Jaw Mass Research Articles

Primitive neuroectodermal tumour of the mandible

Primitive neuroectodermal tumors (PNETs) are relatively rare tumors. Tumors that once would have been diagnosed as Ewing's sarcoma are now often designated as peripheral neuroepithelioma or synonymously PNET. Herein we report the first case of PNET of the mandible in a 6-year-old female who was admitted to the hospital with a two-months history of painless, progressively enlarging lower jaw mass.

Mass properties of the human mandible

Computer simulation of human masticatory dynamics requires specification of the jaw's mass properties. These are difficult to estimate, especially in living subjects. Here, we used calibrated computed tomography (CT) to determine the properties of eight osseous jaw specimens with adult dentitions. When the CT numbers were converted to mineral densities, the mean estimated jaw mass was 13% greater than the mean wet weight. Putative bone marrow accounted for an extra 7% of mass. The mean bone densities for the sample were very consistent (1.72±0.02 g/cm 3). The mass and geometric centers were close (mean linear difference 0.43±0.18 mm), and were always located anteroposteriorly between the second and third molars. The largest moment of inertia (MI) occurred around the jaw's superoinferior axis, and the smallest around its transverse axis. Bone marrow added an extra 7% to the MIs. There were linear relationships between the mandibular length (expressed three dimensionally), the actual and estimated masses, and the moments of inertia. Our study suggests non-invasive imaging (such as magnetic resonance) and even direct linear measurement, may be adequate to estimate jaw mass properties in living humans.

Mass properties of the pig mandible.

Specification of mass properties is an essential step in the modeling of jaw dynamics, but obtaining them can be difficult. Here, we used three-dimensional computed tomography (CT) to estimate jaw mass, mean bone density, anatomical locations of the mass and geometric centers, and moments of inertia in the pig jaw. High-resolution CT scans were performed at one-mm slice intervals on specimens submerged in water. The mean estimated jaw mass was 12% greater than the mean wet weight, and 33% more than the mean dry weight. Putative bone marrow accounted for an extra 13% of mass. There was a positive correlation between estimated mean bone density and age. The mass center was consistently in the midline, near the last molar. The mean distance between the mass center and geometric center was small, especially when bone marrow was taken into account (0.58 +/- 0.21 mm), suggesting that mass distribution in the pig jaw is almost symmetrical with respect to its geometric center. The largest moment of inertia occurred around each mandible's supero-inferior axis, and the smallest around its antero-posterior axis. Bone marrow contributed an extra 9% to the moments of inertia in all three axes. Linear relationships were found between the actual mass and a mass descriptor (product of the bounding volume and mean bone density), and between the moments of inertia and moments of inertia descriptors (products of the mass descriptor and two orthogonal dimensions forming the bounding box). The study suggests that imaging modalities revealing three-dimensional jaw shape may be adequate for estimating the bone mass properties in pigs.

Pheochromocytoma Metastatic to the Mandible Presenting as a Large Jaw Mass

In this case report of an unusual presentation of a metastatic pheochromocytoma as a large jaw mass, the anesthetic management of the resection of a vasoactive tumor in close proximity to the airway is described. The strategy to maintain a stable hemodynamic profile is explained, and a review of current management techniques is given with a discussion of the benefits or contraindications of each method. In summary, this case highlights the importance of preoperative alpha-adrenergic blockade and preparation for rapid fluctuations in blood pressure when operating on patients with pheochromocytoma.

A Search for Age-Related Changes in Bite Force and Diet in Shrews

-Tooth attrition is rapid and extensive in soricine shrews. Seemingly, without compensatory morphological changes to increase bite force, older individuals must shift their diet to softer items and risk greater overlap with trophic niches of more numerous younger individuals of syntopic taxa with lower relative bite force. Initial tests of this hypothesis indicated that neither efficiency of jaw mechanics nor mass of the masticatory muscles increased significantly with age (as indexed by length of II) in 101 Sorex trowbridgii. Similar tests of changes in these characters and hardness of the diet with age for samples of several taxa were inconclusive; coefficients of correlation were significant for a few of the relationships tested. However, a meta-analysis technique for combining coefficients of correlation to test the consensus of sets of independent tests addressing common null hypotheses indicated that overall efficiency of jaw mechanics in western shrews (Sorex) increased significantly with age. Reduction of the length of the resistance moment arm (condyloid-il length) with age contributed most to the jaw mechanics-age relationship. Although the mechanism by which the jaw shortens remains unclear, the effect likely is sufficient to prevent a significant increase in age-related overlap of trophic niches of syntopic species of western shrews.

Case 27-1994: The Numb Chin Syndrome

To the Editor: With regard to Dr. Lynch's discussion (July 14 issue)1 of the case of a 41-year-old woman with a lytic jaw mass, lymphadenopathy, splenomegaly, and a multifocal neurologic disorder, the patient's reports of numbness and impaired sensation on the right side of the chin is typical of mental neuropathy, also known as the numb chin syndrome. This clinical presentation, combined with the finding of a lytic jaw lesion, suggests that the chin numbness resulted from local involvement of the inferior alveolar nerve or the mental nerve. This uncommon cranial neuropathy is mostly associated with neoplastic disorders.2 Its appearance . . .

Lip Paresthesia Associated with a Jaw Mass

A case is reported in which mandibular swelling and lower lip numbness were the first signs of a metastatic adenocarcinoma of the lung. The development of paresthesia, with or without other oral symptoms, requires that a diagnosis of malignancy be considered until confirmed or ruled out by tissue biopsy. A thorough head and neck examination in all patients, especially in those whose history or habits may indicate increased risk of malignancy is necessary.

Juvenile Aggressive Fibromatosis of the Head and Neck

David H. Thompson and coworkers at the US Naval Hospital, Bethesda, Md, reported their experience with three children with aggressive fibromatosis to the Southern Section meeting of the Triological Society recently held in Birmingham, Ala. All three patients presented with a rapidly growing, painless jaw mass (two of the mandible and one of the maxilla) and began to develop airway compromise. The recommended evaluation included enhanced computed tomographic scanning to document the bony destruction and tumor vascularity, both prominent features in the patients described. Wide extirpation was curative, with follow-up from 12 to 33 months. For incompletely excised or unresectable tumors, radiation therapy has been helpful according to some reports, and intravenously administered doxorubicin (Adriamycin) in others. The authors postulated a genetic predisposition to fibromatosis, and prior trauma also has been implicated in some cases.

Some biomechanical correlates of jaw movements

The relative contributions of jaw mass and supporting muscle system stiffness to jaw movements were studied to a first approximation. The amplitude-frequency characteristics of jaw movements were measured in both the normal state and under conditions of increased mass (externally applied weights) and stiffness (spring loading). Vertical jaw movements were produced and controlled by muscle stimulation through wire electrodes implanted directly into the masseter muscle of a single subject. The stimulation signal (2-ms pulse width, 200 pps) was modulated through a function generator to produce oscillatory jaw movements varying from 1 to 15 Hz. Jaw movement was tracked in the vertical dimension using a photoelectric sensing device. It was found that increases in both load and stiffness reduced the amplitude-frequency characteristics of the jaw and that the bandwidth of the amplitude-frequency characteristics of the jaw corresponded to the calculated Eigen frequency of the jaw. These findings suggest that the bandwidth of the amplitude-frequency characteristics of the jaw is determined primarily by the mechanical properties of the controlling muscle. The experimental data were also compared to real speech jaw movement data. [Work supported by NIH Research Grant, NS-10424.]

Periostitis of the mandible. A case report and review of the literature

Periostitis of the mandible has not been previously discussed in the otolaryngologic literature and only infrequently in the dental literature. It is characterized by a hard, painless, fixed mass overlying the mandible in a child or young adult. The etiology is usually an endosteal infection in the molar region with periosteal inflammation. Reactive new bone is deposited beneath the elevated periosteum, external to the outer cortex of the jaw, and separated from it by a layer of suppurative fluid. Treatment consists of removal of involved teeth and infected bone, drainage of the fluid pocked and appropriate antibiotics. Patients are followed with repeat X-rays and erythrocyte sedimentation rates. A case is presented and the world literature is reviewed. The otolaryngologist should be aware of this entity and include it in the differential diagnosis of any fixed jaw mass to avoid mistaking it for a more malignant process with unfortunate consequences.

Osteogenic sarcoma of the mandible

0 steogenic sarcoma of the mandible is not common. Often the initial signs are loose teeth, the presence of a jaw mass, numbness of the lower lip, and pain in the jaw. The lesion occurs more frequently in males than in females. It may occur at any age, but the average age is 33 years. Differential diagnosis should include chondrosarcoma, fibrosarcoma, fibrous dysplasia, ossifying fibroma, and giant-cell granuloma .e Jaw sarcomas have been treated with diathermy, radiotherapy, chemotherapy, conservative resection, radical resection, or a combination of these.2-5* 7 Radical resection is believed to give the best chance of cure and is the treatment of ch0ice.l Following ablation, the question of primary reconstruction should be considered on an individual basis. The decision will depend on the condition of the patient, the size and behavior of the tumor, and the tissue available for the safe replacement of tissue. The iliac crest is favored as the bone donor site.l Metastases, if present, usually spread by the bloodstream, but in 7 per cent of the reported cases there was metastatic disease in the suprahyoid lymph nodes. Recurrent or metastatic disease usually occurs in the first posttreatment year, and the survival rates range from 5 to 50 per cent.5f 7* g In the first case to be presented here the lesion is classified as osteogenic sarcoma because of the presence of osteoid. Even though the predominant cell is the chondroblast, it is classified as a chondroblastic osteogenic sarcoma. In the second case the predominant cell is the osteoblast, and this tumor is classified as an osteoblastic osteogenic sarcoma. Had the fibroblast been the predominant cell, with the presence of osteoid, the diagnosis would have been fibroblastic osteogenic sarcoma.