Maxillomandibular arch width differences at estimated centers of resistance: Comparison between normal occlusion and skeletal Class III malocclusion

Classification and characterization of facial asymmetry in adult patients with skeletal Class III malocclusion using cluster analysis

INTRODUCTION

This study aimed to analyze the comprehensive maxillofacial features of patients with skeletal Class III malocclusion and facial asymmetry to develop a classification system for diagnosis and surgical planning.

METHODS

A total of 161 adult patients were included, with 121 patients in the asymmetry group (menton deviation >2 mm) and 40 patients in the symmetry group (menton deviation ≤2 mm). Twenty-eight variables were determined, including transverse translation, roll and yaw of each facial unit, transverse width, mandibular morphology, and transverse dental compensation. Principal component (PC) analysis was conducted to extract PCs, and cluster analysis was performed using these components to classify the asymmetry group. A decision tree was constructed on the basis of the clustering results.

RESULTS

Six PCs were extracted, explaining 80.622% of the data variability. The asymmetry group was classified into 4 subgroups: (1) atypical type (15.7%) showed an opposite roll direction of maxillary dentition than of menton deviation; (2) compound type (34.71%) demonstrated significant ramus height differences, maxillary roll, and mandibular roll and yaw; (3) mandibular yaw type (44.63%) showed slight mandibular yaw without mandibular morphology asymmetry; and (4) maxillary-shift type (4.96%) shared similarities with the compound type but showed significant maxillary translation. The classification and regression tree model achieved a prediction accuracy of up to 85.11%.

CONCLUSIONS

This study identified 4 distinct phenotypes using cluster analysis and proposed tailored treatment recommendations on the basis of their specific characteristics. The classification results emphasized the importance of spatial displacement features, especially mandibular yaw, in diagnosing facial asymmetry. The established classification and regression tree model enables clinicians to identify patients conveniently.

Combined distalization and lingual cortex remodeling during mandibular growth for facial profile improvement: a case report

Borderline crowding poses a challenge in deciding whether or not to prescribe premolar extraction. This case report describes the two-phase nonextraction orthodontic treatment of an 11-year-old girl with a hyperdivergent skeletal Class I pattern exhibiting anterior crowding and moderate lip protrusion. The initial phase of treatment included maxillary and mandibular expansion to correct the transverse discrepancy as an early intervention. Subsequently, comprehensive treatment was initiated at the age of 13 years, with fully erupted permanent second molars and growth potential remaining. Phase II treatment involved a second round of maxillary expansion, followed by simultaneous bimaxillary total arch intrusive distalization, using interradicular, temporary skeletal anchorage devices to correct dental crowding and improve the facial profile. Although the limited retromolar space posed a challenge to mandibular tooth distalization, gradual bone remodeling was observed in the lingual cortex of the mandibular body, enabling sufficient orthodontic tooth movement without noticeable side effects. After 4 years 3 months of treatment, her dental crowding was relieved, with significant improvement in the facial profile and proper occlusion. The treatment outcomes remained stable 2 years 4 months after retention.

Basal and dentoalveolar transverse parameters in different sagittal and vertical malocclusions in adults: a comparative study

OBJECTIVE

This study sought to three-dimensionally (3D) evaluate the maxillomandibular basal bone and dentoalveolar widths using cone-beam computed tomography (CBCT) scans in adult Chinese populations with different vertical and sagittal facial skeletal patterns whilst no apparent posterior dental crossbite.

MATERIALS AND METHODS

The retrospective cross-sectional comparative study enrolled CBCT images of 259 adult patients (125 males and 134 females). The subjects were divided into the hyperdivergent(n = 82), hypodivergent(n = 88), and normodivergent(n = 89) groups based on the Jarabak ratio (S-GO/N-Me), which were further divided into three subgroups of skeletal Class I, II and III, based on both the ANB angle and AF-BF parameters. ANOVA was used to analyze the extracted data of the studied groups. The intra- and inter-observer reliability was analyzed using the intra-class correlation coefficient (ICC).

RESULTS

In all three vertical facial skeletal patterns, the skeletal Class II had significantly smaller mandibular basal bone width compared to skeletal Class I and Class III, both at the first molar and first premolar levels. The skeletal Class III seemed to have smaller maxillary basal bone width compared to skeletal Class I and Class II malocclusions; however, a significant difference was found only in the normodivergent pattern. As for the dentoalveolar compensation, it was most notable that in the hypodivergent growth pattern, the skeletal Class II had significantly smaller maxillary dentoalveolar width compared to the Class I and Class III groups, both at the first molar and first premolar levels.

CONCLUSIONS

Based on the sample in the present study, skeletal Class II has the narrowest mandibular basal bone regardless of the vertical facial skeletal pattern.

CLINICAL RELEVANCE

For Chinese adults with no apparent transverse discrepancy, the maxillomandibular basal bone and dentoalveolar widths are revealed in specific categories based on different vertical and sagittal facial skeletal patterns. In diagnosis and treatment planning, particular attention should be paid to skeletal Class II for possibly existing mandibular narrowing.

The coordination of bimaxillary alveolar arch widths in subjects with normal occlusion or posterior crossbite: A CBCT retrospective study

OBJECTIVES

To propose a method for evaluating the coordination of maxillomandibular alveolar arch in transverse dimension with cone-beam computed tomography (CBCT) and to apply this method to subjects with normal occlusion at different dentition stages or transverse discrepancy.

MATERIALS AND METHODS

Digital data of 130 patients with normal occlusion at different dentition stages or transverse discrepancy were collected for three-dimensional reconstruction. The patients with normal occlusion were divided into Group 1 (>16 years) and Group 2 (≤16 years) based on their age. Adult patients with posterior crossbite were divided into the Group 3. According to the proposed method, the average alveolar arch coordination angle (AACA) and other parameters were analysed in each group. Group 1 was considered as the control group and compared with Group 2 and Group 3.

RESULTS

Significant differences were observed in the maxillary posterior segment width among patients with normal occlusion. Group 3 demonstrated increased AACA and mandibular alveolar arch width compared with the normal occlusion group. Pearson correlation analysis indicated a positive relationship between maxillomandibular alveolar arch widths in the normal occlusion groups, with a strong correlation between AACA and the disparity in maxillomandibular widths.

CONCLUSION

Adults with normal occlusion exhibit significantly wider maxillary posterior alveolar arches than adolescents, with no marked difference in mandibular widths. The posterior crossbite group showed broader mandibular alveolar arches. There was a strong correlation between AACA and the difference in maxillomandibular widths. This study's method shows potential value for orthodontic transverse diagnosis.

Responsiveness of three measurements in cone-beam computed tomography transverse analyses during both tooth-supported and mini-screw-assisted rapid maxillary expansion

OBJECTIVE

To evaluate the responsiveness of three cone-beam computed tomography (CBCT) transverse analyses (University of the Pennsylvania [UPenn] analysis, Boston University analysis and Yonsei University [YU] analysis).

MATERIALS AND METHODS

A consecutive cohort sample of patients was retrospectively reviewed for eligibility. CBCT records before treatment (T0) and immediately after maxillary expansion (T1) of 71 patients receiving tooth-supported rapid maxillary expansion (RME) and 57 patients receiving mini-screw-assisted RME (MARME) were finally analyzed. Responsiveness was assessed by comparing changes of measures (T1-T0) to mid-palatal suture opening distance (MSOD) at T1. Correlational responsiveness was assessed by Pearson correlation coefficient (r). Absolute agreement responsiveness was assessed by Bland-Altman analysis. A specialized intraclass correlation coefficient (ICC) was selected to assess responsiveness combining correlation and absolute agreement.

RESULTS

Changes of all three measures were moderately to strongly correlated to MSOD (r > 0.5). The highest correlation coefficient (0.79) was found between the YU analysis and MSOD. When exploring absolute agreement responsiveness, the smallest deviation (0.14 mm) was observed in the UPenn analysis. For ICC, the highest ICC value (0.63) was observed when the YU analysis was used. In addition, all three measurements were more responsive to MSOD in the MARME group than to those in RME group.

CONCLUSIONS

All three transverse measurements responded well to true changes of maxillary transverse deficiency during both tooth-supported and mini-screw-assisted RME. Deviations of responsive properties of these measurements from true skeletal changes were below a clinically meaningful level (1 mm).

A Correlation Analysis between Arch Width and Molar Inclination Using Cone-Beam Computed Tomography Transverse Measurements: A Cross-Sectional Study

A new era in 3-dimensional analysis has begun with the use of cone-beam computed tomography (CBCT) in orthodontics, which promises to provide a more thorough understanding of the craniofacial skeletal architecture. This study aimed to investigate the correlation between the transverse basal arches discrepancy and dental compensation by utilizing CBCT width analysis. An observational study was conducted to retrospectively review 88 CBCT scans of patients presented to dental clinics from 2014 to 2020 obtained from the Planmeca Romexis x-ray system at three centers. Dental compensation data across normal and narrow maxillae were analyzed and a Pearson correlation was used to find the relationship between molar inclination and width difference. Significant maxillary molar compensation differences were observed between the normal maxilla and narrow maxilla group, where the amount of dental compensation (164.73 ± 10.15) was higher in the narrow maxilla group. A significant negative correlation (r = -0.37) was observed between width difference and maxillary molar inclination. Maxillary molars were tipped buccally to compensate for the reduced maxillary arch width. These findings are important to determine the amount of needed maxillary expansion taking into account the buccal inclination while treating cases.

Maxillary transverse deficiency diagnosed by 3 methods and its relationship with molar angulation in patients with skeletal Class III malocclusion

INTRODUCTION

The objective of this study was to evaluate the relationship between maxillary transverse deficiency (MTD) diagnosed by 3 methods and molar angulation measured in 3-dimensions in patients with skeletal Class III malocclusion, which could give reference to the selection of diagnostic methods in MTD patients.

METHODS

Cone-beam computed tomography data of 65 patients with skeletal Class III malocclusion (mean age 17.35 ± 4.45 years) were selected and imported into MIMICS software. Transverse deficiencies were evaluated by 3 methods, and molar angulations were measured after reconstructing 3-dimensional planes. Two examiners performed repeated measurements to assess the intraexaminer and interexaminer reliability. Pearson correlation coefficient analyses and linear regressions were performed to determine the relationship between a transverse deficiency and molar angulations. One-way analysis of variance was used to compare the diagnostic results of 3 methods.

RESULTS

The novel molar angulation measurement method and 3 MTD diagnostic methods have the interexaminer and intraexaminer intraclass correlation coefficient values >0.6. The transverse deficiency diagnosed by 3 methods was significantly and positively correlated with the sum of molar angulation. There was a statistically significant difference for the transverse deficiencies diagnosed by the 3 methods. The transverse deficiency was significantly higher in Boston University's analysis than in Yonsei's analysis.

CONCLUSIONS

Clinicians ought to choose the diagnostic methods properly, considering the feature of the 3 methods and the individual difference of each patient.

A novel maxillary transverse deficiency diagnostic method based on ideal teeth position

BACKGROUND

This study proposed a novel maxillary transverse deficiency diagnostic method and evaluated the skeletal Class I and the mild skeletal Class III groups.

METHODS

Pre-treatment data from 30 mild skeletal Class III and 30 skeletal Class I patients were collected and uploaded to the Emeiqi Case Management System to design the ideal teeth positions. On these positions, the first bi-molars width was measured at the central fossa and center resistance, the maxillary first bi-premolars width was measured at the central fossa, and the mandibular first bi-premolars width was measured at the distal contact point by Mimics, then width differences of two groups were calculated respectively.

RESULTS

At ideal teeth positions, there was no statistically significant difference in the maxillomandibular width in the premolar area between the two groups, but there was in the molar area, and this difference was caused by the difference in mandible width between the two groups.

CONCLUSIONS

We proposed a new transverse diagnostic method and found that even the Class I group was not quite up to standard in the molar area on ideal teeth positions, and the Class III group had more severe maxillary transverse deficiency than the Class I group. Meanwhile, the maxillary transverse deficiency in the Class III group was mainly caused by the larger width of the mandible.

Age, Sex, and Maxillary Position Are Associated with Successful Microimplant-Assisted Rapid Palatal Expansion in Adults

The purpose of this study was to investigate the possible predictors of success of microimplant-assisted rapid palatal expansion (MARPE) in skeletally mature patients. Additionally, factors associated with the amount of maxillary expansion were analyzed. Factors associated with MARPE success were analyzed in 53 adult patients (27 males, 26 females, mean age 25.8 ± 8.9 years, and range 18.0 to 56.6 years) who had a maxillary transverse deficiency greater than 2 mm and a cervical vertebral maturation stage of 6. Age at pretreatment (T1), sex, sutural bone density at T1, type of appliance, mode of microimplant fixation, and lateral cephalometric variables at T1 were considered for inclusion as predictors for MARPE success. In patients who showed successful maxillary skeletal expansion, the linear distances of maxillary widths were measured on cone-beam-computed-tomography images at T1 and after MARPE (T2), and factors associated with the amount of expansion were analyzed. In total, 41 of the 53 patients showed successful maxillary expansion. Age (p = 0.019), sex (p = 0.002), and A-N perp (p = 0.015) were significantly associated with the success of MARPE. The factors associated with the amount of maxillary skeletal expansion were SN-MP and midpalatal-suture density at T1. In conclusion, there is a greater chance of failure in male patients who are older and have maxillary retrusion. A greater amount of maxillary expansion can be expected in patients with a higher mandibular-plane angle and with lower midpalatal-suture density.

Effect and stability of miniscrew-assisted rapid palatal expansion: A systematic review and meta-analysis

Objective

This study aimed to systematically analyze the effect and stability of miniscrew-assisted rapid palatal expansion (MARPE) to provide a reference for the clinical treatment of patients with maxillary transverse deficiency (MTD).

Methods

We searched PubMed, Science Direct, Web of Science, Embase, Cochrane Library, CNKI, and Wanfang Database for relevant studies published before February 18, 2021 and selected them according to the eligibility criteria. The Cochrane Handbook for Systematic Reviews (version 5.1.0) criteria were used for the quality assessment of randomized controlled trials, while the scoring protocol of the methodological index for non-randomized studies was used for non-randomized controlled trials. Statistical analysis was performed using the RevMan5.3 software.

Results

All the included studies showed a relatively high success rate of expansion. The changes in both the intermolar and alveolar widths after MARPE were statistically significant. MARPE exhibited greater skeletal expansion effects than did conventional RPE. The midpalatal suture was opened in parallel after MARPE. A small amount of relapse was observed 1 year after expansion. MARPE caused tooth inclination and a decrease in alveolar height, but it was less significant than in conventional RPE.

Conclusions

MARPE may be an effective treatment modality for patients with MTD. It causes great transverse skeletal expansion in late adolescence. In comparison to conventional RPE, MARPE has lower detrimental periodontal effects and has certain clinical advantages.

Comparison of treatment effects after total mandibular arch distalization with miniscrews vs ramal plates in patients with Class III malocclusion

INTRODUCTION

This study aimed to compare treatment effects after total mandibular arch distalization with buccal interradicular miniscrews vs ramal plates in patients with Class III malocclusion.

METHODS

The sample consisted of 40 patients with Class III malocclusion; 20 were treated with distalization via buccal miniscrews (age, 25.8 ± 7.9 years), whereas 20 were treated with ramal plates (age, 26.4 ± 6.1 years). Twenty-three linear and angular measurements were analyzed on pretreatment and posttreatment lateral cephalograms. The changes in each group and differences in treatment effects between the 2 groups were evaluated.

RESULTS

The mean amount of distalization at the crown and root levels of the mandibular first molars and the amount of distal tipping was 1.8 mm, 0.6 mm, and 5.4° in the buccal miniscrew group vs 3.6 mm, 2.0 mm, and 6.8° in the ramal plate group, respectively. In addition, 2.2° of counterclockwise rotation of the occlusal plane was observed in the buccal miniscrew group after 1.3 mm of molar intrusion (P <0.001). The distal movement of the lower lip was 0.6 mm in the buccal miniscrew group vs 2.3 mm in the ramal plate group.

CONCLUSIONS

The buccal miniscrew group showed more molar intrusion and counterclockwise rotation of the occlusal plane than in the ramal plate group. The ramal plate produced more distalization of the mandibular dentition with clockwise rotation of the mandible. Therefore, these results can be useful when selecting the type of temporary skeletal anchorage devices to treat patients with Class III malocclusion, depending on their vertical pattern.

Short-term effects of microimplant-assisted rapid palatal expansion on the circummaxillary sutures in skeletally mature patients: A cone-beam computed tomography study

INTRODUCTION

This study aimed to investigate the short-term effects on the circummaxillary sutures induced by microimplant-assisted rapid palatal expansion (MARPE) in skeletally mature patients.

METHODS

Cone-beam computed tomography (CBCT) images of preexpansion (T0) and postexpansion (T1) of 23 patients (mean age, 20.9 ± 3.65 years) treated with MARPE were evaluated. The T0 and T1 CBCT images were reoriented and superimposed on the basis of the anterior cranial base, using OnDemand3D software (Cybermed, Seoul, Korea). Then, width changes of 9 circummaxillary sutures (frontonasal, frontomaxillary, frontozygomatic, nasomaxillary, zygomaticomaxillary, intermaxillary, midpalatal, zygomaticotemporal, and pterygopalatine sutures) were measured on 1 section of each patient's T0 and T1 CBCT images. In addition, correlation coefficients between changes in the midpalatal sutures, the amount of appliance activation, age, and the changes in other circummaxillary sutural widths were also calculated.

RESULTS

Statistically significant (P <0.05) width increases were found in all 9 circummaxillary sutures. The changes in midpalatal suture at the maxillary central incisor level positively correlated with the intermaxillary sutures at the anterior nasal spine level, midpalatal sutures at the posterior nasal spine level, and frontomaxillary sutures (P <0.05). In addition, the changes in the midpalatal sutures at the posterior nasal spine level also positively correlated with the changes in the intermaxillary sutures at the anterior nasal spine level, frontomaxillary sutures, and medial pterygopalatine sutures (P <0.05).

CONCLUSIONS

All 9 circummaxillary sutural widths increased in skeletally mature patients immediately after MARPE. The greatest increases in width were measured in the midpalatal sutures and the intermaxillary sutures, followed by the frontomaxillary sutures.

The success and effectiveness of miniscrew-assisted rapid palatal expansion are age- and sex-dependent

OBJECTIVES

This study aimed to assess the success rate and the amount of suture separation after the miniscrew-assisted rapid palatal expansion (MARPE) procedure in relation to the chronological age and sex of the patients.

MATERIALS AND METHODS

The periapical radiographs of 215 subjects (95 male; 120 female; range, 6-60 years) who had undergone MARPE treatment were retrospectively analyzed. The success of suture separation was determined and, in suture-separated subjects, the amount of suture separation was evaluated by suture separation ratio calculated from the periapical radiograph obtained after active expansion. Association tests were performed using linear-by-linear association, the Jonckheere-Terpstra test, Fisher's exact test, and the Mann-Whitney U test, and linear regression models were also developed.

RESULTS

The success rate of suture separation was 61.05% in male, 94.17% in female, and 79.53% in both sexes. There was a statistically significant association between older age and suture nonseparation in male (p < 0.001), but not in female (p = 0.221). In suture-separated subjects, there was a statistically significant trend toward a low amount of suture separation with older age subgroups in both sexes (p < 0.001); however, there was no statistically significant difference in the amount of suture separation between male and female in all age subgroups.

CONCLUSIONS

Older patients treated with MARPE, particularly in male, may have a reduced likelihood of both success in suture separation and sufficient basal bone expansion.

CLINICAL RELEVANCE

This study demonstrates that clinicians should consider that the success rate of MARPE and the amount of suture separation may depend on chronological age and sex.

Development of a maxillomandibular arch form based on the center of resistance of teeth using cone-beam computed tomography

INTRODUCTION

Controlling transverse discrepancies is necessary to ensure stable and functional occlusion. Altered molar inclinations can camouflage the transverse relationship. The purpose of this research was to evaluate the maxillomandibular relationship of the center of resistance (CR) of the arch form created by the CR of teeth and compare these CR arch forms by their skeletal patterns.

METHODS

Sixty patients with minor crowding and normal posterior overjet were divided into 3 groups according to ANB angle: skeletal Class I group had ANB angle between 0° and 4° (n = 20), skeletal Class II group had ANB angle >4° (n = 20), and skeletal Class III group had ANB angle <0° (n = 20). The 3-dimensional coordinates of the CR were estimated using cone-beam computed tomography images and projected on the CR occlusal plane to obtain the 2-dimensional coordinates. The CR arch forms were constructed and evaluated using Matlab (MathWorks, Natick, Mass).

RESULTS

On comparing maxillomandibular CR arch form widths, the maxilla was significantly larger than the mandible of the canine and first premolar. The mandible was larger in the first molar of the skeletal Class III group. The maxillomandibular CR arch form width ratios were between 0.97 and 1.35. On comparing maxillomandibular CR arch form areas, the maxilla was significantly larger than the mandible in the anterior segment, and the mandible was larger in the posterior segment. The ratios were between 0.86 and 2.25. In between-group comparison, the skeletal Class III group showed significantly greater arch forms in the mandible.

CONCLUSIONS

CR arch forms had significant maxillomandibular differences throughout the arch. The maxillomandibular ratios could be a reference for site-specific transverse discrepancy analysis.

Correlation between craniofacial changes and respiratory improvement after nasomaxillary skeletal expansion in pediatric obstructive sleep apnea patients

PURPOSE

The aim of this study was to investigate the correlation between the changes in respiratory function and dimensions of the nasomaxillary complex (NMC) and upper airway (UA) compartments after nasomaxillary skeletal expansion (NMSE) treatment for pediatric patients with obstructive sleep apnea (OSA).

METHODS

Nonobese OSA patients (mean age, 13.6 ± 2.9 years; mean body mass index, 18.1 ± 3.0 kg/m²); mean apnea-hypopnea index (AHI, 7.0 ± 5.4 events/h) presenting with transverse nasomaxillary constriction were evaluated before and after NMSE using cone-beam computed tomography (CBCT), home sleep test, and modified pediatric sleep questionnaire (m-PSQ). Paired t tests were performed to examine the treatment-related changes in all the parameters, and a multiple regression analysis adjusted for age and sagittal and vertical skeletal patterns was conducted to determine the dimensional parameters to affect the functional improvement.

RESULTS

Among 26 patients, NMSE treatment significantly increased NMC dimensions at all tested levels and all UA compartments in CBCT, except glossopharyngeal airway. Concurrently, AHI, oxygen desaturation index, the lowest oxygen saturation (LSaO₂), flow limitation (FL), snoring, and m-PSQ were significantly improved. AHI reduction was correlated with UA enlargement with no correlation with NMC expansion, whereas FL reduction was affected by NMC expansion. The minimal cross-sectional area was the most predictive of functional improvement, presenting correlations with AHI, LSaO₂, and m-PSQ.

CONCLUSION

NMSE can be a good treatment for pediatric OSA patients when applied to enhance the nasal and pharyngeal airway patencies beyond the NMC, ultimately to improve pharyngeal collapsibility as well as nasal airflow.

Nonsurgical maxillary expansion in a 60-year-old patient with gingival recession and crowding

Maxillary transverse deficiency often manifests as a posterior crossbite or edge-to-edge bite and anterior crowding. However, arbitrary arch expansion in mature patients has been considered to be challenging due to the possible periodontal adverse effects such as alveolar bone dehiscence and gingival recession. To overcome these limitations, nonsurgical maxillary expansion of the basal bone has been demonstrated in young adults. However, the age range for successful orthopedic expansion has remained a topic of debate, possibly due to the underlying individual variations in suture maturity. This case report illustrates nonsurgical, miniscrew-assisted rapid palatal expansion (MARPE) in a 60-year-old patient with maxillary transverse deficiency accompanied by anterior and posterior crossbites, crowding, and gingival recession. The use of MARPE allowed relief of crowding and correction of the crossbite without causing significant periodontal adverse effects.

Reliability of 2 methods in maxillary transverse deficiency diagnosis

INTRODUCTION

The objective of this research was to evaluate the reliability of 2 methods (Andrews' Element III analysis and Yonsei transverse analysis) in maxillary transverse deficiency diagnosis.

METHODS

Plaster casts and cone-beam computed tomography images of 80 outpatients with skeletal Class I malocclusion (29 males and 51 females, mean age, 20.16 ± 8.22 years) were selected. Maxillary and mandibular width were measured, respectively, and independently by 2 examiners at an interval of 2 weeks, using Andrews' Element III analysis and Yonsei transverse analysis. Intraclass correlation coefficients and Bland-Altman plots of intraexaminer and interexaminer reliability were evaluated. After diagnosis, Cohen's kappa statistics were calculated to evaluate the diagnostic agreement.

RESULTS

The intraclass correlation coefficients were all above 0.85, indicating good to excellent reliability. Compared with Andrews' Element III analysis, Yonsei transverse analysis had higher intraexaminer and interexaminer reliability in both maxillary and mandibular width measurements. Thirty-one to 42 of the patients were diagnosed with maxillary transverse deficiency by 2 examiners using 2 methods. The intraexaminer and interexaminer Cohen's kappa values of Yonsei transverse analysis were all higher than those of Andrews' Element III analysis.

CONCLUSIONS

Both Andrews' Element III analysis and Yonsei transverse analysis had good to excellent reliability and substantial diagnostic agreement. Yonsei transverse analysis had higher reliability in maxillary and mandibular width measurements and higher diagnostic agreement, compared with Andrews' Element III analysis.

Clinical applications of miniscrews that broaden the scope of non-surgical orthodontic treatment

Previously, in the case of malocclusion owing to skeletal discrepancy in adults, the amount of tooth movement was limited since there was no reliable skeletal anchorage device. The only way to treat this case was by repositioning the maxilla and mandible via orthognathic surgery, but most patients are reluctant to undergo surgery owing to the risk and expenses incurred. However, with the current introduction and use of miniscrews as temporary anchorage devices, the entire dental arch can be relocated to a target position without surgery, thus broadening the scope of non-surgical orthodontic treatment compared to the past. For a non-surgical approach to improve skeletal discrepancy, anteroposterior, vertical and transverse displacements of the dental arch are necessary. In this case, the localization of the centre of resistance of the whole arch must precede the appliance design with an appropriate biomechanical design. Especially, in the transverse dimension, the envelope of discrepancy is reportedly narrow, and the tooth movement must accompany the orthopaedic correction involving the midpalatal suture expansion. Recently, in adults with transverse maxillomandibular discrepancy, miniscrew-assisted rapid palatal expansion (MARPE) can be performed. Moreover, compared to surgically assisted rapid palatal expansion, MARPE reduces the cost to the patient and achieves clinically acceptable stable maxillary expansion. In this article, we will discuss the role of total arch movement and MARPE in widening the scope of non-surgical orthodontic treatment, despite the inherent limitations of miniscrews' mechanical aspects.

Stability of bimaxillary surgery involving intraoral vertical ramus osteotomy with or without presurgical miniscrew-assisted rapid palatal expansion in adult patients with skeletal Class III malocclusion

Objective

The aim of this study was to evaluate the stability of bimaxillary surgery involving bilateral intraoral vertical ramus osteotomy performed with or without presurgical miniscrew-assisted rapid palatal expansion (MARPE) in adult patients with skeletal Class III malocclusion.

Methods

A total of 40 adult patients with skeletal Class III malocclusion were retrospectively divided into two groups (n = 20 each) according to the use of MARPE for the correction of transverse maxillomandibular discrepancy during presurgical orthodontic treatment. Serial lateral cephalograms and dental casts were analyzed until 6 months after surgery.

Results

Before presurgical orthodontic treatment, there was no significant differences in terms of sex and age between groups. However, the difference of approximately 3.1 mm in the maxillomandibular intermolar width was statistically significant (p < 0.001). Two days after surgery, the mandible had moved backward and upward without any significant intergroup difference. Six months after surgery, the maxillary intercanine (2.7 ± 2.1 mm), interpremolar (3.6 ± 2.4 mm), and intermolar (2.0 ± 1.3 mm) arch widths were significantly increased (p < 0.001) relative to the values before presurgical orthodontic treatment in the MARPE group; these widths were maintained or decreased in the control group. However, there was no significant difference in surgical changes and the postsurgical stability between the two groups. No significant correlations existed between the amount of maxillary expansion and postsurgical mandibular movement.

Conclusions

MARPE is useful for stable and nonsurgical expansion of the maxilla in adult patients with skeletal Class III malocclusion who are scheduled for bimaxillary surgery.

A comparative study of sagittal dental relationship using digital method of bite mark evaluation

Introduction:

Intercuspation of teeth depends on position of teeth and jaws. Bite mark is the resultant of the intercuspation of teeth produced by an individual.

Aims and Objective:

Comparative evaluation of bite marks in Angle's Class I, II, and III sagittal occlusion.

Materials and Methods:

Three groups as per Angle's classification-Class I, Class II, and Class III relation were taken. Each group comprised 30 samples each. The dental casts were scanned to create digital images. “IC Measure” software was used to determine the angular and linear measurements on scanned images of study model after calibration. Internal angles of odontometric triangle, intercanine width, shape of the arch, size, and shape of the individual teeth was recorded and subjected to the statistical analysis.

Results:

All incisors had rectangular and canine had triangular shape. Bilateral maxillary lateral incisors and mandibular left central incisor were significantly small in size for Class III. Square arch form was found more commonly in Class III and ovoid arch form in Class I and Class II occlusion. Intercanine width was insignificant among all occlusions. All the angles of the odontometric triangle in the maxillary and mandibular arches were significant for Class III.

Conclusion:

Class III occlusion individuals were distinct for shape of the arch and angles of maxillary and mandibular odontometric triangle. The quantified values of odontometric triangle can be utilized for the identification of Class III individuals.

An investigation into structural behaviors of skulls chewing food in different occlusal relationships using FEM

OBJECTIVES

This study aims to investigate the effect of different occlusal relationships on skull structural and mechanical behaviors through simulation of chewing food.

METHODS

Finite element (FE) skull models of occlusion for Class I, end-on Class II, and full-cusp Class II were generated. End-on Class II and full-cusp Class II were chosen as mild and severe Class II occlusions, respectively. A simplified food bolus was introduced between the upper and lower dentition of the right molars. Chewing food was simulated in the skulls by moving the mandible. An experiment was conducted to measure strains at selective locations and compared them to the analytical results for validation.

RESULTS

In the early stages of mandibular movement, masticatory forces predicted from the skull models without food were lower than the skull models with food but increased drastically after occluding teeth full enough. As a result, the relationship between masticatory force and mandible movement shows that there is no significant difference between the skull models with food and without food in the range of human masticatory force, approximately 250 N. In all the cases of skulls including a food bolus, stress was similarly propagated from the mandible to the maxilla and concentrated in the same regions, including the mandibular notch and alveolar bone around the lower molars.

CONCLUSION

It is predicted that there is no significant difference of bite force-mandible movement relationships and stress distributions of skull and teeth, between end-on Class II and full-cusp Class II models. When simulating chewing activities on candy and carrot, it is also found that there is no difference of masticatory performance between Class II occlusions, from structural as well as mechanical perspectives.

Selected Orthodontic Principles for Management of Cranio-Maxillofacial Deformities

An understanding of fundamental orthodontic principles involving diagnosis, treatment planning, and clinical strategies is essential for achieving successful outcomes in the treatment of craniofacial patients, particularly cleft lip/palate. This article focuses on: customizing a mandibular dental arch form using the WALA ridge; accurately diagnosing the maxillary skeletal transverse dimension (cusp to cusp/fossa to fossa); coordinating the upper dental arch with the lower; using a smiling profile and glabella vertical to assess anteroposterior jaw position; and leveling the mandibular curve of Spee while considering the lower one-third of the face. These concepts influence treatment outcomes to the extent they are used.

Expansion in the absence of crossbite – rationale and protocol

Transverse maxillomandibular discrepancies are a major component of several malocclusions. Clinically, posterior crossbite is a common and valid indicator of maxillary transverse problems and orthopedic and orthodontic forces are routinely used to correct maxillary transverse deficiency. However, crossbite and transverse discrepancies are not a homologous group but must be viewed as a continuum with varying degree of abnormality. The etiology, diagnostic protocol, rationale, and procedures employed for correcting maxillary transverse discrepancy in the absence of crossbite are discussed in the article.

Asymmetric nasomaxillary expansion induced by tooth-bone-borne expander producing differential craniofacial changes

OBJECTIVES

To evaluate three-dimensional (3D) craniofacial changes induced by a non-surgical tooth-bone-borne rapid palatal expander (TBB-RPE) according to the symmetrical pattern of expansion, to investigate the 3D changes between the sides in patients with asymmetric expansion, and to identify the related factors of asymmetric expansion.

SETTING AND SAMPLE POPULATION

Sixty-six patients (mean age: 19.3 ± 5.7 years) treated with TBB-RPE were divided into a symmetric expansion group (Group S, n = 46) or asymmetric expansion group (Group A, n = 20). Group S was subdivided into Group Ss (n = 27), with bilateral frontomaxillary suture (FMS) split, and Group Sn (n = 19), with no FMS split.

MATERIALS AND METHODS

Pre- and post-expansion cone-beam computed tomography images were superimposed, and the common coordinated system was set. All landmarks were designated as coordinate pairs, and treatment changes were automatically calculated. Analysis of variance was conducted for intergroup comparison of craniofacial changes, and logistic regression analysis was performed to identify the related factors of asymmetric expansion.

RESULTS

The frequency of asymmetric expansion was 30.3%. Group A with unilateral FMS split showed less craniofacial changes than Group Ss and more changes than Group Sn. Group A exhibited different nasomaxillary displacement between the two halves, showing greater changes in the FMS-split side. Among the tested six variables (age, gender, Angle's classification, unilateral crossbite, maxillary cant and chin deviation), chin deviation was uniquely associated with asymmetric expansion.

CONCLUSIONS

Tooth-bone-borne rapid palatal expander had a risk of asymmetric expansion, especially in facial asymmetric patients with chin deviation, producing different craniofacial changes from symmetric expansion.

Evaluation of the effects of miniscrew incorporation in palatal expanders for young adults using finite element analysis

Objective

The aim of this study was to evaluate the stress distribution and displacement of various craniofacial structures after nonsurgical rapid palatal expansion (RPE) with conventional (C-RPE), bone-borne (B-RPE), and miniscrew-assisted (MARPE) expanders for young adults using three-dimensional finite element analysis (3D FEA).

Methods

Conventional, bone-borne, and miniscrew-assisted palatal expanders were designed to simulate expansion in a 3D FE model created from a 20-year-old human dry skull. Stress distribution and the displacement pattern for each circumaxillary suture and anchor tooth were calculated.

Results

The results showed that C-RPE induced the greatest stress along the frontal process of the maxilla and around the anchor teeth, followed by the suture area, whereas B-RPE generated the greatest stress around the miniscrew, although the area was limited within the suture. Compared with the other appliances, MARPE caused relatively even stress distribution, decreased the stress on the buccal plate of the anchor teeth, and reduced tipping of the anchor teeth.

Conclusions

The findings of this study suggest that the incorporation of miniscrews in RPE devices may contribute to force delivery to the sutures and a decrease in excessive stress on the buccal plate. Thus, MARPE may serve as an effective modality for the nonsurgical treatment of transverse maxillary deficiency in young adults.

Effects of bodily retraction of mandibular incisors versus mandibular setback surgery on pharyngeal airway space: A comparative study

OBJECTIVE

The purpose of this study was to compare the changes induced in the pharyngeal airway space by orthodontic treatment with bodily retraction of the mandibular incisors and mandibular setback surgery without extraction.

METHODS

This retrospective study included 63 adult patients (32 men and 31 women). Thirty-three patients who had been treated via four-bicuspid extraction and bodily retraction of the mandibular incisors (incisor retraction, IR group) were compared with 30 patients who had been treated via mandibular setback surgery (MS group) without extraction. Lateral cephalograms were acquired and analyzed before (T1) and after treatment (T2).

RESULTS

The superior pharyngeal airway space did not change significantly in either group during treatment. The middle pharyngeal airway space decreased by 1.15 ± 1.17 mm and 1.25 ± 1.35 mm after treatment in the IR and MS groups, respectively, and the decrease was comparable between the two groups. In the MS group, the inferior pharyngeal airway space (E-IPW) decreased by 0.88 ± 1.67 mm after treatment (p < 0.01). The E-IPW was larger in the MS group than in IR group at T1, but it did not differ significantly between the two groups at T2. No significant correlation was observed between changes in the pharyngeal airway space and the skeletal and dental variables in each group.

CONCLUSIONS

The middle pharyngeal airway space decreased because of the posterior displacement of the mandibular incisors and/or the mandibular body. The E-IPW decreased only in the MS group because of the posterior displacement of only the mandibular body.