Biomedical subjects
Publications and source records attributed to A E Michanowicz.
This article presents a case of a two-rooted maxillary central incisor with previous endodontic therapy. One root canal was well filled and the other partially filled. A post was present in each root and the tooth had a crown. Surgery was performed and an amalgam retrograde filling was placed. A 6-month postoperative radiograph shows repair.
An injectable thermoplasticized gutta-percha system (Ultrafil) was used to fill 50 teeth which were monitored radiographically over a period of 24 months. An equal number of teeth were filled with the lateral condensation technique and used as controls. Radiographic evidence of success was determined at a 24-month recall. The results were subjected to a 2 x 2 analysis of variance (control versus experimental/before and after treatment. There was a significant amount of repair irrespective of obturation procedure (p greater than 0.0001). Thirteen teeth in the experimental group randomly filled with sealer showed that the sealer did not influence repair.
Three tests were used to obtain a basic understanding of the changes taking place in the physical properties of the Hygienic Ultrafil system. The materials studied were raw gutta-percha, gutta-percha points, and the two Ultrafil materials Blue (firm set) and White (regular set) gutta-percha. In the first test a differential scanning calorimeter was used to determine melting points; two crystalline forms were observed in the dental materials and only one crystalline form in the raw gutta-percha. In the second test a magnetic bearing torsional creep apparatus was used in which the rates of crystallization were observed. The differences seen in the induction times of the crystallization are related to the amount of mastication of the gutta-percha. Mastication in this usage is the manufacturers process of mixing the raw gutta-percha with its other components. The gutta-percha is masticated slightly in the points and considerably more in the Ultrafil material. Ultrafil exhibits longer periods of time required to induce nucleation at any specific temperature due to the increased mastication. Melting points were also decreased with increased mastication. In the third test a dilatometer was used to observe isothermal volumetric shrinkage of the materials during crystallization. When the Ultrafil material was compared with the gutta-percha points, the blue material had approximately the same amount of shrinkage, 2.6%; the white material shrank slightly less, 2.2%. The raw gutta-percha being 100% polymer had the greatest amount of shrinkage, 4.6%.
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This study compared two different dental materials used in endodontic retrosealing procedures. One of these materials was a new low-temperature gutta-percha product, manufactured by the Hygenic Corporation, that involved an injection technique. The second of these materials was silver amalgam. Silver amalgam was selected because it has been recognized by many clinicians as the most effective apical sealing material. Two groups of ten recently extracted teeth were endodontically prepared with one of each of the materials being tested, and the effectiveness of these materials as sealants was determined by their ability to inhibit the penetration of methylene blue dye for a predetermined period of time through the apically sealed root tips. Preliminary results obtained indicated that, although these materials were not 100% effective in inhibiting the dye penetration, each was as effective as the other when evaluated by two observers following completion of the study as determined by its experimental design. No significant difference was exhibited between the amalgam group and the gutta-percha group. The leakage of the dye that was observed in each of the groups might have been caused by the ineffectiveness of, or the ineffective use of, the nail polish or cyanoacrylate used to coat all but the apically sealed tips of the endodonticalled prepared teeth. The function of these coating materials was to prevent penetration of the dye through the surface of the body of the root.(ABSTRACT TRUNCATED AT 250 WORDS)
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The diplomates of the American Association of Endodontists were surveyed regarding difficulties in regionally anesthetizing acutely painful mandibular molar teeth. Frequently patients developed evidence of adequate regional block anesthesia but experienced pain when the dentist attempted access. A pilot projection was undertaken to determine if a scientific basis existed for this problem. With the animal under general anesthesia, the mandibular nerve of a cat was isolated and then regionally blocked. A stimulating electrode was implanted in a cuspid tooth and a receiving electrode in the cortex of the brain. When a state of inflammation was created in the tooth in the presence of a regional block, there was an increasing cortical response to this stimulation. It was concluded that the pilot project offered a realistic technique for the study of this clinical entity.
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