Iron deposits in the human labial minor salivary glands were examined in a series of 195 postmortem subjects. Iron deposits (hemosiderin granules) were found in 7 subjects (3.6%), and the major types of illness in these cases were liver cirrhosis with or without hepatoma, aplastic anemia and acute myelogenous leukemia. Three out of 7 subjects had a history of blood transfusion. Considerable quantities of hemosiderin granules were deposited wihin the cytoplasm of the acinar and ductal epithelial cells, and hemosiderin-laden cells were scattered in the interstitial connective tissue.

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ATP-dependent profiles of phosphofructokinase (PFK) activity were determined in both crude and Sephadex G-25-filtered fractions from rabbit dental pulp. ATP had a dual effect on PFK as an activator and an inhibitor, according to its concentration. Gel-filtered PFK showed a similar profile to that of crude PFK, indicating a lack of low-molecular-weight effector (s) for PFK in rabbit dental pulp. For complete inhibition of the PFK in rabbit dental pulp, 5 mM ATP was required. This level of ATP is much higher than that required for other typical isozymes of PFK from liver, skeletal muscle or brain. It is postulated that differences in the properties of PFK isozymes are due not only to the subunit structure but also to the presence of other effectors.

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Apatitic calcium phosphate cements, formed by the ambient reaction of tetracalcium phosphate (TTCP) with dicalcium phosphates (DCP), have been recently reported. H₂O or dilute aq. H₃PO₄ (0.2%) is used as the liquid vehicle for this reaction. The aim of this study was to ascertain if hydroxyapatite (HAp) can form in self-cured hydrogel composites containing TTCP/DCP mixes. The setting times (ST) and diametral tensile strengths (DTS) of these hydrogel composites were also determined. The hydrogels were of two types : (1) vinyl thermosets derived from the copolymerization of HEMA (2-hydroxyethyl methacrylate) and cross-linking monomers, and (2) polyelectrolyte-based hydrogels formed from aq. poly (alkenoic acids), e. g., poly (acrylic acid). Cylindrical specimens 6 mm D x 3 mm H were prepared and stored in H₂O for up to 30 days. The HEMA composites were hardened in 7-15 min by free radical initiation (benzoyl peroxide/tertiary aromatic amine). The polyelectrolyte cements were hardened in 6-8 min. After various periods of storage in H2O at 37°C, some of the specimens were examined by X-ray spectroscopy for HAp. HAp formation was not observed in the HEMA composites even after 30 days of H₂O storage but was detected in the polyacid cements. The 24-h DTS values of the HEMA composites (14-26 MPa) were higher than those of the polyacid cements (7-12 MPa). Both the H₂O content and pH may thus be factors controlling the rate and extent of HAp formation in hydrogel composites containing TTCP/DCP mixtures.

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A recent study has shown that the presence of lead (Pb) as well as other base metals in esthetic restorative materials, especially dental cements, is detectable by color shifts induced by exposure of hardened specimens to a 0.1% (w/v) aqueous solution of sodium sulfide, Na₂S. The present study was initiated to determine the applicability of this simple exposure test to the detection of Pb in human teeth. Extracted whole teeth as well as sectioned, thin specimens were exposed first to either a 0.01% or a 0.001% (w/v) aqueous solution of lead nitrate, Pb (NO₃) ₂, at 37° C for 24 h. After rinsing with distilled H₂O and a subsequent 24 h exposure to the 0.1% Na₂S solution at 37°C, the tooth specimens were examined visually and by a dental color analyzer for color changes. The latter color measurements were evaluated by the Lab system of Hunter, and the color difference, ΔE, was determined. Neither control specimens exposed to distilled H₂O only or to 0.1% Na₂S only exhibited any significant change in appearance after 24 h of storage at 37°C. However, specimens exposed first to the Pb (NO₃) ₂ solutions showed discernibleΔE values after exposure to the Na₂S solution. ΔE was greatest for specimens exposed to the more concentrated Pb (NO₃) ₂ solution. Most of the discoloration in both thin and intact tooth specimens was confined to the outermost layers of the tooth structure. For the intact specimens, the greatest degree of discoloration occurred in the cementum, the most permeable part of the tooth structure.

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Co-Cr alloy is used more frequently than Ni-Cr alloy as a non-precious alloy for cast plates in Japan. However, since the melting point of Co-Cr alloy is very high, about 1300°C, and since it oxidizes easily, a vacuum-pressure casting machine capable of melting this alloy in a reduced atmosphere has recently been developed.
Using this vacuum-pressure casting machine, the authors studied the effects on the Co-Cr alloy of the attachment direction of sprues and the investment direction of refractory models.
The results clarified that in the vacuum-pressure casting method, sprue attachment direction and the investment direction of refractory models have a significant effect (p <0.01) on the castability of Co-Cr alloy.

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