Infiltration of trace metal ions in the oral mucosa of a rat analyzed using SRXRF,

2018 Fiscal Year Final Research Report

• Project/Area Number: 15K11343
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Orthodontics/Pediatric dentistry
• Research Institution: Tokyo Medical and Dental University
• Principal Investigator: KANNO Zuisei 東京医科歯科大学, 大学院医歯学総合研究科, 講師 (40345301)
• Research Collaborator: IMAMURA Toshihiro
• Project Period (FY): 2015-04-01 – 2019-03-31
• Keywords: 金属イオン溶出 / ICP-MS / SR-XRF / Rhメッキ / 金属アレルギー

Outline of Final Research Achievements

We investigated the amount, distribution, and chemical state of metals in the buccal mucosa using ICP-MS, SRXRF, and XAFS. We observed the infiltration of metals into the oral mucosal connective tissue and found that the metals are present in the form of a hydrated ion and oxide state. Our results help develop a new approach to inhibit metal allergy, which causes orthodontic patients to suffer from inflammation of the oral mucosa due to the contact of orthodontic devices.
Rhodium as coating material is aesthetic and corrosion resistant. However, the coating could not provide absolute resistance against acidic attacks. In combination with the results obtained from both the in-vitro and in-vivo experiments, it shows that NiTi is a stable and durable material, as despite the presence of ion dissolution, they were all under the daily intake threshold.

Free Research Field

歯科矯正学

Academic Significance and Societal Importance of the Research Achievements

本研究は、口腔内に溶出した金属の粘膜への浸透・蓄積の様子を初めてとらえたものであり、用いた手法の斬新さおよび有効性を明らかにした。また、組織への直接接触によってのみ、金属イオンが組織内へと浸透することも明らかとなった。一方で、金属材料の表面改質すなわちコーティングにより、直接接触を抑制した実験では、局所のガルバニー電極効果により金属イオンの溶出の増大が確認された（未発表）ことで、今後の製品開発や臨床応用についてはさらなる検証が必要であるものと思われる。