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PubMed2004

Distribution of tenascin-C and -X, and soft X-ray analysis of the mandibular symphysis during mandible formation in the human fetus.

In the development of the human mandible, the process of bone calcification, distribution and expression of tenascin-C and -X in the mental symphyseal region are unknown. The purpose of this study was to determine the distribution of these extracellular matrices in the connective tissue around calcified tissues located on the mental symphyseal region of the human fetus during development through histological and radiographical studies. The radiographic density increased from 16 weeks to 24 weeks gestation in all examined regions; in contrast, the diameter of muscle fiber in the suprahyoid muscles (digastric anterior and geniohyoid muscles) inserted into the inner mental symphyseal region increased from 24 weeks gestation. The extracellular matrices (tenascin) were shown to have a different distribution in the mental symphyseal region of the human fetus at each stage. These different distributions of tenascin-C and -X were found around the epithelium and the endomysium of the mental symphyseal region, and affect the specific formation of the mandible during ossification with hyoid muscle development in human fetus.

Calcification, Physiologic↗
PubMed2005

Rare courses of the mandibular canal in the molar regions of the human mandible: a cadaveric study.

The inferior alveolar artery, vein and nerve send some branches to the molar teeth via the mandibular canal to the mental foramen. The present study attempted to define the presence and course of the mandibular canal in the mandible with the alveolar process by macroscopic cadaveric dissection and computerized tomography (CT) in order to provide information that might prevent injuries to vessels and nerves at risk during root canal treatment. We identified the position of the mandibular canal within a 30% ratio of the distance from inferior border of mandible to the apices of the root for 39 out of 131 sides (mesial root of first molar, 20%; distal root of first molar, 22.6%; mesial root of second molar, 27.8% and distal root of second molar, 47%) on panoramic X-ray observation. In one cadaver (male, 64 years old), the root apex of the second molar was in close proximity to the upper bony mandibular canal. Macroscopic dissection and computerized tomography showed that the main trunks of the inferior alveolar artery, vein, and nerve were in tight contact with the apex of the second molar. These observations of the anatomic course of the mandibular canal will be important to consider during root canal treatment of mandibular teeth.

Adult↗
PubMed1996

The measurements of some anthropometric landmarks of the mandible; a preliminary anatomical study.

In this study, the morphometric measurements were done on human cadaver mandibles including ramus height and width, angle between ramus and corpus, the relation between foramen mentale and teeth. The aim of this study was to establish some standards with the achieved results in order to expand these studies in some reconstructive surgical areas. As a result, the standard measurements were established under the heads of short and long ramus, acute and obtuse angle mandibles.

Anthropometry↗
PubMed1978

Translative and transformative growth of the rat mandible.

The growth of the rat mandible was studied during a period from 14 to 30 days of age. Roentgencephalometric and alizarin vital staining techniques were employed. Growth in length doubles the growth in breadth; the angle between the mandibular halves decreases slightly. Bone remodeling patterns were revealed with the alizarin technique. Posteriorly facing surfaces and the anterior end of the incisal process show apposition. Lateral facing surfaces of the posterior part of the mandibles were resorptive. A medio-posterior growth direction of these parts were found. The intermandibular articulation plays no role in the translative growth movements, in contrast to other articulations between skull bones as sutures and synchondroses, but serves primarily during biting and chewing.

Animals↗
PubMed1980

Development of deciduous mandibular incisors related to developmental stages in the mandible.

On the basis of morphological and histochemical studies of 71 human mandibles from the former half of prenatal life, five stages (D I to D V) in the development of the deciduous mandibular incisors are described. These stages are related partly to general parameters of fetal development, such as M age (menstrual age), CRL (crown-rump length), CNO (composite number of ossified bones in hand and foot) and partly to stages in the skeletal development of the symphysis menti (SM I to SM V). The investigation revealed close relationship between the development of the deciduous mandibular incisors and the skeletal development of the deciduous mandibular incisors and the skeletal development of the mandible in the region of the incisors. No such relationship was found between the development of the deciduous mandibular incisors and general parameters of fetal development.

Fetus↗
PubMed1986

Intra- and inter-observer variability and accuracy in the determination of linear and angular measurements in computed tomography. An in vitro and in situ study of human mandibles.

The observer variability and accuracy of linear and angular computed tomography (CT) software measurements in the transaxial plane were investigated for the temporomandibular joint with the General Electric 8800 CT/N Scanner. A dried and measured human mandible was embedded in plastic and scanned in vitro. Sixteen observers participated in the study. The following measurements were tested: inter- and extra-condylar distances, transverse condylar dimension, condylar angulation, and the plastic base of the specimen. Three frozen cadaveric heads were similarly scanned and measured in situ. Intra- and inter-observer variabilities were lowest for the specimen base and highest for condylar angulation. Neuroradiologists had the lowest variability as a group, and radiology residents and paramedical personnel had the highest, but the differences were small. No significant difference was found between CT and macroscopic measurement of the mandible. In situ measurement by CT of condyles with structural changes in the transaxial plane was, however, subject to substantial error. It was concluded that transaxial linear measurements of the condylar processes free of significant structural changes had an error and an accuracy well within acceptable limits. The error for angular measurements was significantly greater than the error for linear measurements.

Child↗
PubMed1982

Early tissue reactions after circulatory and skeletal damage to the mandible of the rat.

Skeletal and circulatory damage in the form of a fracture of the mandible, proximal to the entry of the inferior alveolar artery and other perforantes, alone or combined with unilateral or bilateral mucoperiosteal extirpation, was inflicted on growing young rats. A morphological study of the tissue changes in the bone, dental tissues and soft tissues was performed. Cutting of the nutrient vessels together with extirpation of the periosteum was followed after 10 days by extensive infarction of the incisor pulp, the odontoblasts and the apical part of the enamel organ. The bone was damaged centrally in the mandibular corpus and at the lower border of the ramus, and was partly resorbed during the experimental period. The periodontium showed dilated vessels, but was not damaged. The pulps of the three molars showed numerous dilated vessels but were otherwise not damaged. The oral mucosa, bone marrow, peripheral nerve tissue and peripherally situated bone were not altered. In the animals after fracture alone, oedema of the incisor pulp was present, but infarction did not occur with certainty. A similar bone damage as with mucoperiosteal extirpation was present. The incisor with its dentin and enamel-forming cells was most sensitive to circulatory disturbances due to its central location, while the gingivoperiodontal, mucoperiosteal and midline circulatory systems could nourish the peripheral parts of the mandible. The dependence of the different nutrient systems to bone and dental tissues is discussed.

Alveolar Process↗
PubMed1988

Quantitation of blood flow in the rat mandible after vertical osteotomy.

Vertical osteotomies were performed in the mandibles of rats and combined with elevations of the buccal or bilateral mucoperiosteal pedicles. Isotope fractionation and particle distribution were used to measure blood flow in the distal and proximal segments of the mandible, the masseter muscle and the submandibular gland. Average decrease in blood flow ranged from 9-39% in the distal segment and from 8-24% in the proximal segment. Decrease in blood flow was most pronounced when bilateral mucoperiosteal pedicles were performed. Blood flow in the masseter muscle increased by 16-26% after osteotomy with mucoperiosteal elevations.

Animals↗
PubMed1976

The development and structure of the chimpanzee mandible.

The sites of growth and remodeling, and the associated changes in cortical bone structure, have been studied in the chimpanzee mandible and compared with those previously reported in the human and macaque mandibles. The location of the principal sites of growth, and the distribution of the areas of deposition and resorption in the ramus, were found to be similar in all three species. In the chimpanzee, unlike Man, the bone being deposited at the condyle, posterior border of the ramus and coronoid process was plexiform in nature, indicating very rapid growth. The pattern of remodeling in the mandibular body, on the other hand, showed marked species differences at the chin and on the submandibular lingual surface, which account for the contrasts seen in the adult morphology of these regions. Although the pattern of distribution of cortical densities differed from that of surface remodeling, the information they give is complementary in analysing bone growth. The densest regions were found to coincide with sites of consistent lamellar deposition, while the least dense regions were those where plexiform bone was formed. Areas where remodeling led to the greatest reorientation of bone tissue within the cortex showed the greatest disparity between the two patterns.

Age Determination by Teeth↗
PubMed1998

A method with combined prosthetic treatment of mandible with lateral resection and exarticulation.

A part of the people who need prosthetic treatment in the maxillofacial area are in the stage of after-surgical operation of tumors. One of the most commonly discovered defects in the mandible is the lateral resection with exarticulation. Our goal is to examine the possibilities of achieving optimal prosthetic restoration of the patients with lateral resection and exarticulation of the mandible through clinical application and combination of the modern technology and supportive-retentioned elements.

Humans↗
PubMed1998

[Three dimensional observation on revascularization and study on bone metabolism of allogenic transplanted mandible].

In order to observe stereological correlation between new vessels and surrounding tissue, 6 rabbits were used for the following experiments. The mandible defect model was made by cutting 1 cm x 0.5 cm bone from both right and left side of mandible. Then, the left defect was repaired by the bone segment from the right side, and the right defect was repaired by frozen allogenic bone segment. One month later, the metabolism of the bone segments was observed by nuclein scintiphotography. The revascularization of the bone segments was observed by vascular corrosion cast method. It was shown that new vessels from host soft tissue could penetrate the periosteum of allogenic transplanted bone, along the absorbing path, ingrowth into the bone. The metabolism of the bone was active. It was suggested that the vessel growth from host to the graft is one of the main patterns of revascularization.

Animals↗
PubMedDate not supplied

A comparison of 3 different endosseous nonsubmerged implants in edentulous mandibles: a clinical report.

The purpose of this prospective clinical study was to investigate the outcome of 3 different types of endosseous, nonsubmerged implants in the anterior part of the mandible. Fourteen older edentulous patients, 10 females and 4 males, were included. All participants received 3 different types of endosseous implants in the anterior mandible: 1 titanium plasma-sprayed cylindric implant (4 mm in diameter), 1 titanium cylindric implant with hydroxyapatite (HA) coating (4 mm in diameter), and 1 standard threaded titanium implant (3.75 mm in diameter). The 3 types of implants were originally designed to be placed in a 2-step surgical procedure. However, at this stage all implants were simultaneously provided with a temporary abutment that penetrated the mucosa. Three months later the temporary abutments were replaced by ball abutments, which were connected to an overdenture. At 12, 24, and 36 months after surgery, marginal bone resorption and Periotest values were recorded. Two patients died within the 2 first postoperative years. Five of 42 implants (11.9%) failed to osseointegrate. After 3 years, marginal bone resorption around titanium plasma-sprayed implants was significantly greater than that seen around both HA-coated and threaded titanium implants. Threaded titanium implants also had significantly better scores for marginal bone resorption than the HA-coated implants. Periotest values for HA-coated cylinders were significantly lower than test values for the other implants after 3 years (P < .05). The conclusion from this investigation is that nonsubmerged implants showed impaired prognoses compared to implants placed according to the 2-stage concept. Marginal bone resorption around titanium plasma-sprayed cylindric implants was clearly increased compared to the 2 other implant systems. Periotest values for HA-coated cylindric implants were superior to titanium plasma-sprayed and pure titanium implant surfaces.

Aged↗
PubMed1999

[Synovial sarcoma of the mandible in children. Apropos of a case].

UNLABELLED: Synovialosarcoma is an aggressive malignant soft-tissue tumor. It's a mesenchymal tumor rare in the cephalic region in the children. Its occurs most frequently in the extremities, in the adolescents and young adults between 15 and 40 years. His treatment are principally a radical surgical excision. We report the case of a 10 year old boy who had a mandibular tumor developing in the first premolar area and invading the submandibular region. The histologic diagnosis was biphasic synovialosarcoma with epithelial predominance. The staging showed a stage II tumor (5 cm) of the submandibular region with invading the mouth floor and the mandible. After the failure of the polychemotherapy we had performed a radical surgical excision with a functional cervical lymphadenectomy. The tumor was excised in one piece with the horizontal part of the left hemimandible. The treatment was completed by radiotherapy. In a second time a reconstructive surgery was performed with a fibula free flap. The result at one year show a good local control and a perfect esthetic and functional result of the mandible. CONCLUSION: Synovialosarcoma is a very aggressive malignant soft-tissue tumor with a high metastatic risk. Management must be rapid as soon as the diagnosis is made. Surgical excision is the main treatment in association with the chemotherapy and radiotherapy.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1976

Anterior and posterior lingual depressions of the mandible.

Both posterior and anterior lingual depressions occur in the mandible. The posterior lingual mandibular depressions appear to be more common than had been previously reported. This probably due to one or both of the following causes. Shallow lesions are difficult to diagnose radiographically since an appreciable depth of lingual cortical plate must be resorbed before they can be visualized. As these may be active lesions, a slow resorptive process could place the patient into middle age or beyond before the lesion is clinically diagnosed. It is suggested that posterior lingual mandibular depressions may be benign, self-limiting lesions that are caused by a slow resorptive process resulting from pressure of unknown origin. The anterior lingual mandibular depressions are variable findings in dried mandibles that appear grossly as round or oval smooth depressions with intact buccal and lingual cortical plates and, radiographically, as ill-defined radiolucent areas with no radiopaque borders. They are usually located in the incisor-lateral-canine area and are usually bilateral. It is suggested that these depressions may be developmental anomalies related to the buttons of Gaughran or that they may simply be anatomic variants. They differ from posterior depressions in both gross and radiographic appearance, which suggests the existence of two distinct entities.

Bone Resorption↗
PubMed1976

Fractures of the edentulous mandible: the Chalmer J. Lyons Academy study.

Results of a study show a 20% incidence of nonunion of fractures of atrophic edentulous mandibles. Accurate bony reduction is essential in elderly paatients with thin mandibles. Closed reduction should be tried first as open reduction tends to limit vascular supply to the fracture. Maintenance of periosteal coverage seems advisable if open reduction is necessary. Bone grafting should be considered unless contraindicated because of the patient's age or physical condition. Wire mesh is preferable to bone plates for stability.

Adolescent↗
PubMed1976

Desmoplastic fibroma of the mandible in a 3-year-old child.

A 3-year-old white girl was seen because of an enlarging mass in the left side of the mandible. The mass was 10 cm in diameter and the entire left hemimandible was involved. Examination of tissue after incisional biopsy showed desmoplastic fibroma. Surgical removal of the tumor required a hemimandibulectomy. The mandible was replaced immediately with a stainless steel mesh prosthesis with an acrylic condyle. A year later, there was no evidence of recurrence. Though the mesh became exposed in one area, we believe that esthetics and function were best served by its use.

Child, Preschool↗
PubMedDate not supplied

Osseous proliferation of the mandible after placement of endosseous implants.

Spontaneous alveolar ridge growth in the posterior region of the mandible following placement of endosseous implants is reported. The study included 27 patients with totally edentulous mandibles and fixed prostheses supported by osseointegrated implants placed between the mental foramina. In 5 patients, an increase in the height of the alveolar crest was observed in the molar region; the increase ranged from 3.3% to 8.6%. This osseous proliferation may be a physiologic response to stress distribution in the molar region.

Adult↗
PubMed1999

Neurosensory function after sagittal split osteotomy of the mandible: a comparison between subjective evaluation and objective assessment.

A large variety of neurosensory testing modalities have been used to evaluate skin sensitivity of the lower lip and chin after sagittal split osteotomy of the mandible. In this study we compared purely clinical impressions of the sensitivity of the lower lip and chin with objective assessments of it. The examination modalities included visual analogue scale, light-touch perception, and perception thresholds of warm and cold temperatures. The results indicate that there is a relatively good positive correlation between subjective evaluation and objective assessment of the sensitivity of the lower lip and chin after sagittal split osteotomy of the mandible.

Adult↗