Tissue reaction to implantation of unfixed and glutaraldehyde-fixed heterologous tissue

Clinical implications of the smear layer in endodontics: a review

It has been recognized for many years that root canal instrumentation produces a smear layer that covers the surfaces of prepared canal walls. This layer contains inorganic and organic substances such as fragments of odontoblastic processes and necrotic debris. There is a lack of agreement regarding the effect of the smear layer on the quality of instrumentation and obturation, but the smear layer itself may be infected and may protect the bacteria within the dentinal tubules. Various methods have been used to remove the smear layer. Conflicting results have been obtained from numerous in vitro studies regarding the significance of the presence or the removal of the smear layer.

The role of intracanal medication in root canal treatment

The role of intracanal medication as a root canal dressing is re-examined. In pulpectomy and some root canal treatments, where the root canal contains vital pulp tissue, it is doubtful whether a routine intracanal medicament is needed. In infected root canals, intracanal medication has been advocated for many purposes. An intracanal medicament is used to: (i) eliminate any remaining bacteria after canal instrumentation; (ii) reduce inflammation of periapical tissues and pulp remnants; (iii) render canal contents inert and neutralize tissue debris; (iv) act as a barrier against leakage from the temporary filling; (v) help to dry persistently wet canals. However, most of the indications for intracanal medicaments are questionable. Intracanal medicaments should only be used for root canal disinfection as part of controlled asepsis in infected root canals, and their role is secondary to cleaning and shaping of the root canal. Thorough canal debridement and adequate canal preparation are more pertinent, and their importance is emphasized. Bacteriological sampling may be necessary if a tooth does not respond to treatment, to help in the choice of intracanal medicament.

The effect of formocresol and glutaraldehyde on certain enzymes in bovine dental pulp

The effect of a 2-hour formocresol and glutaraldehyde treatment on two enzymes of bovine pulp was measured. Lactic dehydrogenase, a respiratory enzyme, was sharply affected by 0.5 percent and one percent glutaraldehyde and a 1:5 dilution of formocresol, exhibiting 7-, 71-, and 40-fold decreases in activity, respectively. Alkaline phosphatase was much less responsive to these same agents, giving only 4.5-, 17-, and 2.5-fold reductions after treatment, respectively. These findings support histochemical studies which have suggested the sensitivity of respiratory enzymes of the pulp to fixative medicaments.

The distribution of [14C] leucine and 85Sr labeled microspheres from rat incisor root canals

The distribution of [14C] leucine and 85Sr labeled tracer microspheres from rat incisor pulp canals was investigated in an effort to establish the potential for passage of substances from within the root canal to the systemic circulation. Following introduction of the tracer materials into the pulp canals, the radioactivity in the lungs, spleen, kidney, liver, heart, blood, skeletal muscle, adrenal glands, salivary glands, and submandibular lymph nodes was determined. At all of the time intervals studied the incorporation of [14C] leucine into the adrenal gland was significantly greater than the [14C] leucine incorporation into the other organs. High levels of 85Sr labeled microspheres were detected in the ipsilateral submandibular glands and submandibular lymph nodes and in the lungs.

Short-term tissue reactions to enclosed glutaraldehyde-fixed tissue

Polyethylene tubes closed at both ends and with four perforations in the sidewalls were filled with glutaraldehyde-fixed isologous tissue and implanted subcutaneously in rats. The cell reaction during the first 12 days in the tissues adjacent to the tubes was histologically examined. The reaction was compared to the reaction around tubes implanted empty. The examination showed a severe inflammatory reaction with probably immunologic aspects in the tissues adjacent to the filled tubes. The reaction around the empty tubes was slight and transient.

The response of the living organism to dead and fixed dead enclosed homologous tissue

Polyethylene tubes at both ends and with four perforations in the side walls were filled with untreated homologous necrotic muscle tissue or formaldehyde-fixed or glutaraldehyde-fixed homologous necrotic tissue and implanted subcutaneously in rats. The cell reaction in the tissues surrounding the differently filled tubes was examined. It was found that the inflammatory reaction to untreated necrotic homologous tissue was the least severe.

Release of endotoxin in an experimental model simulating the dental root canal

The action of endotoxin on subcutaneous connective tissue was examined in an experimental model simulating the dental root canal. The local Shwartzman reaction was used as a tool to detect slight tissue alterations that might otherwise go unobserved. The experimental results warrent, in our opinion, the tentative conclusion that the primary toxicity of endotoxins has no major part in the initiation or maintenance of chronic periapical inflammation.