Abstract : In order to investigate new sterilization methods for root canal treatment, photodynamic therapy (PDT) and blue light sterilization of Enterococcus faecalis (E. faecalis : 5×10⁶ CFU/ml, and 5×10⁹ CFU/ml) were examined. For PDT, a semiconductor laser of 660-nm wavelength was used. For blue light sterilization, an argon laser of 480-nm wavelength was used. Both light sources were irradiated under several conditions : (Ⅰ) irradiating the deep part of the reaction solution, (Ⅱ) irradiating the surface of the reaction solution, and (Ⅲ) irradiating the light source from a slight angle. Each light source was irradiated for 1 to 5 min. As a result of PDT, irradiation under condition (Ⅰ) was the most effective for both bacteria concentrations. On the other hand, irradiation under condition (Ⅲ) showed the lowest bactericidal effect. Complete bacteria sterilization was not attained after 5 min of irradiation of 5×10⁹ CFU/ml under condition Ⅲ.

 Blue light source irradiation showed no sterilization effect in any of the specimens. These results showed that PDT was able to sterilize E. faecalis under several irradiation conditions, whereas the blue light source had no sterilization effect.

Abstract : Enamel matrix derivative (EMD) has been applied clinically for periodontal tissue regeneration. The status of the periodontal ligament (PDL) of the extracted tooth is critical for the healing of the replanted tooth. Recently, some reports have shown that EMD has been used for root surface treatment to promote the formation of PDL and increase the survival of avulsed teeth subjected to replantation. Mineral trioxide aggregate (MTA) possesses a high sealing ability and a good hard tissue inducing ability, and has been regarded as an ideal material for perforation repair. This case report describes a tooth intentionally replanted following perforation of the root surface of the mandibular second molar. In this case, we shaped the root canal followed by filling with gutta-percha, and repaired the perforation with MTA. Intentional replantation surgery using EMD was then performed on the root surface of the defect of periodontal ligament tissue. We compared preoperative CBCT images with those at 4 years post-surgery, and confirmed that the hard tissue inducing ability of MTA cement can facilitate the recovery of alveolar bone and that EMD possesses the ability to regenerate periodontal tissue. However, reductions in MTA were observed, suggesting that MTA eluted from the treatment site.

 This case report demonstrates the effective closing of perforations by MTA, and that application of EMD is effective for intentional reprocessing.

Abstract : Two clinical cases whose endodontic condition was very difficult to diagnose are described. Based on this experience, the importance of diagnosis prior to root canal treatment and complications related to the treatment are described.

 Case #1 : Mandibular second molar with acute apical periodontitis and fractured instrument in the apical third is described. The patient’s chief complaint was swelling and sinus tract. This tooth had been treated and built up with a metal core by a general dentist more than 20 years ago. The root canal configuration (anatomy) was C-shaped and the isthmus between the mesial and distal canal was infected. Therefore, the canal was shaped with ultrasonic tips and the metal fragment in the apical third was removed. After treatment, both complaints resolved and the prognosis was assessed as good. The tooth remains asymptomatic after more than one year.

 Case #2 : The patient’s chief complaint was pain in the maxillary second premolar. After complete examination, a diagnosis of a trigeminal neuralgia was made. Shortly afterwards the patient was referred to the neurosurgery department and underwent a MRI exam. The final diagnosis rendered was acoustic neuroma.

Abstract : Anatomical knowledge is an essential factor for successful root canal treatment. Maxillary molars have various root canal morphologies, and there are many failures. This report describes our success in finding an untreated root canal using CBCT in the right maxillary second molar of a 34-year-old male patient. It was a rare case of one root with four root canal orifices.

Abstract : We report the case of a 24-year-old Japanese woman who had a single-rooted maxillary first molar with a single canal and a single apical foramen. CBCT examination is an excellent diagnostic tool not only for extra canals but also for a smaller number of canals, as in this case of a maxillary first molar.

Abstract : Dens invaginatus is a malformation of teeth, caused by an invagination of the enamel organ into dental papilla. It used to be called dens in dente ; however, the anatomy is different from general root canal systems. The prevalence of dens invaginatus varies depending on the experimental design. Miyoshi et al. demonstrated that 38.5% of upper lateral incisors showed invagination by visual examination ; however, dens invaginatus was seen in only 5.1% on dental X-ray radiographs. Thus, X-ray observation is necessary to obtain a precise diagnosis.

 A patient was referred to the Department of Oral Surgery, Nihon University Dental Hospital for extraction of an impacted upper left canine. Preoperative cone beam computed tomography (CBCT) demonstrated that radiolucency was present from the apex of the upper left lateral incisor to the impacted canine. Therefore, extraction of the impacted canine and apicoectomy of the lateral incisor were planned, and the patient was referred to our department for endodontic treatment of the lateral incisor.

 Based on the CBCT image, the lateral incisor was diagnosed as Oehlers type 3 dens invaginatus with a severely curved root canal. Operative microscopes and nickel-titanium rotary files were used for the root canal treatment, and favorable results were obtained.