Abstract : Biological root canal treatment is a new concept based on the regulation of functions of host cells, such as pulp cells, periodontal ligament cells and cementblasts, to induce mineralized tissue formation to obturate the root canal or root apex foramen. The most important step to achieve biological root canal treatment is to remove bacteria infected in the root canal without damaging the host cells. Topical application of an anti-microbial agent after mechanical root canal enlargement and chemical root canal irrigation may be effective to remove the infected bacteria and prepare the environment to induce host cell functions because of the agent’s selective toxicity.

 In this report, we introduce our anaerobic culture system for clinical bacterial examination and susceptibility test for endodontic treatment in Hiroshima University Hospital and analyze the data accumulated from clinical bacterial examinations.

 The bacterial samples were taken from cases of pulpectomy and infected root canal treatment at different stages of endodontic treatment : at the first visit, when the clinical symptoms changed during treatment, and before root canal filling (when mechanical enlargement was completed and there was no clinical symptoms).

 In the samples taken before root canal filling, that is, after mechanical enlargement and chemical irrigation have been done and the clinical symptoms have disappeared, 51.5% and 54.8% were positive in pulpectomy cases and infected root canal treatment cases, respectively. Only half of the endodontic treatment cases achieved negative culture by the mechanical enlargement and chemical irrigation. Thus, bacterial examination is useful to decide the timing for root canal filling and to estimate the prognosis of the treated tooth. Since the susceptibility of bacteria against the anti-microbial agents varied among the samples, the susceptibility test is essential for selecting anti-microbial agents for topical application in endodontic treatment.

 Complete removal of infected bacteria is essential for biological endodontic treatment with regulation of host cell functions. The bacterial examination guarantees the progress of the steps of biological endodontic treatment. However, the bacterial examination reported in this paper is an old method that is inconvenient for daily endodontic treatment. The system must be improved by new technology.

Abstract : Endodontic treatment is a highly advanced treatment based on various basic dental sciences. The complete removal of bacteria and antigens in root canals is necessary to prepare an adequate environment for biological endodontic treatment with regulation of host cell functions. Bacterial examination with the anaerobic culture system for root canal samples can objectively indicate the root canal condition and is useful to select antimicrobial agents and to evaluate the effects of root canal cleaning.

 In this paper, we report non-surgical treatment with bacterial examination and topical application of antimicrobial agents for chronic periapical periodontitis with a huge radiolucent area. The root canal exudates at the first visit and during endodontic treatment were collected as samples for bacterial examination with the anaerobic culture system and the detected bacteria were further examined for their susceptibility against various antimicrobial agents. Based on the minimum inhibitory concentration of each antimicrobial agent, minocycline was selected and topically applied. At four years after the root canal filling, no clinical symptom was observed, and X-ray photos indicated shrinking of the radiolucent area. This clinical case suggests that non-surgical endodontic treatment with adequate application of antimicrobial agents is powerful even for chronic periapical periodontitis with a huge radiolucent area.

Abstract : The purpose of this study was to evaluate the effects of methylene blue dye staining on the diagnosis of vertical root fracture. Experimental incomplete vertical root fractures were made for 10 human teeth extracted after root canal preparation. Each image of the fractured teeth was recorded using a dental operating microscope at ×10.6, ×17.0 and ×26.6 magnifications both before and after the methylene blue dye staining. The ratio of fracture line length measured by three dentists on the recorded images to actual fracture line length showed no significant difference between the magnifications and between the observers (p>0.05). Methylene blue dye staining, however, showed a significant effect on fracture line length measurements (p<0.05). It was concluded that methylene blue dye staining could more clearly reveal vertical root fractures under the dental microscope compared to non-stained controls.

Abstract : The purpose of this study was to evaluate the effect of dental speciality or clinical experience on differential diagnosis using dental radiographs between vertical root fracture and periapical inflammation. Sixty-three dentists observed ten dental radiographs and judged whether the lesion was caused by vertical root fracture or periapical inflammation. Whereas clinical experience had no significant effect on the correct answer rate (p>0.05), the speciality of dentists showed a significant difference (p<0.05). The correct answer rate of endodontists was significantly higher than that of oral surgeons (p<0.05). It was concluded that training on how to analyze dental radiographs is very important for the differential diagnosis between vertical root fracture and periapical inflammation.

Abstract : The purpose of this study was to evaluate patients’ attitude toward apicoectomy and early symptoms after surgery. Thirty-two patients underwent apicoectomy using a dental operating microscope and answered a questionnaire after the surgery.

 While postoperative swelling increased with time, postoperative pain showed no distinct relation with time. It was evident that the operator should be discuss matters carefully with the assistant during surgery. Nearly half of the patients ate smaller meals after the surgery. Many patients requested more information about the disadvantages of apicoectomy before the surgery.

Abstract : Irrigation of apical lesion through the root canal over the apical foramen using sodium hypochlorite solution (NaClO) combined with strong electrolyzed acid water was performed in patients with continued periapical exudation after apicoectomy, and a good clinical result was obtained as reported below.

 A 34-year-old male patient, who presented at the dental clinic of Asahi University, complained mainly of pain upon palpation in the left maxillary central incisor. The involved tooth had been treated by apicoectomy at another dental clinic, but the pain upon palpation and percussion remained.

 The tooth was diagnosed as chronic suppurative apical periodontitis caused by incomplete surgical apicoectomy and so conventional intracanal treatment followed by irrigation of the periapical lesion to promote its healing were performed.

 Four months later, the tooth was treated ten times to improve the clinical symptoms, and the root canal was filled with gutta-percha points and canals^®.

 Three years after root canal filling, the clinical course has progressed uneventfully and the lesion in the periapical region has completely disappeared.

Abstract : In this case, we repaired the perforation site on the root canal wall using a microscope. During pulpectomy of the lower second molar, perforation was found on the canal wall of the mesial root. Immediately, the perforation was repaired using calcium hydroxide and glass-ionomer cement under a microscope. 1.5 years after the operation, the tooth is in a clinically good condition.

Abstract : The purpose of this study was to evaluate the cytocompatibility of four different types of root canal sealers in cell culture. Osteoblastic cells, MC3T3-E1, were cultured for 3 days with freshly mixed materials and set ones for 14 days from two resin-based sealers (Super-bond and AH-26), a zinc oxide-eugenol-based sealer (Canals), and a calcium hydroxide-based sealer (Sealapex). Cytotoxic effects were evaluated on the basis of the morphological changes under a light microscope. In the freshly mixed sealers, AH-26 showed the highest cytotoxicity. Super-bond and Canals were less cytotoxic, causing a slight decrease in cell density in the vicinity of the sealers. The cells adjacent to Sealapex revealed normal morphology and growth. On the other hand, in the set sealers, Super-bond and AH-26 exerted little influence on the cells and reached confluency. Canals and Sealapex showed mild cytotoxic effects.

 These results suggest that the 4-META resin-based sealer, Super-bond, is a biocompatible material and has good potential as a root canal sealer.