An Evaluation of Guidelines for the Apical Enlargement of Maxillary Premolars
Kasahara, Yasuda, Yamada, and Miyazawa
Evaluation of Size Variation between Endodontic Finger Spreaders and Accessory Gutta-percha Cones
Hartwell, Barbieri, Gerard, and Gunsolley
Tumor Necrosis Factor Identified in Periapical Tissue Exudates of Teeth with Apical Periodontitis
Safavi and Rossomando
Adhesion of Sealer Cements to Dentin with and without the Smear Layer
Gettleman, Messer, and ElDeeb
Modeling Bacterial Damage to Pulpal Cells In Vitro
Hanks, Syed, Craig, Hartrick, and Van Dyke
Immune Cells in Periapical Granuloma: Morphological and Immunohistochemical Characterization
Piattelli, Artese, Rosini, Quaranta, and Musiani
An Evaluation of Guidelines for the Apical Enlargement of Maxillary Premolars
Etsuo Kasahara, DDS, DDSc, Eiichi Yasuda, DDS, DDSc, Hirohito Yamada, DDS, and Ayako Miyazawa, DDS
A newly proposed set of experimental guidelines for the final size of apical enlargement was evaluated by instrumenting filling and evaluating a series of extracted maxillary premolars. The guidelines were applied to differing anatomical configurations of this type of tooth, and to teeth in which instrumentation terminated at various distances from the foramen. Comparison was made with the conventional guideline of enlarging to three sizes greater than the first instrument that binds, with instrumentation to 0.5 mm from the foramen. All teeth were vacuum injected with India ink and dried, mechanically enlarged according to the experimental or conventional guidelines, and examined for the presence of apically extruded debris. The teeth were then filled, cleared, and visually inspected for the condition of preparation in the apical portion. For the conventional guideline, preparation was generally judged as poor, and debris was usually forced through the foramen. With the experimental guidelines, adequate preparation was obtained for most canal configurations at 0.5 and 1 mm from the foramen, and at 1 mm the incidence of extruded debris fell sharply. Anatomical conditions possibly contraindicating the experimental guidelines were found and characterized.
Evaluation of Size Variation between Endodontic Finger Spreaders and Accessory Gutta-percha Cones
Gary R. Hartwell, DDS, MS, Steven J. Barbieri, DDS, Scott E. Gerard, DDS, and John C. Gunsolley, DDS, MS
The diameter of nine sizes of three brands of endodontic spreaders was measured at D1 and D16 and compared with corresponding sizes of six brands of accessory gutta-percha cones. Two evaluators independently measured 20 randomly selected samples of each size of finger spreader and accessory gutta-percha cone. A standardized method of measurement was used for all samples and the interrater reliability was found to be extremely high using this methodology. Results indicated that very few of the diameters corresponded when like sizes of finger spreaders and accessory gutta-percha cones were compared. We concluded that there is a need for standardization by the manufacturer of finger spreaders so that accessory gutta-percha cones will fit into the space created by corresponding sized finger spreaders.
Tumor Necrosis Factor Identified in Periapical Tissue Exudates of Teeth with Apical Periodontitis
Kamran E. Safavi, DMD, MEd, and Edward F. Rossomando, DDS, PhD
Root canal samples, taken from periapical tissue exudates during routine root canal treatment procedures, were processed for identification of tumor necrosis factor using a mouse anti-human monoclonal antibody and enzyme-linked immunosorbent assay. Detectable levels of tumor necrosis factor were identified in periapical tissue exudates in chronic apical periodontitis.
Adhesion of Sealer Cements to Dentin with and without the Smear Layer
Bradley H. Gettleman, DDS, MS, Harold H. Messer, MDSc, PhD, and Mahmoud E. ElDeeb, BDS, MS
The influence of a smear layer on the adhesion of sealer cements to dentin was assessed in recently extracted human anterior teeth. A total of 120 samples was tested, 40 per sealer; 20 each with and without the smear layer. The teeth were split longitudinally, and the internal surfaces were ground flat. One-half of each tooth was left with the smear layer intact, while the other half had the smear removed by washing for 3 min with 17% EDTA followed by 5.25% NaOCl. Evidence of the ability to remove the smear layer was verified by scanning electron microscopy. Using a specially designed jig, the sealer was placed into a 4-mm wide x 4-mm deep well which was then set onto the tooth at a 90-degree angle and allowed to set for 7 days in 100% humidity at 37°C. This set-up was then placed into a mounting jig which was designed for the Instron Universal Testing Machine so that only a tensile load was applied without shearing or applying preloading forces. The set-up was subjected to a tensile load at a crosshead speed of 1 mm per min.
The results show significant differences (p < 0.001) among AH26, Sultan, and Sealapex, with AH26 being the strongest and Sealapex being the weakest. The only significant difference with regard to the presence or absence of the smear layer was found with AH26, which had a stronger bond when the smear layer was removed.
Modeling Bacterial Damage to Pulpal Cells In Vitro
C.T. Hanks, DDS, PhD, S.A. Syed, PhD, R.G. Craig, PhD, J.M. Hartrick, BS, and T.E. Van Dyke, DDS, PhD
There is increasing evidence that access to patent dentinal tubules by bacteria and their products rather than trauma from restorative materials is responsible for subsequent pulpitides. The purpose of this study was to compare the relative cytotoxicity of centrifugal fractions of two bacteria, Fusobacterium nucleatum and Treponema denticola, on L929 cells in monolayer cultures and in the "in vitro pulp chamber." Neutrophilic chemotaxis assays and Limmulus assays were performed to verify biological activity of the various fractions of these bacteria. It was found that T. denticola inhibits new protein synthesis in cultured cells to a much greater extent than F. nucleatum, but that only F. nucleatum fractions are chemoattractive for human neutrophils in the absence of serum. While the chemical nature and molecular weights of the "toxic" materials were not determined, it appeared that eukaryotic protein synthesis inhibition caused by the T. denticola pellet fraction in the in vitro pulp chamber was at least 1000 times less than that caused by the same concentrations in monolayer cultures.
Immune Cells in Periapical Granuloma: Morphological and Immunohistochemical Characterization
Adriano Piattelli, MD, Luciano Artese, MD, Sandra Rosini, MD, Manlio Quaranta, MD, and Piero Musiani, MD
Samples of periapical granulomas obtained from 12 patients were examined using light and electron microscopes and monoclonal antibodies. Monocytes/macrophages, lymphocytes, and plasma cells were nearly always the most abundant cell populations. Ultrastructural analysis showed close contacts between macrophages and cells of the lymphoid lineage, with the lymphoid cells frequently demonstrating blastic features. Immunohistochemical staining with the anti-interleukin 2 receptor antibody showed that the concentration of labeled cells was quite low. The vast majority were lymphocytes, though some mast cells were also labeled. Mast cells were chiefly located in perivascular areas and interleukin 2 receptor-positive mast cells were frequently associated with lymphoid cells. Mast cells could be part of a negative feedback mechanism in the immune response. By releasing histamine, they would block the immune response and by absorbing interleukin 2 they would remove it as an immune system stimulant.