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Biomedical subjects

D H Enlow

Publications and source records attributed to D H Enlow.

At least 37 records · Page 2Linked to original sources
PubMed1980

An electron microscopic study of attachments between periodontal fibers and bone during alveolar remodeling.

Three types of periodontal membrane-to-bone attachments are described for remodeling surfaces of the bony alveolar wall. An adhesive type, which is the most widespread means for tooth anchorage on resorptive bone surfaces during active tooth movements, involves the following histogenic steps: A layer of ground substance is first deposited by fibroblast-like cells on the naked surface of recently resorbed bone. As this continues, new precollagen and the dissociated ends of collagenous fibrils become embedded in the accumulating ground substance, and these fibrils in turn become joined to intact collagenous fibrils, blending with the remainder of the periodontal stroma. Such adhesive attachments continuously form and re-form as the resorption front proceeds. A continuous type of attachment also occurs on resorptive bone surfaces in which some (not all) bone matrix fibrils survive the resorptive process. These former bone fibrils become incorporated into the periodontal membrane and are continuous between the bone matrix and the stroma of the contiguous periodontal membrane. An intermediate type of attachment also occurs and is primarily an adhesive attachment that also contains a scattering of fibrils which are continuous from the bone matrix across the resorptive bone surface into the fibrous matrix of the periodontal membrane.

Alveolar Process↗
PubMed1980

A histochemical and electron microscopic study of an adhesive type of collagen attachment on resorptive surfaces of alveolar bone.

This study describes (1) the composition of the "adhesive" type of periodontal membrane attachment onto resorptive surfaces of actively remodeling alveolar bone; (2) the structure of reversal lines in alveolar bone; and (3) the role of certain fibroblast-like "osteoclast companion cells" in the attachment process of periodontal fibers onto resorptive bone surfaces. Adesive attachments involve a layering of specific zones at the interface between the periodontal membrane and the resorptive bone surface, and one or more types of osteoclast companion cells appear to function in the secretion of components of proteoglycans (probably glycosaminoglycans) and precollagenous fibrils. The proteoglycans appear to serve as a principal component of the adhesive substance secreted on a bone surface and also as a binding agent for the linking and progressive relinking of new and old collagenous fibers to each other and to the resorbed bone surface. If a reversal in the direction of remodeling occurs, and new bone deposition occurs on a surface that was formerly resorptive, the zones of the adhesive interface become calcified and then constitute a "reversal line."

Alveolar Process↗
PubMed1977

Research on control of craniofacial morphogenesis: an NIDR State-of-the-Art Workshop.

To assess the wide clinical ramifications of control of craniofacial morphogenesis, a State-of-the-Art Workshop was conducted by the National Institute of Dental Research at the initiative of Richard L. Christiansen, Chief of the Craniofacial Anomalies Program. In conjunction with the authors listed above, the format for the workshop was developed and participants were selected. The workshop was designed to provide an in-depth review of present knowledge and to identify future goals and directions for research on guiding, altering, and thus controlling growth and development of the cranofacial skeleton. The agenda for discussion ranged from molecular biology to clinical arts such as orthopedics and surgery. It was evident during the workshop that the mechanisms and procedures for controlling craniofacial morphogenesis must be derived from many biologic, physical, and clinical fields of knowledge. It is hoped that there will evolve an interdisciplinary clinical art which is aimed at preventing and correcting craniofacial deformities. Substantial biologic information has already been accumulated on the craniofacial skeleton. The clinical art of correcting malocclusion through mechanical forces is now applicable to the entire skull. The outstanding technical accomplishments of radical surgery in the correction of congenital craniofacial anomalies show that the needed surgical skills are now available. When these resources are combined, an area of knowledge and a clinical discipline which might be called "orthocephalics" is already identifiable. The workshop was held at the National Institutes of Health in Bethesda, Maryland, on Feb. 12 and 13, 1974. The ideas exchanged were integrated and summarized by the planning committee to produce this report.

Animals↗
PubMed1976

Growth of the maxillary complex in the rhesus monkey (Macaca mulatta).

The growth of the maxillary complex of 36 rhesus monkeys (Macaca mulatta) was analyzed quantitatively and qualitatively during four defined stages of postnatal development (i.e., infant, juvenile, adolescent, young adult). At each stage, growth was observed during a 24 week period. Since some animals were observed during two successive stages of development, 47 periods of growth were studied. The incremental growth data were collected by superimposing serial cephalograms on cranial base implants and on maxillary implants. The largest increments of growth were observed in the infant animals and were successively less during the other periods studied. The horizontal growth component was more more prominent than the vertical component in all age groups. The contribution of sutural growth to the vertical displacement of the maxilla was greater posteriorly, leading to a rotation of the maxillary complex during growth. The occlusal relationship was maintained by selective bone remodeling in conjunction with dentitional migration.

Age Factors↗
PubMed1976

The remodeling of the edentulous mandible.

In a sample of mandibles having complete or nearly complete loss of dentition, the left half of each mandible was serially sectioned. The entire perimeter of each section was analyzed for the distribution of resorptive and depository periosteal surfaces, and from this information, the fields of remodeling were mapped for the mandible as a whole. The most common patterns of combined resorption-deposition and the range of variations were then determined. The over-all distribution of remodeling fields in the edentulous mandible differs markedly from that in the young, growing mandible. In most of the edentulous specimens, the surface of the basal bone on both the medial and lateral sides of the corpus is of a depository nature. The overlying alveolar regions on both the lingual and buccal sides, however, are characteristically resorptive. Significantly, the placement of the reversal line between the alveolar resorptive and the basal depository areas is much lower (i.e., at the level of the mental foramen) on the buccal side. Except for its inferior part, the lateral side of the ramus tends to be largely resorptive in character, and the posterior half of the lingual side also tends to be resorptive. Unlike the child's mandible, the posterior border of the ramus is resorptive, and the posteroanterior dimension of the ramus (not the whole mandible) becomes reduced and narrowed in conjunction with resorption along the anterior border. However, the amount removed from the anterior ramus is actually added to the dimension of the corpus, which becomes longer. Further, removal from the posterior ramus border does not affect the over-all length of the mandible unless condylar reduction is also involved. Also, over-all arch length is not decreased, because the surface of the mental protuberance is retained as a depository type of field (or at least does not become actively resorptive). The corpus-ramus angle (not gonial angle) is increased in the antegonial region. Because of the opening of this angle, over-all mandibular length as well as arch length is increased. In about half of the specimens, arch width was not decreased, because the lateral side of the corpus is usually of a depository nature. Notching of the anterior side of the condylar neck and the inferior part of the anterior ramus border is associated with resorptive fields in these regions, changes that are presumed to be a consequence of pressure contacts made with the articular tubercle and the maxillary tuberosity, respectively, in conjunction with a forward rotation of the whole mandible. The inferior direction of corpus realignment relative to the basal part of the ramus also increases the notching effect in the antegonial region, an effect augmented by the presence of the resorptive field in the notch itself. Certain specific variations commonly occur in several major regions of the mandible on both the lateral and medial sides...

Alveolar Process↗