Biomedical subjects

R F Klinge

Publications and source records attributed to R F Klinge.

4 recordsLinked to original sources

PubMed2001

Further observations on tertiary dentin in human deciduous teeth.

The structure of reparative tertiary dentin in human deciduous teeth has been studied. Reparative dentin is secreted by a new generation of odontoblast-like cells which have been subject to strong stimuli, e.g., trauma or deep active caries lesions with associated pulp inflammation. Ground sections of 25 teeth were prepared, and contact microradiographs were produced. Another 30 teeth were demineralized, embedded in paraffin, sectioned, and stained with hematoxylin and eosin. Some demineralized sections from each tooth were also studied in the scanning electron microscope. Most of the teeth showed some type of tertiary dentin formation. Mineralized tissue with a varied morphology was observed. In teeth which had been subject to trauma, the entire pulp chamber was sometimes obliterated. Mineralization seemed to start in the incisal region, and the central part of the pulp was the last part to be obliterated. Radiolucent voids and canals were seen. The organic matrix was dense and fibrous. In the pulp chamber and especially in the root canals, resorption had often occurred, indicating that signals giving rise to odontoclasts were also present. Resorption was often followed by deposition of various amounts of cementum-like repair tissue. The cells responsible for the formation of reparative dentin are believed to be subodontoblasts or undifferentiated ectomesenchymal cells. The varied morphology of the reparative dentin, observed in the pulp of the teeth examined, indicates that different stimuli lead to induction of hard-tissue-forming cells which produce different types of hard tissue.

Cementogenesis↗

PubMed1999

A microradiographic and electron microscopic study of tertiary dentin in human deciduous teeth.

This study deals with the structure of the inorganic phase of tertiary dentin, and is limited to dentin formation caused by mild or moderate stimuli, e.g., attrition or initial or shallow carious lesions. Ground sections were prepared from 20 human deciduous teeth extracted mainly because of orthodontic treatment, and contact microradiographs were produced. Based on visual inspection of the ground sections in reflected and transmitted light and microradiographic findings, small areas were dissected out and processed for electron microscopy. In the tertiary dentin formed in the pulp horns the number of tubules was reduced, while in that on the side walls of the pulp there was often no marked reduction in the number of tubules. Several tubules could be followed from the physiological (primary and secondary) dentin into the tertiary dentin, and a change in the direction of the tubules was often noted. Interglobular dentin was frequently observed, and in some teeth incremental lines with alternating high and low mineral content were seen, indicating that tertiary dentin, like other mineralized tissues, is subject to biological rhythms during formation. When studied in the electron microscope, tubules with varying size and distribution as well as occluded tubules with a high mineral content were seen. The tubules often had an irregular circumference with projections of mineralized tissue protruding into the lumen. Highly mineralized peritubular dentin was rarely observed. The present results show that orthodentin is formed when dentin in primary human teeth is exposed to mild or moderate stimuli.

Dental Cavity Preparation↗

PubMed1996

The structure of the mandibular condyle in the monkey (Macaca mulatta).

The articulating surfaces of bones which ossify in mesenchyme, like the mandible, are covered by a layer of dense, fibrous tissue. The purpose of the present study was to examine the structure of the mandibular condyle in the monkey. Young Rhesus monkeys (Macaca mulatta) were perfused with glutaraldehyde-paraformaldehyde. Small pieces of the condyles were dissected out, demineralized in 0.5 M EDTA and processed for light microscopy and electron microscopy. The mandibular condyle was covered by an avascular tissue, extending from the surface to the underlying bone. The tissue could be divided into three zones. The zone facing the articular cavity was about 50 microns wide and consisted of a dense, fibrous tissue. Layers of collagen fibers, 1-4SS microns wide and parallel with the articular surface, but oriented at angles to each other, were seen. Between the collagen fibers fibroblast-like cells were noted. The second zone was also approximately 50 microns wide and rich in cells. The cells were ovoid or flat and had a dark staining cytoplasm with some mitochondria and a well developed rough-surfaced endoplasmic reticulum. The third zone was about 150 microns wide and here the cells were larger and located in lacunae. An increase in the size of cells and lacunae was seen approaching the bone. This zone showed hyaline cartilage undergoing maturation. Closer to the bone, degeneration of the chondrocytes was noted. In the underlying bone, soft tissue with several chondroclasts resorbing the hypertrophic cartilage were seen, alternating with areas where bone formation was occurring, partly on the top of cartilage remnants. The observations confirm that in the growing condyle there is an articular part as well as a growth zone, and that the cells in the cell-rich zone serve as precursors for the hyaline cartilage cells in the growth zone, and possibly as a cell reservoir for the articular part as well.

Animals↗

PubMed1993

The ultrastructure of copper amalgam-covered dentin from human deciduous teeth.

The structure of dentin subjacent to Cu-amalgam restorations was studied. The restorations had been inserted 7-8 years before extraction of the teeth. No lining had been applied. The dentin subjacent to the restorations had a greenish-grayish discoloration, and in the pulpal end irregular secondary dentin had formed. Energy-dispersive X-ray microanalysis of areas showing discoloration confirmed the presence of Cu. Semithin and ultrathin undemineralized sections were studied. Vital pulp tissue and irregular secondary dentin were observed. Close to the predentin and halfway into the dentin most of the dentinal tubules were occluded. In the control material only an occasional occluded tubule was seen. Close to the Cu-amalgam restoration some tubules were occluded or partly occluded, and some were open. The odontoblasts had responded to the irritating agent by obturation of the tubules, thus reducing the permeability of the dentin. Furthermore, irregular secondary dentin had formed in another attempt to wall off the irritating agent.

Child↗