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

Evaluation of the Co-Go-Me angle as a predictor in Class II patients treated with Herbst appliance and skeletal anchorage: a retrospective cohort study

Introduction

A condylion-gonion-menton (Co-Go-Me) angle threshold of 125.5° has been introduced as a predictive parameter of cephalometric mandibular response in the orthopedic treatment of growing Class II patients with functional appliances, despite some contradictions in the literature. Considering the lack of studies evaluating the role of skeletal anchorage, this study aims to reassess the threshold of 125.5° in the Co-Go-Me angle as a useful predictor in growing skeletal Class II patients treated with acrylic splint Herbst appliance and two mini-screws in the lower arch (STM2).

Methods

Thirty-five consecutively treated patients (20 males, 15 females; mean age, 11.37 years) with mandibular retrusion were classified into two groups according to their Co-Go-Me baseline values (Group 1, <125.5°; Group 2, >125.5°). The STM2 protocol involved the use of the MTH Herbst appliance with an acrylic splint in the lower arch and two interradicular mini-screws as anchorage reinforcement. Cephalometric analysis was performed by the same operator for each patient at baseline (T0) and at the end of the Herbst phase (T1). The effects of time and group on the variables were assessed by a repeated-measures analysis of variance. The primary research outcome was the difference between the groups in terms of mandibular responsiveness to treatment referred to as the relative difference (T1-T0) in Co_Gn.

Results

The mean duration of the treatment was 9.5 months. No statistically significant differences between groups were detected at baseline, except from the expected SN/GoMe° (p < 0.001) and Co-Go mm (p = 0.028). No statistically significant changes between groups, which were caused by the treatment, were found considering the mandibular sagittal and vertical skeletal parameters. Similarly, no statistically significant differences were found in the dental changes between the high-angle and low-angle patients, apart from the upper molar sagittal position (p = 0.013).

Discussion and conclusions

The 125.5° threshold in the Co-Go-Me value was not a reliable predictive parameter for the mandibular response in growing patients treated with the MTH Herbst appliance and lower skeletal anchorage. Due to its effective control in the sagittal and vertical planes, the STM2 technique might be an appropriate protocol to use in treating skeletal Class II patients, regardless of the growth pattern.

Three-dimensional evaluation using CBCT of the mandibular asymmetry and the compensation mechanism in a growing patient: A case report

Background

This case report aims to evaluate the development and the compensation mechanisms of the mandibular asymmetry in a growing male patient using cone beam computed tomography (CBCT). In this case, the menton deviated on the right, a sporadic condition, which may be the consequence of a disorder in the mandibular growth.

Case presentation

The young male patient was treated with rapid palatal expander (RPE) and Fränkel functional regulator III (FR-3). The initial CBCT was acquired at the beginning of therapy when the patient was 8 years old, and the final CBCT was developed at the end of the treatment when the patient was 12 years old. The patient's CBCT was performed with the head oriented according to the Natural Head Position (NHP); the NHP is a physiological and reproducible posture defined for morphological analysis. The 3D image of the cranium was oriented in the Dolphin software according to NHP posture, and cephalometric measurements were taken in the software's frontal, laterolateral right and left, posteroanterior, and submentovertex views. The therapy lasted 3.8 years and ended with significant regression of the mandibular asymmetry from moderate grade (4.2 mm) to slight grade (1.3 mm).

Conclusion

The literature shows that the left hemi-mandible has grown more than the right side, which affirms that in case of deviation of the menton >4 mm, the bone volume increases on the non-deviated side.

Novel cephalometric parameters for the assessment of vertical skeletal dysplasia

INTRODUCTION:

The accurate diagnosis of vertical skeletal abnormalities presents several challenges. Specific cephalometric parameters can be effectively used for this purpose; however, their diagnostic utility has not been fully ascertained. This study examined the effectiveness of two novel cephalometric parameters in diagnosing vertical dysplasia.

METHODS:

Orthodontic patients were divided into three study groups: average growth group (AGG), horizontal growth group (HGG), and vertical growth group (VGG). The efficacies of the sum of the angles (maxillary, mandibular, and ramal) and the height ratio (lower anterior facial height [LAFH]/upper anterior facial height [UAFH]) in identifying the different growth patterns were examined. Receiver operating characteristic curves were used to quantitatively assess diagnostic precision.

RESULTS:

A total of 150 patients were included and divided equally among the 3 study groups. The ramal and mandibular angles varied across AGG, HGG, and VGG; however, the maxillary angle and the sum of these three angles did not vary significantly. There was a significant difference in LAFH, UAFH, and their ratios among the three groups. The height ratio had a sensitivity of 88% and 92% for the diagnosis of VGG and HGG, respectively, with cutoff values of 46 and 34, respectively (P < 0.001).

CONCLUSIONS:

The height ratio values varied considerably according to facial growth patterns, suggesting its utility as a diagnostic tool for skeletal dysplasia with greater reliability for positive treatment outcomes.

Does Mandibular Gonial Angle Influence the Eruption Pattern of the Lower Third Molar? A Three-Dimensional Study

Lower third molars (M3M) are the most frequent impacted teeth. The aim of this study was to evaluate the correlation between M3M position and gonial angle. A retrospective cross-sectional study was conducted. The study population included patients with unilateral or bilateral M3M and underwent Cone Beam Computed Tomography. A morphometric analysis of the mandible was performed after three-dimensional reconstruction, recording gonial angle (GA), ramus high, ramus width, ramus divergency, and retromolar space. GA was the primary predictor variable. The primary outcome variable was the position of M3M analyzed in sagittal, axial, and coronal planes. Descriptive, bivariate, and multiple regression statistics were performed (p < 0.05). Study sample included 172 patients (mean age: 26.3 ± 4.6 years); 266 M3Ms were analyzed. The average GA was 122.6° ± 4.8°. A reduced GA value was significantly associated with a deeply impacted M3M in the ramus. With a progressive decrease of GA, M3M assumed a more horizontal position closer to the mandibular canal (p < 0.05). A lower GA showed a reduced retromolar space with more complex impacted M3M (p < 0.05). The results confirm a statistically significant correlation between GA and the position of M3M. Higher incidence of impacted M3M was related to a reduction of the GA value.

Frontal and Axial Evaluation of Craniofacial Morphology in Repaired Unilateral Cleft Lip and Palate Patients Utilizing Cone Beam Computed Tomography; An Observational Study

The current study was conducted to assess the extent of maxillary arch collapse on the cleft vis-a-vis non-cleft sides in the same individual presenting withunilateral cleft lip and palate (UCLP), using cone-beam computed tomography (CBCT). Thirty-one children (eighteen boys andthirteen girls) with surgically repaired UCLP, who met the inclusion criteria, were selected. Following the acquisition of CBCT scans, fourteen bilateral landmarks were selected. The distance of the bilateral landmark was calculated from the midsagittal plane on the cleft and non-cleft sides for both frontal and axial views. Tracings were done;the data obtained was subjected to statistical analysis;and intra-observer variability was checked with intraclass correlation coefficient (ICC) and two-way ANOVA. Subsequently, the measurements were subjected to paired t-tests at the 95% level of significance with Bonferroni correction. A significant reduction of pyriforme and an alveolar crest above the maxillary 1st molar were discerned in frontal analysis on the cleft side. In the axial view, the zygomatic arch, malar, porion and alveolar crest at the molar region were non-significant, but the alveolar crest at the premolar region (p < 0.004)) was significantly decreased. In the frontal analysis, pyriforme and the alveolar crest above the maxillary 1st molar, and, in the axial view, premolar widths, showed significant reduction when comparing the cleft vis-a-vis non-cleft sides.

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

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

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

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

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