Angiotensin II acts as an excitatory neurotransmitter of the sympathetic ganglia. In the parasympathetic neurons, however, angiotensin II (angio II)-induced responses have not been recorded. In this study, we investigated the effects of angio II in the hamster submandibular ganglion (SMG) neurons using a intracellular recording technique. Approximately 70% of these ganglion cells responded with persistent depolarization (3-6mV, 5-9min) at a concentration of 10μM. The angio II-induced depolarizations were caused by the combination of an increase in Na⁺ conductance and a decrease in K⁺ conductance. An involvement of K⁺ channels such as M channels and SK channels in the electrogenesis mechanism was suggested by an inhibitory effect of Ba²⁺ ion on the component of the increased membrane input resistance during the angio II-induced depolarization. In addition, the angio II-induced depolarizations were mediated through angio II type I (AT₁) receptors. Thus angio II is probably a neurotransmitter that increases their excitability in most of the neurons in parasympathetic ganglia.

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We characterized a voltage-dependent ionic current in dental pulp cells on dental pulp slices using a nystatin perforated-patch recording configuration. The outward currents in dental pulp cells were inhibited by the following channel blockers: 1) Ca²⁺-free extracellular solution containing 10mM Ba²⁺, 2) extracellular 400nM apamin and 3) extracellular 300nM 4,4´-diisothiocyanatostilbene-2,2´-disulfonic acid (DIDS). On the other hand, 15mM tetraethylammonium (TEA) did not inhibit the outward currents. The inhibitory effects of Ca²⁺-free extracellular solution, apamin and DIDS had voltagedependency. These results indicated that dental pulp cells expressed a small-conductance Ca²⁺-activated K⁺ current (SK current) and a DIDS-sensitive Cl^- current. The functional significance of these channels is discussed.

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Resin bond strength to Er:YAG laser irradiated dentin has been reported to be lower than that of unlased dentin. The reasons have been much discussed, but not clarified. One hypothetical cause has been discussed that lased dentin is acid resistant, therefore, the etching effect of acid conditions decreases. The purpose of this study was to evaluate the acid resistance of laser-irradiated dentin and compare it with the dissolved mineral of Er:YAG laser irradiated dentin and unlased dentin. This experiment was a pilot study to assess the etching effect of pre-conditioner for resin bonding to lased dentin. Bovine dentin was irradiated by Er:YAG laser and immersed in 0.1M lactic buffer solution (pH4.0). The dissolved Ca and P in the solution were then both measured. Dissolved Ca from lased dentin was not significantly different from that coming from unlased dentin (p>0.05). The molar ratio of Ca/P did not differ significantly between lased and unlased dentin, either (p>0.05). Under FE-SEM view before immersion, the dentin surface was covered with a smear layer in unlased dentin, but this layer was not clearly observed in lased dentin. These results suggested that the lased dentin had little or no resistance to lactic buffer solution.

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Dental alloy surface finishing procedures of may influence their electrochemical behavior, which is used to evaluate their corrosion resistance. We examined the polarization resistance and potentiodynamic polarization profile of the precious-metal alloys, Type 4 gold alloy and silver-palladium alloy, and the base-metal alloys, nickel-chromium alloy, cobalt-chromium alloy, and CP-titanium. Three types of finishing procedure were examined: mirror-finishing using 0.05μm alumina particles, polishing using #600 abrasive paper and sandblasting. Dissolution of the alloy elements in 0.9% NaCl solution was also measured and compared with the electrochemical evaluation. The corrosion resistance of the dental alloys was found to relate to finishing as follows: The polarization resistance and potentiodynamic polarization behavior revealed that the corrosion resistance improved in the order of sandblasting, #600-abrasive-paper polishing, and mirror-finishing. While the corrosion potential, critical current density and passive current density varied depending on the type of finishing, the transpassive potential remained unchanged. The influence of finishing on the corrosion resistance of precious-metal alloys was less significant than on that of base-metal alloys. A mirror-finishing specimen was recommended for use in evaluation of the corrosion resistance of various dental alloys.

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The purpose of this study was to examine the influence that the anteroposterior mandibular displacement near the tapping point exerts on the myoelectric activity of masseter and temporal muscles at a specific occluding force and to clarify the possibility of judging the mandibular position by measuring the amount of myoelectric discharge. Eight dentulous subjects were selected for the study. Surface electrodes were placed over the anterior, middle and posterior regions of the masseter muscle and over the anterior, middle and posterior bundles of the temporal muscle. Independently of the measurement region, the changes in the masseter and temporal muscle myoelectric activity which accompanied the anteroposterior mandibular displacement, were low. Moreover, when the mandible was displaced anteoposteriorly, the total amount of the myoelectrical discharge from all the recorded places, as well as the amounts of myolectrical discharge over the middle part of the masseter muscle and the anterior bundle of the temporal muscle reached their lowest values in those mandibular positions which included the tapping point in less than half of the subjects. Therefore, this study indicates that the possibility of judging anteroposterior mandibular displacement by masseter and temporal muscle electromyography is quite low.

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A case of edentulous prognathism in a 46-year-old Japanese male is presented. We described the outcome of the patient who underwent simultaneous sagittal splitting ramus osteotomy of the edentulous mandible, interpositional bone graft of severely atrophic edentulous jaws, and delayed placement of titanium implants for reconstruction. We highly recommend performing a surgical simulation using a craniofacial model of the patient's anatomy created using CT image data. The procedure provides almost ideal maxillary and mandibular contours.

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