Prediction of mandibular growth rotation

Non-surgical correction of an adult Class II high-angle with occlusal plane cant by four compromised permanent first molars extraction, preadjusted lingual appliance and miniscrews: A case report

This case report describes a complex full-step asymmetrical Class II division 1 high-angle in an adult patient treated by extraction of compromised first molars with a preadjusted lingual appliance. Since the patient presented severe sagittal and vertical discrepancies combined with an Izard orthofrontal profile with upper lip protrusion, an extraction camouflage was performed with the twofold aim of obtaining ideal occlusal relationship and profile improvement, correcting occlusal plane cant by selective intrusion with interradicular miniscrews. Appropriate biomechanical strategies, including extraction choice and anchorage control during space closure, were needed to achieve the planned results. This case report demonstrates the possibility of solving successfully severe sagittal and vertical discrepancies with significant asymmetric component in adult patient without surgical treatment by means of a completely invisible technique, with the extraction of the most compromised teeth in both arches. This report also underlines the need for careful planning during both diagnostic and treatment phases, with appropriate skeletal anchorage management, in order to obtain the best results.

Mandibular canal angle, length and curvature in the three facial growth patterns and their association with vertical dysplasia indicators in adult patients: A retrospective cross-sectional 2D cephalometric study

OBJECTIVE

The study compared the cephalometric mandibular canal (MC) morphology in different facial growth patterns and its association with other common vertical dysplasia indicators (VDI).

MATERIAL AND METHODS

Pretreatment lateral cephalograms of 111 individuals (18-40 years) were categorised as normodivergent (ND), hypodivergent (HypoD), and hyperdivergent (HyperD) growth patterns based on SNGoGn. The mandibular canal angle (MCA) and VDI were estimated using cephalometric software. The mandibular canal length (MCL) and mandibular canal curvature (MCC) were calculated using the B-spline curve fitting method. The statistical analyses included comparing the MC variables across the three growth patterns and assessing their correlations with other VDI. Linear models were used to evaluate the multivariate effects of growth pattern, age and sex on MC variables.

RESULTS

The HyperD group showed the highest median MCA (150°) followed by ND (146°) and HypoD (141°), with all intergroup differences significant at P<0.001. There was no statistically significant difference in the MCL between the groups (ND=57±4.3, HypoD=58.2±4.5, HyperD=57.9±5.1mm). The MCC radius was higher in HyperD (44.9±8.7mm) than in ND (39.1±11.7, P=0.034) and HypoD group (38.7±8.5mm, P=0.026), implying a less curved MC in HyperD group. The age and sex of the individual did not have any significant impact on the MC variables. While MCA demonstrated moderate to high correlation with many VDI, the other two were not correlated with most.

CONCLUSION

The mandibular canal angle and curvature are potential cephalometric indicators of facial growth patterns, with the former being more robust and practical for routine clinical applications.

Cephalometric Characteristics of Various Ethnic Groups in Tanzania

Objective: The aim of this study is to investigate the craniofacial skeletal profile features of the Tanzanian population with normal occlusion using lateral skull cephalograms, to determine the differences in craniofacial characteristics among various Tanzanian ethnic groups, and to compare the cephalometric norms of Caucasians with those of Tanzanians. Materials and Methods: Lateral cephalograms were taken from 142 male and 167 female Tanzanians, aged 18-30 years, all with acceptable and pleasing profiles and Class I occlusion, and no history of previous orthodontic treatments. Six linear and 14 angular cephalometric measurements were selected for analysis. A Student t-test was used to compare the mean cephalometric values between Tanzanians and Caucasians, while a one-way analysis of variance was applied to assess the inter-ethnic differences within the Tanzanian group. Results: No significant differences were found between the Tanzanian ethnic groups, except for the ANB and NA-APog angles, which were increased in the Cushite group, and the Md1-ML angle, which was found to be reduced in the Bantu sample. Significant differences were observed between Tanzanians and Caucasians in all measurements (p < 0.05) except for the Wits appraisal in sagittal relationships and the S-Go:N-Me and SN-OcP measurements in vertical relationships. Conclusion: The findings indicate that Tanzanian adults display distinct craniofacial characteristics, including a more convex facial profile, increased lower lip protrusion, dental proclination, and notable ethnic and intergroup variations.

Comparison between the chin position of male and female untreated growing Class I subjects: a mixed-longitudinal study

OBJECTIVES

To evaluate the position of the chin of untreated male and female Class I growing subjects.

MATERIALS AND METHODS

A sample of 51 growing Class I subjects, 29 male and 22 female, from 7 to 16 years of age, was studied. The total number of 359 lateral cephalograms included at least one cephalogram for each subject taken in the early mixed dentition (younger than 10 years), one in late mixed dentition (between 10 and 12 years), and one in the permanent dentition phase (older than 12 years old).

RESULTS

Descriptive statistics for the X component (horizontal) and Y component (vertical) of the cephalometric landmark Gnathion (Gn) were recorded. Student t-tests showed no differences between male and female growing subjects for the X component (horizontal), but significant differences for the Y component (vertical).

CONCLUSIONS

Displacement of the mandible over the timeframe studied differs between male and female untreated subjects. Although most of the orthodontic literature addresses such differences as an anteroposterior phenomenon, this study found that the difference is mainly due to the vertical, and not horizontal, component of such displacement.

Is mandibular posterior dento-alveolar intrusion essential in treatment of skeletal open bite in adult patients? A single center randomized clinical trial

BACKGROUND

Anterior open bite (AOB) malocclusion usually represents a complicated and advanced orthodontic problem. The skeletal variant of AOB used to be treated with a combined orthodontic and surgical approach, until the posterior segments' intrusion has been validated as an alternative, effective and conservative treatment modality for such cases with comparable outcomes to the surgical approach. The objective of this two-arm parallel randomized clinical trial was to compare the effects of mini-screw supported maxillary versus bi-maxillary buccal segments' intrusion on the amount of anterior open bite closure.

METHODS

Twenty-two adult patients aged 17-25 years, with skeletal open bite and anterior dental separation of 3-8 mm were randomized to either the comparator (Maxillary Intrusion with Consolidation of mandibular buccal segments-MIC) or intervention (Bimaxillary buccal segments' intrusion-BMI) groups. Miniscrew-assisted buccal segments' intrusion was instituted using fixed appliances on rigid stainless steel archwires (19 × 25 stainless steel) via nickel-titanium coil springs in the maxilla and memory chains in the mandible. The intrusion force was 200 g per maxillary buccal segment in both groups, and it was 150 g for each mandibular posterior segment in the BMI group. Duration of intrusion was 6 months.

RESULTS

Anterior open bite was significantly closed in both groups with means of 3.8 ± 0.84 (95% confidence interval [CI] 3.2-4.4) and 3.84 ± 1.47 mm (CI;2.8-4.9) for the MIC and BMI groups, respectively with no significant difference between them (p-value < 0.05). Maxillary posterior teeth experienced significant intrusion in both groups, with a mean of 2.89 ± 1.13 mm (CI;2.63-3.14) in the MIC group and 2.26 ± 1.62 mm (CI;1.89-2.62) in the BMI group. Statistically significant mandibular posterior teeth intrusion occurred in both groups with means of 0.86 ± 0.91 (CI;0.65-1.06) and 0.33 ± 0.84 mm (CI;0.14-0.52) in the BMI and MIC groups, respectively, with a statistically significant difference of 0.53 ± 0.14 (CI;0.25-0.8) mm. However, such difference was considered clinically insignificant.

CONCLUSIONS

Anterior open bite closure could be successfully achieved with maxillary buccal segments intrusion without the need for active intrusion of the mandibular posterior segments, as long as the latter are efficiently consolidated.

TRIAL REGISTRATION

The trial was prospectively registered at clinicaltrials.gov with an identifier number of NCT04713280.

Dentoalveolar process remodelling in the anterior mandible after Class III camouflage treatment with lower premolar extractions

BACKGROUND

The aim of this investigation was to evaluate if the hard and soft tissue dentoalveolar process of the mandible follows the tooth movements after lower premolar extractions and anterior retraction in Class III camouflage treatment.

METHODS

This retrospective study included 25 patients in retention (f/m 12,13) who had previously been treated with lower premolar extractions for Class III camouflage with a completely customized lingual appliance (Wits at T0 -6.7, ± 2.5 mm). The periodontal and dental health of the lower 6 anterior teeth was evaluated (T1) by a thermal sensitivity test, probing and visual inspection after a mean retention period of 3.1 years (± 2.5, min/max 1.0/9.6 years). A novel non-invasive method was used to measure the thickness of the hard and soft tissue dentoalveolar process on the labial and lingual side of the teeth before treatment (T0) and in retention (T1) at 3 different levels using superimposed intraoral scans. A paired t-test with α = 5% was used to evaluate differences between the endpoints.

RESULTS

At T1, all 25 patients (mean age 26.8 ± 9.7 years, min/max 16.3/49.5 years) presented uncompromised periodontal and dental situations in the lower anterior segment. The presented digital method for evaluating dimensional changes of the dentoalveolar process had excellent reliability (ICC) with a method error of 0.01 mm. The mean total labio-lingual dimension of the hard and soft tissue dentoalveolar process (min/max 7.89/10.02 mm at T0) was identical at T0 and T1 (mean change of 0.00 ± 0.33 mm, min/max -0.98/0.8 mm). At all levels, the teeth moved only 0.12 mm to the lingual side within the dentoalveolar process and therefore, they moved with the dentoalveolar process and not through it.

CONCLUSION

In non-surgical camouflage treatment with lower premolar extractions in moderate to severe Class III malocclusions, the dentoalveolar process can follow the movement of the mandibular incisors and canines during controlled retraction without any adverse effects.

Non-extraction camouflage on a fully cooperative full-step class II division 2 adult patient treated with en-masse distalization, class II elastics and preadjusted lingual appliance: A case report

This article describes one adult bilateral full-step class II case with severe initial upper incisors retroclination successfully treated by a completely invisible lingual appliance. A non-extraction treatment to compensate for the severe sagittal discrepancy was made possible following the excellent patient cooperation with intermaxillary elastics, combined with upper arch en-masse effective distalization with miniscrews. The application of an auxiliary torque spring was essential to increase upper incisors torque during class II mechanics. This case report shows the possibility of obtaining a full-step class II correction in an hypodivergent adult patient with a completely invisible appliance, taking advantage for the patient cooperation, for a more straightforward and faster non-extraction case resolution. It also underlines on the other hand the importance of successfully controlling incisors torque with auxiliaries in cases of severe retroclination in an adult class II malocclusion, in combination with the simultaneous distalization mechanics for monolateral full-step class II correction, by means of a completely invisible appliance.

Invisible treatment with preadjusted lingual appliance and monolateral space opening for an adult Class II malocclusion with upper lateral incisors agenesis: An ortho-prosthetic case report

This case report describes the treatment of a Class II malocclusion with upper lateral incisors agenesis in an adult patient, performed by an invisible preadjusted lingual appliance, monolateral space opening and dental Class II correction. The patient had previously been treated by clear aligners with the insertion of an implant in upper right canine position in order to close the remaining space. With the twofold aim of obtaining ideal occlusal relationship and smile aesthetic improvement, it highlights how a fixed orthodontic technique is needed to achieve the planned results, when anterior torque, bodily translations and deep-bite correction are necessary. On the other hand, it underlines how the treatment plan should not be adapted to the limits of the employed appliance, but should aim for the best clinical result for the patient. A prosthetic finalisation was in the end performed in order to obtain the best aesthetic result.

Morphologic predictors of mandibular changes induced by Sander's Bite Jumping Appliance

AIM

This study aimed to identify pretreatment cephalometric variables as possible predictors of the mandibular length increase in Class II patients with mandibular retrusion, treated by means of the Bite Jumping Appliance (BJA).

MATERIALS AND METHODS

Forty-three subjects (22 males and 21 females) with Class II malocclusion, treated with a BJA, were selected on the basis of the following inclusion criteria: full Class II molar relationship, Overjet (OVJ) ≥ 6 mm and a skeletal Class II malocclusion with mandibular retrusion at the start of the treatment (T0); cervical vertebral maturation stage 2 or 3 at time 0 (T0). The following mandibular structural features were measured on lateral cephalograms at time 0 and time 1 (15 months of treatment): the width and height of the mandibular symphysis and its width/height ratio, the width and height of the mandibular ramus and its width/height ratio, the antegonial notch depth and the Condilion-Gonion-Menton (Co-Go-Me) angle. Post-treatment changes were assessed by Pancherz's cephalometric analysis, evaluating the increases in mandibular length. A regression statistical model was used to test the association between morphologic variables and mandibular length changes.

RESULTS

At T1, a significant increase in mandibular length (7.1 + 3.4 mm, p < .001) was measured. A significant negative association between the pretreatment Co-Go-Me angle and mandibular length change was found (p < .05). IMPA angle was negatively associated with mandibular length change. All the others morphological feature were not statistically related to mandibular length change.

CONCLUSION

Co-Go-Me angle and IMPA angle at T0 can be used as predictors for mandibular response to the treatment with BJA.

Long-Term Predictive Modelling of the Craniofacial Complex Using Machine Learning on 2D Cephalometric Radiographs

OBJECTIVE

This study aimed to predict long-term growth-related changes in skeletal and dental relationships within the craniofacial complex using machine learning (ML) models.

MATERIALS AND METHODS

Cephalometric radiographs from 301 subjects, taken at pre-pubertal (T1, age 11) and post-pubertal stages (T2, age 18), were analysed. Three ML models-Lasso regression, Random Forest, and Support Vector Regression (SVR)-were trained on a subset of 240 subjects, while 61 subjects were used for testing. Model performance was evaluated using mean absolute error (MAE), intraclass correlation coefficients (ICCs), and clinical thresholds (2 mm or 2°).

RESULTS

MAEs for skeletal measurements ranged from 1.36° (maxilla to cranial base angle) to 4.12 mm (mandibular length), and for dental measurements from 1.26 mm (lower incisor position) to 5.40° (upper incisor inclination). ICCs indicated moderate to excellent agreement between actual and predicted values. The highest prediction accuracy within the 2 mm or 2° clinical thresholds was achieved for maxilla to cranial base angle (80%), lower incisor position (75%), and maxilla to mandible angle (70%). Pre-pubertal measurements and sex consistently emerged as the most important predictive factors.

CONCLUSIONS

ML models demonstrated the ability to predict post-pubertal values for maxilla to cranial base, mandible to cranial base, maxilla to mandible angles, upper and lower incisor positions, and upper face height with a clinically acceptable margin of 2 mm or 2°. Prediction accuracy was higher for skeletal relationships compared to dental relationships over the 8-year growth period. Pre-pubertal values of the measurements and sex emerged consistently as the most important predictors of the post-pubertal values.

A new harmony box supplemented with gonial angle and age based on a growing Swiss population

PURPOSE

The scope of the present study was to create a new harmony box by adding two diagnostically and clinically important cephalometric variables, the gonial and interincisal angles, while also considering the effect of sex and age for a growing Swiss population.

METHODS

A healthy sample with an overjet and overbite between 2 and 4 mm, and 1.5 and 4.5 mm, respectively, of the Zurich Craniofacial Growth Study was considered. Pairwise correlations between the cephalometric angles were evaluated with the Pearson correlation coefficient (r). Regression models were built for each cephalometric variable serving as the dependent one. The Akaike Information Criterion and the Bayesian Information Criterion were used to structure and select the final multivariable regression model. Bland-Altman plots and the Lin's concordance correlation coefficient were used to assess inter- and intraexaminer agreement.

RESULTS

The sample consisted of 301 individuals with a mean age of 13.4 years. Measurement concordance was confirmed both within and between examiners. The strongest correlations were observed between the angles SNB and SNA (r = 0.81), ArGoMe and SN-ML (r = 0.57), and SN-ML and SNB (r = 0.56). The SNB angle qualified as the dependent variable in the multivariable regression that framed the newly provided harmony box, with the predictor variables age (p < 0.001) and the angles SNA (p < 0.001), SN-ML (p < 0.001), SN-NL (p = 0.005), NSBa (p = 0.001), and ArGoMe (p < 0.001). The interincisal angle did not increase the robustness of the model and was excluded (p > 0.05).

CONCLUSION

Contrary to the interincisal angle, gonial angle and age qualified for inclusion in the new harmony box for individualized cephalometrics in a sample of healthy schoolchildren from Zurich, Switzerland.

Effect of Forsus-assisted mandibular advancement on the adaptation of craniocervical posture - A retrospective study

BACKGROUND and OBJECTIVE

Skeletal Class II malocclusion patients frequently exhibit an extended craniocervical position. The study's objective was to evaluate how the craniocervical posture has changed following skeletal class II correction using the Forsus fatigue-resistant device (FFRD).

METHODOLOGY

A retrospective analysis was undertaken using the pre- and post-treatment records of 35 skeletal class II patients who used the FFRD to achieve class II correction. The metrics suggested by Solow and Rocabado were used to evaluate the cranial and cervical positions. Eleven angular parameters were evaluated to determine the relationship between the mandibular ramus and the skull as well as the upper and middle craniocervical positions. To compare the parameters before and after fixed functional therapy, a Wilcoxon signed rank test was used.

RESULTS

Significant differences were obtained in the parameters SNA, SNB, and ANB post-FFRD. Significant differences were also noted in NL/OPT, NSL/OPT, FH/CVT, FH/OPT, NSL/CVT, NL/CVT, ML/CVT, FH/RL, and oropharynx position.

CONCLUSIONS

The upper and middle craniocervical posture altered significantly with the FFRD. Skeletal class II correction obtained with FFRD delivered the patients a more erect craniocervical posture.

Stability of proximal mandibular anatomical structures following bilateral sagittal split osteotomy

The aim of this study was to investigate the stability of the proximal mandibular reference structures that have been proposed in the literature for superimposition. Forty proximal mandibular segments of 20 patients who underwent bilateral sagittal split osteotomy (BSSO) for advancement were reconstructed from a pair of pre- and postoperative (2 years) cone beam computed tomography scans, and spatially divided into the mandibular condyle, the coronoid process, and 20 mandibular ramus regions. To assess the stability of the anatomical regions, the volumetric and surface discrepancy between the superimposed pre- and postoperative regions were calculated. One-sample t-tests were applied to analyse the statistical stability of the individual regions. Two statistically stable (P < 0.05) structures in the proximal segment of the mandible following BSSO were identified: (1) the posterior part of the mandibular ramus above the gonial angle and below the condylar neck, and (2) the sub-coronoid area below the coronoid process/mandibular notch. Using these stable structures for superimposition resulted in an assessment discrepancy in the condylar displacement of up to 1.1 mm and in the volumetric change of up to 2.8%. Hence, it is suggested that these two identified stable structures are used as reference areas when assessing condylar displacement and change using superimposition.

A cephalometric analysis of the antegonial notch in relation to the direction of mandibular growth

Masticatory muscle forces influence craniofacial morphology development. The antegonial notch (Notch) is a bony concavity on the inferior border of the mandible. Considering the Notch is located anteriorly to the insertion of the masseter muscle and varies among individuals, we hypothesised that these muscles influence the formation of the Notch. Therefore, this study aimed to investigate the correlation between mandible morphology and Notch formation. Sixty Japanese patients who visited the Department of Orthodontics at our university hospital were retrospectively evaluated. Morphological and morphometric analyses of the Notch and related craniofacial parameters were conducted using lateral cephalograms taken at the patients' initial visits. Standard values for the Notch area and depth were determined, and the morphology of the Notch and mandible was analysed using Spearman's rank correlation coefficient (p < 0.05). The mean Notch area and depth was 78.71 ± 36.54 mm2 and 3.11 ± 1.09 mm, respectively. The Notch area was significantly correlated with ramus inclination (p = 0.044, r = 0.261) and with the Y-axis (p = 0.039, r = 0.267). This study indicated that both the masticatory muscles and mandibular growth could contribute to the Notch formation.

Nonsurgical treatment of an adult patient with severe transversal skeletal discrepancy: Tooth bone-borne tandem expander and hybrid aligner approach

BACKGROUND

Although they have proven effective in the resolution of mild to moderate malocclusions, aligners demonstrate substantial limitations. More complex malocclusions therefore require a combination of auxiliaries, or a hybrid approach involving both aligners and fixed appliances, such as miniscrew-supported appliances or sectionals. This case report presents a 25-year-old female patient with a severe transversal discrepancy associated with an anterior open-bite tendency effectively treated with a tooth bone-borne palatal expander characterized by two expansion screws (tandem expander) and a hybrid treatment with aligners.

METHODS

After accurate matching between the pretreatment cone-beam computed tomography scan and digital models, four self-drilling miniscrews were inserted palatally using a computer- aided design and computer-aided manufacturing surgical template to guide their correct and safe placement, and a tooth bone-borne appliance was fitted. After this first phase, the hybrid clear aligner approach was used to obtain alignment, leveling, and arch coordination, with the use of a partial lingual fixed appliance.

RESULTS

Transverse maxillary deficiency was corrected, crowding has been resolved, Class I molar and canine relationship were obtained, and marginal ridges has been aligned.

CONCLUSIONS

Double jackscrew of the tandem expander enabled effective expansion of both the posterior segments as required to correct the skeletal discrepancy and the anterior region, thus relieving the dental crowding. Lingual sectional appliances have been shown to increase the effectiveness of clear aligners which, on the other hand, have been shown to be effective in closing the anterior bite by retroclination of the maxillary and mandibular incisors and, only minimally, by extrusion movements.

Dentoalveolar bone height in Class I adults with different vertical patterns: A cross-sectional study

BACKGROUND

Facial divergence during growth and development affects both the anterior and posterior alveolar bone dimensions in the maxilla and mandible, and the dentoalveolar compensation mechanism in severe vertical skeletal discrepancies remains unclear.

AIMS

To evaluate the: (1) difference in dentoalveolar heights among subjects with different vertical facial patterns; (2) association between the dentoalveolar bone height and other cephalometric variables; (3) effect of sex on dentoalveolar height measurements.

MATERIAL AND METHODS

Non-growing subjects with skeletal Class I (0°

RESULTS

Measurements on a total of 204 patients (81 males, 123 females) were analysed. At the level of the incisor and premolar regions, both dentoalveolar and alveolar bone heights were significantly larger in hyperdivergent group when compared to hypodivergent group, whereas at the level of the molar region, no difference was found among groups. Moderate to strong correlations were found between dentoalveolar bone and vertical skeletal measurements.

CONCLUSIONS

In the maxilla and mandible, the dentoalveolar compensation mechanism in skeletal Class I subjects results in an increased vertical height in the anterior dentoalveolar segment in hyperdivergent subjects and a reduced one in hypodivergent subjects.

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Key Words

• Adults
• Alveolar bone
• Dentoalveolar compensatory mechanism
• Dentoalveolar height
• Facial divergence

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MESH Headings

• Humans
• Male
• Cephalometry/methods
• Female
• Cross-Sectional Studies
• Maxilla/anatomy & histology
• Alveolar Process/anatomy & histology
• Alveolar Process/diagnostic imaging
• Vertical Dimension
• Adult
• Malocclusion, Angle Class I/pathology
• Malocclusion, Angle Class I/diagnostic imaging
• Mandible/anatomy & histology
• Young Adult
• Sex Factors
• Incisor/anatomy & histology
• Adolescent
• Molar/anatomy & histology
• Bicuspid/anatomy & histology
• Cuspid/anatomy & histology
• Cuspid/diagnostic imaging

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Affiliation(s)

Farah Khalifeh Private practice, Beirut, Lebanon
Maria Saadeh Department of Orthodontics and Denfofacial Orthopedics, Faculty of Dental Medicine, Lebanese University, Beirut, Lebanon; Department of Dentofacial Medicine, American University of Beirut Medical Center, Beirut, Lebanon.
Ramzi Haddad Department of Dentofacial Medicine, American University of Beirut Medical Center, Beirut, Lebanon; Department of Orthodontics, Centre Hospitalier Universitaire, Dijon, France

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Soft-tissue profile changes in adult patients treated with premolar extractions

INTRODUCTION

The objective of this study was to identify the soft-tissue profile changes and the potential pretreatment cephalometric parameters that clinicians could use to predict the lip response after premolar extraction treatment in adult patients.

METHODS

Pretreatment and posttreatment lateral cephalograms of 75 white patients treated with premolar extractions were analyzed. The following initial cephalometric measurements were recorded: upper and lower lip to E-plane, vermilion thickness, lip length, maxillary and mandibular incisor inclination, and mentolabial and nasolabial angle. Pretreatment and posttreatment radiographs were superimposed using the Björk structural method to record lip retraction and incisor/lip retraction ratio. Pearson correlation and Kruskal-Wallis tests were used to compare lip retraction and incisor/lip retraction ratio with the cephalometric variables. The sample was divided according to different extraction patterns.

RESULTS

The mean upper and lower lip retraction values were 1.4 mm and 1.7 mm, respectively. Vermilion thickness showed a negative and statistically significant correlation (P <0.05) with lip retraction and incisor/lip retraction ratio. In addition, the mean incisor/lip retraction ratio was 61% and 98% for the upper and lower thin lip, respectively, whereas the mean incisor/lip retraction ratio was 17% and 44% for the upper and lower thick lip, respectively. The comparison among extraction patterns did not highlight any noticeable difference.

CONCLUSIONS

The choice of a specific extraction pattern did not impact lip response. The vermilion thickness was the key factor influencing lip retraction: an increase in this parameter was related to a decrease in lip retraction and vice versa.

Anatomic and functional masseter muscle adaptation following orthognathic surgery-MRI analysis in 3 years of follow-up

BACKGROUND

Orthodontic and surgical technical advances in recent years have resulted in treatment opportunities for a whole range of craniofacial skeletal disorders either in the adolescent or adult patient. In the growing child, these can include myofunctional orthodontic appliance therapy or distraction osteogenesis procedures, while in the adult, the mainstay approach revolves around orthognathic surgery. The literature agrees that for a change in craniofacial morphology to remain stable, the muscles acting upon the facial skeleton must be capable of adaptation in their structure and, therefore, their function. Failure of the muscles to adapt to the change in their length or orientation will place undesirable forces on the muscle attachments leading to potential instability of the skeleton. Adaptation can occur through various processes including those within the neuromuscular feedback mechanism, through changes within muscle structure or through altered muscle physiology, and through changes at the muscle/bone interface. It is now accepted that because there is no single method of assessing masticatory function, several measures should be taken, and whenever possible, simultaneously.

METHODS

This investigation was designed to apply several, newly developed and more sophisticated methods of measuring muscle structure and function to a situation where adaptation of muscle is pivotal to the success of a therapeutic approach. Patients attending the combined orthodontic/orthognathic surgery clinic at the Clitrofa - Centro Médico, Dentário e Cirúrgico, in Trofa, Portugal, were screened. Ten patients scheduled for a bimaxillary osteotomy involving a combination of maxillary Le Fort I impaction procedure coupled with a sagittal split advancement of the mandible were selected to form the study group. The patients have MRI of the masseter muscle to evaluate the masseter muscle volume and fibre orientation changes. This exam was taken before surgery (T0), 6 to 12 months after surgery (T1), and 3 years after surgery (T2), by two independent observers, according to the protocol jointly developed between the Eastman Dental Institute - University of London and the MRI Centre - Department of Radiology at John Radcliffe Hospital - University of Oxford.

RESULTS

Significant differences (p < 0.05) have been identified between Time 0 (pre-op) and Time 1 (6-12 months post-op) regarding the masseter area (mm2). The differences against Time 0 (pre-op) seem to disappear at Time 2 (3 years post-op).

CONCLUSIONS

MRI therefore seems to be a valid tool for measuring differences in the masseter muscle area and volume associated with high-severity occlusal deformities, although showing not to be as efficient in detecting the same differences in cases of low-severity occlusal deformities.

Mandibular Contouring in Subjects With Class II or Class III Dentofacial Deformities and Treatment Needs

Facial contouring relates to hard and soft structures that make up the face. Skeletal class II and III subjects present bone structure and position changes, significantly impacting the soft tissues. This study aims to analyze the morphology of the mandible at mandibular ramus and angle level in subjects with skeletal facial deformity class II and III who are candidates for orthognathic surgery and to define implications in facial contour. A cross-sectional study used cone beam computed tomography to compare the mandibular contour (mandibular angle and ramus region) in orthognathic surgery candidates. One hundred sixty orthognathic surgery candidates were analyzed, ranging in age from 18 to 58 years (31.29 ± 11.97). Regarding the skeletal class, 95 (59.37%) were skeletal class II, and 65 (40.62%) were skeletal class III. Class II subjects had a larger antegonial notch than class III subjects. Concerning the mandibular contour, class II subjects presented less vertical distance than class III subjects, but both presented similar gonial angles. Concerning the ideas to assess the need for mandibular contouring surgery, the 2 proposals to determine the need for mandibular contouring surgery in class II and III subjects present a similar distribution. The mandibular notch is an objective element and is commonly present in subjects with a class II facial pattern; this element can be used in contour analysis to define expected facial characteristics, including the patient's facial sex, in the decision of surgical techniques for lower facial contour augmentation or reduction.

Vertical cephalometric characteristics in different populations with Turner syndrome as compared to non-syndromic populations: A meta-analysis

AIMS

The present aim was to evaluate vertical cephalometric characteristics in populations with Turner syndrome (TS) using meta-analysis methodology.

METHODS

Six electronic databases were queried, up to August 2023, to identify studies comparing the vertical cephalometric characteristics in populations with TS, compared to female control groups. Data were extracted from eligible studies and random-effects meta-analysis was employed. Subgroup meta-analyses for age and karyotype were also attempted. Risk of bias was assessed using a modified version of the AXIS tool.

RESULTS

From the initial 195 studies identified, 17 were included in the quantitative synthesis, resulting in a sample of 417 patients with TS, originating from 10 different countries. Risk of bias was overall questionable. Mandibular ramus height was found to be smaller in females with TS, along with a reduction in posterior facial height, a larger anterior-posterior facial height ratio, and an increase in the mandibular plane angle. Subgroup meta-analyses showed that females with the monosomy X karyotype had vertical cephalometric characteristics which deviated more from the norm than those with other karyotypes.

CONCLUSION

The vertical lateral cephalometric characteristics of females with TS differ significantly from those of non-syndromic females, with the largest and most consistent deviation being seen in the monosomy X karyotype. Females with TS show less craniofacial posterior vertical development, with an evident reduction in mandibular ramus height leading to the cephalometric characteristics observed.

Non-compliance treatment in a young adult full-step class II division 2 malocclusion with preadjusted lingual appliance and upper first molars extractions

This case report describes a complex full-step class II case in a young adult patient treated with lingual straight-wire appliance and upper first molar extraction. As the patient refused a surgical treatment, she was offered the best possible camouflage with the double aim of obtaining an ideal occlusal relationship and maintaining the profile; appropriate biomechanical strategies, including extraction choice and anchorage control during space closure, were needed to achieve the planned results. This case report demonstrates the possibility of successfully resolving severe sagittal discrepancies in an adult patient without surgical treatment by means of a completely invisible non-compliance technique, with the extraction of the most compromised teeth. This report also underlines the need for careful planning during both diagnostic and treatment phases, in order to obtain the best results.

Skeletal, dentoalveolar and soft tissue changes after stabilization splint treatment for patients with temporomandibular joint disorders

BACKGROUND

Temporomandibular disorder (TMD) is a grouping of heterogeneous disorders with multifactorial origins. Stabilization splints (SS) have demonstrated an acceptable treatment effect in TMD. The possible changes at the skeletal, dental, and soft tissue levels need to be addressed to evaluate the benefit/risk ratio of this therapeutic procedure. Accordingly, this study aimed to three‑dimensionally evaluate skeletal, dentoalveolar and soft tissue changes after SS treatment for patients with TMD.

METHODS

This retrospective study included 74 adult patients with myofascial and/or intra-articular disorders (25 males and 49 females), with an average age of 22.88 ± 4.8 years, who underwent SS treatment. Pre- and post-treatment Cone beam computed tomography were analysed using Invivo 6.0.3 software. The primary outcome was the vertical skeletal and dentoalveolar changes, while the secondary outcomes were the anteroposterior skeletal, dentoalveolar and soft tissue changes. Paired t-test and Wilcoxon rank sum test were used for statistical analyses.

RESULTS

For the primary outcome; skeletally, there was a significant increase in mandibular plane inclination (difference: 0.82°±1.37), decrease facial height ratio (difference: 0.45%±1.07) and at the dentoalveolar level, the inclination of the functional (FOP-SN, FOP-FH) and bisecting (BOP-SN, BOP-FH) occlusal planes exhibited a significant increase too (difference: 0.38 ± 1.43°, 0.49 ± 1.62°, 0.44 ± 1.29° and 0.41 ± 1.17°, respectively) and also a decrease in the overbite (difference: -0.54 ± 0.83). For the secondary outcomes; there was a significant decrease in mandibular position (SNB) (difference: 1.60 ± 1.36°) and increase in the overjet (difference: 0.93 ± 1.04, p < 0.001) and a significant lower lip retrusion (difference: 0.33 ± 1.01 mm p < 0.01), was observed too.

CONCLUSIONS

SS therapy resulted in significant vertical skeletal and dentoalveolar changes that were manifested mainly by facial height ratio, mandibular and occlusal plane changes, and to a lesser extent, significant anteroposterior skeletal, dentoalveolar, and soft tissue changes in the form of mandibular position, increased overjet and a more retrusive lower lip. These changes should be considered during patients' selection prior to initiating SS therapy.

Three-dimensional mandibular characteristics in skeletal malocclusion : A cross-sectional study

PURPOSE

We aimed to comprehensively analyse a possible correlation between skeletal malocclusions, gender and mandibular characteristics in all three dimensions in adults and to identify mandibular characteristics that are typical for extreme skeletal patterns.

METHODS

A 3D model of the skull was calculated in 111 adult patients (mean age = 27.0 ± 10.2 years; 49 women, 62 men) from available computed tomography or cone beam computed tomography scans of their heads. Based on the 3D models, the skeletal patterns were examined in (a) the transversal dimension regarding asymmetry according to menton deviation, (b) the sagittal dimension according to the Wits appraisal and (c) the vertical dimension according to the maxillomandibular plane angle. The mandibular characteristics assessed were linear (ramus height and width, body length), angular (ramus, gonial and body angle) and volumetric (ramus/mandibular volume, body/mandibular volume) parameters.

RESULTS

No correlation between transversal skeletal asymmetry and mandibular characteristics were found, while sagittal (F(16, 174) = 3.32, p < 0.001, η2 = 0.23) and vertical (F(16, 174) = 3.18, p < 0.001, η2 = 0.23) skeletal patterns were shown to have a significant effect on the mandible. Gender correlated with mandibular characteristics independently from the skeletal pattern. Discriminant analysis revealed that class II and III patients differed in ramus and body angle with class II patients showing higher angles (ramus angle: class II = 89.8 ± 3.9° vs. class III = 84.4 ± 4.8°; body angle: class II = 87.7 ± 4.8° vs. class III = 82.1 ± 5.2°). Hypo- and hyperdivergent patients were discriminated by gonial angle, body angle and body/mandibular volume with hyperdivergent patients having a greater gonial and body angle and body/mandibular volume (gonial angle: hypodivergent = 114 ± 9.3° vs. hyperdivergent = 126.4 ± 8.6°; body angle: hypodivergent = 82.9 ± 4.4° vs. hyperdivergent = 87.7 ± 6.5°; body/mandibular volume: hypodivergent = 72.4 ± 2.7% vs. hyperdivergent = 76.2 ± 2.6%).

CONCLUSION

When analysing 3D data for treatment planning of adult patients, the orthodontist should pay attention to angular and volumetric characteristics of the mandible to identify extreme skeletal sagittal or vertical malocclusions.

Treatment change comparisons between skeletal Class I and II white adolescents with 3 different vertical divergencies-Part 2: Holdaway difference

INTRODUCTION

The Holdaway difference represents the relationship of the NB line to the mandibular incisor (NB-L1) and the bony pogonion (NB-Pog). This study aimed to evaluate treatment changes of NB-L1, NB-Pog, and the Holdaway difference in patients with skeletal Class I and II relationships with 3 different skeletal divergencies.

METHODS

This retrospective study was the second part of treatment outcome assessments of 135 white adolescent patients (females, n = 69; males, n = 66; mean age, 12.8 ± 1.4 years pretreatment and 15.0 ± 1.4 years posttreatment). The NB-L1, NB-Pog, and Holdaway differences (NB-L1 - NB-Pog) were measured. The mixed-model analysis of variance was used to assess within- and between-subject effects responding to horizontal and vertical skeletal discrepancies.

RESULTS

For the group with favorable profile changes, the means of the Holdaway difference were maintained in the hypodivergent and normodivergent subgroups and reduced in the hyperdivergent subgroups for patients with skeletal Class I and II relationships. The means of NB-L1 and Holdaway difference were significantly larger in the skeletal Class II group and became greater as skeletal vertical divergencies increased. The NB-Pog means were significantly different only between the hypodivergent and hyperdivergent subgroups.

CONCLUSIONS

Based on the findings of this study, the Holdaway difference should be adjusted to individualize the incisor positions, considering not only the anteroposterior but also the vertical skeletal relationships of the patients.

Invisible treatment with lingual appliance for the correction of an adult class II subdivision with asymmetrical Wilson and Spee curves: A case report

This article describes a class II subdivision malocclusion successfully treated by an invisible lingual appliance. The combination of en-masse distalization by interradicular palatal mini-screws and inner unilateral class II auxiliaries, first by intermaxillary elastic, later by a class II coil spring, resulted in a dento-alveolar correction, allowing one to maintain the appliance completely invisible. At the same time, the inclination of buccal sectors was normalized by a correct torque expression with set-up overcorrections, resulting in a significant improvement of the buccal corridors. This case report demonstrates the possibility of successfully solving class II division 2 subdivision malocclusion in adult patients without surgery by means of a completely invisible appliance. It also demonstrates that correct levelling and torque expression, for the correction of asymmetrical Spee and Wilson curves, are achievable with an accurate set-up planning. On the other hand, it underlines the necessity of mini-screws, auxiliaries and set-up overcorrections in order to obtain the best results.

Relationship between Skeletal Malocclusion and Radiomorphometric Indices of the Mandible in Long Face Patients

This study aimed to assess the relationship between skeletal malocclusion and radiomorphometric indices of the mandible in long face patients. This cross-sectional study evaluated 174 lateral cephalograms and panoramic radiographs of long face patients between the ages of 17 and 30 presenting at the Orthodontics Department of Qazvin Dental School. The gonial angle, antegonial angle, type of antegonial notch, and depth of antegonial notch were measured bilaterally on panoramic radiographs. The correlation between the radiomorphometric parameters and the type of occlusion was analyzed using one-way ANOVA, independent t-test, Chi-square test, and Fisher's exact test (alpha = 0.05). The mean size of gonial angle was significantly different among the three classes of occlusion (p = 0.046), while the difference was not significant regarding the antegonial angle size and antegonial notch depth (p > 0.05). An independent t-test showed that the mean sizes of gonial angle (p = 0.026) and antegonial angle (p = 0.036), and the antegonial notch depth (p = 0.046) in males, were significantly greater than the values in females. According to the Chi-square and Fisher's exact test, the right antegonial notch type was significantly different among the three classes of malocclusion (p = 0.006), while this difference was not significant in the left side (p = 0.318). The right antegonial notch type II was more common in males, while the right antegonial notch type I was more common in females (p = 0.014). According to the results, the indices of gonial angle and type of antegonial notch can be clinically useful for predicting the growth rate of the mandible and designing the appropriate treatment in long face patients.

Effects of different patterns of movement for correcting a deep curve of Spee with clear aligners on the anterior teeth: a finite element analysis

OBJECTIVE

To analyse the anterior teeth effects of clear aligners on five different patterns of mandibular molar movement and to define the most effective configuration to be implemented with clear aligners through finite element analysis.

METHODS

A three-dimensional mandibular model with a deep overbite in the mandible was constructed using cone beam computerized tomography (CBCT) data. The model included the mandibular dentition, mandibular periodontal ligaments, attachments, and aligners. Five models were created: (1) configuration A: second molar distalization (0.25 mm); (2) configuration B: second molar distalization (0.25 mm), first molar extrusion (0.15 mm); (3) configuration C: second molar distalization (0.25 mmm), first and second premolar extrusion(0.15 mm); (4) configuration D: second molar distalization (0.25 mm), first molar and first/second premolar extrusion(0.15 mm); and (5) configuration E: second molar distalization (0.25 mm), first molar and first/second premolar extrusion (0.15 mm), first molar and first/second premolar expansion (0.15 mm).

RESULTS

In all configurations, the anterior teeth exhibited labial tipping and the mandibular central incisor of configuration E showed the highest labial tipping. Configuration E demonstrated a relatively minor impact on mandibular molars distalization compared with configuration A. Configuration A showed the highest distal displacement value, and configuration E produced the lowest displacement value. Configuration E caused the highest periodontal ligament (PDL) pressure of the central and lateral incisors. The differences in the canines between configurations C and D,were not significant, and the stress distribution differed among the five groups.

CONCLUSIONS

All patterns utilizing clear aligners facilitated mandibular molar distalization. Extruding the premolars and second molar distalization at the same time had little impact on second molar distalization; When expansion and extrusion were simultaneously performed during the distalization of mandibular molars, our prime consideration was the alveolar bone on the labial side of the anterior teeth to prevent the occurrence of gingival recession, dehiscence, and fenestration. Due to the lack of consideration for periodontal tissues in this study, clinical protocols should be designed based on the periodontal status of the mandibular anterior teeth.

Surgical vs nonsurgical treatments in patients with anterior open-bite have similar effects in occlusal function: A 2-year follow-up study

INTRODUCTION

This study aimed to investigate changes in bite force (BF) and occlusal contact area after anterior open-bite (AOB) treatment and compare the changes in surgical vs nonsurgical treatment.

METHODS

This retrospective study included patients with AOB compared with normal occlusion. AOB was corrected by either intrusion of the maxillary molars (intrusion group, n = 19) or orthognathic surgery (surgery group, n = 37). The control group (n = 35) had a normal overbite relationship. Records of lateral cephalograms, BF, and occlusal contact area taken before (T0), immediately after (T1), and 2 years after (T2) orthodontic treatment were compared within and among the 3 groups.

RESULTS

The open-bite group, including intrusion and surgery groups, had a lower BF and less occlusal contact area than the control group at T0 and T1 (P <0.001). However, there were no significant differences among the 3 groups at T2 (P >0.05). The intrusion and surgery groups showed no significant differences throughout the observation period extending from T0 to T2 (P >0.05). Although BF and occlusal contact area decreased at T1 compared with T0, they increased during retention and showed higher values at T2 than at T0.

CONCLUSIONS

Treatment of AOB improved BF and occlusal contact area 2 years posttreatment. Orthognathic surgery and molar intrusion using orthodontic miniscrews can improve occlusal function similarly. Orthodontists can select either method depending on malocclusion severity and patient demand.

Three-dimensional radiographic assessment of the mandibular retromolar donor site in different vertical facial growth types

PURPOSE

To assess volumetrically, the impact of vertical facial growth types (VGFT) on the retromolar area as a bone donor site MATERIAL AND METHODS: 60 cone beam computed tomography (CBCT) scans of adult individuals were classified in three groups according to their SN-GoGn angle: hypodivergent group (hG) (33.33%), normodivergent group (NG) (30%) and hyperdivergent group (HG) (36.67%). Total harvestable bone volume and surface (TBV and TBS respectively), total cortical and cancellous bone volume (TCBV and TcBV respectively) and the percentage of cortical and cancellous bone volume (CBV and cBV respectively) were evaluated.

RESULTS

The whole sample showed a mean TBV of 1220.99±448.81mm³ and a mean TBS of 940.29±259.93mm². Statistically significant differences were found between the different outcome variables and the vertical growth patterns (p<0.001). TBS differs for the different vertical growth patterns with the highest mean of TBS observed in the hG group. TBV also significantly differs between the different vertical growth patterns (p<0.001) with the highest mean observed for the hG individuals. Significant differences in percentages of cBV and CBV were present between the hyper-divergent groups and the other groups (p<0.001) with the hyper-divergent group having the lowest percentage of CBV and the highest percentage of cBV.

CONCLUSION

hypodivergent individuals tend to have thicker bone blocks that can be used in onlay technique while thinner bone blocks harvested from hyperdivergent and normodivergent individuals can be used in three-dimensional grafting approach.

Profile changes in extraction treatments of upper premolars: A case series

This case series describes the soft tissue changes following extraction treatment in two patients with diverse lip thickness, but with similar baseline parameters including: labial competence, soft tissue profile, patient's age, extraction protocol, methods of anchorage, malocclusion, crowding, treatment appliance and mechanics. The same treatment plan involved upper first premolar extractions and lingual appliance combined with skeletal anchorage. The lip thickness played a crucial role in these cases, since a similar change of the incisor position leads to a different profile variation. This difference could be explained by the differing initial lip thicknesses as the patient with thin lips showed a more pronounced profilometric change. The choice of the ideal treatment plan must be tailored to the individual patient, taking into account not only initial skeletal and dental factors but also soft tissue factors, as well as the treatment goals.

A non-invasive system to manage impacted teeth associated with a large dentigerous cyst

A male patient aged 11 years presented a large dentigerous cyst in the lower left quadrant associated with retained deciduous lower lateral incisor and canine and impacted, unerupted corresponding permanent ones. The treatment consisted in marsupialisation and placement of a modified lingual arch that held a tube for decompression used for irrigation of the cystic cavity in a comfortable way for the patient and for the clinician.The same lingual arch was later used as an anchorage method for traction of the retained teeth. The final records showed complete resolution of the cyst and retained teeth were successfully Aligned into the oral cavity.

3D analysis of maxillomandibular morphology in hyperdivergent and hypodivergent individuals: A cross-sectional study

INTRODUCTION

The aim of this cross-sectional study was to investigate maxillomandibular morphology in hyperdivergent and hypodivergent individuals, using 3D surface models generated by cone-beam computed tomography (CBCT).

METHODS

The sample consisted of 60 CBCTs (30 males, 30 females) patients aged 12-30 years, divided into two groups comprising hyperdivergent (≥35°) and hypodivergent (≤30°) individuals, according to the mandibular plane (MP) angle. Multiplanar reconstructions were used to mark the landmarks, and 3D surface models were created to evaluate structures of the maxillomandibular complex, including condyle, ramus, symphysis and palatal height. Intergroup comparisons were performed by independent t-test. Pearson's correlation test was used (P < .05) to evaluate the correlation of the MP angle with the angles and linear measurements of other structures.

RESULTS

Significant differences were found between the groups regarding condylar width, ramus height, condylar plus ramus height, mandibular length, gonial angle, palatal plane angle and palatal-mandibular angle. No differences (P > .05) were found for the condylar height, symphysis inclination angle or palatal height. Correlations (P < .05) were found between the MP angle and structures of the maxillomandibular complex.

CONCLUSIONS

Hyperdivergent (MP ≥ 35°) and hypodivergent (MP ≤ 30°) individuals present different skeletal morphology regarding condylar width, ramus height, condylar plus ramus height, mandibular length, gonial angle, palatal plane angle and palatal-mandibular angle. There is a significant correlation between MP angle and morphological structures such as condyle, ramus, symphysis, palatal plane angle and palatal-mandibular angle.

Mandibular asymmetry types and differences in dental compensations of Class III patients analyzed with cone-beam computed tomography

OBJECTIVES

To assess differences in dental compensation of the incisors and first molars in skeletal Class III patients with roll-, yaw-, and translation-dominant mandibular asymmetries.

MATERIALS AND METHODS

A total of 90 skeletal Class III adult patients (mean age, 22.00 ± 3.31 years; range, 18-37.9 years) with facial asymmetry were enrolled and divided into the roll-, yaw-, and translation-dominant type groups (n = 30 per group). The vertical, transverse, and anteroposterior distances and axial angles of the teeth were measured using cone-beam computed tomography images. The measurements were compared between the deviated and nondeviated sides using a paired t-test and among the three groups using one-way analysis of variance with a Tukey post hoc test.

RESULTS

The roll-dominant groups showed the greatest values for the bilateral difference in the vertical position of the maxillary (2.42 ± 1.24 mm) and mandibular molars (2.23 ± 1.28 mm; P < .001). The transverse deviations of the maxillary (2.19 ± 1.51 mm) and mandibular incisors (-2.11 ± 1.39 mm) were greater in the yaw-dominant groups than those of other groups. Regarding tooth axial angle, the yaw-dominant group showed the greatest tipping of the mandibular incisor (-4.13 ± 3.30°; P < .001).

CONCLUSIONS

Dental compensation differed depending on the type of facial asymmetry. The roll-dominant type showed more vertical compensation of the posterior teeth, whereas the yaw-dominant type exhibited more tipping of the molars and incisors. By precisely assessing dental compensation in each asymmetry type, sufficient dental decompensation could be achieved.

Torque control with set-up and auxiliary spring in an adult severe class II case treated by lingual straight-wire appliance, premolar extractions and orthognathic surgery

This case report describes a complex full-step class II high angle case in an adult patient treated with lingual straight-wire appliance, premolar extractions and orthognathic surgery. With the twofold aim of obtaining ideal occlusal relationship and aesthetic improvement, surgical treatment with appropriate biomechanical strategies, including extraction choice and torque control during space closure, are needed to achieve the planned results. This case report demonstrates the possibility of solving successfully severe sagittal, transverse and vertical discrepancies in an adult patient with surgical treatment by means of an invisible technique. This report also underlines the need for precise biomechanical control, including set-up overcorrections and an auxiliary spring to manage teeth inclination, in lingual orthodontics extraction cases.

Short- and Long-Term Prediction of the Post-Pubertal Mandibular Length and Y-Axis in Females Utilizing Machine Learning

The aim of this study was to create a novel machine learning (ML) algorithm for predicting the post-pubertal mandibular length and Y-axis in females. Cephalometric data from 176 females with Angle Class I occlusion were used to train and test seven ML algorithms. For all ML methods tested, the mean absolute errors (MAEs) for the 2-year prediction ranged from 2.78 to 5.40 mm and 0.88 to 1.48 degrees, respectively. For the 4-year prediction, MAEs of mandibular length and Y-axis ranged from 3.21 to 4.00 mm and 1.19 to 5.12 degrees, respectively. The most predictive factors for post-pubertal mandibular length were mandibular length at previous timepoints, age, sagittal positions of the maxillary and mandibular skeletal bases, mandibular plane angle, and anterior and posterior face heights. The most predictive factors for post-pubertal Y-axis were Y-axis at previous timepoints, mandibular plane angle, and sagittal positions of the maxillary and mandibular skeletal bases. ML methods were identified as capable of predicting mandibular length within 3 mm and Y-axis within 1 degree. Compared to each other, all of the ML algorithms were similarly accurate, with the exception of multilayer perceptron regressor.

Prediction of Pubertal Mandibular Growth in Males with Class II Malocclusion by Utilizing Machine Learning

The goal of this study was to create a novel machine learning (ML) model that can predict the magnitude and direction of pubertal mandibular growth in males with Class II malocclusion. Lateral cephalometric radiographs of 123 males at three time points (T1: 12; T2: 14; T3: 16 years old) were collected from an online database of longitudinal growth studies. Each radiograph was traced, and seven different ML models were trained using 38 data points obtained from 92 subjects. Thirty-one subjects were used as the test group to predict the post-pubertal mandibular length and y-axis, using input data from T1 and T2 combined (2 year prediction), and T1 alone (4 year prediction). Mean absolute errors (MAEs) were used to evaluate the accuracy of each model. For all ML methods tested using the 2 year prediction, the MAEs for post-pubertal mandibular length ranged from 2.11-6.07 mm to 0.85-2.74° for the y-axis. For all ML methods tested with 4 year prediction, the MAEs for post-pubertal mandibular length ranged from 2.32-5.28 mm to 1.25-1.72° for the y-axis. Besides its initial length, the most predictive factors for mandibular length were found to be chronological age, upper and lower face heights, upper and lower incisor positions, and inclinations. For the y-axis, the most predictive factors were found to be y-axis at earlier time points, SN-MP, SN-Pog, SNB, and SNA. Although the potential of ML techniques to accurately forecast future mandibular growth in Class II cases is promising, a requirement for more substantial sample sizes exists to further enhance the precision of these predictions.

Dentoskeletal features and growth pattern in Beckwith-Wiedemann spectrum: is surgical tongue reduction always necessary?

OBJECTIVES

The role of tongue reduction surgery (TRS) in preventing excessive mandibular growth and anterior open bite in children with Beckwith-Wiedemann Spectrum (BWSp) is still controversial. This cross-sectional study aimed at comparing craniofacial growth pattern in children affected by BWSp either treated or not treated with early TRS for severe macroglossia. Considering the invasive nature of such surgery, the present study could help in clarifying the need for TRS to reduce or prevent growth disturbances.

MATERIALS AND METHODS

Orthopantomography and lateral skull x-ray images were taken either from surgically treated or non-surgically treated patients, aged 5 to 8 years, to compare dentoskeletal features and craniofacial growth by cephalometric analysis. Molecular testing results were collected from their medical records.

RESULTS

Eighteen BWSp patients were consecutively recruited: 8 underwent TRS at 14.9 ± 2.2 months of age, while 10 did not. Anterior open bite and dental class III were more frequently observed in the surgically treated group, but none showed skeletal class III. No statistically significant differences were observed in growth pattern, but children treated with TRS showed a tendency towards both maxillary and mandibular prognathism with protruding lower lip. Growth pattern seemed to be not related to molecular subtypes.

CONCLUSIONS

These preliminary data suggest that early TSR does not improve craniofacial growth pattern and dentoskeletal features in BWSp children.

CLINICAL RELEVANCE

Reductive glossectomy may not be justified for preventing or avoiding oro-facial deformities in BWSp; therefore, early monitoring of maxillofacial development of each affected child has a great clinical significance.

Prediction of the Post-Pubertal Mandibular Length and Y Axis of Growth by Using Various Machine Learning Techniques: A Retrospective Longitudinal Study

The aim was to predict the post-pubertal mandibular length and Y axis of growth in males by using various machine learning (ML) techniques. Cephalometric data obtained from 163 males with Class I Angle malocclusion, were used to train various ML algorithms. Analysis of variances (ANOVA) was used to compare the differences between predicted and actual measurements among methods and between time points. All the algorithms revealed an accuracy range from 95.80% to 97.64% while predicting post-pubertal mandibular length. When predicting the Y axis of growth, accuracies ranged from 96.60% to 98.34%. There was no significant interaction between methods and time points used for predicting the mandibular length (p = 0.235) and Y axis of growth (p = 0.549). All tested ML algorithms accurately predicted the post-pubertal mandibular length and Y axis of growth. The best predictors for the mandibular length were mandibular and maxillary lengths, and lower face height, while they were Y axis of growth, lower face height, and mandibular plane angle for the post-pubertal Y axis of growth. No significant difference was found among the accuracies of the techniques, except the least squares method had a significantly larger error than all others in predicting the Y axis of growth.

Skeletal and soft-tissue changes in humans with untreated normal occlusion throughout lifetime: a systematic review

Age-related skeletal and soft-tissue changes are important in orthodontics, especially due to the increase of adult patients seeking treatment. The aim of this study is to assess the available evidence regarding age-related skeletal and soft-tissue changes in untreated Angle Class I. Articles studying skeletal and soft-tissue changes in orthodontically untreated subjects with Angle Class I and comparing them between age groups were included. Studies focusing on a single age group or in languages other than English were excluded. Risk of bias was assessed with both the MINORS and ROBINS-I tools. 50 studies were included, showing high methodological heterogeneity and a lack of information in subjects over 60 years old. In subjects with Angle Class I, the mandibular plane inclination was reported to reduce from 7 and 20 years old, while the anterior and posterior facial height continue to increase in late adult life. The anterior cranial base length increases until 20 years old, afterwards decreasing slowly until late adulthood. Nasal width increases and the nasolabial angle decreases during adolescence. Upper lip length and lower lip length increase from 6 to 18 years along with retrusion of the lips in late adulthood. Age-related skeletal and soft-tissue changes are documented in the literature from childhood until the fifth decade of life, but studies mostly focus on subjects until 20 years old. Changes after the second decade of life are studied only for the vertical and sagittal dimensions. No changes are reported in the transversal dimension beyond 15 years for neither skeletal nor soft tissues. Well-designed, long-term prospective cohort studies considering all three dimensions of skeletal and soft tissues are needed for confirmation of these findings (PROSPERO: CRD42020203206).

Combined use of F22 aligners and intermaxillary elastics in mild skeletal Class II: Two case reports

INTRODUCTION

The aim of these two case-reports is to illustrate and compare the therapeutic effects of Class II elastics in combination with F22 aligners in an adult and an adolescent patient, respectively.

CASE PRESENTATION

Two patients with a mild skeletal Class II malocclusion, associated with mild-to-moderate crowding, presented for orthodontic treatment. The first patient was 12 years old, while the second was 40 years old. In both cases, the goal was to obtain bilateral molar and canine Class I with ideal overjet and overbite, and Class II skeletal relationship improvement in the young patient as well. Both treatments were approached without extractions and using clear aligners (CAs) in combination with Class II elastics, giving the patient the opportunity to take advantage of a therapy that is both comfortable and aesthetic.

DISCUSSION

Final records of both cases demonstrate how appropriate analysis and diagnosis enable CAs in conjunction with Class II elastics to be used with considerable efficiency and efficacy for Class II treatment. In the first case, the key to success was exploiting residual jaw growth, while in the second case it was careful orthodontic digital planning.

CONCLUSION

In the presence of good patient compliance, CAs associated with Class II elastics provide satisfactory occlusal outcomes if biomechanics and digital set-up are carefully evaluated and executed and if diagnosis is appropriate.

Non-surgical occlusal plane cant resolution with lingual straight-wire appliance and miniscrews in a class II asymmetric adult patient

This case report describes a complex class II case with important maxillo-mandibular asymmetry in an adult patient treated with lingual straight-wire appliance. With the twofold aim of obtaining dramatic aesthetic improvement, since the patient refused surgical option, and ideal occlusal relationship, accurate set-up planification and biomechanical strategies with TADS for occlusal plane cant correction are needed to achieve the planned results. This case report demonstrates the possibility of solving successfully class II malocclusion with significant asymmetry in adult patient without surgery by means of an aesthetic appliance; on the other hand, it underlines the necessity of miniscrews and auxiliaries in order to obtain the best results.

A CBCT Investigation of the Sella Turcica Dimension and Sella Turcica Bridging in Different Vertical Growth Patterns

This study aimed to compare the sella turcica dimensions and sella turcica bridging (STB) via cone-beam computed tomography in different vertical patterns and then analyze the link between the sella turcica and vertical growth patterns. The CBCT images of 120 skeletal Class I subjects (an equal proportion of females and males; mean age of 21.46 years) were divided into three vertical growth skeletal groups. Student's t tests and Mann-Whitney U tests were used to assess the possible diversity in genders. The link between sella turcica dimensions and different vertical patterns was explored by one-way analysis of variance, as well as Pearson and Spearman correlation tests. The prevalence of STB was compared using the chi-square test. Sella turcica shapes were not linked to gender, but statistical differences were observed among different vertical patterns. In the low-angle group, a larger posterior clinoid distance and smaller posterior clinoid height, tuberculum sellae height, and dorsum sellae height were determined, and the incidence of STB was higher (p < 0.01). Sella turcica shapes were linked to vertical growth patterns, mainly involving the posterior clinoid process and STB, which could be used as an index to assess vertical growth trends.

Geometric Morphometric Analysis of Mandibular Symphysis Growth between 12 and 15 Years of Age in Class II Malocclusion Subjects

The aim of the present paper was to evaluate the morphology changes of the mandibular symphysis (MS) in a longitudinal retrospective cohort of class II untreated subjects. The study sample included 120 subjects followed during normal growth and examined at the age of 12 (T0) and 15 (T1) years. MS was traced using two landmarks and ten sliding semi-landmarks. The acquired morphological data were processed via Procrustes superimposition that allowed to study variation and covariation in MS'form according to specific variables such as age, gender, and skeletal pattern. The first two principal components (PCs) described more than 90 % of the total morphological variation. Both types of form changes of the symphysis could be associated with the different skeletal vertical growth patterns. Age and sex did not interfere with the form of chin symphysis. Moreover, there was no significant covariation between initial MS morphology and form modifications. Clinicians should not expect to be faced with spontaneous changes of the form of the symphysis during the orthodontic treatment of adolescents.

Natural course of severe temporomandibular joint osteoarthrosis evaluated by a novel condylar remodelling scoring system and quantitative volumetric analysis

Temporomandibular joint osteoarthrosis (TMJ-OA) frequently causes mild, moderate, or severe condylar morphological changes. A novel condylar remodelling scoring system (CRSS) based on three-dimensional cone beam computed tomography images is proposed, which is used to grade condylar morphological changes. In the CRSS, the condyle is divided into 10 regions by 11 reference points. For each increase in the number of regions involved in TMJ-OA, one point is subtracted from the full score of 10. The intra-class correlation coefficients for intra- and inter-observer agreement (range 0.656-0.898 and 0.841-0.906, respectively) indicated that the CRSS had good reliability. Cephalometric analysis showed that the condyles with severe morphological changes were prone to present with a retrognathic and clockwise rotating mandible, shorter ramus height, reduced mandibular length, larger mandibular angle, and maxillary retrusion. Qualitative CRSS evaluation and quantitative volumetric analysis were performed to evaluate the stability of severe TMJ-OA in its natural course (343 condyles). The continuous cortex group showed no remarkable changes with an average follow-up of 2 years. In the discontinuous cortex group, most (74.4%) converted into a continuous cortex during follow-up (mean 2 years).

Barcelona line. A multicentre validation study of a facial projection reference in orthognathic surgery

The purpose of this study was to validate an already published facial anteroposterior reference: upper incisor (UI) to soft tissue plane or so-called Barcelona line (BL) to trace the most aesthetic sagittal position of the maxilla. A cross-sectional multicentre evaluation of Caucasian patients from Spain and Brazil with different anteroposterior maxillary positions was designed. Sagittal images in natural head orientation of grouped patients according to the horizontal distance from the UI to BL were ranked by healthcare professionals and non-professional Caucasian raters according to the aesthetic perception of each profile, using a digital survey. Seventy-four raters (50 laypeople, 12 orthodontists, and 12 maxillofacial surgeons) rated 40 profiles. The best-rated profile corresponded to group 3 (0-4 mm UI-BL) with 61.8% of positive evaluations, followed by group 4 (≥ 4 mm UI-BL): with 61.1%. On the other hand, group 1 (≤-4 mm UI-BL) was the worst-ranked profile with 71.8% of negative evaluations, followed by group 2 (-4-0 mm UI-BL): with 59.6% of negative evaluations. The correlation between the mean assessment score and UI-BL showed a moderately-strong association (r = 0.68, p < 0.001). The inter-rater reliability of assessment (74 evaluators) was moderate (k = 0.49, 95% CI: 0.39 to 0.59). The results suggest that protrusive middle-third facial profiles are preferable. The BL is proposed as a simple, individualised, and reproducible tool to trace an aesthetic sagittal position of the maxilla in orthognathic surgery.

Mesial movement of maxillary first molars and vertical dimensional changes in orthodontic extraction treatment for patients with different facial morphology

Objectives: Primarily, to compare anchorage loss and changes in mandibular plane (MP) angle, overbite, and amount of horizontal, vertical, and angular movements of maxillary incisors in groups of hypodivergent, hyperdivergent, and normodivergent patients. Secondarily, to analyze the relationship between those factors. Methods: Pre- and post-treatment cephalograms of 89 patients treated with extraction of four bicuspids or two maxillary bicuspids were analyzed. The sample was divided into three groups based on their facial pattern measured by SN-MP angle (hypodivergent: < 270, hyperdivergent: >380, and normodivergent: 270-380). Linear and angular measurements included the distances of U1 tip and U6 mesial height of contour to Y-axis (i.e., line perpendicular to the X-axis, passing through Sella turcica), distance of U1 tip to Sella on X-axis, overbite, angulation of U1 to palatal plane, and SN-MP and ANB angles. Inferential statistics included one-way ANOVA, Chi-square test, independent t-test, and Pearson’s correlation coefficients. Results: Facial morphology did not primarily affect anchorage loss, because other factors such as crowding, severity of Class II molar relationship, and extraction modality played more impactful role (P< 0.01). Change in mandibular plane angle was neither influenced by, nor correlated with, initial facial morphology or anchorage loss (P> 0.05). Positive change in overbite was significantly correlated with facial pattern, incisor extrusion and retroclination (r= 0.30, 0.44, and -0.35, respectively, P< 0.01). Conclusion: Anchorage loss in extraction orthodontic treatment is not influenced primarily by initial facial morphology. Anchorage loss is not significantly associated with MP angle reduction. Change in overbite can be achieved through incisor extrusion and retroclination.

Research on the correlation between the size of condyle and occlusion plane in skeletal Class II malocclusions

OBJECTIVES

This study was designed to investigate the relationship between the morphological structure of condyle and occlusal plane in skeletal Class II malocclusions by imaging measurement.

MATERIALS AND METHODS

This study included 65 skeletal Class II adult patients (18-35 years old) who met the criteria, and all were taken with cone beam computed tomography (CBCT) images (skeletal Class II high angle 38 cases, average angle 18 cases, and low angle nine cases). The statistical methods of mean standard deviation, Pearson correlation, and analysis of variance were used to study the correlation between the size of the condyle and occlusal plane in skeletal Class II malocclusion.

RESULTS

The FMA and SN-OP between the groups in skeletal Class II malocclusion are considered statistically significant, p < .05 high angle group > average angle group > low angle group, whereas there are significant correlations between FMA, FH-OP, SN-OP, and the medial-lateral diameter (MLD) of the condyle, p < .05, showing a negative correlation. The anteroposterior diameter of the condyle has no significant correlation with these angles, and the high-angle group size is smaller than the other groups.

CONCLUSION

In patients with skeletal Class II high angle malocclusion, the MLD and anteroposterior diameters of condyle were smaller than those of average angle and low angle groups, and negatively correlated with the FMA and SN-OP. That is the steeper occlusal plane, the smaller MLD of the condyle. It suggests whether orthodontists can promote the stability of the morphological structure of the condyle by changing the inclination of the occlusal plane during the orthodontic process.

Craniofacial growth and morphology among intersecting clinical categories

Differential patterns of craniofacial growth are important sources of variation that can result in skeletal malocclusion. Understanding the timing of growth milestones and morphological change associated with adult skeletal malocclusions is critical for developing individualized orthodontic growth modification strategies. To identify patterns in the timing and geometry of growth, we used Bayesian modeling of cephalometrics and geometric morphometric analyses with a dense, longitudinal sample consisting of 15,407 cephalograms from 1,913 individuals between 2 and 31 years of age. Individuals were classified into vertical facial types (hyper-, normo-, hypo-divergent) and anteroposterior (A-P) skeletal classes (Class I, Class II, Class III) based on adult mandibular plane angle and ANB angle, respectively. These classifications yielded eight facial type-skeletal class categories with sufficient sample sizes to be included in the study. Four linear cephalometrics representing facial heights and maxillary and mandibular lengths were fit to standard double logistic models generating type-class category-specific estimates for age, size, and rate of growth at growth milestones. Mean landmark configurations were compared among type-class categories at four time points between 6 and 20 years of age. Overall, morphology and growth patterns were more similar within vertical facial types than within A-P classes and variation among A-P classes typically nested within variation among vertical types. Further, type-class-associated variation in the rate and magnitude of growth in specific regions identified here may serve as targets for clinical treatment of complex vertical and A-P skeletal malocclusion and provide a clearer picture of the development of variation in craniofacial form.

Diagnostic value of routine dental radiographs for predicting the mandibular canal localization validated by cone-beam computed tomogram measurements

OBJECTIVES

To test the hypothesis that routine dental radiographs can be used to draw conclusions regarding the mandibular canal (MC) localization. MATERIAL AND METHODS: A total of 108 radiographs (36 orthopantomograms [OPTs], 36 lateral cephalograms [LCs], and 36 cone-beam computed tomograms [CBCTs]) of 36 patients were analyzed. Statistical analysis included all cephalometric parameters obtained by OPTs, LCs, and CBCTs. Potential influencing parameters were calculated using linear and logistic regression with a backward removal algorithm. For predictability of MC localization, parameters were correlated using Pearson's correlation.

RESULTS

The MC ran along the lingual half (n = 24) twice as often as in the buccal half (n = 12) in the population studied. The position was always symmetrical contralaterally. No sex-specific influence was observed (p = .34). Lingual and buccal MC courses were statistically significantly correlated to increased and decreased jaw angles (LC/OPT), respectively (p = .003; r = -.48/p = .010; r = -.42). An increased jaw angle was significantly correlated with a more cranial MC position (p = .013; r = -.41); a deep and distal bite position was significantly correlated with a caudal and buccal MC position (p = .004; r = -.47/p = .001; r = .57). Moreover, an increase of 1 point in the Hasund score predicted an increased probability of a buccal MC position by 18.6%. The jaw angle analyzed in OPT and LC images were positively correlated (r = .89, p < .001).

CONCLUSIONS

Routine dental radiographs provide informative guidance on the location of the MC in the vertical and transverse levels. This finding could be used in the initial consultation and treatment planning to consider more invasive diagnostic methods further down the line.