Abstract : Purpose : The purpose of this study was to analyze the morphology of alveolar bone fenestration (ABF) in the Japanese population using dental cone-beam computed tomography (CBCT) images.

 Material and Methods : We investigated 1,784 teeth (maxilla : 867 teeth, mandible : 917 teeth) and CBCT images of 76 patients. The examination included the incidence of ABF, position of the dental root/extent (long diameter and width), and incidence/extent with respect to age (20-39 and ≥40 years).

 Results and Discussion : The incidence of ABF was 8.2％. With respect to tooth type, the incidence of ABF at the maxillary canines was 19.8％, followed by the maxillary first premolars (17.6％) and the maxillary lateral incisors (12.4％). In 71.3％ of the maxillary teeth with ABF, the 1/4 apical-side extent of the dental root was affected. On the other hand, in 88.7％ of mandibular teeth with ABF, it was located on the crown side from the 1/4 apical-side area of the dental root. The long diameter of the ABF at the maxillary anterior teeth was significantly greater than at the other sites (p＜0.05). The width of ABF at the maxillary anterior teeth was significantly greater than at the maxillary molars (p＜0.05). There were no significant differences in incidence or extent of ABF with respect to age.

 Conclusion : Maxillary tooth ABF was adjacent to the root apex in many cases, and its extent was slightly larger at the maxillary anterior teeth.

Abstract : Purpose : This case report describes combined endodontic and periodontal approaches that led to a favorable outcome for a maxillary right central incisor which was diagnosed as invasive cervical resorption (ICR).

 Case : A 43-year-old female patient visited Hiroshima University Hospital with a chief complaint of discomfort and gingival swelling of the affected tooth. She had no history of trauma and orthodontic treatment. There was no relevant medical history. The patient had good oral hygiene and her gingiva in all areas of the mouth except the affected tooth was healthy. The pocket probing depth on the affected tooth was 2 mm except for 6 mm at the central part of the palatal side. Bleeding and pus discharge were observed upon probing and fibrous tissue was touched by the probe tip. The tooth responded positively to thermal and electric pulp vitality tests using PULPER^® (GC, Tokyo, Japan) and Digitest^® (Parkell, Farmingdale, NY, USA), respectively. There was no spontaneous pain. To determine the extent and depth of the lesion area in three spatial levels, CBCT was taken. Before the surgical procedure, pulpectomy and root canal filling of the maxillary right central incisor were performed under rubber dam isolation. The surgical procedure was performed under local infiltration anesthesia (2％ lidocaine with 1 : 100,000 adrenaline). After the full thickness mucoperiosteal flap was elevated, granulomatous tissue within the bone defect was removed. After isolation of the surgical site, the defect was restored with composite resin. The flap was repositioned without tension and sutured interproximally with nonabsorbable sutures. One year after surgery, the patient was asymptomatic, and the tooth was deemed healthy.

 Discussion : In this case, the affected tooth which was vital underwent pulpectomy before surgical treatment. When performing a surgical procedure for ICR, determination of the necessity and the appropriate timing of root canal treatment needs a multifaceted clinical examination.

 Conclusion : The diagnosis of ICR using CBCT, root canal treatment, and curettage/repair of the resorption part contributed to a favorable clinical outcome in this case.

Abstract : Purpose : We report two cases of successful root canal treatment of invaginated canals with peri-invagination periodontitis of maxillary lateral incisors, which were Oehlers Type Ⅲa dens invaginatus.

 Cases : The two patients were an 18-year-old man and an 11-year-old boy. The maxillary lateral incisor of each patient, which was a dwarf tooth, was diagnosed as Oehlers Type Ⅲa with peri-invagination periodontitis due to infection of invaginated canals by dental cone beam computed tomography (CBCT). Each invaginated canal was treated with root canal treatment and obturation. In both cases, there were no pulpitis symptoms and the radiolucent area due to peri-invagination periodontitis was reduced.

 Discussion : The present case report confirms the importance of evaluating the clinical symptoms, vital pulp response by electric pulp test, and the anatomical location of a root canal containing the pulp and an invaginated canal in the dens invaginatus to diagnose peri-invagination periodontitis and to select a treatment option that minimizes invasiveness.

 Conclusion : Root canal treatment was performed on the invaginated canal only. As a result, the peri-invaginated periodontitis was allowed to heal without treatment of the root canal containing the pulp of the affected teeth.

Abstract : Purpose : This report introduces a method for locating the mesio-lingual canal in mesiobuccal roots (MB2) in maxillary molars under a dental operating microscope.

 Case : After the completion of root canal preparation for MB1, DB, and P, the search for MB2 was conducted. MB2 was found near the MB1-P line. Using a round bur, dentin was meticulously shaved away from MB1 at an approximately 35-degree angle in the direction rotated mesially from the MB1-P line around the pivot point until the isthmus was visible. The area about 4 mm parallel to the mesial wall from MB1 and about 2 mm in depth toward the apex was removed under the microscope. Once the isthmus was visible, the dentin on the mesial side of the isthmus was removed with an ultrasonic tip. A 21 mm #20 K-file was inserted into the palatal end of the isthmus to near the center of the canal, and root canal preparation was performed. After confirming the absence of symptoms, the root canal was obturated.

 Discussion : By using MB1 as a pivot after canal preparation and cutting in a direction slightly rotated mesially from the MB1-P line, the isthmus of the MB root can be safely located and MB2 can be prepared. MB2 is more curved than MB1, and the surrounding dentin is also thinner. Inexperienced dentists should be careful not to overcut and cause perforation.

 Conclusion : This report introduces a method for locating MB2 of maxillary molars under a dental operating microscope.