Abstract : This report discusses two cases of referred and acute pain from an endodontically treated tooth with a constricted root canal. The acute pain was identified by diagnostic anesthesia. Using a modified file and crown down technique, we were able to overcome the constriction and then reach the apical foramen while eliminating the residual pulp. This procedure resulted in disappearance of acute pain. It is suggested that the use of a modified file and the crown down technique is effective for endodontic treatment of teeth with constricted root canals with residual pulp. Diagnostic anesthesia was also helpful for differential diagnosis of referred pain.

Abstract : Retreatment of root canals that had been filled using silver point was performed for three teeth of two patients.

 Case 1 : A 58-year-old woman, whose chief complaint was occlusal pain of the right lower first molar. Only the distal buccal root canal of the tooth, of which the apical end of silver point protruded from the root apex, was treated. The point was removed by a Masserann kit^®, and corrosion was observed over a large region of the removed point. The root canal was filled with gutta-percha point and Sealapex^® after cleaning the root canal, and good prognosis was observed for about 8 years.

 Case 2 : A 48-year-old woman, whose chief complaint was gingival swelling around the right lower canine. A metal core had been placed in the upper part of the root canal, and the root canal under the metal core had been filled with silver point. The apical end of silver point was found to protrude from the root apex. The point was removed by a Masserann kit^®, and corrosion was observed over a large region of the removed point. The root canal was filled with gutta-percha point and Canals^® after cleaning the root canal. Concurrently, another root canal treatment of her lower right first premolar was performed. Good prognosis was observed for about 4 years.

 If silver point protrudes from the root apex, the point may always be saturated with tissue fluid and may not properly fit the canal, and widespread corrosion may occur over time.

Abstract : A sucking operation of sodium hypochlorite (NaClO) and installation of a rubber dam are necessary to prevent leakage of NaClO solution, which is the cleaning agent used for root canals.

 In the present study, the reaction of iodine solution with NaClO solution used to disinfect the operative field in the rubber dam was examined. The results showed that iodine solution of 435 nm was detected at the peak of the absorbency wavelength, iodine solution reacted with the sodium hypochlorite, and increasing the concentration of the sodium hypochlorite created a clear solution.

 From these research results, it was suggested that the iodine discoloration on the rubber dam seat due to the NaClO solution is useful for evaluating the certainty of the sucking operation of the NaClO solution.

Abstract : The purpose of this study was to evaluate a new root-dentin adhesion method for vertical root fractures in endodontically treated teeth. The new root-dentin adhesion method consists of the elimination of infected dentin, followed by root-adhesion by 4-methacryloxyethyl trimellitate anhydride, methyl methacrylate and tri-n-butyl borane (4-META/MMA-TBB) and fiberposts. The elimination of infected dentin is expected to inhibit root perforation when using an apex locator for measuring the distance to the tooth root surface during grooving for enlarging the tooth cracks. Ninety-two teeth with vertical root fractures were treated by this method under a dental operating microscope. Clinical symptoms and radiographic appearance of bony lesions were followed up from 12 to 46 months. The success rate of treatment was 96.0%.

 The results showed that the new root-adhesion method using the apex locator is an effective therapy for teeth with vertical root fractures without extracting the tooth.

Abstract : The present study assessed warm vertical obturation and the sealing ability of canals filled with resin-based sealer and Resilon by Obturator β (Pentoron^TM Japan). A total of 96 plastic standard teeth were used and divided into four groups of 24 teeth each. The root canals were filled with Resilon/Epiphany in group 1, with Resilon/AH plus jet in group 2, with gutta-percha/Epiphany in group 3, and with gutta-percha/AH plus jet sealer in group 4. The mean penetration of Resilon and gutta-percha was measured up to the root apex by an Olympus SZX16 microscope with a DP71 digital camera. The sealing ability of obturation was evaluated by the dye leakage test. All obturated teeth were sectioned horizontally at 1, 3, and 5 mm from the root apex. Sections were taken by a digital microscope, and the proportion of core material in each canal was quantified. A one-way analysis of variance (ANOVA) and Scheffe test were used to compare and identify any statistically significant differences at p<0.05. The results indicated that both the gutta-percha and Resilon penetrated completely as far as the root apex, and that the sealing ability of both Epiphany and AH plus jet was significantly higher than in the other experimental groups. The proportion of both the Resilon and gutta-percha was more than 90% at 1 mm from the apex. It was concluded that the Resilon/Epiphany and Resilon/AH plus jet groups showed significantly less leakage with root canal obturation by Obturator β.

Abstract : This study evaluated the effect of removing broken H-file pieces and removal times for various conditions of the ultrasonic device or broken file pieces. Cut H-files as broken files were pushed into transparent resin blocks at apical parts, and models of intracanal broken instruments were reproduced. The relationships among the output strength of the ultrasonic device, lengths and sizes of broken file pieces, presence or absence of water coolant and the parts contacted by the tip of the ultrasonic device were examined. The times taken to remove broken files were compared and discussed. A stronger output power of the ultrasonic device was more effective for removing broken files. The relationship with the length of broken files was not regular, but the time was short for the shortest length of 3 mm ; the larger pieces of broken files were more difficult to remove. The use of water coolant was effective. Regarding the contact parts, the time for removal was short when contacting the cut surface. It is suggested that the time taken to remove broken files closely corresponded with the conditions of the ultrasonic device or status of broken file pieces using transparent resin blocks.

Abstract : MTA is a bioactive material that releases inorganic ions into the surrounding environment. This study analyzed the changes in elemental distribution in root canal dentin in contact with MTA-canal filling. Slices of bovine incisor roots were root-canal filled with MTA (ProRoot^® MTA ; white) and immersed in phosphate-buffered saline (PBS) for 90 days. Morphological and elemental compositional analysis of the MTA-dentin interfacial layer was carried out by wavelength-dispersive X-ray spectroscopy electron-probe microanalysis. Formation of a layer of high Si concentration, approximately 10 μm wide, was detected in the outermost layer of the dentin in contact with MTA. A Ca-concentrated layer approximately 30 μm wide was also recognized just adjacent to the Si-concentrated layer. Such elemental incorporation in root canal dentin, most likely resulting from MTA-dentin-PBS interaction, may contribute to the biocompatibility, biomineralization ability and sealing ability of this material.

Abstract : The purpose of this study was to compare the sealing ability of root canal filling materials with or without using root canal dentin primer.

 Thirty-four single-rooted human mandibular premolars were divided randomly into four experimental groups (n=8) and one negative control group (n=2).

 Group A : Gutta-percha point (GP, GC) +Sealapex (SybronEndo) with lateral condensation

 Group B : GP+Superbond sealer (SunMedical) with single-cone technique

 Group C : GP+MetaSEAL^TM (Parkell) with single-cone technique

 Group D : GP+AH Plus (Dentsply) with lateral condensation

 A split chamber leakage model was used. Methylene blue dye solution was placed in the upper chamber so that the dye could reach the lower chamber only through the filled canal. The amount of dye that penetrated to the lower chamber was measured with a spectrophotometer at 1, 4, 8, 15 and 30 days following placement of the dye solution.

 There were significant differences among the groups and experimental time intervals (2-way ANOVA, p<0.05). The amounts of leaked dye in Groups A and B on the 30th day were significantly larger than those in Groups C and D (Tukey-Kramer, p<0.05).

 The resin-based root canal sealers without using root canal dentin primer showed an effective sealing ability.

Abstract : These two case reports describe the root canal procedures and 20-year follow-up after combination root canal filling of an incisal tooth with a large periapical lesion. The involved teeth were radicular cyst cases spreading to the adjacent teeth. Sodium hypochlorite solution (NaClO) worked well as a solvent agent for the epithelial lining and sub-epithelial hemorrhage of the lesion. The root canal was cleaned by biomechanical and biochemical preparation with NaClO and hydrogen peroxide. The use of NaClO promotes drainage of the pus and destruction of the epithelial lining, and then the large lesions changed quickly from cyst to granulomatous tissue. After disinfection of the root canal, FR-Ca paste containing guaiacol-formaldehyde resin and calcium hydroxide was estimated to occupy 2 mm of the apical canal and the residual space was obturated with gutta-percha and sealer. Radiographic images showed apical osteogenic healing, disappearance of radiolucency of FR-Ca paste, and slight thickening of lamina dura. This report suggests that proper procedures using canal irrigation with solvent agent are effective for the conservative treatment of large periapical lesions, and that follow-up should be continued for longer to obtain a more accurate prognosis.

Abstract : Recently, there have been many reports on the usefulness of cone beam computed tomography (CBCT) and an operating microscope in endodontic therapy. CBCT is useful to diagnose cases in which the disease condition and anatomical relationships cannot be fully understood from dental X-rays and panoramic X-rays only. An operating microscope is also useful to increase the accuracy and safety of treatment by more clearly demonstrating treatment procedures that could not otherwise be seen during endodontic therapy.

 In this study, we report three cases that required endodontic therapy using CBCT and an operating microscope. CBCT was very useful to detect a second mesiobuccal canal in the mesiobuccal root of the first maxillary molar, to understand the position and length of broken endodontic tools in the root canal, to clarify the shape of the root canal and the spread of apical disease, and to detect the position of perforation and condition of alveolar bone. The microscope was also very useful to identify the entrance of the root canal, to remove broken endodontic tools from the root canal, to repair the perforation, and to confirm that cleaning of the root canal was complete. In conclusion, we consider that prognosis in endodontic therapy will be improved if CBCT and an operating microscope are routinely used.

Abstract : The present study assessed warm vertical obturation and evaluated the sealing ability of canals filled with resin-based sealer and gutta-percha by ObturaⅡ^TM. A total of 72 plastic standard teeth were used and were divided into two groups of 36 teeth. In group 1, root canals were filled with gutta-percha/Epiphany and in group 2 with gutta-percha/AH plus jet sealer. The mean penetration of gutta-percha was measured until the root apex by an Olympus SZX16 microscope with DP71 digital camera. The sealing ability of obturation was evaluated by the dye leakage test. All canals were obturated, and the teeth were sectioned horizontally at 1, 3, and 5 mm from the root apex. Sections were taken by a digital microscope, and the proportion of core material in each canal was quantified. A one-way analysis of variance (ANOVA) and Scheffe test were used to compare and identify any statistically significant differences at p<0.05. The results indicated that both types of gutta-percha completely penetrated to the root apex, and the sealing ability of both Epiphany and AH plus jet was significantly high in both groups. The proportion of both types of gutta-percha was more than 83% at 1 mm, and more than 94% at 3 and 5 mm from the apex. It was concluded that gutta-percha/Epiphany and gutta-percha/AH plus jet obturation showed significantly less leakage with warm vertical obturation by ObturaⅡ.