Abstract : Microorganisms are capable initiators of the host immune responses in periapical tissues via root canal systems. Therefore, the pathogenic process is related to the virulence of bacteria and to the host's resistance. Microbiological investigations revealed the micro biota of human infected root canals as being polymicrobial and anaerobic. Periapical exudates via root canals were found to contain inflammatory mediators produced in the periapical lesions to reflect the immune responses occurring. The temporal context of lesion activity was associated with quantitative differences in inflammatory mediators. The association of immunological changes in periapical lesions and the presence of clinical symptoms of the involved teeth was also suggested. A retrospective study was carried out to evaluate the potential of clinical risk factors as being markers of recurrent periapical lesions. Intracanal findings which can reflect the qualitative and quantitative differences of root canal infections may serve as clinical risk factors of recurrent periapical periodontitis. Further studies are required to reveal the regulatory mechanisms which control the disease activity of periapical lesions. However, microbiological and immunological investigations may provide a new conceptual diagnosis of periapical periodontitis.

Abstract : This paper reviews the recent concept of pain mechanisms in the orofacial region including the tooth. Acute pain is considered to be a warning signal to us and an excellent defense system, whereas chronic pain does not have any physiological advantages for painful patients. Aδ- and C-fibers conduct pain signals to the central nervous system, and dentinal pain is conducted by Aδ-fibers and pulpal pain by C-fibers in the tooth. Deep pain, referred pain, and the disfunction of pain sensory system are also important to understand pain. Current idea of dentin hypersensitivity and the relationship between tooth pain and inflammation are introduced here. We need to understand both peripheral and central pain mechanisms for the control of pain. Pain from temporomandibular disfunction, trigeminal neuralgia, atypical facial pain, and cancer are also described in this paper along with the mechanisms of intractable orofacial pain. Through knowledge on pain is necessary for diagnosis and treatment in the dental clinic.

Abstract : It is well known that bacteria are one of the most important causative agents of pulpitis and apical periodontitis. Various kinds of bacteria such as Eubacterium, Peptococcus, Peptostreptococcus, Prevotella, and Porphyromonas have been isolated from infected root canals. A great abundance of bacteria seems to be associated with pulpitis and apical periodontitis. Also bacteria with enzyme activity such as collagenase, chondroitinase, and hyaluronidase may play very important roles in the pathogenesis of pulpitis and periapical disease.

 Endotoxin, a cell component of gram-negative bacteria, has gained attention as a provocative factor of pulpitis and apical periodontitis. This consideration of endotoxin is important, for endotoxin has many inflammatory actions, such as the causing Schwartzman reaction and leukocyte migration, and it also has adjuvant and complement-fixing activities. The endotoxin content in the dentin wall was higher in teeth with radiolucent areas than in those without them. Endotoxin may be one of the causes of apical periodontitis. However, in general, we suggest that there are multiple causes of pulpitis and apical periodontitis, such as bacteria, their products, and many other kinds of factors.

Abstract : A new technique using K files with modified tips has been developed for the penetration of constricted canals. The tip of a ＃10 K file was sliced diagonally to make it thinner. Since this modified K file has an especially fine tip and an appropriate stiffness, it followed constricted or sharply curved canals well and had a high penetration potential.

 The author attempted to penetrate to the apical foramen in all 1884 canals of 977 teeth treated from 1987 to 1994. In 264 canals (14.3%) which could not be penetrated with conventional ＃10 K files, further attempts were made with the modified K files. As a result, the number of the non-penetrated canals was reduced to 75 (4.1%). There were 7 file breakages and 14 accidental perforations.

Abstract : The aims of this study were to investigate the effects of on pulpal blood flow and anesthesia in human teeth during dental local anesthesia using either 2% lidocaine with epinephrine (Xylocaine) or 2% lidocaine with epinephrine bitartrate (Ora).

 The duration of anesthesia and the occurrence of a reduction in blood flow were examined in the dental pulps of maxillary central incisor teeth. The local anesthetic solution was injected into the soft tissues adjacent to the apex of the sound maxillary incisor tooth. The pulpal blood flow was monitored by a laser Doppler flowmeter. At selected times, pulpal anesthesia was tested with an electric pulp tester.

 Following injection of 0.5 ml of dental local anesthetic solutions, the reduction of pulpal blood flow were 45. 4% (Xylocaine) and 51.6% (Ora). The duration of reduced blood flow were 34 min (Xylocaine) and 39 min (Ora). The duration of pulpal anesthesia were 74 min (Xylocaine) and 70 min (Ora).

 This study indicated that there was no significant difference on the effects of between 2% lidocaine with epinephrine and 2% lidocaine with epinephrine bitartrate.

Abstract : In order to confirm the clinical anesthetic effectiveness of ORA Injection Cartridge, this research was carried out in the field of conservative treatment. The main component of this anesthetic solution was lidocaine HCl (0.02 g/ml) with Sodium Pyrusulfite Adrenaline. For this clinical study, 128 teeth of 90 patients were used including the cases of caries treatments, vital pulp extirpation and extraction of the decayed teeth. The clinical examinations were carried out as follows : 1. The dental treatment could be carried out without pain or not. 2. How did the pain degree show at the time of needle injection ? 3. How long did the anesthetic effectiveness continue ? As a result, 72 out of 90 patients (80%) did not feel pain. 16 patients felt a slight pain. Only one patient felt a severe pain and the dental treatment could not be done. Concerning with the pain production at the time of needle injection, 22 out of 90 patients (22.4%) did not feel the pain. 54 out of 90 patients (60%) showed a slight pain. The case of severe pain was 14 (15.6%). The post operative pain showed 13 cases (14.4%). Side effects could not be observed.

Abstract : The Obturation System is the method of injecting the thermo-plastic Obturation Gutta in the root canal with the exclusive use injector and filling it by the vertical condensation method with pluggers.

 But this method is apt to become over obturation when the narrow part of the apex of root is above ＃35. In this case, the following method is recommended that after the apex of root is sealed with the apical cone technique, the upper part is filled by the Obturation System.

 This time, we have standardized the apex of root preparing by ＃50 apical reamer using extracted teeth and the sealing ability of the apex of root is compared the case that the root canal is filled by the Obturation System only using the hard Obturation Gutta without a sealer with the case that the apex of root is filled by both the apical cone technique using a marketing guttapercha cone and the Obturation System.

 We have obtained the results that the Obturation System using the Obturation Gutta only has the most excellent sealing ability.

Abstract : The magnetic resonance image (MRI) has recently been prevalent for the diagnosis of tumors and TMJ disorders.

 Compared with the conventional radiograph, MRI has the following advantages ;

 1. No risk of ionizing radiation exporsure.

 2. Less limitation in setting the body section for conventional tomography.

 3. Better identification of inflammation and anatomical structure in the soft tissue.

  This study concerned with MR assessment and diagnosis of the periapical lesions found in two patients.

 Case 1 : The patient had no clinical symptoms. The large periapical lesion was well defined on radiography.

 On MRI, the lesion had the signal of very high in T2W image and low/iso mixed in T1W image.

 These findings obtained by MRI showed the typical characteristic of cyst, which had a good agreement with the histopathological diagnosis.

 Case 2 : The Patient complained of the swelling in gingiva.

 The small periapical lesion involving one tooth was ill defined on radiograph.

 On MRI, signals of bone marrow was low and extended to three adjoining teeth by T1W image. Although clinical diagnosis was acute periapical periodontitis, with the use of MRI, this case was diagnosed as osteomyelitis of mandible.

Abstract : The treatment of the root canal is indispensable in the daily clinical work and it is pain for a clinician.

 I have performed the root canal filling using the file made from the nickel-titanium super elastic alloy developed by the Maryland Silver Spring Naval Laboratory in America this time.

 The enlargement of the root canal has been done with the file and the filling with a tool called condenser made from the alloy using the obturation-gutta of the vertical condensation filling method.

 I have obtained the result that the filling of the curved root canal is performed surely in short time, so the method will be reported.

Abstract : The ISO enacted and promulgated the standard of the dental root-canal obturating points as first edition on June 1, 1995.

 The standard and the JIS T 6515 of the dental root canal filling point were compared and examined.

 Then, such difference between two standards as the allowance of size, biological safety and their ways of thinking concerning the quality of the material for the examination samples will be reported.