Abstract : Two endodontically treated teeth with perforation repair extracted because of persistent symptoms were fractured vertically ; one was fractured vertically from the middle to the apical portion of the root and the other at the furcation area. Both the fractures would have been difficult to detect nonsurgically. It is suggested that the possibility of vertical root fracture should be considered for the endodontic cases with persistent symptoms.

Abstract : The purpose of this study was to evaluate the sealing and/or adhesive ability of different resin-based root canal sealers (AH Plus, AH Plus Jet, Epiphany SE sealer and MetaSEAL). Canals N was used as the control material. Scanning electron microscopy was conducted to evaluate the ultrastructure of (1) set sealer surfaces, (2) root canal dentin surfaces treated with the sealers, and (3) sealer-root canal dentin interfaces. Coronal seal was evaluated by the linear leakage of methylene blue dye.

 The results were as follows :

 1. Many voids were observed on the surface of hand-mixing type sealers (AH Plus, MetaSEAL and Canals N), whereas auto-mixing type sealers (AH Plus Jet and Epiphany SE sealer) showed a smooth surface profile.

 2. The resin-based sealers examined showed a demineralizing effect on the surface of root canal dentin.

 3. Gap-free sealer-dentin interfaces with the formation of resin tags were frequently observed in canals filled with the resin-based sealers.

 4. The resin-based sealers showed significantly less leakage compared with Canals N (p<0.05).

 It was concluded that the resin-based sealers examined show better coronal seal than Canals N, probably through their self-adhesive properties.

Abstract : We developed a new simple system for the evaluation of root canal irrigation. This system measures the magnitude of light permeating a transparent root canal model. The permeated light is detected by a photo-diode, the signal of which is converted by an amplifier to DC potential which is proportional to illumination intensity. As a light source, a blue LED (light emitting diode) lit by a constant voltage power source is used. The transparent model is a 10-μL pipette having a 0.4-mm apical foramen in diameter and a 0.06 taper root canal.

 Using this model, the efficacy of root canal irrigation was evaluated for four irrigation needles.

Abstract : Rubber dam isolation is an essential procedure for root canal treatment. However, the procedure is sometimes difficult because of insufficient tooth structure such as subgingival caries. This case report describes a case for whom the distal wedge operation was performed for rubber dam isolation. After the operation, rubber dam isolation could be performed completely without any gingival inflammation.

Abstract : The purpose of this study was to evaluate the ability of ObturaⅡ^® and HotShot^® for gutta-percha penetration and apical sealing. A total of 192 plastic teeth were prepared for the root canal by a ProTaper file. Half of the plastic teeth were prepared for a 7% tapered canal by a ProTaper F1 file, and the other half were prepared for a 9% tapered canal by a ProTaper F3 file. Both the F1 and F3 groups were compared with ObturaⅡ^® and HotShot^®. The mean penetration was measured to the apical foramen by an SZX16 Olympus microscope with a DP71 digital camera. The sealing ability of obturation was evaluated by dye leakage test. One-way analysis of variance (ANOVA) and Scheffe tests were used to compare and identify any statistically significant differences at the level of p<0.05. The results indicated that the gutta-percha penetration of HotShot^® was perfect to the apical foramen, although the obturation of the ObturaⅡ^® F1 canal was significantly lower than that of the other experimental groups. The sealing ability of the HotShot^® F3 canal was significantly lower than that of the other experimental groups. It was concluded that Hotshot^® obturation is useful for 7% tapered root canals prepared by ProTaper, and ObturaⅡ^® obturation is superior to HotShot^® obturation in preventing apical leakage.

Abstract : The purpose of this study was to compare the gutta-percha penetration and sealing ability of obturation with different gutta-percha flows by ObturaⅡ^®. A total of 175 plastic teeth were prepared to 7% tapered root canals by NiTi ProTaper file and divided into three groups. In group 1, teeth were filled by soft gutta-percha flow at 90°C ; in group 2, teeth were filled by hard gutta-percha flow at 90°C ; and in group 3, teeth were filled by obtura soft gutta-percha flow at 200°C. The mean penetration was measured as far as the root apex by an Olympus microscope (SZX16) with digital camera (DP71). The sealing ability of the obturation was evaluated by the dye leakage test. 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 the flow penetration of hard gutta-percha flow at 90°C was better than the other gutta-perchas. The sealing ability of hard gutta-percha flow at 90°C was the same as the obtura soft gutta-percha flow at 200°C, and was excellent. It was concluded that obturation of roots with hard gutta-percha flow at 90°C was useful for 7% tapered root canals after preparation by NiTi ProTaper file, and increased the resistance to microleakage.