Midline Of Mandible Research Articles

Condylar Resorption Following Compressive Mechanical Stress in Rabbit Model - Association of Matrix Metalloproteinases.

Idiopathic condylar resorption (ICR) is a morphological change of the condylar head that occurs following orthodontic treatment or orthognathic surgery. This complication is serious, as it can cause relapse after mandible treatment. The aim of this experimental study was to evaluate the mechanism of influence of condylar resorption on compressive mechanical stress in temporomandibular joint following a change in occlusal position by mandible advancement. An osteotomy procedure at the midline of mandible was performed in 15 rabbits, with the left side moved forward by 3.5 mm. Advancement of the left side of the mandible resulted in compressive mechanical stress on condylar head on the left side. Samples were subjected to micro-computed tomography, histological staining and immunohistochemistry. The area and depth of anterior condylar resorption at two weeks were significantly different as compared to those at one week (p<0.05). TRAP staining confirmed the significantly largest number of TRAP-positive cells after two weeks (p=0.02), compared to one week. MMP-3 and MMP-13 immunostaining of the anterior condylar head at two weeks revealed high levels of both proteins from the surface to the deep layer of cartilage. Compressive mechanical stress following mandible advancement results in load on the anterior surface of the condylar head, which leads to bone resorption there, and induces MMP-3 and MMP-13 related to degradation of condylar head cartilage.

Median Lingual Foramen, a new midmandibular cephalometric landmark.

PurposeIn asymmetrical mandibles, it is often challenging to identify the mandibular midline. The median lingual foramen (MLF) is located at the midline of the anterior mandible. The purpose of this study is to evaluate the reproducibility of identifying the MLF compared to conventional landmarks on cone beam computed tomography's (CBCT's) to mark the mandibular midline.Material and MethodsTen symmetrical class II, 10 symmetrical class III, ten asymmetrical class II and 10 asymmetrical class III patients were included. On CBCTs, the cephalometric landmarks menton, pogonion, genial tubercle and MLF were identified twice by two observers.ResultsA high intra‐ and interobserver reproducibility was found for all landmarks, the highest being the MLF. The gain in accuracy is 0.998 mm, 0.824 mm and 0.361 mm compared to pogonion, genial tubercle and menton, respectively (P‐value <.05).ConclusionMLF is a reliable and reproducible landmark to indicate the midline of the mandible, particularly in Class II asymmetric mandibles.

Single mandibular implant study - denture satisfaction in the elderly.

To investigate whether there are differences in patients' denture satisfaction when an implant placed in the midline of the edentulous mandible is loaded either immediately or three months later, after second-stage surgery. One hundred and fifty-eight edentulous patients received a single implant in the midline of the mandible. After randomisation, it was loaded either immediately after implant placement (N = 81, group A) or three months later, after a submerged healing phase and a second-stage surgery (N = 77, group B). Patients' denture satisfaction aspects were assessed, using visual analogue scales (VAS), before treatment, one month after implant placement during the submerged healing phase (only group B) and one and four months after implant loading. The statistical analysis was performed using the Wilcoxon signed-rank and rank-sum tests. One month after loading, a significant improvement in comfort, function and stability of the mandibular denture could be observed in both groups (P ≤ 0·05). A slight but not significant improvement was found between one and four months after loading. Patients with second-stage surgery and delayed loading rated the stability and fit of the mandibular denture as significantly better than patients who had immediate loading. A single implant in the edentulous mandible significantly increased patients' denture satisfaction. After four months, stability and fit of the mandibular denture were considered better when a delayed loading protocol had been followed. A single mandibular implant in the edentulous mandible significantly increases patients' denture satisfaction, regardless of the loading protocol.

Customized Titanium Plate Virtual Design and Deformation Simulation Analysis of Human Lateral Mandible Defect

Aiming to improve the defect mandible reconstruction operation success rate, the original mandible and fibular 3D model were modeling separately. According to the patient’s virtual reconstruction mandible 3D model, the mandible customized virtual ti-plate was designed and modeling. Through comparing the deformation simulation analysis of reconstructive mandible, the maximum deformation occurred near the mandible midline. There was little deformation at bilateral mandible ramus posterior. As the loading on the reconstructive mandible increasing, the maximum deformation near the mandible midline was increasing. According to the customized titanium plate virtual design and deformation simulation analysis of human lateral mandible defect before operation, the simulation could predict the mandible maximum deformation position after the surgery. The doctors could improve the operation precision of mandible reconstruction and probability of success significantly.

Three-year clinical outcome of single implant-retained mandibular overdentures—Results of preliminary prospective study

Objectives The aim of this preliminary prospective study was to evaluate the clinical outcome, the oral health-related quality of life (OHRQoL), and the subjective chewing ability of patients with mandibular complete dentures retained by a single implant placed in the mandible midline. Methods Patients wearing complete dentures were treated with a single implant in the mandible, followed by relining of the dentures and incorporation of ball attachments for implant retention. Implant outcome, prosthodontic maintenance, subjective chewing ability, and the oral health impact profile of the patients were assessed at baseline and at four weeks after connecting the denture and implant. Results Eleven patients were enrolled in this investigation, and the mean observation period was 43.4 months (minimum period: 35, maximum period: 52 months). No implants were lost during observation period, but four dentures needed repair because of the fracture of the denture base in the midline area. A significant improvement was observed in the OHRQoL of the patients after the attachment of the mandibular dentures with a single midline implant. Furthermore, the subjective chewing ability of the patients was significantly improved after implant connection. Conclusions Within the limitations of this preliminary prospective clinical study, single implant-supported mandibular overdentures were a successful treatment option for older edentulous patients who showed improvements in their OHRQoL and chewing ability.

유한요소법을 이용한 응력 및 변형 분포의 분석 - 하악골의 이모장치효과 -

두개안면부에서 하악은 태생 4주에 발생하는 첫번째 아가미궁에서 분화되며 맥켈연골이라 알려져 있는 긴 막대기 모양의 연골의 외측부에서 골화가 시작된다. 이후 하악골은 골의 첨가와 흡수에 의해 성장 발육하게 된다. 이런 하악골의 성장 발육이 과하거나 부족한 경우 상하악골의 부조화에 의한 부정교합이 발생되게 되고, 이를 3급 또는 2급 부정교합이라 부른다. 3급 부정교합의 치료를 위해 지금까지 많은 방법들이 사용되어 왔으며, 그중 가장 널리 사용되어지는것이 이모장치이다. Distraction osteogenesis는 강한 힘이나 수술에 의해 분리된 두 개의 골표면 사이에서 새로운 신생골이 형성되는 일련의 생물학적인 과정을 말한다. Distraction force가 callus tissue에 작용되어 골이 분리되면 골과 연조직에 가해지는 신장력이 새로운 골 생성을 자극하게 된다. 이번 연구의 목적은 3차원 유한요소 model을 이용하여 이모장치의 하중에 대한 하악골의 응력분포를 알아보고, 하악골 절개 (mandibular midline distraction) 후 강제변형에 대한 응력분포를 알아보는 것이다. The aims of this study were analyze the amount of stress condition when the traction force was applied to the condyle head from the chin area of mandible and amount of distortion condition when intended 0.5 mm distraction distance from surface or one point of dissected midline of mandible. For this study, 3D finite element analysis were performed. The following results were obtained : 1. When traction force of 500 g was applied to the condyle head from the chin area, condylar neck area showed the greatest amount of stress and coronoid process was the least amount of stress area. For the amount of distortion condition, infra dental area showed the greatest. 2. When 0.5 mm of intended surface distortion was applied after dissection of mid-mandible area, base anterior area showed the greatest amount of stress but the least stress area was coronoid process. For the amount of distortion, infra dental, menton area showed the greatest amount. 3. One point distortion was applied after dissection of mid-mandible area, ramus posterior area showed the greatest amount of stress and menton area were the least stress condition. For the amount of distortion, menton area showed the greatest amount of distortion condition.

Malocclusion as a Common Occurrence in Temporomandibular Joint Arthroscopic Disc Repositioning: Outcomes at 49 Days After Surgery

To evaluate the incidence, clinical manifestation, and prognosis of malocclusion after arthroscopic disc repositioning and suturing of the temporomandibular joint (TMJ). The study included 211 patients (270 joints) with internal derangement of the TMJ who underwent arthroscopic disc repositioning and suturing from November 2005 to August 2006. The occlusion was checked and recorded preoperatively and at different intervals (0, 3, 7, 14, 21, 28, 35, 42, and 49 days after surgery) for all patients. The incidence of malocclusion after surgery was determined for every follow-up period. The χ(2) test was applied to assess the statistical significance of the changes of the incidence of malocclusion. The incidences of malocclusion were 100%, 80.1%, 67.8%, 46.9%, 28.9%, 18.0%, 15.7%, 14.6%, and 14.2% at 0, 3, 7, 14, 21, 28, 35, 42, and 49 days after surgery, respectively. There was a significant difference between neighboring follow-up periods within 28 days after surgery, whereas there was no significant difference from 28 to 49 days after surgery (P > .05). The main clinical manifestations of malocclusion were posterior open bite on the surgery side, incisal prematurities, and mandible midline deviated or nondeviated. Malocclusion commonly occurs after TMJ arthroscopic disc repositioning and suturing. However, it will improve within 28 days after surgery in most patients. If malocclusion lasts over 28 days, appropriate treatments should be considered.

上顎骨延長法と下顎正中分割を併用した下顎枝垂直骨切り術により治療を行った重度の骨格性ＩＩＩ級の１例

In this report, we describe the case of a 22-year-old male with severe skeletal Class III who was treated with distraction osteogenesis of the maxilla and intraoral vertical ramus osteotomy (IVRO). The severe skeletal Class III was accompanied by hypoplasia of the maxilla and overgrowth of the mandible (overjet, -20.0 mm; overbite, 1.0 mm). A high Le Fort I osteotomy was carried out, and the maxilla was distracted using the rigid external distraction II (RED II) system. After the active distraction and consolidation period, rigid fixation of the maxilla and IVRO were carried out; splitting of the mandible midline was added to the procedure to achieve a narrow mandibular arch width. After 6 months of postoperative orthodontic treatment, the occlusion and masticatory function of the patient had improved, and he was satisfied with the outcome of the treatment.

Transmigration of impacted mandibular canine to opposite side

A boy visited a local dentist for the treatment of other teeth at the age of 12 years, and the same dentist at the age of 17 years and 6 months. Comparison of panoramic X-rays taken at the age of 17 years and 12 years revealed that the impacted left mandibular canine had transmigrated to the right side, and so the patient was referred to our department for a more detailed examination. The panoramic X-ray obtained at the age of 12 years showed that the left mandibular canine was horizontally impacted almost in the center of the mandibular bone, with its tooth crown oriented toward the right. The panoramic X-ray taken at the age of 17 years and 6 months showed that the apex of the impacted left mandibular canine had horizontally migrated to the tooth root apical area of the right mandibular first molar. Transmigration of the mandibular canine across the mandible midline is an uncommon phenomenon. When delayed eruption of primary teeth occurs, it is necessary to confirm the position of permanent tooth germs using panoramic X-rays.

The Appearance of Foramen in the Internal Aspect of the Mental Region of Mandible from Japanese Cadavers and Dry Skulls Under Macroscopic Observation and Three-dimensional CT Images

The lingual canal with foramen displays different appearances on the internal surfaces of mandible as confirmed by macroscopic observation and computerized tomography (CT). The lingual canal was observed in the inside of mental region run to the outside of lingual foramen, which is extend internally from mandibular canal in right and left sides of the mandible in cadavers (13 sides out of 88 sides) and in dry skulls (43 out of 94 sides) examined. The spinal foramen connected with mental canal occurred at the midline of mandible in 6 cases (6 out of 47 cases) in dry skulls. In this small foramen, the inferior alveolar artery give some branches to the inside of mental region at the anterior mandible and which may be run pass through the lingual canal to the lingual foramen, where they emerge to enter the mylohyoid or anterior belly of digastric muscles. The observations of these are important considerations for surgical placement of dental implants in the region in the mandible.