025 reversed curve of Spee NiTi archwires were placed. Anterior vertical elastics were applied between laterals and the canines on both sides. The effects of treatments were investigated on cone-beam computed tomography images acquired before use of elastics and after correction of open-bite.

RESULTS

Open-bite closure was achieved in 2.85 ± 0.85 and 4.1 ± 1.58 months in the piezocision and control groups, respectively, while total treatment lasted 1.4 ± 0.42 and 1.7 ± 0.43 years, respectively. Extrusion of lower posterior teeth (p < 0.05) was observed together with extrusion of incisors and canines (p < 0.001) in the piezocision group, while only incisors and canines were extruded in the control group (p < 0.001). There were no significant differences between the groups (p > 0.05) except significant lower incisor extrusion (p < 0.05) and counter-clockwise rotation of the lower occlusal plane in the piezocision group (p < 0.001).

CONCLUSION

The duration of open-bite correction was significantly shorter in the piezocision group. No molar intrusion was observed in either group. Open bite correction was achieved mainly by extrusion and retrusion of the incisors while maintaining upper molar positions.

Surgical benefit of mandibular morphometric analysis: A new tool to standardize mandibular reconstruction

PURPOSE

The gold-standard for reconstruction of large mandibular defects is the use of free flaps of vascularized autologous bone with the fibula as the preferred donor site. The use of "custom cutting guides" for this indication is becoming increasingly prevalent. But cost of the procedure averages around 2,500 dollars per patient excluding treatment and entails selection criteria. We think it is possible to standardize mandibular reconstructions from an anatomical mean. The objective of this study was to perform a mandibular morphometric analysis in order to obtain a set of "mean" measurements, which can be used by all surgeons interested in mandibular reconstruction.

METHODS

We performed a morphometric analysis consisting of three-dimensional mandibular reconstructions of 30 men and 30 women. Several reference points were set and defined to evaluate specific lengths and angles of interest. We conducted an intra and inter-sexual descriptive analysis of measurements obtained.

RESULTS

We did not identify any major intra-sexual differences within each group. The gonial angle is more open in women and the measurements characterizing the basilar contour are more prominent in men. We did not identify any differences in alveolar region parameters.

CONCLUSION

The results of this study constitute a morphological tool for surgeons, from bone graft to free flap. These results also confirm us that the use of «custom cutting guides» for mandibular reconstruction may be excessive. It is pertinent to examine the value of "custom made" mandibular reconstructions since the differences observed are of the order of millimeters.

Mandibular shape prediction using cephalometric analysis: applications in craniofacial analysis, forensic anthropology and archaeological reconstruction

Background

The human mandible is variable in shape, size and position and any deviation from normal can affect the facial appearance and dental occlusion.

Objectives

The objectives of this study were to determine whether the Sassouni cephalometric analysis could help predict two-dimensional mandibular shape in humans using cephalometric planes and landmarks.

Materials and methods

A retrospective computerised analysis of 100 lateral cephalometric radiographs taken at Kingston Hospital Orthodontic Department was carried out.

Results

Results showed that the Euclidean straight-line mean difference between the estimated position of gonion and traced position of gonion was 7.89 mm and the Euclidean straight-line mean difference between the estimated position of pogonion and the traced position of pogonion was 11.15 mm. The length of the anterior cranial base as measured by sella-nasion was positively correlated with the length of the mandibular body gonion-menton, r = 0.381 and regression analysis showed the length of the anterior cranial base sella-nasion could be predictive of the length of the mandibular body gonion-menton by the equation 22.65 + 0.5426x, where x = length of the anterior cranial base (SN). There was a significant association with convex shaped palates and oblique shaped mandibles, p = 0.0004.

Conclusions

The method described in this study can be used to help estimate the position of cephalometric points gonion and pogonion and thereby sagittal mandibular length. This method is more accurate in skeletal class I cases and therefore has potential applications in craniofacial anthropology and the ‘missing mandible’ problem in forensic and archaeological reconstruction.

Correlation between Dentoalveolar Heights and Vertical Skeletal Patterns in Class I Malocclusion in Ethnic Javanese

Objectives  Vertical proportions of the face are important determining factors for diagnosis and planning appropriate orthodontic treatment. Orthodontic patients have different vertical and sagittal skeletal discrepancies, as well as associated varying degrees of dentoalveolar compensations. Dentoalveolar is a functional component of the jaw; it plays a role in occlusal dynamics and forms sagittal and vertical maxilla–mandibula relationships. This study aims to analyze the relationship between dentoalveolar heights and several vertical skeletal patterns in patients with Class I malocclusion in ethnic Javanese.

Materials and Methods  The sample consisted of lateral cephalograms of 75 patients (18 samples were male, and 57 were female). Determined by inclusion and exclusion criteria, the participants were selected from an initial sample of 196 patients with skeletal Class I malocclusion (sella–nasion–A and B [ANB] = 1–4 degrees). Cephalometric analysis was performed using OrthoVision2017 digital software. This analysis measured upper anterior dental height (UADH), upper posterior dental height (UPDH), lower anterior dental height (LADH), lower posterior dental height (LPDH), ANB angle, sella–nasion and mandibular plane (SN-MP), sella–nasion and palatal plane (SN-PP), palatal plane and mandibular plane (PP-MP), Frankfort horizontal plane and mandibular plane (FH-MP), sella to gonion (S-Go), articulare to gonion (Ar-Go), nasion to menton (N-Me), nasion to anterior nasal spine (N-ANS), and anterior nasal spine to menton (ANS-Me). Pearson correlation test was used to assess correlations among all variables ( p < 0.05).

Results  Significant correlations were observed between dentoalveolar heights and SN-MP, S-Go, Ar-Go, N-Me, and ANS-Me ( p < 0.05).

Conclusions  Patients with Class I malocclusion in ethnic Javanese exhibit a significant correlation between dentoalveolar and vertical skeletal patterns. UPDH and/or LPDH have a significantly positive correlation with SN-MP, S-Go, Ar-Go, N-Me, and ANS-Me. The orthodontic correction of the decreased or increased facial height included either the extrusion or intrusion of the anterior or posterior teeth in different ways.

Evaluation of open bite closure using clear aligners: a retrospective study

Objectives

To evaluate the dental and skeletal effects that occur in the correction of anterior open bite with clear aligners.

Materials and method

In this single-center retrospective study, the mechanism of anterior open bite closure using clear aligners (Invisalign, Align Technology, Santa Clara, CA, USA) was evaluated by cephalometric superimposition based on records of patients consecutively treated by a single, experienced Invisalign provider. Inclusion criteria consisted of anterior open bite (overbite < 0.5 mm), adult patients (18+) at the beginning of treatment, consecutive records, and good quality pre- and post-treatment records, where the required landmarks were clearly visible.

Results

A total of 45 patients were included for data analysis with a mean age of 30.73 ± 8.0 years and initial open bite of − 1.21 ± 1.15 mm. During treatment, the upper incisors showed significant (p < 0.05) retraction [U1-SN′(°) = − 10.91 ± 6.95°], [U1-SN′_perp(mm) = − 2.57 ± 1.75 mm] and extrusion [U1-SN′(mm) = 1.45 ± 0.89 mm]. The lower incisors also showed significant retraction [IMPA(°) = − 3.73 ± 4.91°), (ΔL1-MP′_perp (mm) = − 1.08 ± 1.59] and extrusion (ΔL1-MP′(mm) = 0.53 ± 0.74). Regarding molar position, no significant changes were noted in the anteroposterior position of the upper [ΔU6-SN′_perp(mm) = 0.01 ± 1.08 mm] and lower molar [ΔL6-MP′_perp(mm) = 0.03 ± 0.87 mm]; however, there was a statistically significant intrusion of the upper [ΔU6-SN′(mm) = − 0.47 ± 0.59 mm] and lower molar [ΔL6-MP′(mm) = − 0.39 ± 0.76 mm].

Conclusion

Open bite closure with clear aligners occurred due to a combination of maxillary and mandibular incisor extrusion and maxillary and mandibular molar intrusion, with slight mandibular auto rotation. Significant retraction of maxillary and mandibular incisors was also observed with treatment. Clear aligners are effective in reducing/controlling the vertical dimension in open bite patients.

Treatment of adult patient with hyperdivergent retrognathic phenotype and anterior open bite: report of a case with non-surgical orthodontic approach

Adult patients with anterior open bite and hyperdivergent retrognathic phenotype demand complex treatments, as premolar extractions, molar intrusion or orthognathic surgery. In the present clinical case, a young adult patient without significant growth, with Class I and anterior open bite, was treated with four premolar extractions. The therapeutic result shows good intercuspation, good facial esthetic, good function balance, and stability in a two-year post-fixed treatment follow-up.

Variation in Chin and Mandibular Symphysis Size and Shape in Males and Females: A CT-Based Study

The chin is a unique anatomical landmark of modern humans. Its size and shape play an important role from the esthetic perspective. However, disagreement exists in the dental and anthropological literature regarding the sex differences in chin and symphysis morphometrics. The "sexual selection" theory is presented as a possible reason for chin formation in our species; however, many other contradictory theories also exist. This study's aims were therefore to determine how chin and symphysis size and shape vary with sex, and to discuss "sexual selection" theory as a reason for its formation. Head and neck computed tomography (CT) scans of 419 adults were utilized to measure chin and symphysis sizes and shapes. The chin and symphysis measures were compared between the sexes using an independent-samples t-test, a Mann-Whitney test, and the F-statistic. The chin width was significantly greater in males than in females (p < 0.001), whereas the chin height, area, and size index were significantly greater in females (p < 0.001). Symphysis measures did not differ significantly between the sexes. Size accounted for 2-14% of the chin variance and between 24-33% of the symphysis variance. Overall, the chin was found to be a more heterogeneous anatomical structure than the symphysis, as well as more sexually dimorphic.

Assessment of methods used for 3-dimensional superimposition of craniofacial skeletal structures: a systematic review

Background

So far, several techniques have been recommended for the assessment of craniofacial changes through skeletal tissue superimposition, but the evidence that supports them remains unexplored. The purpose of the present study is to assess the available literature on skeletal-tissue superimpositions of serial craniofacial CT or CBCT images used to detect morphological changes.

Materials and Methods

Medline (via Pubmed), EMBASE, Google Scholar, Cochrane Library, Open Grey and Grey Literature Report were searched (last search: 17.11.2019) using specific terms that fulfilled the requirements of each database in the context of the study aim. Hand searches were also performed. The outcomes of interest were the accuracy, precision, or agreement between skeletal-tissue superimposition techniques to assess changes in the morphology of craniofacial structures. Studies of any design with sample size ≥3 were assessed by two authors independently. The study protocol was registered in PROSPERO (ID: CRD42019143356).

Results

Out of 832 studies, fifteen met the eligibility criteria. From the 15 included studies, 12 have shown high total risk of bias, one low risk of bias, and two studies have shown unclear risk of bias. Thirteen out of the 15 studies showed high applicability concerns, two unclear and no study had low applicability concerns. There was high heterogeneity among studies regarding the type of participants, sample size, growth status, machines, acquisition parameters, superimposition techniques, assessment techniques and outcomes measured. Fourteen of them were performed on Cone Beam Computed Tomography (CBCT) and one on Computed Tomography (CT) derived 3D models. Most of the studies (eleven) used voxel-based registration, one landmark-based registration and three studies compared different registration techniques, which include the surface-based registration. Concerning the area of interest, nine studies focused on the anterior cranial base and certain facial structures, four on maxillary structures and four on mandibular structures. Non-growing participants were included in six studies, growing in eight, whereas one study had both.

Conclusion

Most of the available studies had methodological shortcomings and high applicability concerns. At the moment, certain voxel-based and surface-based superimpositions seem to work properly and to be superior to landmark-based superimposition. However, further research in the field is required to develop and properly validate these techniques on different samples, through high quality studies with low applicability concerns.

Evaluation of growth changes induced by functional appliances in children with Class II malocclusion: Superimposition of lateral cephalograms on stable structures

Objective

To compare short- and long-term dentoalveolar, skeletal, and rotational changes evaluated by Björk’s structural method of superimposition between children with Class II malocclusion treated by functional appliances and untreated matched controls.

Methods

Seventy-nine prepubertal or pubertal children (mean age, 11.57 ± 1.40 years) with Class II malocclusion were included. Thirty-four children were treated using an activator with a high-pull headgear (Z-activator), while 28 were treated using an activator without a headgear (E-activator). Seventeen untreated children were included as controls. Lateral cephalograms were obtained before treatment (T1), after functional appliance treatment (T2), and after retention in the postpubertal phase (T3). Changes from T1 to T2 and T1 to T3 were compared between the treated groups and control group using multiple linear regression analysis.

Results

Relative to the findings in the control group at T2, the sagittal jaw relationship (subspinale-nasion-pogonion, p < 0.001), maxillary prognathism (sella-nasion-subspinale, p < 0.05), and condylar growth (p < 0.001) exhibited significant improvements in the Z- and E-activator groups, which also showed a significantly increased maxillary incisor retraction (p < 0.001) and decreased overjet (p < 0.001). Only the E-activator group exhibited significant backward rotation of the maxilla at T2 (p < 0.01). The improvements in the sagittal jaw relationship (p < 0.01) and dental relationship (p < 0.001) remained significant at T3. Condylar growth and jaw rotations were not significant at T3.

Conclusions

Functional appliance treatment in children with Class II malocclusion can significantly improve the sagittal jaw relationship and dental relationships in the long term.

Relationship between the Condylion-Gonion-Menton Angle and Dentoalveolar Heights

An accurate estimation of both facial growth and the dentoalveolar dimension is key to successful treatment. The aim of this study was to analyze the relation between the Condylion–Gonion–Menton angle (CoGoMe^) and dentoalveolar heights in a population of patients from southern Italy. This retrospective study analyzed 270 cephalograms of 115 males (42.1%, mean age 15.5 ± 5.2 years) and 155 females (57.9%, mean age 15.6 ± 5.9 years). The facial divergency was evaluated with the Sella–Nasion and Gonion–Gnation angle (SN^GoGn), mandibular structure with the CoGoMe^, and dentoalveolar heights were assessed in four measurements: upper anterior (UADH), lower anterior (LADH), upper posterior (UPDH), and lower posterior (LPDH). Data were analyzed by means of Pearson’s correlation and linear regression model (p < 0.05). All the dentoalveolar heights were strongly correlated among them (p < 0.001). The UADH was correlated with the SN^GoGn (r = 0.145; p = 0.017), while the LPDH was correlated with the CoGoMe^ (r = −0.183; p = 0.003). Moreover, there was a positive association between the UADH and the SN^GoGn (B = 0.08; 95% CI: 0.014–0.144; p = 0.017), and a negative association between the CoGoMe^ and the LPDH (B = −0.098; 95% CI: −0.161–0.035; p = 0.003). Facial divergency and mandibular structure are associated with dentoalveolar heights.

Upper airways evaluation in young adults with an anterior open bite: A CBCT retrospective controlled and cross-sectional study

OBJECTIVE

To compare the dimensions of the upper airway in young adults with anterior open bite versus matched individuals with an adequate overbite (control group) using different measurement approaches (linear, area, and volume measures).

MATERIALS AND METHODS

The sample included 137 cone-beam computed tomographies (CBCTs) of young adults (74 men and 63 women) divided into two groups: 47 CBCTs of individuals (mean age 27.89) with open bite (overbite depth indicator (ODI) 56.84°±9.48° and Frankfort mandibular plane angle (FMA) 31.21°±6.44°) and 90 CBCTs of individuals (mean age 26.87) without an open bite (ODI 62.24°±9.47°, FMA 26.79°±5.81°). Two trained and calibrated orthodontists made all linear, area, and volume measurements on the CBCT records of the upper airways using Planmeca Romexis software. The Mann-Whitney U-test, chi-squared test, and multiple linear regression were applied. Significance was set at P<0.05.

RESULTS

There were no differences in linear or volume measurements between groups, but there was a greater area in the open bite group (greater mean difference between groups 928.3 mm²) than the control group. No variable influenced nasopharyngeal airway volume, but ANB angle affected oropharyngeal airway volume (β=-623.87) and total airway volume (β=-651.48).

CONCLUSIONS

Orthodontists should be aware that the airways diagnosis can vary depending on the measurement approach used, the volumetric method being the gold standard. The pharyngeal airway volume was similar in individuals with vs. without an open bite and is mainly influenced by ANB angle in both groups.

Clinical implications of age-related change of the mandibular plane angle

OBJECTIVE

To identify trajectories of ontogenetic change in the mandibular plane angle (MPA) and to describe the influence of sex and other factors on MPA during growth.

SETTING/SAMPLE

The data consisted of 7026 MPA measurements from lateral cephalographs representing longitudinal series from ages 6 to 21 for 728 individuals from the Craniofacial Growth Consortium Study (CGCS).

MATERIALS AND METHODS

Facial type was determined from MPA for each assessment, with the assessment closest to age 18 representing the adult facial type. The sample includes 366 males and 362 females, each with between 2 and 15 cephalographs. The mean number of cephalographs per individual is 10. Variation in childhood MPA (earliest assessment between 6 and 9 years of age) and adult MPA (closest assessment to age 18 between 15 and 21 years of age), and change in MPA from childhood to adulthood were compared by sex and adult facial type using ANOVA and post hoc t tests.

RESULTS

Mandibular plane angle decreased from childhood to adulthood in 92% of males and 81% of females, yet increased in 36% of males and 50% of females with the hyper-divergent adult facial type. Childhood MPA and overall change in MPA were significantly different by adult facial type.

CONCLUSIONS

Adult facial type is associated with differences in childhood MPA and change in MPA during growth. There are multiple ontogenetic pathways by which an individual can achieve a normo-divergent adult facial type, and an individual's childhood MPA does not necessarily correspond to his or her adult facial type.

Automated Skeletal Classification with Lateral Cephalometry Based on Artificial Intelligence

Lateral cephalometry has been widely used for skeletal classification in orthodontic diagnosis and treatment planning. However, this conventional system, requiring manual tracing of individual landmarks, contains possible errors of inter- and intravariability and is highly time-consuming. This study aims to provide an accurate and robust skeletal diagnostic system by incorporating a convolutional neural network (CNN) into a 1-step, end-to-end diagnostic system with lateral cephalograms. A multimodal CNN model was constructed on the basis of 5,890 lateral cephalograms and demographic data as an input. The model was optimized with transfer learning and data augmentation techniques. Diagnostic performance was evaluated with statistical analysis. The proposed system exhibited >90% sensitivity, specificity, and accuracy for vertical and sagittal skeletal diagnosis. Clinical performance of the vertical classification showed the highest accuracy at 96.40 (95% CI, 93.06 to 98.39; model III). The receiver operating characteristic curve and the area under the curve both demonstrated the excellent performance of the system, with a mean area under the curve >95%. The heat maps of cephalograms were also provided for deeper understanding of the quality of the learned model by visually representing the region of the cephalogram that is most informative in distinguishing skeletal classes. In addition, we present broad applicability of this system through subtasks. The proposed CNN-incorporated system showed potential for skeletal orthodontic diagnosis without the need for intermediary steps requiring complicated diagnostic procedures.