Abstract : This study investigated the discomfort of patients for whom a rubber dam was used during endodontic treatment. An attitude survey was carried out on 87 dentists and 201 patients. It was found that the patients did not feel so uncomfortable about rubber dam usage as the dentists had thought. It was concluded that most of the patients could relax during endodontic treatment with a rubber dam and that they requested it in subsequent treatment.

Abstract : Diagnosis of incomplete vertical root fractures is very difficult. This case report describes an incomplete vertical root fracture detected after removing cementum under a dental operating microscope. Vertical root fractures should be diagnosed carefully following a proper procedure.

Abstract : This study investigated the effects of root canal irrigants for 2 weeks on the surface of Mineral Trioxide Aggregate (MTA) using a scanning electron microscope (SEM) and electron probe X-ray microanalyzer (EPMA). SEM observation of the control samples revealed growing crystals in various shapes and sizes. In the H₂O₂ treatment group, numerous triangular crystals grew to form cubic crystals on the mesh-like structure. In the NaClO treatment group, numerous square type crystals were growing. In the EDTA treatment group, rounded crystals were growing. We assume the crystals were formed with S and Bi oxide in the control samples ; Al, silicate and S formed a compound in the NaClO samples ; and that there was no change in the H₂O₂, and Bi oxide changed to Bi compound by chelating action in the EDTA samples. In the elemental analysis of the H₂O, NaClO and EDTA treatment groups, the rate of Ca was low. However, no change was observed in the H₂O₂ treatment group.

Abstract : It has been reported that the various biostimulatory effects of Ga-Al-As laser irradiation involved the acceleration of mineralization in human dental pulp (HDP). However, its effects on dental pulp have not yet been clarified. The present study investigated the effects of temperature elevation by the laser irradiation on the acceleration of mineralization in HDP cells. The HDP cells were irradiated once by a Ga-Al-As laser, and the laser irradiation caused a maximum temperature rise of 1.4°C. Consequently, the other HDP cells were heated by a water bath set at 1.4°C higher than room temperature. We compared the ALP staining and ALP activity of irradiated cells, non-irradiated cells (control) and heated cells. A larger number of irradiated cells showed positive on ALP staining than did non-irradiated cells or heated cells. The ALP activity in the irradiated cells was higher than in non-irradiated cells or heated cells. These results suggest that the ALP activity was enhanced by the laser irradiation.

Abstract : This study compared the smear layers on the root canal surface after using various tips of ENDO-HOLDER^® for root canal shaping. The root canal walls after shaping were observed using a scanning electron microscope (SEM).

 SEM observations of the diamond tips revealed rough surfaces with deep ditches on the canal wall, and those ditches were deepened. The formation of ditches on the canal wall was slightly different depending on the particle size of diamond. On the other hand, in the case of the stainless steel files, scale-like smear layers were observed on the canal wall.

 It was suggested that the different types of tips formed various types of smear layers on the canal wall.

Abstract : The etiology and pathogenesis of internal resorption of the dentin are poorly understood. Advanced internal resorption is often associated with the appearance of the “pink spots” in teeth. The progressive internal resorption may result in perforation of the tooth crown or the root. This study presents a case of internal resorption in the coronal portion of the upper left central incisor in a 15-year-old girl, which was observed clinically and histopathologically. Only 7 months after the internal resorption was first noted by clinical and roentgenographic examinations, the tooth had to be extracted because of extensive resorption. Decalcified serial paraffin sections were prepared and stained. The coronal sections showed that a portion of the pulp was replaced by granulation tissue with inflammatory cells, revealing osteoid dentin replacement of most of the coronal pulp, even in the absence of continuity of dentin or cementum between the crown and the root. The resorbed dentin walls were irregular and scalloped, and multinucleated giant cells were seen in resorption lacunae. In the granulation tissue, severe inflammation with pulp abscess was observed. The apical pulp changed to fibrous tissue and included scattered particles of denticles. Cementoid hard tissues were added at the apical canal wall.