Gifu Shika Gakkai zasshi = The Journal of Gifu Dental Society最新文献

In an effort to assess the influence of acid etching and air drying on the production of cracks in the surface of glass-ionomer cement, the two procedures were employed over progressively increased durations, and any resulting surface cracks in the cement, were examined by replica techniques under an SEM (Scanning Electron Microscope). The results showed that acid etching alone did not produce cracks, but air-drying by compressed air produced cracks at durations between 5 and 30 sec.

Eight endodontic agents were tested for their reactivity with DNA by the rec-assay system. Employing 2 strains of Bacillus subtilis with different recombination capacities, the assay suggested that DNA damage is produced by agents for root canal cleaning containing sodium hypochloride. Other endodontic drugs, including disinfectants for caries cavities, sedatives for pulp, root canal disinfectants, and pulp devitalizing agents containing phenol, camphor, tricresol, formalin, and paraformaldehyde were also positive by rec-assay and would seem to potentially of damage cellular DNA in Bacillus subtilis. Though no clear evidence exists that drugs showing positive results by rec-assay induce malignant tumors in the oral region, these agents should be used carefully since they would seem to possibly cause genetic toxicity in mammalian cells.

Local anesthetics have been shown to affect a variety of cellular activities, such as exocytosis, membrane transport, permeability of calcium, and platelet aggregation, among others. Despite the disparate nature of the above phenomena, the calcium ion is essential for all of these cellular processes. Recently, it has been shown that local anesthetics inhibit specific calmodulin-dependent enzymes and protein kinase C-dependent enzymes. Therefore, the mode of action of local anesthetics in the activation of guinea pig neutrophils was examined in this study in order to understand the effect of local anesthetics on the intracellular calcium messenger system. In the presence of calmodulin inhibitors, FMLP-induced chemotaxis and superoxide anion production were strongly suppressed, whereas 1-oleoyl-2-acetylglycerol(OAG)(a direct activator of protein kinase C)-induced superoxide anion production was not affected. In contrast, protein kinase C inhibitors suppressed OAG-induced superoxide anion production but no inhibiting effect on FMLP-induced chemotaxis and superoxide anion production. Local anesthetics suppressed both FMLP- and OAG-induced activation of guinea pig neutrophils. These findings suggest that the inhibiting effect of local anesthetics on the activation of the intracellular calcium messenger system may be part of the pharmacological mechanism of local anesthetics in cellular activities.

In orthodontic diagnosis, one of the most important factors is to decide whether or not to extract permanent teeth. There are many so-called borderline cases. In analyzing and determining whether or not to extract, discrepancy, profile, growth, and the patient's understanding and cooperation must be considered. We treated a borderline case without extraction, and established good occlusion and profile. Soft tissue changes are chiefly discussed.

The cytotoxic effects of an oxide-anodized titanium alloy were investigated by cell and organic culture studies. Toxicity was estimated based on cell survival and growth rates compared with those of control materials (glass) after cultivation of cells (L 929) and chicken embryonic femurs expose to alloy plates. The oxide-anodized titanium alloy showed no cytotoxicity with respect to survival or growth rates in either cells or chicken embryonic femurs. Furthermore, the oxide-anodized titanium alloy was more acid and alkali resistant than intact titanium alloys. The results suggest that oxide-anodized titanium has greater stability and its metallic ions may be leachedless under various conditions following dental implantations. Therefore, this alloy should be suitable for use as a dental implant material.

The use of soft lasers in dental therapy has increased dramatically in recent years. However, there is a dearth of reports in the literature of controlled in vivo and in vitro studies of soft laser effectiveness with respect to dentinal pain. The purpose of this study was to assess the analgesic effects of soft laser treatment by the following five studies: (1) Clinical evaluation of soft laser irradiation of hypersensitive dentin. (2) Morphological study of dentinal surfaces following soft laser irradiation. (3) Study of the effect of soft laser irradiation on dentinal fluid movement. (4) Study of the effect of soft laser irradiation on the jaw opening reflex (JOR) in rats. (5) Study of thermal changes on the internal wall of pulp chamber with soft laser irradiation. After soft laser treatment of 3 min to hypersensitive dentin, patients experiences diminished sensitivity in 46 of 55 teeth (83.6%). In model experiment with extracted human teeth, the energy levels of this laser were too low to produce any morphological changes on the surface of exposed dentin, and dentinal fluid movements induced by air blasts for 15 sec to exposed dentin were not affected by laser irradiation to the dentin for 3 min. Moreover, there was an immediate 0.7 degree C increase in the temperature of the internal wall of the pulp chamber by laser irradiation to the tooth surface. In experimental rats, the digastric EMG induced by 1.3 x T (T: threshold value producing the JOR) was reduced by 3 min soft laser irradiation to teeth or Ho-ku points, but not at 2.0 x T. These results suggest that soft lasers have an analgesic effect, but the latter is affected by the degree of stimuli-elicited pain, and may be due in addition to descending inhibition in the central nervous system.

The induction of mutation by cadmium chloride (CdCl2), platinum tetrachloride (PtCl4), and rhodium trichloride (RhCl3.3H2O) was measured utilizing the hypoxanthine-guanine phosphoribosyl transferase (HGPRT) locus in V-79 cells. Cadmium chloride at a concentration of 0.05 microM induced ford mutation in V-79 cells 4 times that of their control mutation frequency. Platinum tetrachloride at a concentration of 15 microM and 300 microM rhodium trichloride also induced ford mutation in V-79 cells at rates of around 7 and 4 times control rates, respectively. Platinum is often, and rhodium sometimes added to dental metallic alloys to improve their metallurgic characteristics and cadmium has been mingled in such alloys as well. Moreover, metallic dental drugs such as K2PtCl4 are used a dentine desensitizers. Thus, the genetic hazards of metal ions including cadmium, platinum, and rhodium that dissolve from dental materials and drugs must be investigated and caution exercised for their safe use in dental clinics.

We evaluated 12% Au-Ag-Pd alloy cast lower denture plates prepared by dental students in laboratory exercises for casting defects. First, we determined the most suitable exposure conditions for nondestructive radiographic test of 12% Au-Ag-Pd alloy. Subsequently, 130 plates were nondestructively evaluated by radiography under the most suitable exposure conditions. In radiographic testing using X-Omat RP films (Eastman Kodak Co.) and X-Omatic Fine Screen (Eastman Kodak Co.), the most suitable exposure conditions involved a target-to-film distance of 1.9 m, tube voltage of 148 Kvp, tube current of 10 mA, and exposure time of 1.5 sec. Preliminary radiographic examination of artificial casting defects revealed semispherical defects in the diameter of 0.25 mm in 1.6 mm-thick 12% Au-Ag-Pd alloy plates and detects of 0.26 mm in 2.4 mm thick plates. In the 130 cast plates, 56 casting defects were detected. These defects were found at the left webbing part in 40 (30.8%), right webbing part in 36 (27.7%), lingual bar in 7 (5.4%), I-bar in 4 (3.0%), and at other regions of the metal frames in 3 (2.3%) cases. These results indicate that nondestructive radiographic testing is as effective in detection of casting defects in 12% Au-Ag-Pd alloy cast plates as it is in Co-Cr and Ni-Cr alloy plates. This method was also found to be effective in evaluation of the practice metal frames constructed by dental students.