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Biomedical subjects

R A Danforth

Publications and source records attributed to R A Danforth.

11 recordsLinked to original sources
PubMed1991

Corrected TMJ tomography: effectiveness of alternatives to SMV tracing.

An axial (SMV) radiograph has been widely used to determine parasagittal head position in TMJ tomograms. The purpose of this study was to investigate the efficacy of alternative anatomic methods for patient positioning in TMJ tomograms. The positioning methods studied included (1) rotation of the patient's head toward the film plane on the basis of the condylar orientation as determined by an SMV radiograph, (2) arbitrary rotation of the patient's head 20 degrees toward the film plane, (3) placement of the zygomatic arch parallel to the film plane, and (4) positioning of the posterior occlusal plane parallel to the film plane. Statistical analysis of the accuracy of the positioning techniques revealed no differences in the SMV, the zygomatic arch, and the arbitrary 20 degrees positioning. Aligning the posterior occlusal plane did not adequately align the mandible into a favorable radiographic position.

Analysis of Variance↗
PubMed1991

[Evaluation of radiation risk associated with endodontic radiography].

Endodontic patients are sometimes concerned about the risks of tumors or cataracts from radiation exposure during root canal therapy. By using established dose and risk information, we calculated the extent of these risks. The chance of getting leukemia from an endodontic x-ray survey using 90 kVp was found to be 1 in 7.69 million, the same as the risk of dying from cancer from smoking 0.94 cigarettes or from an auto accident when driving 3.7 km. Risk of thyroid gland neoplasia was 1 in 667,000 (smoking 11.6 cigarettes, driving 45 km) and risk of salivary gland neoplasia 1 in 1.35 million (smoking 5.4 cigarettes, driving 21.1 km). Use of 70 kVp radiography reduced these risks only slightly. To receive the threshold dose to eyes to produce cataract changes, a patient would have to undergo 10,900 endodontic surveys.

Cataract↗
PubMed1990

Segmental odontomaxillary dysplasia. Report of eight cases and comparison with hemimaxillofacial dysplasia.

We report an analysis of eight cases with features as described for hemimaxillofacial dysplasia and compare our cases with those of that original report by Miles and associates. Patients were young and had bone and/or gingival enlargement, dental abnormalities, and unique radiographic and histologic features. Osseous and dental abnormalities were confined to the maxillary alveolus extending from the canine region to the tuberosity. Ipsilateral facial hypertrichosis was not observed. The condition seems to remain stable without significant progression and is hypothesized to be a developmental abnormality. We propose the term segmental odontomaxillary dysplasia (SOD) as a more precise descriptor for the constellation of features observed.

Adolescent↗
PubMed1990

Axial temporomandibular joint morphology: a correlative study of radiographic and gross anatomic findings.

In degenerative diseases of the temporomandibular joint the mandibular condyle demonstrates changes in contour, including flattening and enlargement, resulting in an increased diameter of the articular surface. The purpose of this study was to determine if such alterations in the shape of the mandibular condyle can be visualized in submentovertex (axial) radiographs and correlated with pathologic changes of the temporomandibular joint. Submentovertex radiographs of 18 human cadaver specimens were made. The radiographic condylar dimensions, morphologic condylar outline, and angle of the condylar axis with respect to the transmeatal line were determined. The specimens were dissected and disarticulated, and radiographic findings were compared to anatomic structure. Osseous abnormalities were found in 21 of the 36 joints studied (58%). Perforations of the disk were found in nine of 31 joints (29%) investigated. No statistically significant differences between the normal condyles and condyles displaying osseous abnormalities were found in any of the radiographic parameters studied.

Adult↗
PubMed1990

Estimated radiation risks associated with endodontic radiography.

Endodontic patients are sometimes concerned about the risks of tumors or cataracts from radiation exposure during root canal therapy. By using established dose and risk information, we calculated the extent of these risks. The chance of getting leukemia from an endodontic x-ray survey using 90 kVp was found to be 1 in 7.69 million, the same as the risk of dying from cancer from smoking 0.94 cigarettes or from an auto accident when driving 3.7 km. Risk of thyroid gland neoplasia was 1 in 667,000 (smoking 11.6 cigarettes, driving 45 km) and risk of salivary gland neoplasia 1 in 1.35 million (smoking 5.4 cigarettes, driving 21.1 km). Use of 70 kVp radiography reduced these risks only slightly. To receive the threshold dose to eyes to produce cataract changes, a patient would have to undergo 10,900 endodontic surveys.

Cataract↗
PubMed1990

Radiation absorbed from dental implant radiography: a comparison of linear tomography, CT scan, and panoramic and intra-oral techniques.

Absorbed radiation dose in bone marrow, thyroid, salivary gland, eye, and skin entrance was determined by placement of lithium fluoride thermoluminescent dosimeters (TLD's) at selected anatomical sites within and on a human-like x-ray phantom. The phantom was exposed to radiation from linear tomographic and computer-assisted tomographic (CT) simulated dental implant radiographic examinations. The mean dose was determined for each anatomical site. Resulting dose measurements from linear tomography and computer-assisted tomography are compared with reported panoramic and intra-oral doses. CT examination delivered the greatest dose, while linear tomography was generally lowest. Panoramic and intra-oral doses were similar to those of linear tomography.

Dental Implantation, Endosseous↗
PubMed1986

Human cervical and hamster oral epithelial neoplasia--colposcopic similarities.

Epithelial dysplasias and squamous carcinomas were experimentally produced in the cheek pouches of Syrian hamsters. These lesions were observed and photographed in the living animals with the aid of a stereoscopic microscope at magnifications of 20 and 40 times. Very apparent similarities were noted in the vascular patterns and epithelial configurations between the hamster oral dysplasias and carcinomas and the corresponding lesions seen in published cases of cervical intraepithlial neoplasia and invasive squamous carcinoma. It is speculated that these similarities reflect common factors in the interaction between neoplastic squamous epithelium and its blood supply. These findings are important in understanding the biology of cervical neoplasia and may be useful in the diagnosis and management of human oral neoplasia.

Animals↗
PubMed1979

Chievitz's organ: a potential pitfall in oral cancer diagnosis.

It has been reported that epithelial nests associated with sensory nerve fibers may simulate perineural invasion and pose a potential diagnostic problem for surgical pathologists working on frozen tissue specimens from patients with oral cancer. The epithelial structures are not neoplastic, and no known pathologic condition has been associated with them. They are believed to be those structures described scantily in the English literature as Chievitz's organ. The fact that the epithelial nests lie near the plane of injection for the inferior alveolar nerve should be of special interest to dentists, especially oral surgeons and pathologists. Controversy exists as to the exact nature of Chievitz's organ, but the potential hazard of misdiagnosis exists nonetheless. This study of cadaver and autopsy material reaffirms the existence of the epithelial rests and outlines a simple technique for locating them.

Aged↗