歯髄処置

The root dentine of human deciduous tooth is physiologically resorbed by multinucleated odontoclasts. Previously, authors investigated the distribution of number of nuclei per human odontoclast and showed that the mean number of nuclei per cell is 5.3 and the median is 4. After endodontic treatments of human deciduous tooth, odontoblasts were removed and root canals were filled with material with alkaline calcium hydroxide. Therefore, the structure of root dentine after endodontic treatments is different from that before treatments. The present study aims to clarify the number of nuclei per odontoclast in human deciduous teeth after endodontic treatments with Vitapex®, a calcium hydroxide-based root canal filling material, and to compare it with that in human deciduous teeth without endodontic treatments. After extraction of deciduous teeth, they were fixed, decalcificated and embedded in paraffin, and six specimens were selected randomly. The specimens were serially sectioned into 4 ㎛-thick sections and they were stained with TRAP and methyl green, and sections were observed by light microscopy. TRAP-positive cells forming resorptive lacunae on the dentine were identified as odontoclasts, and 99 odontoclasts in anterior teeth and 101 cells in molar ones were investigated to determine the distribution of nuclei per cell. The mean number of nuclei per cell was 20.8 and the median was 14. In the distribution of number of nuclei per odontoclast, there were statistically significant differences between teeth with endodontic treatments and ones without them. These results suggest that the presence of calcium hydroxide-based root canal filling material and root dentine with different structure may cause change in number of nuclei of odontoclasts.