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PubMed1986

Preliminary observations on the BK 8518 mandible from Baringo, Kenya.

A newly discovered adult hominid mandible (BK 8518) from Baringo, Kenya, is described and assessed. The corpus, many of the tooth crowns, and most of the left ascending ramus are preserved. The teeth are heavily and asymmetrically worn. Compared with BK 67 (the 1966 mandible) the body of BK 8518 is more robust; the internal symphyseal buttressing is more pronounced; the M3s have seven cusps and exceed the M2s in size. There are no compelling reasons, however, to attribute the two mandibles to different taxa and, in view of the lack of any comprehensive taxonomic diagnosis for Homo erectus, "erectus-like," and habiline mandibular remains, the new specimen is also best regarded as Homo sp. indet. (aff. erectus).

Fossils↗
PubMed1991

Tooth and bone development in a Danish medieval mandible with unilateral absence of the mandibular canal.

A Danish anthropological collection of medieval human skeletons excavated in 1986 involves a mandible (No. 212) from an adult female born without the lower alveolar nerve and mandibular canal. It is believed that the defect has resulted in lack of tooth development on the affected side and that the mylohyoid nerve has partially compensated for this defect by development of teeth in localized areas. The defective mandibular dentition has caused a compensatory development of the alveolar process in the maxilla. The missing occlusal support has altered muscular traction on the mandible. This has caused an alteration in mandibular shape. Whether the asymmetric development of the mandible is caused by muscular dysfunction, by failure in angular growth apposition, or by a combination of these factors is discussed. The case presents valuable data in the ongoing discussion about the interaction between nerve tissue and tooth formation and about the interaction between occlusion, jaw morphology, and muscular traction. The study shows how archeological material in an interdisciplinary cooperation between archeological, embryological and orthodontic research can contribute to the clarification of current biological problems.

Alveolar Process↗
PubMed1992

Influence of teeth, alveoli, and periodontal ligaments on torsional rigidity in human mandibles.

We investigated the influence of teeth, periodontal ligaments, and alveoli on the structural integrity of human mandibles loaded in torsion. Surface bone strain was recorded from the mandibular corpus below the first molar on each of four specimens. These specimens were loaded by an external force that caused primarily torsion about the long axis of the corpus, and bone strain was recorded under the following conditions: 1) all supporting structures intact, 2) all supporting structures intact and the M1 loaded by a simulated bite force, 3) M1 removed and 4) alveolar bone of the M1 removed. For comparative purposes, experiments were also designed to investigate the effects of intermittent holes on the torsional rigidity of a baboon femur. This permitted comparison of the mechanical behavior of the mandibles with that of a more homogeneous bony member. These experiments suggest that the presence of teeth within alveoli has a measurable role in the maintenance of torsional rigidity. The condition of the periodontal ligament also appears to influence these stress-bearing capabilities. Moreover, the alveolar bone supporting the teeth also provides structural support for countering torsional loads. For the specific case of corpus twisting, the mandible does not behave as a member with open or closed sections as predicted by theoretical models. The observed magnitudes of bone strain, however, conform more closely to the predictions generated by a closed-section model.

Adult↗
PubMed1986

Inhibition of membrane bone formation by vitamin A in the embryonic chick mandible.

Embryonic chick mandibles (Hamburger and Hamilton [HH] stages 17-25) were cultured in the presence of various concentrations of vitamin A to determine the effect of hypervitaminosis A on membrane bone formation. In normal development, the mandible differentiates a centrally located Meckel's cartilage surrounded by membrane bones. Mandibles cultured without added vitamin A differentiated normally, though the timing of differentiation was retarded from that in ovo. Treatment with vitamin A interfered with skeletogenesis to varying degrees depending upon the initial age of the explant and the concentration of vitamin A. At low concentrations of vitamin A (1 microgram/ml), neither cartilage nor membrane bone formed in young explants (HH stage 17), whereas cartilage formed in 78% and membrane bone in 11% of older explants (HH stage 25). Higher concentrations of vitamin A (2-4 micrograms/ml) inhibited membrane bone formation in all explants, and 4 micrograms/ml of vitamin A inhibited chondrogenesis in most (88%) of the older explants. To determine whether tissue interactions influence this effect of vitamin A on skeletogenesis, mandibular mesenchyme was separated from its epithelium and treated with vitamin A. Under normal culture conditions, isolated mesenchyme (HH stage 25) differentiated both cartilage and membrane bone. Hypervitaminosis A inhibited membrane bone formation in the isolated mesenchyme at all levels tested (1-4 micrograms/ml) and inhibited chondrogenesis at levels 2-4 micrograms/ml. Hence, vitamin A can act directly upon the mesenchyme to inhibit both membrane bone formation and chondrogenesis, but its action is mitigated by the presence of the epithelium.

Animals↗
PubMedDate not supplied

Primary lymphoma of the mandible.

The mandible is an uncommon presentation site for lymphoma and misdiagnosis is common. Eleven patients with lymphoma of the mandible were seen between 1947 and 1983. In 5 of the 11 patients, the diagnosis of lymphoma could not be established from the initial biopsy and additional material for examination was required. In three patients, this resulted in a partial or total removal of the mandible. In a recent histopathologic review, the diagnosis of diffuse large cell was made in seven, diffuse undifferentiated (non-Burkitt's) in two, diffuse undifferentiated (Burkitt's) in one, and unclassified in one. Using the Ann Arbor method of staging, six patients were determined to have stage IE disease; three had stage IIE, and two had stage IV. In 10 patients definitive treatment consisted of radiotherapy, chemotherapy, or a combination of both. Treatment was limited to surgery in one patient. The 5-year overall and disease-free survival rates were 62% and 50%, respectively. These results are comparable to those for lymphoma of other extranodal head and neck sites.

Adolescent↗
PubMed2007

Development of a three-dimensional finite element model of a human mandible containing endosseous dental implants. I. Mathematical validation and experimental verification.

The purpose of this study was to mathematically validate and clinically verify a finite element model (FEM) of the human mandible and to compare the functional deformation predicted by the model with that detected clinically. Mandibular surface strain, using 11 single strain gauges, and medial convergence (MC), using a custom-fabricated linear variable differential transformer (LVDT), were recorded in a dried human jaw. The mandible was treated with two endosseous implants, placed bilaterally in the premolar area, and mounted in a rig that simulated natural function of the jaw. Measurements were made in real time using a multichannel analogue/digital converter and a personal computer for data storage and analysis. A FEM of the mandible was constructed, using commercially available finite element software, based on CT scan images of the jaw. MC was predicted as the linear change in the orientation of the two implants in the horizontal plane. Predicted and measured values of MC ranged between 60 and 109 microm. The differences between the measured and predicted strain magnitudes were expressed as absolute percentages of the measured values and ranged between 3 and 18%. The limits of agreement between the predicted and measured strain values, as suggested by Bland and Altman (Lancet 1986; 1:307-310), were small enough for the predictions from the FEM to be considered clinically acceptable. The good agreement between the predicted and measured strain values indicates the accuracy of the present FEM. Finite element analysis is a powerful technique that provides a better insight into understanding the complex phenomena of mandibular functional deformation.

Computer Simulation↗
PubMed2006

Complete rehabilitation of the mandible following segmental resection.

Segmental resection of the mandible leads to significant patient morbidity. Loss of mandibular support to the teeth, tongue and lip causes dysfunctional mastication, swallowing, speech, airway protection and oral competence. Patients also suffer disfigurement following segmental mandibulectomy because the mandible is an important aesthetic landmark. The degrees to which dysfunction and disfigurement occur depend both on the location of the mandibular segment removed and the amount of surrounding soft tissue excised. Between January 1985 and December 2004, 780 fibula osteoseptocutaneous flaps have been used for head and neck reconstruction at the Chang Gung Memorial Hospital, Taiwan. The fibula flap has proven to be the bony flap of choice because it has a lengthy bicortical segment of bone available, a reasonably long vascular pedicle, large diameter vessels, good bone quality, and is easily contoured with multiple osteotomies. The flap can be harvested while ablation is being performed. In addition, a reliable, mobile, thin skin component can always be included to address the soft tissue reconstructive requirements. A chimeric design employing a portion of the soleus muscle can provide further reconstructive options. Ideally complete rehabilitation of the mandible involves placement of titanium osseointegrated implants, which allow dental restoration. Primary placement of implants is preferred in patients without cancer. Selection of candidates to receive osseointegrated implants is paramount. The temporomandibular joint remains a challenge to reconstruct adequately.

Bone Transplantation↗
PubMed1994

Fibula osteoseptocutaneous flap for mandible reconstruction.

The fibula free flap has become an established flap for mandible reconstruction when vascularized bone is desirable. Recreating mandibular contour, providing soft tissue coverage, and restoring masticatory function are equally important in mandible reconstruction, and these can be provided by the fibula osteoseptocutaneous flap. This article is a summary of the anatomy, indications, and operative technique of the fibula osteoseptocutaneous flap accumulated from 49 consecutive mandible reconstructions.

Ameloblastoma↗
PubMedDate not supplied

Management of the mandible in oral cancer.

Modern head and neck surgery has focused on patient rehabilitation and restoration of form and function in the treatment of oral cancers. An important aspect of that process has been the conservation of the mandible in tumor ablation and the reconstruction of the mandible if segmental resection is indicated. This article outlines the science and clinical data behind rim mandibulectomy and the mandibular osteotomy and "swing" to gain access to tumors of the posterior tongues and pharynx. Additionally, the various methods of reconstruction of the mandible in use today as well as the advantages and disadvantages of each are addressed.

Algorithms↗
PubMed1997

A reconsideration of the Archi 1 Neandertal mandible.

A reassessment of the early last glacial immature Neandertal mandibular corpus from Archi indicates a series of features in which it closely resembles other pre-adolescent Neandertal mandibles and contrasts with those of similarly aged recent humans. These are in the context of a re-aging of the specimen to ca. 3 years on the basis of deciduous dental eruption and attrition and permanent dental calcification. The Archi 1 mandible resembles other immature. Neandertals in having a "retreating" symphyseal profile in the context of moderate development of mental trigone features. It is relatively robust in the development of lateral and basilar corpus features and some increased symphyseal and lateral corpus thickness. And it exhibits, along with other Middle Paleolithic immature mandibles, anteriorly wide dental arcades, probably due to large developing anterior permanent tooth crowns.

Age Factors↗
PubMed2000

Temporal trends and metric variation in the mandibles and dentition of Australopithecus afarensis.

The Pliocene hominin samples from Hadar and Laetoli are thought to represent one species, Australopithecus afarensis, that exhibits stasis throughout its temporal range and has high levels of skeletal sexual dimorphism. In this paper, we test the hypothesis of stasis in dental and mandibular dimensions using nonparametric rank correlation methods to detect temporal trends and randomization tests to evaluate their statistical significance. We then use two methods (CV resampling; Fligner-Killeen test) to compare overall levels of variation in the fossil sample to those of extant hominoid species. Together, these analyses allow us to gauge the effects of changes through time on variation in mandibles and teeth of A. afarensis.P(3)mesiodistal length, M(3)size, and canine shape change through time but do not appear unusually variable in the sample as a whole. These temporal trends possibly reflect differences between the Laetoli and Hadar site-samples. For mandibles, a pronounced trend towards greater corpus size occurs late in the temporal sequence and contributes to high levels of variation compared to African apes. These results show that significant directional changes do occur in the A. afarensis mandibles and teeth, and in these elements, at least, the species is not static. Temporal variation is clearly an important component of overall variation in the A. afarensis lineage, even though other factors, such as sexual dimorphism, may also play a part.

Animals↗
PubMed1986

Concentration of cefuroxime in the bones of albino white rats: a comparative study of femur, humerus, and mandible.

The levels of cefuroxime in rat bones with a different morphology, function, blood supply, and proportion between lamellar and cancellous bone were studied, after a 24-h administration of 750mg/kg X 3. The concentrations in the right and left femora, humeri, and mandibles of the same animal were measured 2 h after the last administration. The result indicate statistically significant differences between femur and humerus (P less than 0.001), femur and mandible (P less than 0.05), and humerus and mandible (P less than 0.05).

Animals↗
PubMed1992

Structural analysis of the mandible by quantitative computed tomography.

The study presents quantitative computed tomography (QCT) as a noninvasive method for analyzing the inner bone structure. Randomly selected mandibles from the osteological collection of the "Drago Perović" Institute of Anatomy, School of Medicine, Zagreb were CT-scanned in five bone areas. Analyzing the densitometry curve in two horizontal levels the relation between the compact and spongy bone and the total amount of bone substance in each area were determined. The smallest bone quantity was found in the area of the neck and angle of the mandible, the areas of most frequent bone fractures. The alveolar part of the bone, apart from the area of the angle, was considerably less thick than the base of the mandible. The compact bone was predominant in all CT-scans.

Adult↗
PubMed1985

Hepatocellular carcinoma metastatic to the oral cavity including the maxilla and the mandible: report of two cases and review of the literature.

Two cases of hepatocellular carcinoma metastatic to the oral cavity are presented. One patient had metastases to the maxilla and finally, to the mandible, and the other patient, to the mandible. Both cases histologically showed highly-differentiated trabecular hepatocellular carcinoma which had vascularized stroma, explaining the frequently observed oral hemorrhage. The clinical signs and symptoms described here suggested the existence of a tumor metastatic to the oral cavity, and might indicate an unusual manifestation of hepatocellular carcinoma. Reports of metastatic lesions of hepatocellular carcinoma to the oral cavity, including the mandible, maxilla and gingiva proper, are reviewed.

Aged↗
PubMed2001

Bone remodeling of the human mandible during prenatal development.

MATERIAL AND METHOD: Based on histological serial sections of human fetuses (22-117 mm crown-rump length) the remodeling of the bone surfaces of the fetal mandible was characterized and visualized in 3D reconstructions. RESULTS: In the embryo of 22 mm crown-rump length the mandible was completely covered by cells producing bone apposition, but beginning with the embryo of 25 mm crown-rump length, morphological differentiations of these cells leading to bone modeling were visible. These modeling processes were found to be much more complicated than described in the literature so far. CONCLUSION: Bone growth of the fetal mandible is a complex process comprising not only lingual resorption and buccal apposition. Instead, we found well differentiated remodeling processes, represented by variable portions of apposition, resorption and resting areas seamed by lining cells.

Bone Remodeling↗
PubMed2000

[Effect of bFGF on regeneration of distracted mandibles after radiation].

The potential of distraction osteogenesis in mandibular reconstruction has been limited by its questionable efficacy in previously irradiated bone. The possible osteogenetic effect of recombinant human basic fibroblast growth factor (bFGF) on lengthening of irradiated mandibles was investigated in beagle dogs. We studied nine adult dogs which underwent a full course of external beam radiation therapy (60 Gy/30 fractions). Six months after completion of radiotherapy, the molars were extracted bilaterally followed by bone lengthening of the mandible using an intraoral device. On postoperative day 3 and 7 we injected 10 micrograms bFGF into the osteotomy site of each right hemimandible. The left sides were used as controls. The time course in ossification of the distracted area was evaluated at 2, 4, and 6 weeks after completion of bone lengthening. The radiographs of the newly formed bone tissue were measured by digital image analysis. Corresponding to the radiographic findings, the histological examination of the removed jaws showed an earlier and more intensive bone formation in the treated side after 2, 4, and 6 weeks compared to the control side. We conclude that bFGF promotes the ossification of distracted mandibles after radiation therapy in dogs.

Adult↗
PubMed2000

A new find of a Middle Pleistocene mandible from Bilzingsleben, Germany.

The Middle Pleistocene site at Bilzingsleben is being excavated by the Forschungsstelle Bilzingsleben, FSU Jena. It is a living floor with structures of settlement and a great number of Lower Palaeolithic cultural remains. So far, 28 human skull fragments have been discovered, which can be reconstructed into two individual skulls. Recently, the right mandible has also been discovered (Bilzingsleben E7). Morphological comparisons indicate that there is a great similarity to the mandibles of HI and BI of Sinanthropus. A strong likeness to Arago II and XIII was also discovered. There are various different archaic features which assign the Bilzingsleben mandible and the two skulls to the advanced Homo erectus.

Animals↗
PubMed2006

Anastomosis between the inferior alveolar artery branches and submental artery in human mandible.

The mental artery displays several branches internal to the anterior region of the mandible as confirmed by macroscopic observation and computed tomography. The inferior alveolar artery formed complex branches and divided into mental and incisive branches, which were found in the right internal side of the mandible of one male cadaver (88 years old). The branches of these two arteries ran through the bony lingual canal to the lingual foramen between the canine and premolar region of the inner surface of the mandible body, where they emerged to enter the mylohyoid and anterior belly of the digastric muscles and communicate with the submental artery. The observation of the anastomotic artery is considered important for surgical placement of dental implants in the mandibular region.

Aged, 80 and over↗