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Biomedical subjects

T E Underhill

Publications and source records attributed to T E Underhill.

13 recordsLinked to original sources
PubMed1996

Comparison of film, direct digital, and tuned-aperture computed tomography images to identify the location of crestal defects around endosseous titanium implants.

This study compared diagnostic performance obtained from two-dimensional and three-dimensional x-ray images. The latter were produced with a new tomosynthetic method based on aperture theory called tuned-aperture computed tomography. Seven human cadaver mandibular segments containing a total of 20 endosseous implants with a small randomly positioned alveolar crestal defect at each implant site were imaged in two dimensions with periapical film and with a charge-coupled digital detector, and digitally with the same detector in three dimensions with tuned-aperture computed tomography and subtracted tuned-aperture computed tomography techniques. Seven trained dentists viewed randomized displays of all modalities. Outcomes of the diagnostic task of identifying the locations of crestal defects were quantified with accuracy, confidence, and time performance measures. Analyses of variance demonstrated that differences between either three-dimensional technique and either two-dimensional modality were significant for all measures (p < 0.001). These findings suggest that clinically applied TACT methods hold promise as an improvement over the status quo.

Alveolar Bone Loss↗
PubMed1994

Multilocular radiolucencies.

This article discusses lesions that commonly present as multilocular radiolucencies and, therefore, should be considered when the clinician is forming a differential diagnosis. These lesions include odontogenic keratocyst, ameloblastoma, central giant cell granuloma, cherubism, odontogenic myxoma, aneurysmal bone cyst, and central hemangioma and other vascular lesions. There is much variation in the clinical nature of multilocular lesions and, thus, variation in management. The clinician always must consider the possibility of a vascular lesion whenever evaluating a multilocular radiolucency.

Ameloblastoma↗
PubMed1992

Radiologic findings of diseases involving the maxilla and mandible.

The purpose of this pictorial essay is to illustrate the radiologic appearances of diseases involving the maxilla and mandible. The high prevalence of dental disease results in inflammatory, infectious, and reactive processes that must be distinguished from more serious conditions with similar radiologic features. Because of their association with odontogenic tissues, lesions of the maxilla and mandible may have radiologic findings not seen in other bones. Furthermore, nonodontogenic cysts and tumors that occur elsewhere in the skeleton may exhibit unique radiologic characteristics when associated with teeth. This pictorial essay presents the radiologic characteristics of inflammatory lesions, developmental abnormalities, fibroosseous lesions, benign cysts and tumors, and malignant lesions of the maxilla and mandible.

Cysts↗
PubMed1991

Clinical implications of anomalous muscle insertion relative to jaw movement and mandibular dysfunction: the anterior belly of the digastric muscle in a cadaver.

This case report of an anomalous insertion of the anterior belly of the digastric muscle in a cadaver considers the components involved in mandibular movement as well as the radiologic changes that could be expected in asymmetric function of the temporomandibular joints. The occlusal scheme of the cadaver was noted and, after transcranial radiographs were taken, both joints were anatomically dissected. While the left condyle-disc relationship appeared normal and properly approximated, the right joint (which was assumed to be translating in an anterior, inferior, and medial direction on each opening, ie, left lateral deviation) was found to have a complete articular disc perforation with severe bony erosion and condylar spicule formation. These findings may shed some light on dyskinesia diagnosis and treatment outcome; ie (1) what degree occlusally related etiologies may be affixed to individuals with aberrant mandibular movement, (2) why many diagnosed cases of mandibular dysfunction continue following irreversible dental restorative treatment via augmentation of the existing "malocclusion," and (3) what may be the clinical implications of or limitations inherent in the use of jaw-tracking devices in the diagnosis and interpretation of dyskinetic movement in the presence of aberrant muscle attachments.

Aged↗
PubMed1989

Localization of paraoral soft tissue calcifications: the known object rule.

The interpretation of panoramic radiographs requires an understanding of the formation of real and ghost images in rotational panoramic radiology. This article illustrates the use of principles of interpretation in panoramic radiology to identify paraoral soft tissue calcifications, which appear as lesions in the third molar-ramus region of the mandible. The known object rule, a variation of the buccal object rule, is presented as an aid in identifying soft tissue calcifications of the region of the head and neck.

Aged↗
PubMed1988

Radiobiologic risk estimation from dental radiology. Part I. Absorbed doses to critical organs.

The aim of the present study was to generate one consistent set of data for evaluating and comparing radiobiologic risks from different dental radiographic techniques. To accomplish this goal, absorbed doses were measured in fourteen anatomic sites from (1) five different panoramic machines with the use of rare-earth screens, (2) a twenty-film complete-mouth survey with E-speed film, long round cone, (3) a twenty-film complete-mouth survey with E-speed film, long rectangular cone, (4) a four-film interproximal survey with E-speed film, long round cone, and (5) a four-film interproximal survey with E-speed film, long rectangular cone. The dose to the thyroid gland, the active bone marrow, the brain, and the salivary glands was evaluated by means of exposure of a tissue-equivalent phantom, fitted with lithium fluoride thermoluminescent dosimeters (TLDs) at the relevant locations.

Bone Marrow↗
PubMed1988

Radiobiologic risk estimation from dental radiology. Part II. Cancer incidence and fatality.

With the use of the measured absorbed doses from part I of this article, the specific radiobiologic risk to the patient from (1) five different panoramic machines with rare-earth screens, (2) a 20-film complete-mouth survey with E-speed film, long round cone, (3) a 20-film complete-mouth survey with E-speed film, long rectangular cone, (4) a 4-film interproximal survey with E-speed film, long round cone, and (5) a 4-film interproximal survey with E-speed film, long rectangular cone, was calculated. The estimated risks are expressed in two ways: the probability of radiation-induced cancer in specific organs per million examinations and the probability of expression of a fatal cancer per million examinations. The highest risks calculated were from the complete-mouth survey with the use of round collimation. The lowest risks calculated were from panoramic radiography and four interproximal radiographs with rectangular collimation.

Adult↗
PubMed1986

Use of E-speed film with added filtration.

The use of aluminum, gadolinium, and yttrium filters in conjunction with E-speed film was studied. The resulting radiographs were judged to be acceptable for diagnostic purposes, although clinicians showed a preference for E-speed radiographs made at reduced exposure times and for D-speed radiographs. There was no detectable difference between the radiographs produced with the various filter materials.

Equipment Design↗
PubMedDate not supplied

Reasons patients stay with a dentist.

The intent of the study was twofold. The primary objective was to identify the reasons why patients remain with a practitioner. The secondary objective was to explore a procedure that practitioners could employ to assess the strengths and weaknesses of the way they and their staff interact with patients. The majority of patients indicated that honesty of their dentist was the primary reason that they continued in a dental practice. Patients also cited cleanliness, professional appearance, knowledge of dentistry, gentleness, concern, and quality of work as factors that influenced their decision to stay in a dental practice. The patient survey forms used in this study were designed to be utilized by a private practitioner. The feedback obtained from the survey may be used to improve patient's perceptions and relationship with a dental practitioner.

Adult↗