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Biomedical subjects

D R Cahill

Publications and source records attributed to D R Cahill.

50 records · Page 3Linked to original sources
PubMed1984

Experimental study in the dog of the non-active role of the tooth in the eruptive process.

The role of the tooth in eruption was studied radiographically and histologically after experimental manipulations of the crowns of permanent mandibular premolars in dogs. Crowns were removed and dead crown shells or metal or silicone replicas were substituted into dental follicles just prior to scheduled eruption. These replacements erupted on schedule after formation of the usual eruption pathways and formation of trabecular bone from the base of the bony crypt. Removal of crowns, but without adding replacements, also exhibited these same hallmarks of eruption. We conclude that tooth eruption is a series of metabolic events in alveolar bone characterized by bone resorption and formation on opposite sides of the dental follicle and the tooth does not contribute to this process.

Alveolar Process↗
PubMed1983

Deep facial osteology as revealed by coronal sections of the dried skull.

An understanding of the bony framework and relationships of the face is essential to the facial reconstructor. A dried human skull was immersed in a hardening agent to preserve the ethmoidal labyrinth and then cut in the coronal plane to produce six sections. The anterior and posterior surface of each section was photographed and landmarks were labeled. Since the thick anterior bony structures were removed with the first slice, the normal delicate laminae of the deep face, within the deeper sections, were exposed for study.

Facial Bones↗
PubMed1983

The cytology of the dental follicle and adjacent alveolar bone during tooth eruption in the dog.

Previous studies from our laboratories have shown that premolar eruption in dogs depends upon the presence of the dental follicle and is independent of root or crown growth or attachment to the oral epithelium. The present study is an analysis of the cellular composition of the dental follicle and the cellular investment of the adjacent walls of the bony crypt before and during eruption of the third and fourth mandibular permanent premolars in young beagle dogs. Four premolar follicles and their adjacent bony crypts were examined at 2-week intervals over 12 weeks before and during eruption of these teeth. Tissues were removed, fixed, processed, and oriented so that each follicle and the adjacent crypt wall could be reproducibly examined in vertical and horizontal planes. Mononuclear cells with abundant cytoplasm, euchromatic nuclei, and prominent nucleoli were present in juxtavascular location in the coronal part of the dental follicle; and these cells increased in number immediately preceding and during tooth eruption in parallel with an increase in osteoclasts on the adjacent crypt wall. These data are interpreted to mean that the coronal part of the dental follicle may coordinate the alveolar bone resorption required for tooth eruption by attracting and directing to the crypt wall a population of mononuclear cells, which either become osteoclasts and/or direct osteoclastic activity during tooth eruption.

Alveolar Process↗
PubMed1982

Chronology and histology of exfoliation and eruption of mandibular premolars in dogs.

Exfoliation of third deciduous mandibular premolars and their replacement by the third permanent premolars were compared in young dogs of purebred beagle and mongrel stock. Radiographic and histologic studies showed that eruption of the permanent premolar begins during the 16th postnatal week and is completed in 7 weeks. Root elongation proceeds with eruption, but fibers of the periodontal ligaments are not anchored in alveolar bone and do not attain their final orientation with respect to the long axis of the tooth until final phase of the eruptive period. These data define a predictable system in which various stages in the mechanism of eruption of noncontinuously erupting teeth may be examined experimentally. Furthermore, the observation that these processes are identical in timing and sequence in beagle and mongrel dogs suggests that less expensive, more readily available mongrel dogs can be used for these studies.

Animals↗
PubMed1980

Tooth eruption: evidence for the central role of the dental follicle.

The roles of the gubernaculum dentis, root formation, tooth crown and dental follicle in prefunctional eruption of a mandibular premolar have been studied in nine beagle dogs by radiographic and histologic evaluations of the effects of surgical ablation or removal of these structures on tooth eruption. The dental follicle was the only one of these structures required for the coordinated enlargement of the eruption pathway and formation of bone in the base of the bony crypt, the radiographic and histologic hallmarks of tooth eruption. These data, together with the topographic relationships of the dental follicle to areas of localized bone resorption and formation, are interpreted to mean that the dental follicle may influence, if not coordinate, these processes in tooth eruption.

Alveolar Process↗
PubMed1975

The deceptive aortic root.

Coronal, horizontal, and sagittal sections through the mid-line are excellent ways of depicting the anatomical position of the aortic root and for studying its topographical relationship to the surrounding vascular structures. Minimal radiographic abnormalities or no abnormalities at all may be present with an enlarged ascending portion of the thoracic aorta. Thus, frontal chest roentgenograms obtained with high kilovoltage, fluoroscopy and left anterior oblique projections should be utilized routinely for the evaluation of the ascending aorta. Calcification of the aortic valve and of the coronary arteries and the study of aortic valve prosthesis also demand a dynamic study and the use of complementary views, such as lateral and both oblique projections.

Aorta, Thoracic↗
PubMedDate not supplied

Defining the cross-sectional anatomy important to interscalene brachial plexus block with magnetic resonance imaging.

BACKGROUND AND OBJECTIVES: Interscalene brachial plexus block is a useful technique to provide anesthesia and analgesia for the shoulder and proximal upper extremity. The initial needle direction at the interscalene groove has been described as being "perpendicular to the skin in every plane" (1). A cross-sectional (axial) approach may offer a more easily conceptualized directed needle placement. The purpose of this study is to define the cross-sectional anatomy and idealized needle angles important to interscalene brachial plexus block. METHODS: Following IRB approval, 50 patients were studied. Cross-sectional volume coil T1-weighted magnetic resonance images (MRI) were obtained from 50 patients undergoing cervical region imaging for other reasons. At the interscalene groove, a simulated needle path to contact the ventral rami or trunks of the brachial plexus was approximated at the level of C6 or C6-C7 interspace. The angle of this needle path intersecting the sagittal plane was recorded for each patient. RESULTS: The mean angle of the simulated needle path relative to sagittal plane was determined to be 61.1 +/- 6.1 degrees (range, 50-78 degrees). In 13 of 50 (26%) MRI scans, the cervical nerve roots were not visualized at the level of C6 and were measured at the C6-C7 level. CONCLUSIONS: These findings suggest initial needle placement at the interscalene groove should be angled less perpendicularly relative to the sagittal plane than is often observed. A cross-sectional approach enables more practical visualization of initial needle placement. A more accurate initial needle placement may minimize the number of needle passes necessary to contact the nerve roots, thereby more efficiently obtaining a successful block.

Adult↗