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Introduction Mandibular Advancement Devices (MAD) have been reported to be an alternative treatment to CPAP in moderate to severe obstructive sleep apnea (OSA) cases. The design of MAD has a major influence on its success rate on the patient, and design features that have an influence on efficacy, tolerance, and compliance. The aim of this study was to determine the range of mandibular protrusion at different vertical points; 2, 5, 8 and 11 mm in a young adult population. Methods Fifty two students aged 19 to 23 years (mean 21.3 ± 1.7; 29 females and 23 males), with full permanent dentition participated in the study. The absolute range of maximal mandibular protrusion and retrusion was measured (mm) with the use of the George Gauge. Descriptive statistics, ANOVA and paired t-test using SPSS were used. Results Range of mandibular advancement was possible to be determined for the 4 levels of vertical opening with the gauges: 2 mm fork mean mandibular advance 13,10 mm ± 0.604; 5 mm mean 11.98 mm ± 1.075; 8 mm mean 11.20 mm ± 1.369; 11 mm mean 9.87 mm ± 1.886. No significant differences were found between class I, II, and III. Conclusions There is an impact of increased inter-incisal distance of effective mandibular protrusion when constructing a MAD. As vertical dimension increases the mandible rotates posteriorly and places itself in a more retrusive location, and the range of mandibular advancement reduces (0.3 mm for every 1 mm of vertical increase).

Background The edentulous patients with unstable mandibular position (MP) and uncoordinated mandibular movement (MM) usually complain the poor therapeutic effect when conventional complete dentures (CCDs) are delivered. This case report aims to observe whether neuromuscular training (NT) using therapeutic complete dentures (TCDs) can improve the MP and MM, thereby promoting the effect of the definitive dentures. Case presentation NT was conducted using TCDs for an edentulous patient with unstable MP and uncoordinated MM. After a period of masticatory exercises, the patient’s MP and MM improved. Finally, the definitive dentures were delivered, achieving satisfactory results. Conclusion NT with TCDs can improve unstable MP and uncoordinated MM, leading to successful rehabilitation in edentulous patient.

Background: We compared photogrammetry-assessed body posture between young adults with and without unilateral posterior crossbite (UPCB). Assessments were controlled by vision, mandibular position and sitting/standing position. In addition, we aimed to determine the relationship between UPCB laterality and the direction of body posture using photogrammetry and a static postural platform. Methods: Adults with natural dentition, with and without UPCB, were enrolled. Static body posture was assessed by photogrammetry based on horizontal acromial alignment and horizontal anterior-superior iliac spine (ASIS) alignment. Frontal photographs were taken with participants asked to open or close their eyes and hold their jaws at rest, at an intercuspal position, and at left or right lateral positions. Distribution of foot pressure was recorded using a static postural platform at different visual input and mandibular positions. General linear models with repeated measures were used to assess the effect of the various within- and between-subject factors. Results: In total, 36 adults (left UPCB = 12; Right UPCB = 6; controls = 18) participated. There were significant differences between the control and UPCB groups in horizontal alignment at the acromion (p = 0.035) and ASIS (p = 0.026) levels when controlled by visual input and mandibular position. No significant differences in horizontal alignment or foot pressure distribution were observed by laterality in the UPCB group. Conclusion: The presence of UPCB affects static body posture, but the side of crossbite is not related to the direction of effect on static body posture.

Background A comprehensive analysis of the occlusal plane (OP) inclination in predicting anteroposterior mandibular position (APMP) changes is still lacking. This study aimed to analyse the relationships between inclinations of different OPs and APMP metrics and explore the feasibility of OP inclination in predicting changes in APMP. Methods Overall, 115 three-dimensional (3D) models were reconstructed using deep learning-based cone-beam computed tomography (CBCT) segmentation, and their accuracy in supporting cusps was compared with that of intraoral scanning models. The anatomical landmarks of seven OPs and three APMP metrics were identified, and their values were measured on the sagittal reference plane. The receiver operating characteristic curves of inclinations of seven OPs in distinguishing different anteroposterior skeletal patterns and correlations between inclinations of these OPs and APMP metrics were calculated and compared. For the OP inclination wit h the highest area under the curve (AUC) values and correlation coefficients, the regression models between this OP inclination and APMP metrics were further calculated. Results The deviations in supporting cusps between deep learning-based and intraoral scanning models were < 0.300 mm. The improved functional OP (IFOP) inclination could distinguish different skeletal classification determinations (AUC Class I VS Class II = 0.693, AUC Class I VS Class II I = 0.763, AUC Class II VS Class II I = 0.899, all P values < 0.01) and the AUC value in skeletal Classes II and III determination was statistically higher than the inclinations of other OPs (all P values < 0.01). Moreover, the IFOP inclination showed statistical correlations with APMP metrics ( r APDI = -0.557, r ANB = 0.543, r AF−BF = 0.731, all P values < 0.001) and had the highest correlation coefficients among all OP inclinations (all P values < 0.05). The regression analysis models of IFOP inclination and APMP metrics were y APDI = -0.917x + 91.144, y ANB = 0.395x + 0.292, and y AF−BF = 0.738x − 2.331. Conclusions Constructing the OP using deep learning-based 3D models from CBCT data is feasible. IFOP inclination could be used in predicting the APMP changes. A steeper IFOP inclination corresponded to a more retrognathic mandibular posture.

Background An oral appliance (OA) can alleviate upper airway obstruction by pulling the mandible forward during sleep. While a large mandibular advancement with an OA decreases the number of apnea and hypopnea events, long‐term use may cause side effects, such as toothache, stiffness, and pain in the temporomandibular joint. Objetives This study aimed to evaluate the effectiveness of different mandibular positions for obstructive sleep apnea (OSA) and determine the optimal therapeutic mandibular position. Methods Thirty‐two patients (17 males and 15 females) with mild to moderate OSA participated in this prospective study. All patients were randomly allocated to receive a 50% mandibular advancement or a 75% mandibular advancement with an OA. The pre‐ and posttreatment apnea‐hypopnea index (AHI), apnea index (AI), and Epworth Sleepiness Scale (ESS) were compared. Treatment effectiveness and treatment success were compared between groups. Results AHI improved significantly in both groups, and AI improved significantly in the group with 50% mandibular advancement. No significant improvements in the ESS were observed in either group. There was no significant difference in treatment effectiveness between groups. In the proportion of females and males whose treatment was effective in the two groups, females were significantly greater than males. Conclusions For patients with mild to moderate OSA, 50% mandibular advancement is recommended as the initial therapeutic mandibular position. It was suggested that gender differences also affect treatment effectiveness.

Background The mandibular opening path movements have different directions according to the craniofacial morphology of the patient but always downward and backward, therefore increasing the collapse of the upper airway. The aim of this work is to determine if there is a relationship between the craniofacial morphology and the mandibular movement to help understand the impact on the mandibular position. Methods 52 students with full permanent dentition aged 19 to 23 years (mean 21.3 SD 1.7; 29 females and 23 males), participated in the study. Each subject had a lateral cephalometric radiograph taken. The opening angle was determined for two levels of vertical openings at 5 and 10 mm. Results The opening angle showed a greater variability between subjects ranging from 63.15 to 77.08 for 5 mm angle and from for 61.65 to 75.72 for the 10 mm angle. Differences of facial phenotypes was evident when comparing the individual dissoccluding angle of the low angle horizontal pattern and high angle vertical pattern. Conclusions The opening angle is related to craniofacial morphology with higher vertical anterior and shorter anteroposterior faces having a more horizontal path of mandibular movement than shorter vertical anterior and longer anteroposterior subjects who have a more vertical path.

Background Oral appliances (OAs) are generally designed to displace the mandible anteriorly and downward, to increase the airway patency. The present study aimed to examine the relationship between genioglossus (GG) muscle activity and mandibular position, considering both anterior and vertical displacements during sleep. Methods Seven healthy male adults aged 29.4 ± 1.99 years were evaluated. Maxillary and mandibular OAs were fabricated from 2-mm-thick resin plates with pressure-welding. The activity of the left GG was recorded using two silver ball electrodes attached to the lingual edge of the mandibular OA. Respiratory status and right masseter muscle activity were measured by an airflow sensor and surface electrodes, respectively. Electroencephalography was used to determine the sleep status. Stage 2 (the second stage of sleep) was defined as the state of sleeping. Four test conditions with different mandibular positions (0 and 50% anterior protrusion) and bite openings (4 mm and 12 mm) were examined. Results GG activity in SL4A (4 mm bite opening, 50% protrusion during sleep) and SL12 (12 mm bite opening, 0% protrusion during sleep) were significantly higher than that in SL4 (4 mm bite opening, 0% protrusion during sleep). Respiratory volume did not significantly differ between all test conditions. Conclusion GG activity is influenced not only by anterior protrusion of the mandible but also by vertical displacement during sleep. Thus, when determining the effectiveness of intraoral appliances in the treatment of obstructive sleep apnea, both protrusion and the size of the mandibular opening should be evaluated and taken into account.

Children with beta thalassemia major have anemia. The cause of anemia is massive erythropoiesis. Massive erythropoiesis attacks the cortex of the bone, resulting in bone abnormalities. Blood transfusions are used to treat anemia. The aim of this study was to evaluate the relationship between duration of transfusion and the anteroposterior position of the maxilla and mandible in beta thalassemia major children aged 12-14years (Javanese study). This type of research is observational with a crosssectional design. The research subjects were children with beta thalassemia major aged 12-14years. The number of research subjects was 40 children. Data on the duration of the transfusion were obtained from data from the Indonesian Thalassemia Foundation in Jakarta. A cephalometric X-ray was taken on the subject, then the SNA, SNB, and ANB angle measurements were taken. The results showed that the mean SNA angle was 86.83±3.75, the SNB angle was 77.11±2.49 and the ANB angle was 9.71±5.73. The regression line equation for the duration of transfusion against the SNA angle is y= 88.43–0.29x, the duration of the transfusion to the SNB angle is y=75.85+0.23x, the duration transfusion time to the ANB angle is y=12.57– 0.521x. The results of the Spearman correlation test showed that there was a significant relationship between the length of the transfusion and the SNA angle (r: -0.356, p: 0.024), SNB (r: 0.382, p: 0.015), ANB (r:-0.411, p:0.008). Conclusions: The longer the transfusion, the closer the anteroposterior position of the maxilla (reduced SNA angle); mandible (increased SNB angle); maxilla and mandible (reduced ANB angle) to the cranium is to normal

Oral appliance (OA) can effectively treat obstructive sleep apnea; however, numerous types of oral appliances and designs are variable and the precise mechanisms behind differences in treatment outcomes are uncertain. The objective of this study was to evaluate the effects of different degrees of mandibular position [4° of bite openings (BO): 2, 4, 8 and 12 mm; and protrusion (P): 0, 50%, MAX], for both the upright and supine positions: BO2 mm_P0%, BO4 mm_P0%, BO4 mm_P50%, BO4 mm_PMAX, BO8 mm_P0%, BO12 mm_P0%; with an OA on the: (1) activity of the genioglossus (GG) muscle by electromyogram, (2) inspiration by airflow sensor, and (3) recording mandibular movements (incisor and mandibular condyle point) in each position. Nine healthy male adults (age 27.5 ± 1.30 years) were recruited. The results show that GG muscle activity increased significantly from BO4 mm_P0% to BO12 mm_P0% during the supine position, and the strongest signal was found in BO4 mm_PMAX, compared to all of the other positions, and GG muscle activity in BO4 mm_P0% tended to be lower. From supine to upright position the inspiration increased significantly but GG muscle activity did not. These results might be a stimulus to augment a compensatory mechanism of GG muscle induced by OA, however, mainly in protrusion position. The increase of BO (2–12 mm) and even maximum protrusion might not negatively affect the temporomandibular joint.

This study aimed at evaluating the mandibular condyle position changes before and after bimaxillary orthognathic surgery in class II and III malocclusion patients. CBCT scans from patients who underwent bimaxillary orthognathic surgery were analyzed: Le Fort I osteotomy and bilateral sagittal split osteotomy (BSSO). Both condyles were independently assessed for their largest anterior and posterior joint spaces, smallest medial joint spaces, and condyle angles concerning the transverse line. In the sagittal plane, the minimum size of the anterior and posterior joint spaces was measured. In the coronal plane, the smallest medial joint space was measured. The position of the condyle within the glenoid fossa was determined before and after surgery. A total of 56 TMJs from 28 patients were studied. Following orthognathic surgery, the anterior and posterior space in class II increased. Postoperatively, the anterior joint space in class III decreased. In 42.85% of malocclusion class II patients and 57.14% of malocclusion class III patients, the pre-and post-surgical position of the condyle changed, the condyle was anteriorly positioned (42.85%) in class II patients and centrically positioned (71.4%) in class III patients. Significant changes in the joint space, condylar position, and condyle angle were found in the class II and class III subjects.