Abstract : Purpose : The aim of this study was to evaluate the efficacy of heat-treated nickel-titanium (NiTi) files and an endodontic motor with reciprocating motion on the establishment of apical patency.

 Materials and Methods : Seventy S-shaped root canal blocks were used in this study. Dentists with 6 to 11 years of clinical experience (Practician Group, n=7) and trainee dentists with 1 year of clinical experience (Trainee Group, n=7) tried to establish apical patency using the following five techniques. Group 1 : Manual operation with stainless steel (SS) files (#15/.02 K file). Group 2 : Tri Auto ZX2 Optimum Glide Path (OGP) mode with SS files (#15/.02 Superfile [SPF] ; OGP＋SPF). Group 3 : Tri Auto ZX2 OGP mode with heat-treated NiTi files (#16/.02-.08 ProGlider [PRG] ; OGP＋PRG). Group 4 : Tri Auto ZX2 new OGP (N-OGP) mode with Superfile (N-OGP＋SPF). Group 5 : Tri Auto ZX2 N-OGP mode with ProGlider (N-OGP＋PRG). The time required to establish apical patency was measured. The surface of the K file, Superfile, and ProGlider before and after the establishment of apical patency was observed by scanning electron microscope.

 Results and Discussion : The rate of establishment of apical patency was 100% and 97.1% in the Practician Group and Trainee Group, respectively. One file fracture was observed in OGP＋PRG in the Trainee Group. KF required significantly more time than the other four groups in the Practician Group. This tendency was also observed in the Trainee Group, however there was no significant difference among the five groups. No significant difference was observed between the Practician Group and Trainee Group in the five methods. No morphological change was observed on the surface of the K file, Superfile, and ProGlider after the establishment of apical patency.

 Conclusion : N-OGP＋PRG is a new treatment option that enables apical patency to be established in a shorter time than manual operation with a K file.

Abstract : Objective : The presence of accessory root canals, such as furcation canals and lateral branches of the root canal, complicates the pathophysiology of inflammation in the pulp and periodontal tissues, as the accessory root canals may become routes for the transmission of inflammation. In 1972, Simon used a diagram to describe the pathology related to both endodontic and periodontal lesions as endodontic-periodontal lesions. In recent years these lesions have often been categorized into three types. The Type 2 endodontic-periodontal lesion is considered to be caused by periodontal disease with secondary pulpal involvement, but this condition has not been observed in detail. Therefore, this study examined the role of lateral root canals in Type 2 endodontic-periodontal disease in terms of microstructure.

 Materials and Methods : The mandibular right second premolar of a 78-year-old male was extracted because of periodontal disease and observed by micro X-ray CT and scanning electron microscopy.

 Results : Two lateral root canals were seen, at 3.7 mm and 4.5 mm from the root apex. Cementum resorption at the foramina of these branches was apparent, indicating that the periodontal disease had progressed to the foramina. However, fibrous tissue was present within the lateral branches, and no inflammation had invaded the pulp.

 Conclusion : When there is blood circulation from the root apex foramen to the pulp, the lateral branches may resist the progression of inflammation into the pulp, even if the inflammation progresses to the foramina of the lateral canals.

Abstract : Purpose : Oehlers’ classification of teeth is divided into three types based on the degree of entrapment and the presence or absence of linkage with the periodontal ligament space. Type Ⅲ is classified as having entrapment that reaches the root apex and is open at the root surface. In this study, we report a well-healed tooth with Oehlers Type ⅢA periapical periodontitis at the bifurcation of a maxillary right lateral incisor that had an erosion from the blind hole in the crown to the apical periodontal tissue.

 Subject : The patient was a 17-year-old female with the chief complaint of gingival discomfort. Regarding her recent medical history, she began to have a fistula on the gingiva of her right upper anterior tooth around the end of July 2019 and visited her general practitioner at the beginning of August. She brought a letter of referral and visited the Department of Conservative Dentistry, Matsumoto Dental University Hospital in September. Presently, she has a normal response to the electric pulp test, with no pathological periodontal pockets.

 Discussion : Although it is easy to assume that the presence of a fistula indicates inactivation of the tooth, CBCT imaging revealed that the root apex had reached the periodontal ligament and that the root was extremely folded and bifurcated into two roots. In addition, the electric pulp test study showed a viable response and it was confirmed that the root apex lesion was caused by the root cap. This confirmed that the electric pulp test should be performed even when an endodontic fistula is observed and that CBCT can be used to accurately treat the fistula.

 Conclusion : In Type ⅢA lesions of ingrown teeth, treating the invaginated part alone is thought to enable pulp protection.