Abstract : Calcium hydroxide is used to assist the formation of dentin in direct pulp capping and pupotomies. In recent years, it has come to replace phenol or formaldehyde in root canal treatment.

 Our purpose was to study the role of calcium hydroxide (UltraCal^TM XS^TM, Calcipex^® and home-made calcium hydroxide paste) in the sealing process of intra-canal dressings.

 The root canals of fifty extracted mandibular incisors were endodontically prepared and dressed with calcium hydroxide paste, then irrigated by ultrasonic files with water and guttapercha obturated (the sectional method). Obturated teeth were then immersed in the India ink, and the penetration distance of the dye measured from the apex of the root.

 Meanwhile, we scanned using a SEM (scanning electron microscope) the paste type medication used in root canal treatments after irrigation by ultrasonic files with water.

 The results were as follows :

 1. UltraCal XS dressings : the dye penetration distance was 0.41 mm. Calcipex : 0.25 mm. Home-made calcium hydroxide paste : 0.11 mm. Dressing without paste : 0.23 mm. However, no difference appeared when results were Dunn multi-comparison tested.

 2. UlraCal XS dressing : 30.2% non penetration of the distance from the apex of the root. Calcipex : 75.6%. Home-made calcium hydroxide paste : 84.6%. No medication : 50.0%. A two way analysis (test for the proportion) showed that both Calcipex and home-made paste offer apical sealing capability.

 3. Fisher’s exact probability test showed differences between UltraCal XS and Calcipex/UltraCal XS and home-made paste sealing capability. The other hand, it was not showed diffrences between non-paste and other calcium hydroxide pastes.

 4. Those differences can be explained by the different ratio of those medications’ components.

Abstract : It is assumed that the measurement of the root canal filling material softened by heat foolows JIS T6507 to seek the rate of pressure reduction is ordinary way but we felt doubt about it from results of the various tests we had done, then we took note of measurement using the Reo meter applied the principle of the newtonian fluid and practiced and had the results of which we could be convinced, so we will report them now.

Abstract : In the previous study, we reported that the hyaloid structure was formed on the smear layer which irrigated by Cu²⁺/H₂O₂ mixed solution. However clinical meaning of the hyaroid structure has not been clarified yet. In this study, we performed the dye penetration test on the root dentin with the formed hyaroid structure. Dye penetrated to 0.92±0.34 mm in the without smear group, and 0.46±0.24 mm in the smear layer group. When the smear layer was irrigated by 1 mM CuCl₂ solution for 1 min, 3 min and 5 min, the dye penetrated to 0.27±0.11 mm, 0.29±0.08 mm and 0.33±0.21 mm, respectively. Also, when the smear layer was irrigated by 1 mM CuCl₂ and 1 M H₂O₂ mixed solution for 1 min, 3 min and 5 min, the dye penetrated to 0.11±0.05 mm, 0.15±0.07 mm and 0.16±0.12 mm, respectively. There was significant difference between the without smear layer group and the smear layer group. There was no significant difference for the irrigation time in 1 mM CuCl₂ solution or 1 mM CuCl₂ and 1 M H₂O₂ mixed solution. However, there was no significant difference between the smear layer group and the irrigated by 1 mM CuCl₂ solution for 5 min, and between the irrigated by 1 mM CuCl₂ solution for 1 min and the irrigated by 1 mM CuCl₂ and 1 M H₂O₂ mixed solution for 3 min. It is suggested that 1 to 3 min irrigation by 1 mM CuCl₂ and 1 M H₂O₂ mixed solution is the most effective agent for preventing dye penetration.

Abstract : When the root canals are shaped with files, smear layers are always formed on the root canal dentin surfaces. The smear layers may reduce bacteria penetration, but residual bacteria in the smear layers may proliferate and play an important role producing periapical lesion. So, the absence or presence of smear layers on the root canal dentin is important clinically. The purpose of this study is to observate of root canal surfaces after shaping with nickel-titanium files or steinless steel files using scanning electron microscope. In the case of using nickel-titanium files, filed root canal dentin surfaces were observed as steps diagonally. And after removal smear layers with polyacrylic acid, dentinal tubules were observed clearly. On the other hand, the root canal surfaces showed like the fish scales when using steinless steel files. And after removal of smear layers with polyacrylic acid, dentinal plugs were observed.

Abstract : We isolated and identified causative bacteria in many cases with infection of the root canal of teeth. The growth inhibitory effect of tannin and tannic acid was tested in pure cultures of the dominant bacteria. Infected root canals of the tooth were filled with gutta-percha after extensive cleaning. Quick improvement was observed by using the sealant containing tannic acid whose effect on the causative bacteria was confirmed even when some infectious symptoms had remained. We report in this paper a case with infection of the root canal of the right lower first molar tooth.

Abstract : Root canal treatment to the incomplete root formed tooth has been difficult. In the open apex cases, physical enlargement, chemical cleaning and tight filling to the root canal are difficult. Apexification is commonly applied to these cases. In the case with large apical lesion and pus discharge, however, the success of apexification may not be certain. We had a young female patient with an incompletely root formed upper central incisor that had a traumatic damage and an apical periodontitis. Pus was discharged through the canal of right central incisor. Paste containing calcium-hydroxide and iodoform was applied into the middle of pulp chamber. After 14 months, under the paste the incomplete dentin bridge was formed and apex was closed with two apical foramina. We performed usual endodontic therapy and any symptom has not appeared for 12 months after the root canal obturation.

Abstract : The Japanese edition has been published by Nankodo Press. The author is an American physician. He collect a lot of wise saying which originated not only from literature but also from his teachers and colleagues, and arranged them into 425 rules about doctors’moral attitude towards patients in medical practice. These rules are also duly applicable to dental practice. Some examples of the rules are cited below. Furthermore, this book reminds us of our lack of the training or study of the mental and/or moral aspects of modern dentistry. We are concered that we dentists are liable to confine ourselves within technological details and apt to ignore mental aspects of patients. The ignorance may cause to in hibit future development of dentistry. We hope this book will be guide, especially for young dentists, to the best way of dental practice.