Inspection technique of dental implant with instantaneous frequency of ultrasonic pulse wave

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K04023
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 20010:Mechanics and mechatronics-related
• Research Institution: Kyushu University
• Principal Investigator: Inoue Takumi 九州大学, 工学研究院, 教授 (40274485)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 診断 / 超音波 / 信号処理 / 同定

Outline of Final Research Achievements

In this study, a technique to evaluate the fastening torque of implant screw quantitatively was proposed by means of a diagnosis technique with ultrasonic pulse wave, which was devised by the applicant.
Firstly, a conversion of the ultrasonic pulse wave from longitudinal wave into shear wave during the transmission through the screw thread was found. And, the conversion revealed that an instantaneous frequency of the converted shear pulse wave significantly changes according to the fastening torque of the screw. Secondly, indirect expression of the fastening torque as a contact stiffness between internal and external screw thread was employed. Although the evaluated value was slightly lower than the real value, the fastening torque was evaluated in a relatively high accuracy. This study derived a basic technique enable us to evaluate the fastening torque of implant screw quantitatively.

Free Research Field

機械力学，振動学

Academic Significance and Societal Importance of the Research Achievements

歯周病等により失われた歯に代わり歯科インプラント（人工歯）が広く用いられてきている．一方で，インプラントねじの緩みにより侵入した細菌に感染し，歯槽骨や顎骨が溶けインプラントが脱落する問題が知られている．特に，患者が自覚できない程度の小さな緩みが問題とされ，この緩みを確実に検出する方法は未だ存在しないことから，臨床現場ではインプラントの締結状態を高精度に評価できる検査技術の確立が望まれている．本技術により歯科インプラント治療で懸案となっている大きな問題が解決されるとともに，人工関節など他のインプラント技術への応用も期待できる．