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Biomedical subjects

J C Maltha

Publications and source records attributed to J C Maltha.

87 records · Page 5Linked to original sources
PubMed1984

Effect of splint placement on black-pigmented Bacteroides and spirochetes in the dental plaque of beagle dogs.

The gingival microbiota in beagle dogs was investigated during a period of 42 days after the placement of continuous wire and arch bar splints. The splints were found to induce an increase in helicoidal-shaped micro-organisms and black-pigmented Bacteroides. Two different asaccharolytic Bacteroides types were isolated and tentatively identified as B. gingivalis and B. asaccharolyticus. In addition, B. intermedius-like organisms were isolated. The last two species were observed only after splint placement. The local accumulation of helicoidal-shaped micro-organisms in the epithelial tissue rather than in the micro-ulcerations was regarded as an indication of an active role for these spirochetes in the disease process. The observed shift toward tissue-invading and potentially pathogenic micro-organisms after splinting stresses the need for antimicrobial measures during splint placement in order to minimize periodontal destruction.

Animals↗
PubMed1982

The effect of cavity preparation on the metabolism of protein in dentin.

Tritiated proline was administered to domestic cats during the development of their permanent dentition. The amount of residual radioactivity was determined autoradiographically at various times after cavity preparation in mature molars and premolars. Two wk after cavity preparation, the amount of radiolabel beneath the axial cavity wall decreased to about 50% of that present in corresponding contralateral cavity-free teeth. The observed decreases are ascribed to an enhancement of the protein metabolism in dentin. At 45 wk, 80-90% of the radiolabel has disappeared. This paper discusses the role of an eventual effect of microleakage on the latter results.

Animals↗
PubMed1980

Reactions of guinea pig subcutaneous connective tissue following exposure to sodium hypochlorite.

Experiments aimed at determining which concentration of sodium hypochlorite should be used clinically to achieve optimal dissolving and bactericidal but nonirritating effect are reported. The results of in vivo experiments, with polyethylene tubes implanted in the backs of guinea pigs, show that there is no significant difference in inflammatory response between sodium hypochlorite solutions in the concentration range of 2 to 8 percent, pH 12, and sterile physiologic saline.

Animals↗
PubMed1978

Preservation of rat liver tissue by endodontic therapeutic agents.

The preservation action of seven endodontic therapeutic agents has been tested on rat liver tissue. Such agents can be divided into three catagories: formaldehyde-containing, parachlorophenol-containing, and miscellaneous compounds. Besides their bactericidal and fungicidal effects, they also have a fixative action on tissue components. Because of this double action, they are called preservatives. In this series of experiments 25 percent formalin in 80 percent ethanol gave the best combination of bactericidal, fungicidal, and fixation properties.

Animals↗
PubMed1977

Procion brilliant orange, a counterstain for decalcified sections vitally labeled with procion brilliant red H-8 bs.

Procion brilliant red H-8 BS is a fluorescent dye that stains the organic matrix of bone supravitally. A procedure is described for counterstaining sections of such bone for visible light examination without interfering with the demonstration of sites of bound dye under UV illumination. Sections are brought to water, stained in Delafield's alum hematoxylin for 10 minutes, washed in tap water for 10 minutes, counterstained in 1% Procion brillant orange M-GS for 15 minutes and washed in distilled water for 10 minutes. After dehydration the sections were mounted in Eukitt.

Animals↗
PubMed1976

"Long distance" action of parachlorophenol and formalin in polyethylene tubes implanted in guinea pigs.

Two endodontic intracanal medicaments (parachlorophenol and formalin) in polyethylene tubes were tested for their irritant effect by implantation in the backs of guinea pigs. Histologic evaluation at 3 days showed an exudate with polymorphonuclear leukocytes in the open part of the tube. At 10 days most of the tubes showed fibroblast migration into the open lumen, with necrotic tissue trapped between the fibroblast migration and the exudate. At 90 days only a little fibroblast migration was found in all of the tubes. No necrotic tissue was trapped and no irritation was seen. No difference could be observed between the reaction in the experimental and the control situations.

Animals↗
PubMedDate not supplied

Cranio-maxillo-facial tissue expansion, experimentally based or clinically empiric? A review of the literature.

The literature over 10 years covering tissue expansion in cranio-maxillo-facial surgery is reviewed. Since 1981, an evolving set of indications for application of the soft-tissue expansion technique has been published. However, it seems to be based much more on clinical experience (empiricism) than on the results of thorough experimental research. The direction of future research should be aimed at effects on bone, cartilage and mucosa at a microscopical level, and at the influence on growth and development of cranio-maxillo-facial structures.

Face↗
PubMedDate not supplied

Preparation-induced stability of bioactive apatite coatings.

The stability of the bioactive surface is a major concern in the chemical and physical design of apatite ceramic coatings. In clinical studies, no sintered-hydroxyapatite bulk coating material was present in the surrounding bone tissue after loading periods up to 11 years. In in vitro studies, hydroxyapatite plasma-sprayed coatings dissolved considerably, possibly because of loss of crystallinity during the plasma-spraying procedure. A heat treatment at 600 degrees C reconstituted the crystallinity and promoted the transformation of alpha-tricalcium phosphate into the more stable beta-tricalcium phosphate. Fluorapatite coatings did not lose their crystallinity and had the added advantage of stability as a result of the fluoride ion.

Animals↗
PubMedDate not supplied

Mandibular bone response to plasma-sprayed coatings of hydroxyapatite.

Sintered hydroxyapatite ceramic particles can be applied as a coating on a titanium substrate using a plasma-spraying technique. The biological and mechanical properties of implants with such a coating were studied in the mandible of a dog. The results indicated that a very strong and direct bonding between the hydroxyapatite coating and the mandibular bone developed. The shear strength of the bone/ceramic interface was higher than the interfacial strength between ceramic and titanium substrate. From the radiologic, macroscopic, and microscopic observations it was concluded that the biological properties of plasma-sprayed coatings of hydroxyapatite are the same as those of sintered hydroxyapatite ceramic. As a result of mechanical failure of the coherence of the hydroxyapatite particles at the outer layer of the coating, free particles of hydroxyapatite were observed in the surrounding bone tissue.

Alveolar Process↗