In situ proliferation and differentiation of macrophages in dental pulp.

The presence of macrophages in dental pulp is well known. However, whether these macrophages proliferate and differentiate in the dental pulp in situ, or whether they constantly migrate from the blood stream into the dental pulp remains unknown. We have examined and compared the development of dental pulp macrophages in an organ culture system with in vivo tooth organs to clarify the developmental mechanism of these macrophages. The first mandibular molar tooth organs from ICR mice aged between 16 days of gestation (E16) to 5 days postnatally were used for in vivo experiments. Those from E16 were cultured for up to 14 days with or without 10% fetal bovine serum. Dental pulp tissues were analyzed with immunohistochemistry to detect the macrophages and with reverse transcription and the polymerase chain reaction (RT-PCR) for the detection of factors related to macrophage development. The growth curves for the in vivo and in vitro cultured cells revealed similar numbers of F4/80-positive macrophages in the dental pulp. RT-PCR analysis indicated the constant expression of myeloid colony-stimulating factor (M-CSF) in both in-vivo- and in-vitro-cultured dental pulp tissues. Anti-M-CSF antibodies significantly inhibited the increase in the number of macrophages in the dental pulp. These results suggest that (1) most of the dental pulp macrophages proliferate and differentiate in the dental pulp without a supply of precursor cells from the blood stream, (2) M-CSF might be a candidate molecule for dental pulp macrophage development, and (3) serum factors might not directly affect the development of macrophages.

In vitro comparison of three caries dyes.

PURPOSE: To evaluate the efficacy of a conventional and newly-developed caries detector (Caries Check) by measuring the Vickers microhardness (VMH) and DIAGNOdent value of the dentin cavity wall of extracted human teeth after removing carious dentin that was stained by the caries detector. METHODS: 30 human teeth with coronal dentin caries extending halfway through the dentin were sectioned and extracted for use in this study. As a control, the longitudinal section of a caries-free extracted human tooth was prepared. The VMH and DIAGNOdent values were measured and the microstructure of the dentin cavity wall was examined using a scanning electron microscope (SEM). RESULTS: When Caries Check was employed as a guide for carious dentin removal, the microhardness of the cavity wall was significantly lower than the normal dentin and the DIAGNOdent value indicated that the dentin may have recalcified. SEM observations of the stained regions revealed that Caries Check did not stain the sclerotic dentin. Based on these findings, Caries Check may be a useful modality because the excavation of the dentin structure was shallower and the sclerotic dentin was preserved.

Guinea Pig Maximization Test of tri-ethylene glycol mono-methacrylate.

The aim of this study was to evaluate tri-ethylene glycol mono-methacrylate (TEGMA) in terms of dermatological allergic reaction using a Guinea Pig Maximization Test. Skin reaction was evaluated according to the criteria of International Contact Dermatitis Research Group. TEGMA, as a constituent in new primers, has been reported to contribute to a priming ability similar to that of highly purified glyceryl mono-methacrylate (GM). In this study, it was found that its adverse effect was less than that of 2-hydroxy ethyl methacrylate (2-HEMA), but similar to that of highly purified GM. In conclusion, it was anticipated that TEGMA would hereafter replace 2-HEMA as a primer, as it posed a lower risk of triggering dermatological allergic reaction.