Nihon Shishubyo Gakkai Kaishi (Journal of the Japanese Society of Periodontology)
Online ISSN : 1880-408X
Print ISSN : 0385-0110
ISSN-L : 0385-0110
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Original Work
  • Chihiro Kano, Hiroaki Kobayashi, Kosuke Nozaki, Yuka Tsumanuma, Takeak ...
    2020 Volume 62 Issue 1 Pages 1-15
    Published: March 31, 2020
    Released: March 28, 2020

    Periodontal treatment is performed to achieve a biologically acceptable exposed root surface. Root planing removes the part of the root surface that contains inflammation-inducing substances. Previous studies reported that lipopolysaccharide (LPS) existed on superficial exposed root surfaces and deep root planing was not necessary for periodontal treatment. However, recently, it was reported that not only LPS but also various pathogen-associated molecular pattern molecules (PAMPs) and damage-associated molecular pattern molecules (DAMPs) cause biological immune responses. Advanced therapies, such as periodontal tissue regeneration, use periodontal ligament stem cells (PDL-MSCs), but the influence of substances on the PDL-MSCs on the root surface is unclear.

    In this study, we analyzed the permeability of the inflammation-inducing substance on the root surface to determine a suitable root surface for optimal periodontal regeneration.

    Extracted teeth were planed, and the shaving extracts from root surfaces were used to measure the bacterial genome. The IL-1β expression in THP-1 cells stimulated by the shavings was measured and the production pathway of IL-1β was investigated using inhibitors. PDL-MSCs were used to examine cell attachment and proliferation on the planed root surface.

    By laser microscope, the root planed depth of the periodontitis-affected exposed root surface was 32.2±3.86 μm after the first stroke, 51.9±9.31 μm after the second, 85.4±10.2 μm after the third, and 96.2±4.64 μm after the fourth stroke. Bacterial genome and IL-1β mRNA expression were detected from all shaving extracts up to 8 strokes. The 3-stroke planing showed a significantly high number of PDL-MSCs on the planed root surface. PAMPs and DAMPs in the shaving extracts were involved in the IL-1β production pathway.

    These results indicated that bacterial penetration was observed up to at least the eighth stroke and 3-stroke root planing was necessary for the adherence of the PDL-MSCs.

    Our research highlights the need for further studies by setting a standard for the ideal preparation of a root surface to receive periodontal stem cells for regenerative procedures.

Case Report
  • Yumi Matsumoto, Hideo Arai
    2020 Volume 62 Issue 1 Pages 16-26
    Published: March 31, 2020
    Released: March 28, 2020

    Diabetes is one of the well-known risk factors for periodontal disease. Herein, we report on comprehensive periodontal treatment, including initial periodontal therapy, orthodontic treatment, periodontal surgery (periodontal regenerative surgery and periodontal plastic surgery), and treatment for oral function recovery, provided to a 36-year-old woman with type I diabetes who was suffering from generalized aggressive periodontitis, in collaboration with her physician for maintaining appropriate glycemic control. At present, 10 years since her initial visit, both the periodontal health and stable occlusion are well-maintained. This case highlights the fact that for patients having advanced periodontal disease with malocclusion, it is important to create a periodontal environment that is conducive to infection control, stable occlusion, and SPT, based on an understanding of the systemic condition and local risks in patients with periodontitis.

  • Meri Fukaya, Ayaka Suzuki, Taichiro Funatsu, Yuji Matsushima, Akihiro ...
    2020 Volume 62 Issue 1 Pages 27-37
    Published: March 31, 2020
    Released: March 28, 2020

    Cone beam CT (CBCT) can evaluate the three-dimensional morphology of the target sites for diagnosis and the surrounding tissues, and also allows measurement of the distance and angle from the specified sites. Bone defect morphology inferred from dental radiographs may differ from the actual bone defect state during surgery. When performing periodontal tissue regeneration therapy, it is important to know the exact state of bone loss in advance for ensuring the success of the surgery. Therefore, at our department, it is obligatory to obtain a CBCT image in patients scheduled for periodontal tissue regeneration therapy, prepare a model with a 3D printer, and hold a conference on periodontal tissue regeneration therapy prior to the treatment.

    We report on the flow of the periodontal tissue regeneration therapy conference in our course and for the two cases in which the therapy was actually undertaken. These cases are of patients with a vertical bone defect. A preoperative conference was held based on the CBCT images of the operation site, 3D models, and clinical protocol data. The 3D model almost reproduced the actual bone defect.

    For patients undergoing periodontal tissue regeneration therapy, CBCT imaging and preparation of a 3D model with a 3D printer can allow the surgeon to obtain a grasp of the bone defect form at the surgical site in advance and allow a satisfactory conference to be conducted before surgery. Our results indicate that the operation can be performed safely and effectively. Conducting a satisfactory conference before surgery is also a useful means for training young dentists and explaining to patients.

Educational Award
  • Akira Aoki, Yasuo Takeuchi, Tatsuya Akizuki, Koji Mizutani, Sayaka Kat ...
    2020 Volume 62 Issue 1 Pages 38-46
    Published: March 31, 2020
    Released: March 28, 2020
    Supplementary material

    During the fifth and sixth year of Dental School at Tokyo Medical and Dental University (TMDU), predoctoral dental students participate in comprehensive clinical practice at the Dental Hospital. The student clinical practice experience is organized into three phases. Phase I consists of clinical simulation practice at each of the Dental Hospital's clinics from September to October of year 5 (6 weeks). This occurs just prior to the start of actual clinical practice. Phase II consists of comprehensive clinical practice at the Student Clinic from November of year 5 to October of year 6 (47 weeks). Phase III involves advanced clinical simulation practice or lectures, where students gain advanced exposure to an area of their interest (5 weeks). This starts after the National Exams held in February of year 6.

    Regarding the clinical practice of periodontal therapy, every student practices periodontal examination, oral hygiene instruction, initial treatment, and assists with surgical treatment. During Phase II, the clinical practice is supervised by Dental Faculty members. A credit system is employed for the evaluation with points awarded for successful completion of training in each clinical procedure.

    The graduating class of 2018 (51 students) had periodontal therapy experiences totaling 51 examination cases (one case/student), 129 general cases (on average 2.5±1.9 cases/student), and 615 supportive periodontal therapy (SPT) /maintenance cases (on average 12.1±4.0 cases/student). All the students passed the oral examinations based on one examination case ("Main Case"), achieved the essential requirements for administering periodontal therapy, and completed the requirements for clinical practice.

    The system of student clinical practice is also evaluated by the students using a Course Evaluation. Findings from the students' Course Evaluations are used when considering modifications to the system of predoctoral dental clinical practice at TMDU. In this article, the present status of clinical practice of periodontal therapy by predoctoral dental students at TMDU is reported based on the schedule and performance of students of the graduating class of 2018.