Mandibular Advancement Group Research Articles

DLL4/Notch blockade disrupts mandibular advancement-induced condylar osteogenesis by inhibiting H-type angiogenesis.

Blocking Delta-like 4 (DLL4)/Notch has emerged as a promising therapeutic target for the treatment of tumours by deregulating angiogenesis. However, DLL4/Notch serves as a negative regulator of angiogenesis in multiple organs while acting as a positive regulator of H-type angiogenesis in postnatal long bones. Therefore, the effect of DLL4/Notch signalling blockade on mandibular condylar osteogenesis attracted our attention. To explore the effect of blocking DLL4/Notch on mandibular advancement (MA)-induced condylar osteogenesis. Six-week-old young male C57BL/6J mice (n = 40) were randomly divided into four groups: control group, MA group, MA + Anti-DLL4 group and MA + IgG group. Of note, IgG served as the isotype control for the anti-DLL4. The femurs, tibias and mandibular condyles were collected after sacrificing mice on Day 31 for morphology, micro-computed tomography, immunofluorescence, histology and immunohistochemistry evaluation. First, DLL4/Notch blockade shortened femoral length and reduced bone mass by inhibiting H-type angiogenesis. Second, DLL4/Notch blockade disrupted MA-induced condylar head volume and quality by inhibiting H-type angiogenesis. Mechanistically, blocking DLL4/Notch reduced the number of runt-related transcription factor 2+ (RUNX2+ ) early osteoprogenitors and the expression of Noggin protein in the condylar subchondral bone by inhibiting H-type angiogenesis. In addition, blockade of DLL4/Notch also destroyed the condylar cartilage layer. DLL4/Notch blockade results in shortened femurs and osteopenia, as well as impaired MA-induced condylar osteogenic volume and quality in growing mice by inhibiting H-type angiogenesis. Therefore, when blocking DLL4/Notch is used as a treatment target for diseases, attention should be paid to its impact on the bone mass of mandibular condyle.

Dentoskeletal effects of clear aligner vs twin block-ashort-term study of functional appliances.

The twin block (TB) is one of the most widely used functional appliances for the correction of classII malocclusions. Align Technology (San Jose, CA, USA) developed the Invisalign® mandibular advancement (MA) that replicates the mechanism of action of afunctional appliance. The aim of this study was to compare the changes produced by the TB versus those by MA. The records of 56classII patients treated with the TB (TB group: n = 35) or the MA (MA group: n = 21) were compared to acontrol sample of 15 untreated classII subjects (UC2). The TB and MA groups showed asignificant reduction of the ANB angle, compared to the controls (TB group: -1.5°; MA group: -1.5°; UC2 group: +0.2°). For the Co-Gn values, the TB and MA groups showed significant differences when compared with the UC2 group with an increase of 8.4 mm in TB patients and of 8.3 mm in MA patients. The increase of the distance of Pg to the true vertical line (TVL) was the only measurement where significant differences between the three groups were found with agreater advancement of the soft tissue pogonion in the TB group compared with the MA group and the UC2 group (TB group: +3 mm; MA group: +0.9 mm; UC2 group: -1.6 mm). The angle between the palatal plane and mandibular plane revealed amore relevant reduction in the TB and MA groups. Both appliances were able to reduce overjet and vertical overbite values. Treatment with the MA and TB appliances produced asignificant elongation of the mandible with an improvement in sagittal relationship, overjet, and vertical overbite and with good control of the vertical relationship. TB subjects showed agreater advancement of the soft tissue chin.

Do simultaneous mandibular advancement and temporomandibular joint prosthesis impact the upper airway in TMJ ankylosis patients?

BackgroundAnkylosis of the temporomandibular joint (TMJ) is a pathological disorder which results in patients’ limited or even complete failure of mouth opening. When TMJ ankylosis occurs during the growing age, moderate to severe micrognathia might be the proposed scenario of such cases, accompanied by obstructive sleep apnea and hypopnea syndrome (OSAHS). TMJ reconstruction using total TMJ prostheses with mandibular advancement (MA) can simultaneously improve the function and aesthetic profile of such patients. The purpose of this study was to determine whether the upper airway can be improved after TMJ reconstruction with total TMJ prostheses combined with or without MA in TMJ ankylosis patients.MethodsFourteen patients with pre-(T1) and post-(T2) operative CT scans were included. Patients were divided into two groups according to the operation with or without MA (MA/WoMA). The changes of the upper airway and jaw bones were comparatively analyzed within and between the two groups.ResultsIn MA Group, the volume of the total upper airway (Vt) and palatopharynx (V1), together with the surface area (SA) of the total upper airway (SAt) and palatopharynx (SA1) increased significantly after the operation by 41.4%, 43.2%, 36.3% and 36.6%, respectively. In WoMA Group, V1, SAt and SA1 increased significantly by 21.0%, 19.0% and 23.1% following surgery. The changes of Point B (P<0.01), Y-axis angle (P<0.01), SNB (P<0.01), and ANB (P<0.01) were significantly greater in MA Group than in WoMA Group. Comparing both groups, the maxilla, and mandible were more backward in MA Group than in WoMA group before the operation, but there was no significant difference of the final position of the maxilla and mandible after the operation between both groups.ConclusionsRelease of TMJ ankylosis and condylar reconstruction using total joint prostheses simultaneously with MA could significantly improve the total volume and other various parameters of the upper airway, while, only the dimension of the palatopharynx increased in cases without MA.

Mandibular advancement appliances for the treatment of obstructive sleep apnea in children: a systematic review and meta-analysis

The objective of this review was to evaluate the effect of mandibular advancement appliances (MAAs) for obstructive sleep apnea (OSA) in children. To this end, several electronic databases (PubMed, EMBASE, Cochrane Library) were systematically searched until 18 June 2018. Randomized and non-randomized clinical trials were included. Articles of high-quality were included for the meta-analysis. Data extraction and quality assessment were conducted by two independent reviewers. Four randomized controlled trials (RCTs) and three non-RCTs were finally included in the review; of these, two RCTs of high-quality were included in the meta-analysis. The mean difference in apnea–hypopnea index (AHI) change for mandibular advancement group compared with control group was −1.75 events/h (95% confidence interval (CI) −2.07, −1.44), p < 0.00001. Sensitivity analysis including the quasi-randomized RCT and non-RCTs showed stable favorable results for MAAs.The meta-analysis showed supportive evidence for MAA treatment in pediatric OSA patients. Subgroup analysis suggested that MAA can be effective for mild to severe patients before the end of the pubertal peak. Long-term treatment (at least six months) may be more effective than short-term treatment.

Pharyngeal Airway Space and Hyoid Bone Positioning After Different Orthognathic Surgeries in Skeletal Class II Patients

To obtain good profiles, patients with severe skeletal Class II malocclusion require orthognathic surgery, which might change their airway space and, hence, influence their quality of sleep. The present study aimed to 1) determine the effect of different orthognathic surgeries on pharyngeal airway space and hyoid bone position in patients with skeletal Class II malocclusion and 2) evaluate the stability of changes in the pharyngeal airway space and hyoid bone position after orthognathic surgeries. Patients with severe skeletal Class II malocclusion who underwent mandibular advancement (MA) or mandibular advancement and maxillary setback (MAMS) were included in this retrospective cohort study. Changes in the pharyngeal airway space and hyoid bone position were evaluated as the primary outcome variables. Measurements were obtained before surgery (T1), 1month after surgery (T2), and 2years after surgery (T3) using Dolphin Imaging Software 11.0. Differences in measurements between T2 and T1 and between T3 and T1 were calculated and imported into SPSS 22.0 for data analysis. Fifty patients were included (25 in MA group and 25 in MAMS group). Oropharyngeal and hypopharyngeal airway cross-dimensions and areas were significantly increased in the MA group (P<.05) and the increases were stable at T3. In the MAMS group, the nasopharyngeal airway cross-dimension and area were decreased (P>.05), but the hypopharyngeal cross-dimension and area were significantly increased (P<.05). The hyoid bone moved superiorly and forward after surgery in the MA group (P<.05), and the movement was stable at T3. MA can widen the oropharyngeal and hypopharyngeal airway space, and maxillary setback can narrow the nasopharyngeal airway space. Some relapse related to the width of the oropharynx and hypopharynx was found at the long-term observation. The hyoid bone moved superiorly and forward in the MA group.

Upper airway changes following single-step or stepwise advancement using the Functional Mandibular Advancer.

Purpose of the present study was to determine and compare possible changes in the dimensions of the pharyngeal airway, morphology of the soft palate, and position of the tongue and hyoid bone after single-step or stepwise mandibular advancement using the Functional Mandibular Advancer (FMA). The sample included 51 peak-pubertal Class II subjects. In all, 34patients were allocated to two groups using matched randomization: a single-step mandibular advancement group (SSG) and a stepwise mandibular advancement group (SWG). Both groups were treated with FMA followed by fixed appliance therapy; the remaining 17 subjects who underwent only fixed appliance therapy constituted the control group (CG). The study was conducted using pre- and posttreatment lateral cephalometric radiographs. Data were analyzed by paired t test, one-way analysis of variance, and Pearson's correlation coefficient. In the SWG and SSG, although increases in nasopharyngeal airway dimensions were not significant compared with those in the CG, enlargements in the oropharyngeal airway dimensions at the level of the soft palate tip and behind the tongue, and decreases in soft palate angulation, were significant. Tongue height increased significantly only in the SWG. Compared with the CG, while forward movement of the hyoid was more prominent in SSG and SWG, the change in the vertical movement of the hyoid was not significant. No significant difference between SWG and SSG was observed in pharyngeal airway, soft palate, tongue or hyoid measurements. The mode of mandibular advancement in FMA treatment did not significantly affect changes in the pharyngeal airway, soft palate, tongue, and hyoid bone.

Comparison of stepwise vs single-step advancement with the Functional Mandibular Advancer in Class II division 1 treatment

To compare two groups of subjects at the peak of the pubertal growth period treated with the Functional Mandibular Advancer (FMA; Forestadent, Pforzheim, Germany) appliance using either single-step or stepwise mandibular advancement. This study was conducted on 34 Class II division 1 malocclusion subjects at or just before the peak phase of pubertal growth as assessed by hand-wrist radiographs. Subjects were assigned to two groups of mandibular advancement, using matched randomization. Both groups were treated with the FMA. While the mandible was advanced to a super Class I molar relation in the single-step advancement group (SSG), patients in the stepwise mandibular advancement group (SWG) had a 4-mm initial bite advancement and subsequent 2-mm advancements at bimonthly intervals. The material consisted of lateral cephalograms taken before treatment and after 10 months of FMA treatment. Data were analyzed by means paired t-tests and an independent t-test. There were statistically significant changes in SNB, Pg horizontal, ANB, Co-Gn, and Co-Go measurements in both groups (P < .001); these changes were greater in the SWG with the exception of Co-Go (P < .05). While significant differences were found in U1-SN, IMPA, L6 horizontal, overjet, and overbite appraisals in each group (P < .001), these changes were comparable (P > .05). Because of the higher rates of sagittal mandibular skeletal changes, FMA using stepwise advancement of the mandible might be the appliance of choice for treating Class II division 1 malocclusions.

Computerized cephalometric evaluation of orthognathic surgical precision and stability in relation to maxillary superior repositioning combined with mandibular advancement or setback

Purpose A computerized, cephalometric, orthognathic surgical program (TIOPS) was applied in orthognathic surgical simulation, treatment planning, and postoperatively to assess precision and stability of bimaxillary orthognathic surgery. Patients and Methods Forty consecutive patients with dentofacial deformities requiring bimaxillary orthognathic surgery with maxillary superior repositioning combined with mandibular advancement or setback were included. All patients were managed with rigid internal fixation (RIF) of the maxilla and mandible and without maxillomandibular fixation (MMF). Preoperative cephalograms were analyzed and treatment plans produced by computerized surgical simulation. Planned, 5-week postoperative and 1-year postoperative maxillary and mandibular cephalometric positions were compared. Results In the mandibular advancement group, the anterior maxilla was placed too far superiorly, with an inaccuracy of 0.4 mm. The posterior maxilla and the anterior mandible were placed in the planned positions. The lower posterior part of the mandibular ramus was placed too far anteriorly, with an inaccuracy of 2.0 mm. However, the mandibular condyles were accurately placed. In the setback group, the anterior maxilla was placed too far superiorly and posteriorly, with a vertical and sagittal inaccuracy of 1.0 mm and 0.7 mm, respectively. The posterior part of the maxilla was placed in a posterior position with an inaccuracy of 1.9 mm. The anterior mandible was placed too far anteriorly with an inaccuracy of 0.9 mm. The lower posterior part of the mandibular ramus was placed in a posterior position with an inaccuracy of 0.9 mm. However, the mandibular condyles were accurately placed. The statistical analysis of the 1-year stability data showed that the maxilla had moved 0.3 mm posteriorly in the advancement group and the lower incisors had moved 0.8 mm superiorly. No other significant positional maxillary or mandibular changes were found. In the setback group, the maxilla had moved 0.5 mm posteriorly, the anterior mandible 0.5 mm anteriorly, and the lower incisors 0.7 mm superiorly. No significant positional changes were seen in the mandibular ramus. Conclusion The TIOPS computerized, cephalometric, orthognathic program is useful in orthognathic surgical simulation, planning, and prediction, and in postoperative evaluation of surgical precision and stability. The simulated treatment plan can be transferred to model surgery and finally to the orthognathic surgical procedures. The results show that this technique yields acceptable postoperative precision and stability.

Short-term consequences of orthognathic surgery on stomatognathic function

Craniomandibular dysfunction, mandibular range of motion and occlusal contacts subsequent to surgical-orthodontic treatment were studied in 20 adults with Le Fort I impaction and/or advancement, 34 with vertical ramus setback, 12 with sagittal split advancement and 16 with Le Fort I impaction, and/or advancement and bilateral vertical ramus setback. All subjects were examined 1 week before surgery and 6 months post-operatively. The results of the study indicated that 6 months post-operatively: (a) There was a decrease (NS) in dysfunction patients in the maxillary and double-jaw osteotomy groups, and an increase in the mandibular advancement osteotomy sample (P < 0.05). (b) There was a significant decrease in maximal interincisal opening in both mandibular osteotomy groups (P < 0.01) and in laterotrusive movements in the mandibular advancement group (P < 0.05). (c) The number and intensity of occlusal contacts increased significantly in the maxillary and mandibular setback osteotomy groups (P < 0.01 and P < 0.001, respectively).

The effect of orthognathic surgery on head posture

Changes in resting head and neck posture were studied in 201 patients following five different orthognathic surgery procedures: (1) LeFort I osteotomy for superior repositioning (intrusion) of the maxilla (n = 45); (2) bilateral sagittal split ramus osteotomy for mandibular advancement (n = 78); (3) mandibular setback (n = 19); (4) combined maxillary intrusion and mandibular advancement (n = 46); (5) combined maxillary intrusion and mandibular setback (n = 13). Head and neck posture were measured on standardized serial cephalograms taken in natural head position prior to, immediately after, and 1 year after surgery for each subject. Immediately after surgery, there was flexion of the head as measured by the craniovertical and craniocervical angles in all of the groups except the mandibular setback group, which showed little change. By 1 year post-surgery, the mean craniovertical and craniocervical angles were approximately the same as before surgery in the groups with one-jaw surgery. Statistically significant head flexion at 1 year (P less than 0.05) was observed in the combined maxillary intrusion and mandibular advancement group, and with maxillary intrusion plus mandibular setback, there was a trend toward persistent flexion. Neck posture showed no significant short- or long-term changes in any of the surgical groups.