Shika Hoshasen
Online ISSN : 2185-6311
Print ISSN : 0389-9705
ISSN-L : 0389-9705
Volume 58, Issue 1
Displaying 1-6 of 6 articles from this issue
  • Kiyomi Kohinata, Kunihiko Sawada, Toshihiko Amemiya, Ko Dezawa, Yusuke ...
    2018 Volume 58 Issue 1 Pages 1-5
    Published: 2018
    Released on J-STAGE: September 29, 2018
    JOURNAL FREE ACCESS
    Objectives: In this study, we examined the relationship between the angle of elevation and artifacts on cone-beam computed tomography (CBCT) of the temporomandibular joint (TMJ) using the subtraction method. The scans were obtained using a hybrid unit for dental CBCT and panoramic radiography (hybrid CBCT).
    Methods: We used a model to simulate the head of the mandibular condyle and the glenoid fossa. The model was fixed to the hybrid CBCT scanner. First, it was set in the home position, in which the height of the deepest point of the glenoid fossa matched the height of the X-ray tube’s focal spot. Thus, the X-ray beam passed through the model in a horizontal direction (angle of elevation: 0°). Then, CBCT images were taken with different incident angles of elevation to determine how this influenced the obtained images. The approximate angles of elevation at model heights of 0-60mm (relative to the home position) were: 0mm: 0°, 20mm: 3.5°, 40mm: 7.0°, and 60mm: 10.5°. We also calculated standard deviation (SD) values for subtraction images produced by comparing the 0° images with those obtained at other angles.
    Results: As the angle of elevation increased, more image distortion arose (the greater the SD values of the subtraction images were).
    Conclusions: When TMJ images are obtained using a hybrid CBCT scanner, the target area of the TMJ should have a low angle of elevation. If the angle is >3.5°, image artifacts can appear.
    Download PDF (655K)
  • Hirotaka Muraoka, Takashi Kaneda, Naohisa Hirahara, Norihito Iizuka, S ...
    2018 Volume 58 Issue 1 Pages 6-10
    Published: 2018
    Released on J-STAGE: September 29, 2018
    JOURNAL FREE ACCESS
    Background and Purpose: The most common type of supernumerary tooth is the mesiodens, which occurs along the palatal midline and can assume a number of shapes and positions relative to the adjacent teeth. Extraction should be performed carefully to prevent damage to the adjacent permanent teeth because it can cause ankylosis and maleruption of these teeth. Therefore, a thorough investigation of the optimal treatment for supernumerary teeth is required. The purpose of this study was to investigate the age-related changes in the shapes and positions of supernumerary teeth using computed tomography (CT).
    Materials and Methods: The study population comprised 266 patients (179 males, 87 females; 4-83 years of age, mean age: 17.4 years) with a total of 337 supernumerary teeth, which were examined using multidetector CT. The subjects were divided into two groups: those aged < 19 years and > 20 years. The distance from the nasal cavity to each supernumerary tooth and the state of the supernumerary tooth roots were evaluated on 3-dimensional CT images. The between-group differences in these parameters were analyzed using a statistical software package (SPSS version 21.0; IBM Japan Inc., Tokyo, Japan). P < 0.05 was considered to indicate significance.
    Results: The mean distance from the nasal cavity to the supernumerary teeth differed significantly between the two age groups (P < 0.05). The states of the supernumerary tooth roots also differed significantly between the two age groups (P < 0.05).
    Conclusion: Our study found that changes in the shapes and positions of supernumerary teeth occur with aging. This knowledge may contribute to the diagnosis of supernumerary teeth and avoid errors in their treatment.
    Download PDF (1265K)
  • Tatsumasa Fukui, Wataru Nishiyama, Hiroyasu Yoshida, Noriyuki Shibata, ...
    2018 Volume 58 Issue 1 Pages 11-14
    Published: 2018
    Released on J-STAGE: September 29, 2018
    JOURNAL FREE ACCESS
    A 14-year-old girl complained of difficulty opening her mouth and clicking sounds in the bilateral temporomandibular joints. On magnetic resonance imaging, anterior displacement of the joint disk without reduction was seen in the bilateral temporomandibular joints. In addition, a cystic lesion (12×6mm) was detected on the outside of the right temporomandibular joint. The movement of synovial fluid between the cystic lesion and upper joint space was observed during mouth opening/closing. We diagnosed a synovial cyst concomitant with temporomandibular joint disorder.
    Although the patient required conservative treatment, her symptoms were not resolved. Future surgical treatment is under consideration.
    Download PDF (611K)
  • Atsushi Musha, Takuya Kumazawa, Yuya Yoshimoto, Takanori Abe, Tatsuji ...
    2018 Volume 58 Issue 1 Pages 15-18
    Published: 2018
    Released on J-STAGE: September 29, 2018
    JOURNAL FREE ACCESS
    Introduction: Temporomandibular joint luxation has various causes, such as bruising and external force, as well as excessive opening of the mouth during eating, yawning, dental treatment, or oral intubation procedures for general anesthesia. Due to its sudden onset, it can have a significant psychological impact on patients, and early and appropriate treatment is necessary. We report a case in which temporomandibular joint luxation occurred during computed tomographic planning for postoperative chemoradiotherapy for oral cancer.
    Case presentation: The patient was a 74-year-old female with squamous cell carcinoma of the right mandibular gingiva (cT4aN2bM0, stage Ⅳ, World Health Organization grade 1, INF-b). We performed right mandibular segmental resection, right radical neck dissection, a free rectus abdominis muscle dermal flap transfer and wrap-around reconstruction, and tracheotomy with a reconstruction plate for right mandible squamous cell carcinoma. Two months after the surgery, temporomandibular joint luxation was detected during computed tomographic planning (with a mouthpiece) for postoperative chemoradiotherapy. The left mandibular condyle had deviated forward from the glenoid cavity. However, when we subsequently performed computed tomographic treatment planning without a mouthpiece the jaw dislocation could not be confirmed, and the left mandibular condyle was present in the glenoid cavity. There was no recurrence of the temporomandibular joint luxation, and the subsequent radiotherapy (60Gy/30fr) was effective.
    Conclusion: It is considered that thorough anatomical confirmation during postoperative computed tomographic treatment planning is important in oral cancer cases, especially those involving mandibular segmental resection.
    Download PDF (822K)
  • Keisuke Saitou, Tomonori Ozawa, Nobutoshi Takahashi, Maki Izawa, Yasuh ...
    2018 Volume 58 Issue 1 Pages 19-23
    Published: 2018
    Released on J-STAGE: September 29, 2018
    JOURNAL FREE ACCESS
    Methotrexate (MTX) is widely used to treat rheumatoid arthritis. However, it has been suggested that MTX-treated rheumatoid arthritis patients are at risk of lymphoma. Recently, the occurrence of this lymphoproliferative disorder in the oral cavity has been reported as an MTX-associated lymphoproliferative disorder (MTX-LPD). We report a case of MTX-LPD combined with ulceration and jaw necrosis in a 72-year-old male, who had received MTX for 7 years for rheumatoid arthritis. He was referred to our clinic to receive treatment for pain in the posterior maxillary gingiva. Computed tomography showed bone resorption around the root of the maxillary premolar, and bone sequestration was suspected. At first, we diagnosed the patient with osteomyelitis, but the pathological diagnosis was MTX-LPD.
    We reviewed this case and 23 previously reported cases of oral MTX-LPD that occurred in Japan. The oral MTX-LPD developed outside of the lymph nodes in 40-50% of cases. Ulceration was seen in 20 cases, 23 cases involved no or slight swelling, the maxillary and/or mandibular gingiva was affected in 22 cases, and 14 cases involved bone resorption or bone defects. Many cases were clinically diagnosed as osteomyelitis, malignant tumors, or chronic periodontitis. When oral MTX-LPD is suspected, the patient’s medical history should be taken, and a systemic examination should be performed.
    Download PDF (541K)
feedback
Top