Abstract : This study investigated the effects of root canal irrigants on the surface of mineral trioxide aggregate (MTA) by using a scanning electron microscope (SEM) and elemental analyzer.

 The SEM observation of the control samples revealed crystals growing in various shapes and sizes as the treatment progressed. In the H₂O₂ treatment group, numerous triangular crystals were observed after 1 week and these grew into cubic crystals after 2 weeks. Small amorphous crystals were observed among other crystals after 3 weeks. In the NaClO treated samples, numerous square type crystals were observed on the surface of all samples. In the EDTA treatment group, rounded crystals grew as the treatment progressed.

 We assume the crystals will form with silicate oxide or tricalcium in NaClO, Bi oxide will change to Bi compound in H₂O₂, and ferrous oxide will change to ferrous compound by chelating action in EDTA.

 In the elemental analysis of H₂O, H₂O₂ and NaClO treatment groups, Ca was high rate, but in the EDTA treatment group, Bi was high rate.

Abstract : The healing of persistent periapical lesions such as cyst or granuloma is difficult by infected root canal treatment. Usually, endodontic surgery with infected root canal treatment will be required in such cases.

 In this study, the tube procedure was used to treat a large lesion with pus discharge. It was observed that the lesion became small and pus discharge decreased. Then the foramen was calcified using Ca(OH)₂ treatment.

Abstract : Infected root canal treatment was performed for an upper left second premolar with incomplete dental root and buccal periapical abscess, and the prognosis was observed for 10 years.

 The patient was a Japanese boy of 10 years old. Fracture of the central tubercle seemed to be the cause of the problem and periapical abscess had sometimes occurred during the 3 months before treatment. The dental root was incomplete, and the root canal was very large with a widely opened apex. The pulp of this tooth was vital in spite of the occurrence of periapical abscess.

 Mechanical cleaning was impossible because of the incomplete root canal, so chemical surgery for 15 minutes using 2.5% NaClO and application of iodoglycerin were repeated two times, and the root canal was filled using Vitapex^® paste which is a calcium hydroxide-iodoform preparation. The X-ray after filling showed that Vitapex^® reached almost 2/3 of the root canal.

 The periapical abscess disappeared after the second treatment, and the abscess did not return during the 10 years. The dental root was formed almost normally and the root apex was completed after 3 years of treatment. Furthermore, no periapical lesion was observed for 10 years.

 The one of the main reasons for the favorable formation of dental root in this case would be the existence of dental pulp in spite of the occurrence of periapical abscess.

Abstract : This study analyzed referral notes submitted to the outpatient clinic for new patients in Tsurumi University Hospital from January 2000 to August 2001 (20 months), and analyzed those clinical records.

 The results were as follows :

 1. Most referral notes (about 25%) were for endodontic treatments.

 2. Although most diagnoses in the referral notes were apical periodontitis, principal diagnoses in 35% of these cases in the hospital were different.

 3. Most teeth fractures and perforations that were overlooked in referral notes could be confirmed without specialized instruments or diagnostic methods.

 4. Of the cases diagnosed as apical periodontitis in the referral notes, 66.3% were successfully treated.

 5. Of the 8 cases suggested for endodontic surgery in the referral notes, 4 were successfully treated using general endodontic treatments.

 These results suggest that most cases that undergo referral as cases involving difficult conditions or poor prognosis can be successfully treated if standard treatments are used based on correct diagnosis, without the need for special instruments or therapies.

Abstract : The goal of endodontic treatment is completed with the sealing of the apical foramen at the cementodentinal junction with an inert material. At present the gutta-percha technique is dominant for obturation of curved canals.

 An aim of this study was to compare the new soft-type gutta-percha point FGP-3 (GC Corporation) and the current commercial gutta-percha point (GC Corporation) by using the lateral condensation technique.

 As a root canal model, we used a plastic model, which had a middle degree curved root canal model. We enlarged the root canal with K-files from ＃15 to ＃45, and applied the step-back technique. After the canal preparation, we obturated the root canal with a cold lateral condensation technique using two kinds of gutta-percha master points and ＃35 accessory points.

 To evaluate the sufficiency of obturated gutta-percha, the root canal model was horizontally cut at 1, 5, and 8 mm from the apex. The cross sectional image at 1, 5, and 8 mm was analyzed using Scion Image analysis software (Scion Corporation).

 Soft-type gutta-percha points changed in shape and dimension more easily than the current commercial type under the lateral condensation. At 1 and 8 mm, we found a statistical difference between the soft type and the current commercial type.

Abstract : A 23-year-old male was referred to our dental clinic complaining of pain in the mandibular first premolar tooth. Radiographic and clinical examination with endodontic instruments revealed three root canal orifices : one lingual canal with one apical foramen and two buccal canals joining in one common apical foramen. Because of the unusual canal anatomy the canals were carefully instrumented so as to avoid packing debris moving from one canal to the other. The larger two canals were enlarged with a K-file after packing off the small canal with another K-file. Subsequently, the smaller diameter canal was enlarged in the same manner. The canals were then obturated with gutta-percha points using the lateral condensation technique. Ten months later, a marked reduction in size of the periapical lesion was seen on radiographic examination. This case suggests that prior to the treatment of any multi-rooted tooth, a careful clinical and radiographic examination utilizing tube-shift techniques is required to detect multiple canals.

Abstract : This study investigated radiographic evaluations of 261 root canal treatments in 131 cases (73 apical periodontitis, 35 irreversible pulpitis and 23 reversible pulpitis) by the ProTaper and ObturaⅡ systems. Radiographs taken immediately post-obturation were used to evaluate the outcome of ProTaper preparation and ObturaⅡ obturation. The level of the final root filling was classified as short (more than 2 mm short of the apex), flush (within 2 mm) or over (beyond) in 11.1, 83.9 and 5.0% of cases, respectively. All broken files were removed by an ultrasonic instrument, when SX files were broken twice after 50 times repetition. No ProTaper files broke until the 25th repetition in this study. The results showed that the ProTaper and ObturaⅡ systems are rapid and relatively safe for curved root canal treatment.

Abstract : Histological examination was carried out to assess the biocompatibility of CalcipexⅡ and Calcipex PlaneⅡ, new calcium hydroxide-containing pastes. Tissue reactions after filling bony defects in rats with either of the two pastes were observed under light microscopy at 1, 3 and 6 weeks after the operation. CalcipexⅡ and Calcipex PlaneⅡ showed almost identical tissue reactions. Although macrophages and foreign-body giant cells were observed around the residual particles of pastes during all experimental time periods, these cells and particles decreased in number in a time-dependent manner. As time passed, however, newly formed bone was observed in the bony defects without severe inflammatory reactions. Some residual particles seemed to be in direct contact with newly formed bone, while others were surrounded by fibrous tissues. These results suggest that CalcipexⅡ and Calcipex PlaneⅡ are biocompatible.