著者

Takeshi Kase Tetsuo Ohyama Shinya Nakabayashi Hiroyasu Yasuda Takayuki Yoneyama

出版者

Nihon University School of Dentistry

雑誌

Journal of Oral Science (ISSN:13434934)

巻号頁・発行日

pp.19-0427, (Released:2020-08-01)

参考文献数

25

被引用文献数

1

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In this study, analytic models were used to simulate marginal resection in the area of the second premolar to the second molar region, and the mechanical effects on the mandible of residual bone mass, a maxillofacial prosthesis, and a reconstruction plate were evaluated by three-dimensional finite element analysis. As residual bone mass decreased, maximum principal stress increased near the anterior ramus of the mandible, and maximum shear stress increased at the anterior buccal region of the resected area. In the mandible with a maxillofacial prosthesis, the maximum principal stress distribution at the anterior ramus was lower, and the distribution of maximum shear stress at the anterior buccal region of the resected area was higher. When a reconstruction plate was used, maximum principal stress and maximum shear stress were lower. Thus, lower residual bone mass was associated with increased mandible deflection and torsion. In addition, presence of a maxillofacial prosthesis decreased deflection but increased torsion, and presence of a reconstruction plate decreased deflection and greatly decreased torsion. These findings suggest that decreased residual bone mass and maxillofacial prostheses increase fracture risk; however, presence of a reconstruction plate was effective in decreasing torsional stress, thereby reducing fracture risk in the mandible.

著者

Yaeko Hara Hiroshi Shiratsuchi Takaaki Tamagawa Ryosuke Koshi Chihiro Miya Maki Nagasaki Tetsuo Ohyama Shunichi Oka Hideaki Sakashita Tadayoshi Kaneko

出版者

Nihon University School of Dentistry

雑誌

Journal of Oral Science (ISSN:13434934)

巻号頁・発行日

vol.60, no.3, pp.321-328, 2018 (Released:2018-09-23)

参考文献数

31

被引用文献数

7

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Recently, reports regarding a foreign body in the maxillary sinus have considerably increased, with the majority being iatrogenic cases resulting from dental treatment. This study involves an extensive review of the Japanese literature, including 112 papers from 1978 to 2017. These papers documented total 407 cases of a foreign body in the maxillary sinus. Among the 392 cases for which treatment details were available, the Caldwell-Luc approach was used for 216, the alveolar approach for 116, extraction using nasal endoscopy for 15, and extraction using oral endoscopy for eight. Spontaneous passage occurred in 19 cases, follow-up with medication was used in 17, and “other” was noted in one. This study determined that surgical removal remains the most common method for treating both tooth roots and other foreign bodies and that the Caldwell-Luc approach is used in majority of the surgeries. No marked differences were noted among the removal methods used in relation to the foreign body type.

著者

Tetsuo Ohyama Hiroyasu Yasuda Norio Shibuya Satomi Tadokoro Shinya Nakabayashi Shunsuke Namaki Yaeko Hara Takahiro Ogawa Tomohiko Ishigami

出版者

日本大学歯学部

雑誌

Journal of Oral Science (ISSN:13434934)

巻号頁・発行日

vol.59, no.2, pp.273-278, 2017 (Released:2017-06-22)

参考文献数

24

被引用文献数

14

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Previous finite element analyses of peri-implant stress assumed a bone-implant contact (BIC) ratio of 100%, even though the BIC ratio is known to be approximately 50% or less. However, the recent development of ultraviolet treatment of titanium immediately before use, known as photofunctionalization, significantly increased the BIC ratio, to 98.2%. We used a unique finite element analysis model that enabled us to examine the effects of different BIC ratios on peri-implant stress. A three-dimensional model was constructed under conditions of vertical or oblique loading, an implant diameter of 3.3, 3.75, or 5.0 mm, and a BIC ratio of 53.0% or 98.2%. Photofunctionalization and larger implant diameters were associated with reduced stress on surrounding tissues. Under vertical loading, photofunctionalization had a greater effect than increased implant diameter on stress reduction. Under oblique loading, increased implant diameter had a greater effect than photofunctionalization on stress reduction.