Abstract : Purpose : A type Ⅰ endo-periodontal lesion is a disease in which an endodontic lesion first occurs and subsequently bacterial infection of the endodontic lesion extends to periodontal tissues through, for example, an apical foramen and an accessory canal. A tooth affected by a type Ⅰ endo-periodontal lesion has devitalized pulp and localized periodontal tissue inflammation. The basic treatment policy for type Ⅰ endo-periodontal lesions is endodontic treatment, that is, periodontal lesions as well as endodontic lesions are improved with treatment of the infected root canal. This case report describes two cases in which two different treatments were conducted for two teeth affected by chronic apical periodontitis with a localized deep periodontal pocket. The two cases were referred from two other dental clinics.

 Case 1 : the affected tooth : 7┐ with a C-shaped root canal, the patient : a 38-year-old woman.

 The probing pocket depth (PPD) of 7┐ was 3 mm in five areas except for the midbuccal area whose PPD was 7 mm at the first visit. A ledged root canal was observed at the middle site of a mesial root canal, and calcium hydroxide as an intracanal medication had been applied.

 Case 2 : the affected tooth : 7┘, the patient : a 49-year-old woman.

 The PPD on 7┘ was 3 mm in five areas except for the mesiobuccal area whose PPD was 8 mm at the first visit. A sinus tract was observed on the buccal marginal gingival area. Radiography showed that the three obturated root canals of 7┘ had a dense appearance. Dental calculus was found at the root apex of the mesiobuccal root which was close to a deep mesiobuccal-area periodontal pocket after 7┘ had been extracted.

 Discussion : Although endodontic treatment is the first choice for treatment of type Ⅰ endo-periodontal lesions, intentional reimplantation in addition to combined endodontic and periodontal treatment should be conducted as needed in consideration of both the present condition of the affected tooth and the past course of treatment.

 Conclusion : Infected root canal treatment and intentional replantation were conducted in case 1 and case 2, respectively, and both treatments gave successful clinical outcomes in both cases.

Abstract : Purpose : Instrument separations are unintentional complications that can occur during root canal treatment, causing serious mental stress for not only the operator but also the patient. Separated instruments can be removed by non-surgical or surgical approaches, but surgical approaches must sometimes be avoided for various reasons. Recently, non-surgical removal techniques under a dental operative microscope have been globally established. Among these, the wire loop and tube method with straight-line coronal and radicular access has been validated for cases involving straight canals, which offer high visibility under microscopy. In addition, this method allows non-surgical removal when separations are long enough to be captured within the root canal, even if these separations are markedly overextended.

 Case : A 71-year-old woman was referred to the Division of General Dentistry 1 (Endodontics) at Nippon Dental University Hospital for removal of a separated instrument in the left mandibular first premolar. Periapical radiography and 3-dimensional cone-beam computed tomography revealed an instrument overextended into cancellous bone approximately 7 mm from the apical foramen. According to pretreatment planning, straight-line coronal radicular access with a #35/.05 taper was prepared under a dental operative microscope. The middle part of the partial platform was formed using an ultrasonic diamond-coated tip to provide sufficient cutting efficiency, whereas the sensitive part near the fragment was more gently formed using a #25/.05 taper ultrasonic tip and endodontic micro-files. Subsequently, the wire loop and tube were applied to capture the fragment. After removal of the separated instrument was confirmed visually and on periapical radiography, root canal treatment was completed under the standard protocol.

 Discussion : A smooth broach can be easily pulled out if it can be firmly captured. However, the possibility of further extension from the apical foramen if external vertical force is applied in an apical direction must also be considered. The current case indicated that the straight-line coronal radicular access with #35/.05 taper is a suitable platform design from which insertion of the needle along the root canal wall is effective to retrieve a separated instrument without overextension.

 Conclusion : A comprehensive treatment plan and advanced instrumentation allow the successful removal of separated instruments. The wire loop and tube method provides a safe, predictable method of removing separated instruments that have been markedly overextended.

Abstract : Purpose : The aim of this case study was to clarify the structure of an accessory root canal found in a gutter-shaped root.

 Case : The patient was a 68-year-old woman who had been experiencing movement and swelling of her mandibular left second molar and occlusal pain for a month. She had started her usual periodontal treatment, but underwent a tooth extraction after initial treatment. When the microstructure of the extracted tooth was observed by micro X-ray CT and SEM, a secondary root canal opened in the longitudinal groove on the buccal side at 5 mm from the apex was found.

 Discussion : In Japan, the mandibular second molar has a 30% chance of having a gutter-shaped root. Many c-type root canals are found in the root canals of gutter-shaped roots, and isthmus is also seen, so root canal treatment requires care.

 Conclusion : When there is an accessory root canal shorter than the root canal that opens at the apex, it is necessary to be careful of perforation during root canal treatment.