Abstract : The last ten years have seen endodontic treatments benefit from the development of new equipment including the operating microscope, the cone-beam CT, and laser, which have improved therapeutic outcomes and predictability. Above all, lasers have become increasingly useful in various applications in endodontic procedures such as pulp diagnosis, dentin hypersensitivity, direct pulp capping and pulpotomy, cleaning and sterilization of the root canal system, also in addition to endodontic surgery. The purpose of this paper is to review different aspects of the use of lasers in clinical endodontics, and emphasize the broad applications in a modern-day endodontic practice.

Abstract : I have filled canals with easily absorbable root canal filling materials. I developed the double injection method for filling the canal with two types of gutta-percha : gutta-percha of ObturaⅡ and GP Sealer (Toyo Chemical Laboratories). These gutta-perchas were injected using two ObturaⅡ guns. With this method, the absorption of the GP Sealer was very fast, and strong inflammation of the periapical tissue was observed when GP Sealer extruded beyond the apical foramen.

 In some clinical cases, I have experienced recurrence of periapical lesions, in which cases gutta-percha was absorbed in apical third canals.

 The following conclusions were obtained :

1. Easily absorbable root canal filling materials induce strong inflammation post-operatively.

2. Absorption of the filling materials may induce recurrence of periapical lesions.

3. Non-absorbable root canal filling materials should be used.

Abstract : Recently, the applications of dental cone-beam CT and a microscope have been increasing in endodontic therapy. These two devices are also very effective for the examination and treatment of root perforations. Dental cone-beam CT reveals the three-dimensional position of the perforations. Furthermore, the high magnification with coaxial illumination of a microscope allows precise detection and visualization of perforations.

 This case report describes endodontic treatment with perforation repair using dental cone-beam CT and a microscope.

Abstract : Calcium silicate-based endodontic materials are thought to possess bioactivity by releasing inorganic ions into the surrounding environment. This study examined the bioactivity of three calcium silicate-based endodontic materials, i. e., white mineral trioxide aggregate (WMTA), BioDentine and EndoSequence BC Sealer (BC Sealer), in the presence of phosphate-buffered saline (PBS). Morphology and elemental composition of surface precipitates formed after 30-day immersion of set materials in PBS were analyzed with a wavelength-dispersive X-ray spectroscopy electron probe microanalyzer with image observation function (SEM-EPMA). Chemical composition of the precipitates was also analyzed by X-ray diffraction. Root segments of extracted human teeth, after the root canal had been filled with one of the materials and immersed in PBS for 30 days, were subjected to SEM-EPMA analysis of the material-dentin interfacial layer. The analysis for the precipitates revealed that they had spherulitic structures and showed diffraction peaks corresponding to those of apatite. Moreover, the formation of tag-like structures and Ca-and Si-incorporation were recognized in the dentin adjacent to the materials. BC Sealer showed significantly smaller Ca-and Si-incorporation depths compared with WMTA and BioDentine (p<0.05). These findings suggest that the three calcium silicate-based materials possess bioactivity and that the degree of such activity differs among the materials.

Abstract : The present study assessed the salivary levels of cortisol and chromogranin A (CgA) in patients with dry mouth compared to age-matched controls.

 We studied 146 subjects, including dry-mouth patients (n=116) and control subjects (n=30). The dry-mouth group was further classified into two subgroups : subjects with perceived xerostomia and normosalivation (dry-mouth 1, n=45), and subjects with perceived xerostomia and hyposalivation (dry-mouth 2, n=71). The control subjects were healthy volunteers. Cortisol and CgA levels in stimulated whole saliva were measured using ELISA kits.

 All subjects with dry mouth had significantly higher cortisol and CgA levels than the controls. Furthermore, when comparing the controls with each dry-mouth subgroup, salivary levels of cortisol were significantly higher in both subgroups than controls. In contrast, the level of CgA was significantly higher than in controls in the dry-mouth 2 subgroup only. Multiple regression analysis revealed a significant independent association between salivary levels of cortisol and each dry-mouth subgroup, or salivary levels of CgA and dry-mouth 2 subgroup, even after adjustment for age, gender and xerogenic drugs.

 We found significant associations between salivary cortisol and CgA levels and symptoms of oral dryness and reduced salivary flow.

Abstract : Laser-activated irrigation (LAI) has recently been introduced as an innovative method for root canal irrigation. The cleaning mechanism of LAI is thought to depend on the fluid flow and pressure waves. However, there is limited information about the pressure acting in the apical direction. In this study, we analyzed in a root canal model the pressure waves induced by an Er:YAG laser equipped with a novel cone-shaped tip of 200 μm diameter with a needle-type hydrophone, using ultrasonic vibration as a control. The laser was emitted at a pulse energy of 30 or 50 mJ and a repetition rate of 1 pulse per second, without air or water spray. The pressure waves of the laser showed two steep peaks that corresponded to shock waves. By contrast, the ultrasonic device revealed regular waveforms. The magnitude of the pressure of the laser was lower than that of ultrasonic vibration. It was concluded that the pressure waves induced by Er:YAG laser irradiation might have little adverse effects on periapical tissue, suggesting the feasibility of LAI as a new irrigation system.

Abstract : The purpose of this study is to investigate antimicrobial effect and cytotoxicity of Ozone Nano-bubble (onb) Water as a cleaning agent for root canal irrigation. We investigated the antimicrobial effect of onb water against following 10 bacterial species (Staphylococcus aureus, Streptococcus mutans, Streptococcus gordonii, Lactobacillus casei, Actinomyces viscosus, Enterococcus faecalis, Escherichia coli, Porphyromonas gingivalis, Fusobacterium nucleatum, Candida albicans) that have been reported to exist in the oral cavity and an infected root canal. The cytotoxicity of onb water was studied using human gingival fibroblasts. The onb water showed remarkable antimicrobial activity against all species after a one-minute treatment at a 100% concentration. The onb water was then diluted with phosphate buffered saline (100%, 75%, 50%, 25%, 10%, 0%), and the antibacterial effect was examined. L. casei and A. viscosus were killed at the lower concentration of onb water (25%) after a five-minute treatment and the bactericidal effect was also observed in other bacterial species at a 50% concentration. On the other hand, the cytotoxic activity of onb water in relation to human gingival fibroblasts was not observed at a 100% concentration. These results suggest that onb water is useful in an application for root canal irrigation.

Abstract : Periapical periodontitis is considered to be caused by infectious agents persisting in the root canal system triggering the host immune reaction. Disinfection is the key point for endodontic treatment, but it is difficult to completely remove all causal agents from the root canal system because of the morphological complexities. In this study, we focused on the potential usefulness of electro-magnetic wave irradiation (EMWI) for clinical application to promote healing. The aims of this study were : 1) to determine the characteristics of EMW and 2) to evaluate the clinical application of EMWI to endodontic treatment. The analysis of EMW characteristics demonstrated that it is important to make the diameter of the active electrode tip smaller and to keep the insertion depth within 5 mm for effective generation of Joule heat, and revealed that Joule heat conduction spreads 1.0-1.5 mm wide in the horizontal direction. The success rate of clinical application of EMWI was 99.1%, which is higher than that of the EMWI-untreated group (95.1%). Moreover, the reduction rate of the diameter of periapical lesion in the EMWI-treated group (75.62%) was significantly increased. These findings demonstrate that EMWI accelerates healing of periapical lesions and suggest that it may be useful for clinical application to refractory periapical periodontitis as non-surgical treatment.

Abstract : In this article, a case of a root fractured tooth which was treated with mineral trioxide aggregate is reported. The root canal of the vertical root fractured tooth was filled with mineral trioxide aggregate. After 6 years, restoration of the surrounding alveolar bone was observed.

Abstract : To clarify the current status of endodontics, we analyzed clinical examinations of new patients at the clinic of operative dentistry and endodontics in Kyushu Dental College Hospital, from April 2008 to March 2011. We separated patients with pulpitis and apical periodontitis from the new patients, and surveyed age, chief complaint, presence or absence of introduction from general practitioners, and details of treatment (endodontic treatment, retreatment, or tooth extraction). It was shown that the rate of endodontic retreatment was over 50%, which exhibited no improvement upon a comparison with the rate over the past 12 years. These results indicate that we have to develop and promote education programs using the latest apparatus, as well as educate the basic skills of endodontics. Also, we have to disseminate information about the current rate of the endodontic retreatment to general practitioners.

Abstract : The purpose of this study was to evaluate the biocompatibility of resin sealers (Superbond^® sealer and AH Plus^®) for root canal filling. The mimic root canal (0.45 mm in diameter and 1.0 mm in length) filled with the test materials was implanted into cylindrical cavities of alveolar in 16 rats. At 1, 3, 5 and 7 days postoperatively, specimens were prepared for light microscopy. The blocks were dehydrated in ethanol and embedded in epoxy resin. Semithin sections were stained with toluidine blue. At day 1, inflammatory cell infiltration was observed around the apex of the roots in both groups. At day 3, a fragmented structure of AH Plus^® was observed and moderate inflammatory reaction existed. After 5 and 7 days, AH Plus^® still showed moderate inflammatory response around the sealers. However, Superbond^® sealer showed remarkable proliferation of fibroblast around the apex of the root. These findings indicate that Superbond^® sealer may be a more biocompatible medicament.

Abstract : Maxillary premolars often have complicated anatomies with one to three roots and two to four root canals. These complications are compounded because the root canals on resected surfaces during apicoectomy may differ depending on the locations and resected angles. In this paper, two cases of apicoectomy in maxillary premolars with complicated root canal anatomy on the resected surfaces are described and discussed. The surgery was performed using an operating microscope and biocompatible root-end filling materials. Microsurgical approaches with a better understanding of root canal anatomy can lead to more predictable outcomes in the healing of apical lesions.

Abstract : One of the expected effects of adhesive root canal filling sealers is the reinforcement of root canal dentin. These reinforcement effects were evaluated by measuring the surface strain of root canal dentin upon application of a load to the internal wall of the root canal before and after root canal filling using various types of root canal filling sealer.

 Thirty-three freshly extracted single-rooted teeth without cracks were cut at 15 mm from the root apex and randomly divided into 3 groups. Root canal preparation was performed so that a stainless steel rod could be inserted 5 mm from the root apex. A three-axis foil-type strain gage was placed at 5 mm from the root apex on the buccal and lingual root surface. The root was fixed to the fixation device to apply the load onto the stainless-steel rod at a right angle to the tooth axis using a testing machine and changes in root surface strain were recorded on a computer. The same measurements were performed after the root canal filling using 3 different root canal filling sealers with or without adhesive to root dentin.

 Changes in root surface strain before and after the root canal filling were not statistically different among 3 different types of sealers used.

Abstract : Cone-beam computed tomography (CBCT) and dental microscope are useful for diagnosis and treatment in endodontic therapy. CBCT is designed to produce three-dimensional information about undistorted tooth root canals and the shape of periapical lesions. A dental microscope is effective for identifying the subvisible narrow root canal orifice, location of root perforation and fractured instrument in the root canal. This report describes the treatment by CBCT and microscope of an endodontic lesion caused by perforation.

 The patient was a 49-year-old woman. X-ray photographs of the mandibular right first molar showed a periapical lesion and a perforation near the intracanal post on the middle of the distal surface of the distal root. The closed orifice of the distal root canal was searched for on CBCT images, and located under a dental microscope. The root canals and perforation area were filled by gutta-percha after checking sterilization with a bacterial examination. The prognosis was good 18 months after the root canal filling.

 This case suggests that an exact diagnosis with CBCT and fine treatment under a dental microscope improve the success rate of complex cases of infected root canal and infected root perforation.