近年, 培養歯根膜細胞やそこから分取した組織幹細胞の歯周組織再生への応用は, より確実な歯周組織再生療法を確立するための一つの戦略であると考えられている.しかし, この細胞集団はヘテロであり, 現時点では種々の問葉系細胞の前駆細胞や問葉系幹細胞がどの程度存在するかを直接的に知ることはできない.そこで本研究では, このような細胞療法を確実なものにするための第一段階として, 培養ヒト歯根膜細胞 (HPL cells) の骨, 脂肪, 軟骨への分化能を, コントロールとして使用したヒト骨髄問葉系幹細胞との比較において定性的に評価した.その結果, HPL cells中には骨芽細胞様細胞が豊富に存在しており, また脂肪細胞前駆細胞も存在するもののその数は著しく少ないこと, 一方, 軟骨細胞前駆細胞の存在の可能性は著しく低いことが明らかになった.さらに, 脂肪細胞前駆細胞はHPL cellsから分取したalkaline phosphatase陽性細胞率の低い細胞集団に多く存在していた.

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To prevent over-cutting of the sclerotic dentin, we developed a new caries detector (Caries Check, Nippon Shika Yakuhin Co., Ltd., Japan) composed of polypropylene glycol containing acid red. The purpose of this study was to observe the ultra microstructure of the adhesive interface between resin composite and dentin after cutting the dentin in accordance with the conventional Caries Detector or Caries Check staining. In the Caries Check specimen, the dentin tubules were filled with debris and penetration of the bonding agent was limited in the peri-tubular dentin. In the Caries Detector specimen, the dentin tubules were open and a resin tag formed in the dentin tubules. It was possible to conclude that the sclerotic dentin was preserved under the guide of staining by Caries Check. The results suggest that dentin bonding was not obtained by monomer penetration into the superficial substrate dentin or into the dentin tubules.

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The aim of the present study was to investigate systematically the effects of noxious stimulation applied to the oral-facial region on visceromotor responses to colorectal distention. In the present study an electromyogram (EMG) of the external abdominal oblique muscle evoked by colorectal distention was measured as a visceromotor reflex response, and inhibitory effects of noxious stimulation were estimated by the decrease of EMG activity. Under halothane anesthesia (1 % in air), colorectal distentions (60 or 80 mmHg) were produced by inflating a balloon inside the descending colon and rectum. Innocuous brush and press stimuli applied to the facial skin did not induce any change in EMG responses evoked by colorectal distention. Noxious pinch stimuli produced a profound reduction of EMG responses during application of pinch. This inhibitory effect remained even after the cessation of pinch stimulation. Pinch stimulation was effective both ipsilaterally and contralaterally indicating a bilateral effect. When the inhibitory effects of ipsilateral pinch stimulation at various parts of the oral-facial region were examined, no significant difference in the inhibitory effect was observed among the oral mucosa, the tip of the tongue and the root of the tongue. A comparison of the inhibitory effects of ipsilateral pinch stimulation among the areas innervated by three branches of the trigeminal nerve showed no significant difference in the inhibitory effect among areas. Electrical stimulation of the tooth pulp (1.6 mA, 50 Hz, 0.1 ms pulses) also reduced the EMG responses to colorectal distention. Following the application of naloxone (2 mg/kg, i.p.), an opioid receptor antagonist, the decreased EMG responses during pinch stimulation were reversed. These results suggest that noxious stimulation to the oral-facial region can suppress visceromotor reflex responses to colorectal distention and that this suppression is mediated by the opioid system. A possible mechanism for trigeminal suppression of visceromotor function is discussed.

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乳歯の外傷では脱臼が起こりやすいことはよく知られているが, 脱臼症例への対応については近年, 見解の変化がみられる.種々の基礎・臨床研究をべ一スにした脱臼乳歯への対応法の変化について概説する.とくに陥入 (埋入) 症例への対応が, 再萌出を期待できるものは整復などの侵襲を加えずに経過観察する方針がとられるようになってきたことや, 完全脱臼 (脱落) 症例でも条件が許せば再植が実施されるようになったことなど, 最新の対応法について述べる.また, 外傷乳歯の予後の診かたについても, 最近の情報を提供する.

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