Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “MANDIBLE”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 811 records · Page 45Linked to original sources
PubMed2004

The three-dimensional microstructure of the trabecular bone in the mandible.

This study investigated the three dimensional (3D) trabecular microstructure of the alveolar and basal bone in the mandible using micro-CT and compared the morphometric values of the different sites. Ten specimens were prepared and scanned using a micro-CT system. Both the alveolar and basal trabecular bone of the premolar region in the mandible were measured for the structural analysis. Cross-sectional 1024x1024 pixel images were created. From the two-dimensional (2D) images produced, 3D structural images were reconstructed. After scanning the specimen, the volumes of interest (VOI) of the alveolar and basal bone regions were selected from the 3D reconstruction images, and the structural parameters such as bone volume fraction, bone surface density, trabecular thickness, trabecular separation, trabecular number and structural model index were analyzed. The trabecular structure showed a marked variation within the sites of the specimen, especially in the basal trabecular bone inferior to the mandibular canal. In both the alveolar and basal bone regions, a mixture of both plate-like and rod-like structures was observed. The alveolar region showed a more compact, plate-type trabecular structure than the basal regions. In parametric comparison with the basal bone, the alveolar bone generally had a higher bone volume fraction, bone trabecular thickness and trabecular number, and lower bone surface density, trabecular separation and structural model index. The alveolar bone consisted of a compact bone structure with a large amount of thick plate-type trabecular bone, which was effectively resistant to the masticatory forces. As the measurements were made closer to the basal bone, a loose structure was observed with lower bone volume and fewer, thin, rod-like trabeculae.

Adult↗
PubMed1998

Molecular evidence for the gnathobasic derivation of arthropod mandibles and for the appendicular origin of the labrum and other structures.

Mandibles are feeding appendages functioning as "jaws" in the arthropod groups in which they occur. Which part of this appendage is involved in food manipulation (limb tip versus limb base), has been used to suggest phylogenetic relationships among some of the major taxa of arthropods (myriapods, crustaceans, and insects). As a way to independently verify the conclusions drawn from previous morphological analyses, we have studied the expression pattern of the gene Distal-less (Dll), which specifies the distal part of appendages. Our results show, in contrast to the traditional view, that both insect and crustacean adult mandibles are gnathobasic, handling food with the basal portion of the appendage. Furthermore, as is evident by the reduction in the number of Dll-expressing cells in the later developmental stages, adult diplopod jaws are also gnathobasic. Thus, jaws of all mandibulates (myriapods, crustaceans, and insects) seem to have a similar gnathobasic structure. We have also found that Dll is expressed in the labra of all arthropod taxa examined, suggesting that this structure is of appendicular derivation. Additionally, the spinnerets and book lungs of spiders, long considered on other grounds to be modified appendages, express Dll, confirming this interpretation. This study shows that, in addition to their use in phylogenetic and population genetic studies, molecular markers can be very useful for inferring the origins of a particular morphological feature.

Animals↗
PubMed2005

Deletion of the endothelin-A receptor gene within the developing mandible.

Signaling from the endothelin-A (Ednra) receptor is responsible for initiating multiple signaling pathways within neural crest cells (NCCs). Loss of this initiation is presumably the basis for the craniofacial defects observed in Ednra-/- embryos. However, it is not known whether continued Ednra signaling in NCC derivatives is required for subsequent development of the lower jaw. To address this question, mice containing loxP recombination sequences flanking a portion of the Ednra gene were bred with transgenic mice that express Cre recombinase under control of a Dlx5/6 enhancer element. We find that while Ednra gene inactivation within the mandibular arch of these Ednra conditional knockout embryos is detectable by embryonic day (E) 10.5, mandibular arch-specific gene expression is normal, as is overall mandible development. These results suggest that while Ednra receptor signaling is crucial for early NCC patterning, subsequent Ednra signaling is not essential for mandible bone development.

Animals↗
PubMed2006

Neurosensory disturbances after immediate loading of implants in the anterior mandible: an initial questionnaire approach followed by a psychophysical assessment.

The aim of the study was to assess past and present neurosensory disturbances using a questionnaire and a psychophysical approach in patients treated with immediate loaded implants in the edentulous anterior mandible. A group of 65 patients (age range 30-84 years, mean 58 years, 30 women) was enrolled. All were treated by means of three immediately loaded implants (Branemark Novum System). A self-designed questionnaire was used for data collection. The response rate was 89%. Of the 58 responders, 33% (n=19) reported neurosensory disturbances after implant surgery. Nine of these patients (mean age 56 years, seven women) participated in an objective evaluation and were subjected to a psychological and several psychophysical tests. At the moment of the evaluation none of the nine patients still had clinical complaints. Psychological testing revealed no statistical differences between the patients, who had previously experienced subjective complaints, and the control group. Two-point discrimination and thermal sensation tests revealed no sensory lesions. The light touch sensation test at the lower lip indicated a more frequent reduction of tactility for the test group (p<or=0.03). Neurosensory disturbances can occur in the anterior region of the mandible after implant surgery.

Adult↗
PubMed2002

[Life threatening oral hemorrhage after implantation into the distal right mandible].

In dental practice, surgical implant procedures are frequently conducted for pre-prosthetic surgery. Intra-operative complications are rare and can mostly be prevented effectively with adequate preparatory measures. However, not all risks can be anticipated a priori. Anatomical variation, such as variation in the path of blood vessels, is often unpredictable. This paper describes a life-threatening hemorrhage that occurred in a 60-year-old male during the insertion of an implant in the distal right mandible. It was impossible to stop the bleeding using local measures. Only extraoral ligation of the facial artery proved effective in suppressing the hemorrhage. The submentalis artery, a branch of the facial artery, had an atypical path directly below the caudal ridge of the mandible. The possibility of similar complications should make us re-evaluate preoperative preventive measures, and places greater demands on intra-operative complication prophylaxis. The international literature on this topic is discussed.

Arteries↗
PubMed2003

[Experimental and clinical study of the stability of an osteosynthesis plate for the atrophic mandible].

BACKGROUND: The high rate of complications led us to develop a new osteosynthesis plate for the treatment of the fractured atrophied mandible. The development of the new so-called pencil-bone plate is based on the 2.0 mini-plate system manufactured by the Medartis Company. MATERIAL AND METHODS: Finite elements (FE) analysis of the new plate as well as flexibility experiments were undertaken, and 14 patients with 16 fractures of the atrophied mandible were treated with the pencil-bone plate between October 2000 and November 2001. RESULTS: The results clearly show that the pencil-bone plate reacted in both the FE model and the static flexibility experiment in a more stable way than a standard 2.0 plate. In 13 patients, healing proceeded without serious complications; all of the patients showed subjective, nearly unchanged chewing, speaking, and swallowing abilities and no complications occurred when wearing dentures. One patient underwent surgical intervention after a new trauma. CONCLUSION: The clinical outcome of the treated fractures confirmed the experimental results, which proved the high stability of the plate in the area of the fracture site. Due to the mini-plate format the intraoral application of the plate is possible without problems. The intraoral access allows rapid operation followed by a minimum of morbidity. A great advantage of the small dimension system is the unrestricted wearing of dentures after the application.

Aged↗
PubMed2005

[Glandular odontogenic cyst of the mandible. Case report].

BACKGROUND: Glandular odontogenic cyst (GOC) is a rare lesion of both, the maxilla and mandible, leading to extensive osteolysis. Histologically, it shows thin layers of squamous and cylindrical cells, lined with mucinous metaplasia. This makes it difficult to differentiate from a mucoepidermoid carcinoma. The recurrence rate is high. CASE REPORT: During a routine X-ray examination we saw massive osteolysis of the whole mandible in a 30-year-old female. All teeth were vital. The biopsy taken showed a benign cyst although the clinical aspect was similar to an ameloblastoma. The cyst was removed after intravital fixation with Carnoy's solution. The bony cavity was left without filling material. Uneventful bony healing occurred. DISCUSSION: Due to rare occurrence and similarity to botryoid odontogenic cyst and low-grade mucoepidermoid carcinoma GOC is difficult to identify. It remains without clinical signs for years and is identified in routine X-rays in most cases. We recommend cystectomy after use of Carnoy's solution for intravital fixation. No filling material is required for complete bony healing.

Adult↗
PubMed2000

[Monstrous benign schwannoma of the mandible. Clinical aspects, morphology and therapy].

BACKGROUND: Schwannomas are rare benign neurogenic tumors that arise from Schwann cells of the peripheral nervous system. The most frequent localisation is the head and neck area. Extracranial schwannomas are most often located in the deep soft tissues. Intraosseous tumor types are rare; the mandible is the most common site. CASE REPORT: We present the case of a 63-year-old woman with a schwannoma which originated from the mandible nerve and describe the therapy of this neoplasm. A rare malignant transformation cannot be excluded. Therefore, the treatment of choice is radical local resection.

Aged↗
PubMed2001

[Stress analysis of the human mandible in standard trauma situations with numerical simulation].

For the stress analysis of the human mandible a flexible simulation concept basing on finite element-method has been developed. One of the main issues is the prediction of fractures as a consequence of known forces as well as the forensic reconstruction of the traumatologic situation. At first, the individual geometry was reconstructed by 3D-CT-Scans. To reduce the simulation efforts, for the time being the anisotropic structural mechanics of the jaw bone was neglected in favour of an homogeneous and isotropic material law. Assuming the Von-Mises-Stress as a failure indicator the results of the simulations were in good agreement with typical traumatologic situations. For further validation of the model, a real failure case, shown on a radiograph of a injured human mandible with three fractures, was simulated and, by this, the real incident was reconstructed. Reasonable planned extensions of the actual simulation concept have the regard on the nerve channel, the temporomandibular joint's function, the paradontal apparatus and the individual mechanical properties of the bone.

Biomechanical Phenomena↗
PubMed2001

[Cortical thickness of the mandible with special reference to miniplate osteosynthesis. Morphometric analysis of autopsy material].

Thirty-two human mandibles were marked with three typical fracture lines: a low condylar fracture, a fracture of the mandibular angle, and one through the mental foramen on each side. The mandibles were sectioned at the fixation sites of the miniplate screws. The thickness of the cortical layer was measured with a scaled magnifying glass at the points of anthropological interest and at the marked screw holes. The inferior cortical layer turned out to be thickest in the anterior area. In contrast, it was very thin at the mandibular angle, which might explain the higher complication rate in treating fractures in this region. The thickness of the lingual cortex increased up to the symphysis, whereas the buccal cortical layer showed a decline in size from the mandibular angle up to the chin. The cortical bone at the alveolar ridge was porous. The cortical supply for miniplate osteosynthesis at the condylus ranged from 1.1 mm up to 1.74 mm, which seems to be limited, but due to the small diameter of the condylus most common screws obtain additional anchorage in the inner cortex. The thickness of the cortical layer at the mandibular angle increased from 1.47 mm at the ramus up to 1.97 mm at the beginning of the corpus, reaching 2.14-2.38 mm for the lower plate at the mental foramen. The results for the upper plate were slightly lower.

Bone Plates↗
PubMed2003

A modified method of immediate loading using Brånemark implants in edentulous mandibles.

According to the original protocol, Brånemark implants require a two-step surgical procedure in order to become osseointegrated. The two-stage surgery is sometimes uncomfortable for the patient, and recent research has shown that osseointegration can also be achieved with a one-stage technique with early or immediate loading of the implants in good quality bone, which simplifies and shortens treatment for the patient's benefit. The aim of this study was to evaluate the immediate loading of Brånemark implants with a screw-retained prosthesis in edentulous mandibles. Forty-three patients each had three Brånemark implants of varying lengths and diameters installed in the inter-foramina mandibular area. The implant installation procedures were performed according to the standard protocol with avoidance of over-preparation of the implant sites. The prosthesis framework was prefabricated in advance and was cast and separated into three parts, followed by adjustment in the mouth, with a soldering, impression made in situ; finally, the framework was sent to the laboratory for completion of the bridge. The fixed implant bridge was usually delivered to the patient later the same day. Three of the 129 implants failed to osseointegrate, yielding a success rate of 97.6%, with a follow-up period ranging from 3 to 49 months. The results obtained in this study were encouraging, and thus far this modified method of immediate loading in the anterior edentulous mandible appears to be predictable.

Aged↗
PubMed1976

Orthopedic effect of the extraoral chin cup appliance on the mandible.

An anatomic photoelastic model of a human skull was constructed with the use of individual simulants for teeth, bone, and periodontal ligaments. The following effects of extraoral chin cup traction were observed: 1. Stresses were noted in the area of the pterygoid plates of the sphenoid bone due to the insertion of the simulated external pterygoid muscle. 2. Because of direct contact of the condyle against the posterior surface of the glenoid fossa, forces were seen to be transmitted to this anatomic area. 3. Stress trajectories followed the trabecular pattern of the anatomic configuration of the mandible. 4. Beginning at the apices of the incisor teeth, the stresses emanated through the body, the angle and retromolar triangle of the mandible, radiating in a posterosuperior fashion and concentrating at the neck of the condyle. 5. Selected sectioning of the mandibular model showed evidence of stress concentration at the lingual aspect of the angle and retromolar area as well as at the condylar neck at the level of the external pterygoid muscle insertion. The effects of orthopedic forces produced by an extraoral chin cup in this study are correlated with the histologic and clinical observations during the utilization of this appliance in the treatment of Class III malocclusion.

Facial Bones↗
PubMed1980

Surgical superior repositioning of the maxilla: what to do with the mandible?

During superior repositioning of the maxilla (SRM), the mandible autorotates forward and upward at pogonion, with the condyle as the center of rotation. Thus, in each instance when planning surgical superior repositioning of the maxilla one must decide, on the basis of esthetics and cephalometric prediction criteria, the magnitude of autorotation and the contribution of this rotation toward the desired occlusal and esthetic result. In many instances the maxilla can be moved somewhat posteriorly or anteriorly, and thus simultaneous mandibular surgery is not required to achieve the desired result. In some cases, however, simultaneous mandibular advancement or set-back is required to achieve the desired occlusal and esthetic result. This article discusses the specifics of making the decision regarding what to do with the mandible when superiorly repositioning the maxilla.

Adolescent↗
PubMed1982

Surgical advancement of the retrognathic mandible in growing children.

Orthodontists and surgeons may occasionally decide that there are compelling reasons for correcting a retrognathic mandible surgically before facial growth is completed. The literature implies that there will be no untoward effects. This study on twenty-two growing children demonstrated that there are severe growth disturbances after surgery. The response varied with the amount of surgical correction: Type A cases (those advanced more than 10 mm.) showed either resorption of the condyle, bizarre bony outgrowths in the posterior symphysis, or both. Relapse may continue in these cases for several years. Once condylar resorption occurred, there was no recovery. Type B cases (those advanced less than 9 mm.) had a milder response. Even in Type B cases, however, there was no clinically significant increase in mandibular length subsequent to surgery. There is a one-year recovery period, after which further growth and remodeling of the condyle are directed (if our hypothesis is correct) towards achieving an equilibrium of forces and a return to the preoperative growth pattern. We found that movement of the Y point (intersection of the posterior surface of the symphysis with the inferior border of the mandible) reflected a stable growth pattern prior to surgery and returned to the same pattern, usually within 2 years after surgery.

Adolescent↗
PubMed1985

The effects of chin cup therapy on the mandible: a longitudinal study.

This study was conducted to evaluate the effects of chin cup therapy on the mandible and its dentition in persons with skeletal Class III malocclusion. The patients selected for this study were Japanese females treated with the extraoral chin cup appliance. Both the control and treatment samples were obtained from Japanese Universities where the longitudinal data were gathered. Lateral cephalometric radiographs were taken on the average of every 6 months for the treatment group and every year for the control group. Ten treated patients and seven control patients were studied. The duration of chin cup therapy was variable but averaged 3 years 1 month. The cephalograms were digitized on an electronic screen, and a cephalometric analysis was recorded from a computer program. The rate change values were then compared with those of the control group to yield a comparison of changes in mandibular growth rate, direction, and pattern in the treatment group. Active and posttreatment effects were evaluated. All measurements for the rate of change of absolute mandibular length were reduced by 60% to 68% from the control rate of growth during therapy. The mandible exhibited less downward displacement relative to cranial base during treatment. The mandibular plane angle and the gonial angle closed with growth in the Class III control sample but were variable in the treatment group. The skeletal profile was improved with treatment. This study indicates that the chin cup may be a viable mode of treatment for the preadolescent and adolescent mandibular prognathism patients.

Adolescent↗
PubMed1986

Simultaneous repositioning of the maxilla, mandible, and chin. Treatment planning and analysis of soft tissues.

There is a clinical, biologic, and biomechanical foundation for simultaneous surgical repositioning of the maxilla, mandible, and chin in a significant proportion of adult and adolescent patients. The restoration of normal jaw function, optimal facial esthetics, and long-term stability are the sine qua non of successful orthognathic surgical procedures to simultaneously reposition the jaws. The key to the achievement of these objectives is to carefully and systematically analyze facial esthetics, establish esthetic priorities, and then coordinate and implement them through the use of cephalometric planning and occlusal studies. By meticulous and precise surgical technique, properly programmed, coordinated, and sequenced with efficient presurgical and postsurgical edgewise orthodontic therapy, and systematic postsurgical neuromuscular rehabilitation, the maxilla, mandible, and chin can be simultaneously repositioned with relatively few postoperative complications or sequelae. This article purposes to elucidate on the indications for two-jaw surgery and describe a simplified clinical-cephalometric analysis for orthognathic surgery. Representative case reports are presented and discussed to illustrate the esthetic, orthodontic, and surgical treatment objectives. The basic problems involved in diagnosis and treatment planning of patients who require two-jaw surgery are discussed as well.

Adolescent↗
PubMed1980

Microvascular reconstruction of the mandible.

Five microvascular reconstructions of the mandible were performed in the past 2 years. One dorsalis pedis osteocutaneous flap was used to reconstruct the alveolar ridge and four groin osteocutaneous flaps were used for various defects of the mandible. Free microvascular bone grafts were found useful in previously irradiated fields, in anterior arch reconstruction, and in patients with massive soft tissue and bone loss.

Adult↗