Abstract : The purpose of this study was to examine the efficacy of essential oils, which are used in aromatherapy, for root canal treatment. Enterococcus faecalis frequently detected in intractable infected root canals was used as an experimental bacterium. Seven types of essential oils were tested : clove, myrrh, Indian sandalwood, patchouli, cedarwood (atlas), juniper and West Indian lemongrass. The antibacterial effect of each essential oil was evaluated by measuring minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC).

 The lowest MIC was that of myrrh, followed by clove and patchouli, and the highest was that of cedarwood. Regarding MBC, clove was the lowest, followed by West Indian lemongrass. Myrrh, Indian sandalwood and cedarwood could not be observed.

 Comprehensively considering MIC and MBC values for Enterococcus faecalis, clove oil, which has long been used in dental practice, is considered to be effective. However, all the experimental essential oils demonstrated antimicrobial effects against Enterococcus faecalis, suggesting their usefulness as root canal medicaments in clinical applications. Myrrh is also effective for single-visit treatment.

Abstract : Purpose : The objective of this study was to determine the influence of the autoclave on the effect of controlled memory files of a martensite (M) Ni-Ti rotary file (NiTi-RF) and austenite (A) NiTi-RF.

 Methods : Two types of NiTi-RFs were selected : M-NiTi-RF (Hyflex EDM One File, n=10) and A-NiTi-RF (ProTaper Universal F2, n=10). Each file was prepared in a simulated artificial root canal. Pre-preparation, post-preparation and post-autoclave images of each file were recorded. Assessment of deformation of the files and their subsequent shape recovery was carried out visually and by comparing the digital images. The data was analyzed using Student's t-tests.

 Results : Visual assessment of files post-preparation revealed that M-NiTi-RF caused more ductile deformation than A-NiTi-RF. As a result of the measurement after autoclaving, M-NiTi-RF was unwound in shape more than A-NiTi-RF due to the shape memory effect.

 Conclusion : Post-preparation files became deformed as a result of use. However, M-NiTi-RF recovered in shape following autoclaving.

Abstract : A 47-year-old woman visited for autotransplantation and conservative treatment of a lingually displaced second premolar and transplant. Imaging examinations were performed before treatment, revealing the lingually displaced second premolar with a conical shaped single root. Using multiple and full-sized teeth-jawbone 3D models, a careful operational plan was established and deemed operable and practical. Because it was expected that the tooth 35 to be transplanted would have a crown-to-root ratio that would be difficult to preserve long term prosthetically, we planned to establish a longer fixation term than the common method. In the operation, a trephine bar was used to create a transplantation socket with a flat bottom. Tooth extraction and socket creation were performed by an oral surgeon, and the treatment and transplantation of the extracted tooth were simultaneously performed by an endodontist. Postoperatively, the root canal treatment of tooth 35, which was initially planned, was postponed because the transplanted tooth 35 was vital. Three months after the operation, the temporary fixation was removed and the occlusal surface was restored with composite resin. At the one-year post-operational recall, the patient could chew with the transplanted tooth without pain and no significant abnormalities, indicating a satisfactory recovery. After 18 months, the pulp of the transplanted tooth was vital ; the use of the trephine bar was thought to have contributed to the success, especially to the restoration of blood flow. Our experience of using 3D models fabricated with a low-cost desktop 3D printer for operational simulation suggests that this technique is extremely useful in tooth autotransplantation.

Abstract : In contrast to deciduous teeth, root resorption does not normally occur in permanent teeth. However, it may be triggered by damage to the precementum on the surface of the root, causing inflammatory external root resorption. We investigated whether a patient with trauma-induced external root resorption of the maxillary lateral incisor could be successfully treated by performing endodontic micro-surgery. A 34-year-old man had undergone pulp extirpation after traumatic injury when he was young. Apical periodontitis and inflammatory external root resorption subsequently developed, and apicoectomy of the maxillary left lateral incisor was performed under surgical microscopy. The lesion and granulation tissue were removed completely, and the malacic tooth substance at the resorption site was mechanically removed. Retrograde cavity preparation was conducted, and the cavity and resorption site were filled with MTA cement. Two years post-treatment, the patient had no clinical symptoms and X-rays showed scar healing at the site of the resorption-induced bone defect. Surgical removal of the granulation tissue at the resorption site, mechanical removal of the tooth substance, and filling with a highly biocompatible cement stopped the progress of resorption and successfully saved the tooth. This case suggests that endodontic micro-surgery may be a useful treatment method for inflammatory external root resorption.

Abstract : When treating a mandibular first premolar, an important point to consider is the potential existence of two root canals. Double root canals appear at a rate of about 20%. Clinicians should take care to avoid ledge formation due to a fracture caused by the tip of the file biting into a severely curved root canal or excessive rotational torque. Ledge formation can prevent cleaning to the root apex. Since the root canal diverges at the center of the root and the lingual root canal branches from the buccal root canal at an angle close to vertical, it may be difficult to prepare an inverted Y-shaped root canal (h type) (Vertucci classification V) and to clearly indicate the root canal orifice.

 Accurate access cavity preparation is needed when performing root canal treatment. If the presence of a lingual canal is suspected, the lingual cavity can be approached by extending access cavity preparation to the area near the buccal cusp. Of course, clinicians must take care to prevent overcutting and must complete root canal preparation without deviating from the original anatomy of the root canal.

 This case report describes the diagnosis, treatment, and evaluation of prognosis in a case involving the treatment of an inverted Y-shaped (h type) root canal.