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Eugenol is a main ingredient of clove oil, and either eugenol or clove oil is important constituent in various dental preparations. Rather strong allergenicity of eugenol was confirmed in examination with two methods of modified guinea pig maximization test, which is called adjuvant and patch test, and ear swelling test in mice. Possibility that delayed contact hypersensitivity is induced by use of an eugenol preparation must be admitted. It is found that eugenol in various dental preparations is applied to contact with gingiva or teeth in an enough concentration to cause hypersensitivity especially in the case of some zinc oxide-eugenol preparations such as periodontal dressings and root canal cements. On the other hand clove oil and eugenol are more widely and frequently used for cosmetic and food processing than for dental treatment, and there would be many opportunities in man to get hypersensitivity to eugenol. Even in the case of a new patient the correlation between the allergic symptoms and dental treatment will give rise to the supposition that an eugenol preparation is causing the trouble.

A newly developed calcium phosphate cement, MM, was evaluated for tissue irritability by means of cell cultures. In this study, MM showed extensive mild cytotoxicity compared with other cements before setting. Inhibition of adhesion of L-929 cells was not observed after contact with MM for 24 hours. The influence of MM on colony formation was approximately the same as that of another calcium phosphate cement and less than that of a glass ionomer cement. Toxicity of MM after setting was compared with four cements; another calcium phosphate cement, glass ionomer cement, silicate cement and zinc oxide eugenol cement, but MM showed the least influence on cell morphology. Judging from these results, MM appears to be less cytotoxic than the cements in current use.

ペプトンで誘導したマウス腹腔マクロファージ (P-M) とlipopolysaccharideで誘導したマウス腹腔マクロファージ (L-M) を, in witroで培養すると, いずれのマクロファージも, 球状の細胞 (Aタイプ), 短い紡錘状の細胞 (Bタイプ), 長い紡錘状または伸展した細胞 (Cタイプ) の3タイプに分けられる。本研究では, P-MとL-Mをホルマリンとクレゾールの等量混合物であるホルマリンクレゾール (FC) に, 5～1000μg/mlの濃度で5～30分間接触させ, FCの影響を形態的に調べてP-MとL-Mの比較, およびA, B, Cタイプ間の比較を行なった。P-MもL-MもFC濃度が5μg/mlの場合は殆ど変化せず, 10μg/mlの場合は細胞の収縮による変形を起こし, 100μg/ml以上の場合には細胞の変形は少なく, 殆ど固定された状態となった。10μg/mlの場合に見られる細胞の変形はP-MよりもL-Mの方が軽度であった。P-MもL-MもFCによってCタイプが減少し, Aタイプが増加する傾向が認められた。位相差顕微鏡下で経時的に観察すると, CタイプがFCに最も強く反応した。走査型電子顕微鏡でP-Mを観察すると, 10μg/mlのFCにより, Aタイプでは細胞表面にフリル状のラッフルが見られ, B, Cタイプでは細胞表面に大小さまざまな丸い突起物が見られた。以上により, (1) 10μg/mlと100μg/ml以上の場合ではFCのマクロファージに対する作用の機序が異なること, (2) 100μg/mlより低い濃度では, L-MはFCに対してP-Mよりも強い抵抗性を示すこと, (3) 形態的変化を蒙る程度はP-MもL-MもCタイプ, Bタイプ, Aタイプの順に大であること, が明らかとなった。

To examine the significance of combined administration of formalin and cresol, antimicrobic efficacy, topical irritability and acute toxicity of FC (formlin: cresol=50%: 50%) were observed, and were compared with those of formalin or cresol administered individually. Obtained results were as follows:1. When formalin was administered with cresol, the disinfective effect of formalin was potentiated, and evaporating capacities of both formalin and cresol and the diffusing capacity of formaldehyde in the fatty subsance were increased remarkably. Accordingly, it is considered that FC is extremely effective for root canal disinfection. In addition, the best ratio between formalin and cresol was turned out to be 50%: 50%, but the ratio 70%: 30% was effective as well.2. While a large part of FC applied in the root canal evaporated rapidly to fill up the sealed cavity, a part of it changed to a kind of resin, which was determined to be the products of acidified polimerization of formaldehyde and cresol. This resin is expected to decrease the topical irritation and to show the disinfective effect less potent but more lasting at the admininistered spot than FC is.3. When formalin was applied with cresol on the rabbit skin, the conspicuous increase ofcapillary permeability to be caused by formalin alone was reduced. The protein coagulability of formlin was increased by combined administration with cresol. It is considered that irritability of formalin combined with cresol can be more restrained and more limited topically than the case of formalin alone.4. The combined adminitration of formalin and cresol showed antagonistic effect in acute toxicity, and LD50 value of FC was higher than those of formalin and cresol.5. To conclude, the combined administration of formalin and cresol has merits of potentiationof the disinfective efficacy: of formalin and alleviation of the side effect and toxicity of it.

Physical and mechanical properties of 18 commercial light-activated composite resins were measured and the correlation between their properties was discussed. Hardness of the material, which was polymerized in accordance with the manufacturer's recommendation, increased considerably after exposure to light and reached approximately constant values after 24 hours. Hardness and elastic modulus were strongly dependent upon the filler fraction. On the other hand, there was no significant correlation between filler fraction and compressive strength. Most of the curing shrinkage was brought together at the bottom part of the cavity, as the light-activated composite resins polymerized from the surface exposed to light.The resistance to toothbrush abrasion increased according to the increase of inorganic filler content level.

In dental treatment some drugs containing phenol are used. Especially the‘compound iodine glycerin’, a remedy for oral mucous diseases, contains 0.43 to 0.53 % phenol. It is directly applied to the mucous membrane, although there are some opinions that phenol is contraindicative for the mucous membrane because of its systemic toxicity. In this experiment buccal absorption of phenol or p-chlorophenol was examined for a period of 120 minutes using the rat. The absorption increased with an increase in the fraction of the nonionized molecules existing in the solution in association with its pH. Reflecting the larger partition coefficient of p-chlorophenol, a much larger-amount of p-chlorophenol was absorbed from the buccal membrane than phenol. In both phenol and p-chlorophenol, a linear relationship was found between the logarithmic absorption and time. This means that their buccal absortion was a first order rate process. Moreover, the absorption rate was independent from the concentration of the solution, indicating that the buccal absorptions of phenol and p-chlorophenol was governed by a passive transfer mechanism.