Recently, microscopes are using for dental treatment and many materials and methods were developed. In endodontic therapy, success ratio were increased using microscope, however, invasion of endodontic surgery to patients is still problem. If patient tooth has morphological problem or huge cyst at upper molar palatal root, basically we have to select intentional replantation or extraction. In these difficult cases, we developed new method named internal apicoectomy. We never give surgical damage to patient, root apical is cut off by long shank round bur via root canal, and remove apical lesion, gutta-percha and any problem materials under microscope. Finally, root canal including apical part was filled by MTA. We have been procedure 20 cases internal apicoectomy, and good prognosis was obtained in all cases.

Dens invaginatus (DI) is an abnormality in which the tooth’s enamel surface and dentin fold inward toward the dental pulp, often creating a tooth within a tooth. In extreme cases, this abnormality can extend from the crown to its periodontal membrane at the base of the root. The present case is such an extreme case, and was therefore diagnosed as Oehlers’ type III. X-ray showed a thumb head-sized radiolucency on the root’s mesial surface, but tests showed that the dental pulp was still viable. As root canal treatment of similar cases is difficult, extraction is typically the only treatment. In this case, however, a maxillary lateral incisor with Oehlers’ type III invagination’s location was detected by cone-beam computed tomography (CBCT) prior to treatment. Subsequently, using a surgical operating microscope (SOM) and an ultrasonic tip, the invaginated enamel was removed successfully without damaging the tooth’s healthy parts, and then root canal preparation was initiated. By packing mineral trioxide aggregate (MTA) into the root canal, the dental pulp was saved and the inflammation around the tip of the DI was treated successfully. In treating DI, it is necessary to accurately assess and very precisely treat without destroying the surrounding dental tissue; thus, CBCT and SOM are very useful.

Operative microscopes have been utilized in otolaryngology since 1922, and owing to recent advancements, endodontic treatment with the use of microscopes has been a topic of significant interest in the field of dentistry. However, although some beneficial indications have been suggested, few cases have been reported in the field of oral and maxillofacial surgery with an exception for microvascular surgeries in maxillary reconstructions. In this paper, a new surgical concept is introduced where the operative microscope is used throughout all surgical procedures. The high magnification and clear view of the surgical field resulted in good post-operative outcomes and have the possibility to shorten the surgical time.

Mineral trioxide aggregate (MTA) is used for several endodontic treatments. However, gas generation from the MTA and H₂O₂ reaction mixture is not known. We therefore investigated the generated gas using a dissolved O₂ meter, and assessed the density of H₂O₂ changes before and after the reaction using the potassium permanganate and X-ray diffraction (XRD) methods. On measurement of the dissolved O₂ in the solution, the dissolved oxygen density did not the change when MTA was immersed in pure water. On the other hand, the dissolved O₂ density increased when MTA was immersed in 3% and 30% H₂O₂. The results of XRD suggested that oxygen was generated by the resolution of the H₂O₂. In addition, H₂O₂ density decreased after the reaction between White Portland Cement and H₂O₂. The oxygen gas source was the resolution of H₂O₂. We must therefore pay attention during the use of H₂O₂ in root canal irrigation or bleaching agents.

The purpose of this study was to investigate the resistance to torsional stress and cyclic fatigue of R-phase Ni-Ti files experiencing different phase-transformation temperatures with identical geometric characteristics. In the cyclic fatigue failure test, the values were SILK 5481±1307.18 and SILK-N (before heat-treatment of SILK) 2922±702.55, respectively. SILK was significantly greater than SILK-N (p < 0.01).

In the torsional torque test, the values were SILK 57.24±2.65 gfcm and SILK-N 58.58±3.15 gfcm, respectively, and there were no significant differences.

In the torsional bending test, SILK was 514.91±84.78° and SILK-N was 521.63±78.13°, and there were no significant differences. In scanning electron microscope examination of factors causing fatigue fracture, the dimpling percentages for SILK and SILK-N were 7.25±3.02 and 5.69±2.76, respectively, and there were no significant differences. The results of the present study suggest that, at clinical temperatures, the R-phase Ni-Ti files have a higher cyclic fatigue resistance than those with the austenite phase.

The aim of this study was to determine the prevalence and frequency of rubber dam usage by analyzing the awareness of patients, general practitioners, hygienists and undergraduate students toward using rubber dams during endodontic procedures.

This survey was conducted at Kanagawa Dental University Hospital and included personnel involved in endodontic treatment using an operative dental microscope. A total of 301 people were surveyed: 50 patients, 90 general practitioners, 38 hygienists and 123 undergraduate students. The same questionnaire was used for all participants. Respondents were asked about the length of time a rubber dam could be applied, discomfort and desirability of usage. We also asked general practitioners about rubber dam usage and why some of them did not use one. We asked hygienists and undergraduate students about their experience using rubber dams and patients about their experience. Furthermore, we asked how the respondents learned about rubber dams.

Approximately 82.2% of patients, 20.4% of dental practitioners (33.3% of general dental practitioners, 15.8% of dental hygienists, and 12.2% of undergraduate students) answered that rubber dam usage was desirable. Some patients (30.0%) knew about rubber dams. While 40 patients (80.0%) felt that the use of rubber dams was desirable, only 30 general dental practitioners (33.3%), 6 dental hygienists (15.8) and 15 undergraduate students (12.2%) thought that patients found them desirable. Our findings suggest a significant gap between the awareness of patients and dental caregivers on rubber dam usage.

A patient with an unusually rare case of gemination of a maxillary lateral incisor was referred for endodontic therapy. A diagnosis of pulpal necrosis with asymptomatic periradicular periodontitis was made. Preoperative radiographs revealed a complex root canal anatomy associated with periradicular pathosis. A combination of laser-assisted non-surgical and micro-surgical treatments are discussed.