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Background and Objectives: The occlusal angle (OA), influenced by pillow height, may affect muscle tension in the head and neck. However, its optimal range for minimizing muscle activation has not been clearly defined. This study aimed to investigate the effects of OA on the resting muscle activity of masticatory and cervical muscles and to identify an optimal OA range using cluster analysis and linear mixed-effects modeling. Materials and Methods: The resting muscle activities of the masseter (MAS), temporalis (TEM), sternocleidomastoid (SCM), and posterior vertebral muscles (PVM) were measured at OA conditions modulated by pillow heights of 0, 5, and 10 cm at 0, 1, and 5 min in the supine position. Intraclass correlation coefficients (ICCs) assessed measurement reliability. Statistical analyses included ANOVA, ROC curve analysis, k-means clustering, and linear mixed-effects models. Results: MAS and TEM resting muscle activity ratio (RMR) significantly increased with larger OA values (p < 0.001), while SCM showed decreased activation (p = 0.001). An OA range of 105°–111° was identified as the center of a low-activity cluster, and an upper cut-off of 138° was associated with potential muscular overload. ICC values for MAS and SCM ranged from 0.82 to 0.89, indicating excellent test–retest reliability. Conclusions: OA modulated by pillow height is a modifiable factor that influences muscle activity. An OA of 105°–111° may serve as a practical comfort zone, especially for individuals at risk of TMDs.

Objectives The correlations between the incisal guidance angle (IGA) and occlusal plane angles and temporomandibular joint (TMJ) morphology were investigated in adults with skeletal Class II division II malocclusion. Materials and methods CBCT images of 37 patients were analyzed. It included 19 cases of skeletal Class II division II malocclusion with low angle (study group) and 18 cases of skeletal Class I average angle (control group). The Invivo Dental 5 software was employed to acquire the data of the incisal guidance angle (IGA), occlusal plane angle (FH-OP), anterior occlusal plane angle (FH-AOP) and the TMJ measurement items. Results The results of IGA, FH-AOP angle and FH-OP angle showed the study group > the control group ( P  < 0.05). There were statistically difference in the condylar mediolateral diameters, articular eminence inclination and height, and posterior joint spaces between two groups. No differences were revealed in the condylar anteroposterior diameters, the condylar inclination angle, condylar head width and height, condylar length, glenoid fossa depth and width between two groups. In the study group, IGA showed a moderate correlation with FH-AOP, a weak correlation with FH-OP and condylar mediolateral diameters. Meanwhile, there was a correlation between FH-AOP, FH-OP, and TMJ indicators. Conclusions The IGA was not only related to FH-AOP and FH-OP, but also to the condylar mediolateral diameters. In addition, there was a correlation between the occlusal plane angles and TMJ morphology in skeletal Class II division II low angle malocclusion. Clinical relevance For patients with skeletal Class II division II low angle malocclusion, adjusting the IGA and the occlusal plane angles could improve the esthetic appearance of the anterior teeth, occlusal function, and TMJ morphology.

Background The shape and structure of the temporomandibular joint (TMJ) can be affected by many factors and occlusal factors are considered important factors. Although many scholars have studied the correlation between the occlusal plane (OP) and TMJ morphological characteristics in different types of malocclusion, it is still unclear whether the Balkwill angle and mandibular occlusal plane (MOP) angle affect the TMJ morphology. The aim of this study was to investigate the correlations between the Balkwill angle, the MOP angle and TMJ morphology in adults with skeletal Class II Division II malocclusion using cone-beam computed tomography (CBCT). Methods Seventy adult patients (29 males and 41 females, mean age 23.32 ± 3.22 years) with no symptoms of temporomandibular disorders were divided equally into two groups: skeletal Class II division II low angle-study group (14 males, 21 females, 23.66 ± 3.29 years) and skeletal Class I average angle-control group (15 males, 20 females, 22.98 ± 3.15 years). The Balkwill angle, OP angle (FH-OP), MOP angle (FH-MOP), DPO (vertical distance from the condylar center to the MOP) and TMJ measurement items were measured. Results The mean values of FH-OP and FH-MOP angles were smaller in the study group ( P  < 0.05), while the average values of Balkwill angle and DPO were larger in the study group than in the control group ( P  < 0.05). Significant differences were found in the condylar mediolateral diameters, condylar head width, articular eminence inclination and height, and superior joint space between the two groups. The correlation analysis showed that the Balkwill angle was strongly positively correlated with DPO and negatively correlated with MOP angle. In the control group, the Balkwill angle, MOP angle and DPO had weak correlations with TMJ morphology. However, in the study group, the Balkwill angle, MOP angle and DPO had moderate correlations with TMJ morphology. Conclusions The DPO had a significant impact on TMJ morphology, followed by the MOP angle, and finally the Balkwill angle in skeletal Class II Division II low angle malocclusion.

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.

Abstrac This study evaluated the influence of scanning method, abutment position, and preparation angle on the vertical seal of three-unit posterior zirconia structures. Sixty differently angled metallic models were machined to receive 30 bridge frameworks. For each preparation type, half of the structures were waxed-up and digitized, whereas the other half were computer-designed after the abutments were scanned. Once milled, the samples were cemented in standard fashion. Misfit was assessed by scanning electron microscopy. Three-way analysis of variance showed significant differences. Computer-designed structures achieved the highest accuracy ( P < 0.0001). No significant differences were recorded concerning the abutment position and convergence angle. All discrepancy values were within the clinically acceptable range.

Rotation of the maxillomandibular complex (MMC) as an alternative treatment design to conventional orthognathic treatment planning was first described as the 'rotation of the occlusal plane' or the 'manipulation of the occlusal plane' for the correction of Class II low angle mandibular plane cases. The orthodontic preparation for cases planned for surgical rotation of the MMC is the same as for all orthog‐nathic cases. However, the consequential change of the occlusal plane will result in a change in the inclinations of the incisor teeth. Many dentofacial deformities can be corrected by means of conventional orthognathic treatment planning. Basic surgical orthodontic principles demand the early recognition of a skeletal component as aetiology of a malocclusion and it should be considered during treatment planning. The relationship between the vertical and antero‐posterior dimensions of the face is influenced by the anterior cranial base length, the steepness of the cranial base and the occlusal plane angle.

Background: Optimal management of hypodivergent growing patients demands a strict control of vertical dimension and to exploit the growth potential. If a deep bite malocclusion causes a traumatic contact between the upper and lower incisors and affects the facial appearance, an early interceptive treatment is recommended. The aim of this case report is to outline the clinical management of the occlusal plane of a growing Class II division 1 deep bite patient treated with aligners and Class II elastics. Methods: The treatment lasted 11 months and was divided into two phases. Treatment goals included improvement of the soft tissue profile and basal bone relationships through an increase in the mandibular third of the face and a sagittal advancement of the mandible. The correction of the curve of Spee involved intrusion of the mandibular incisors and extrusion of the mandibular premolars. Results: The cephalometric analysis at the end of the treatment displayed significant differences in the skeletal and occlusal pattern along with aesthetic improvements. Conclusion: The final cephalogram showed a consistency between the planned tooth movement and the clinical results. Although definitive recommendations must be withheld until longer follow-up is available, the patient presented here shows that the treatment protocol yielded positive mandibular growth.

Background Temporomandibular joint (TMJ) disc repositioning through open suturing (OSu) is a new disc repositioning method. Its result for adolescents with condylar resorption and dentofacial deformities combined with and without postoperative occlusal splints (POS) has not been well studied. Objective This study was to evaluate and compare the effects of OSu with and without POS in the treatment of TMJ anterior disc displacement without reduction (ADDwoR) in adolescent skeletal Class II malocclusion. Methods A total of 60 adolescents with bilateral ADDwoR were enrolled in this study. They were randomly allocated into two groups: OSu with and without POS. Magnetic resonance imaging (MRI) and lateral cephalometric radiographs were used to measure changes in condylar height and the degree of skeletal Class II malocclusion from before operation and at 12 months postoperatively. Changes in these indicators were compared within and between the two groups. Results After OSu, both groups exhibited significant improvements in condylar height and occlusion at the end of 12 months follow-up ( P  < 0.05). The group of OSu with POS had significantly more new bone formation (2.83 ± 0.75 mm vs. 1.42 ± 0.81 mm, P  < 0.001) and improvement in dentofacial deformity than the group of OSu only ( P  < 0.05). The new bone height was significantly correlated with POS ( P  < 0.001), the changes of SNB ( P  = 0.018), overjet ( P  = 0.012), and Wits appraisal ( P  < 0.001). Conclusion These findings indicated that OSu can effectively stimulate condylar regeneration and improve skeletal Class II malocclusion in adolescents with bilateral ADDwoR. The results are better when combined with POS. Trial registration This trial was prospectively registered on the chictr.org.cn registry with ID: ChiCTR1900021821 on 11/03/2019

Malocclusion may lead to the development of occlusal trauma, which can exacerbate periodontal disease. Here, we present a skeletal Class II adult patient with occlusal traumatic periodontitis of upper incisors, who was treated with a two-phased orthodontic treatment. In the first phase, a Twin Block appliance (TBA) was used to increase the vertical dimension of the posterior teeth, to eliminate the anterior occlusal trauma. In addition, TBA also improved mandibular retrusion by forwarding the mandible. In the second phase of fixed orthodontics, occlusion was fine-tuned with infrazygomatic crest (IZC) miniscrews and Class II intermaxillary elastics. At the end of treatment, anterior occlusal trauma was eliminated, periodontal conditions of upper incisors were improved, a stable occlusion and a harmonious profile were obtained. The successful two-phased orthodontic treatment showed that the TBA can effectively eliminate anterior occlusal trauma through restoration of posterior vertical dimension, and can improve mandibular retrusion by forwarding mandible and reconstructing stable occlusion in adult patient.