Development of inner surface machining design as micro retentive groove to prevent debonding of CAD / CAM crown

2021 Fiscal Year Final Research Report

• Project/Area Number: 18K09710
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 57050:Prosthodontics-related
• Research Institution: The Nippon Dental University
• Principal Investigator: SHINYA AKIKAZU 日本歯科大学, 生命歯学部, 教授 (60440054)
• Co-Investigator(Kenkyū-buntansha): 白鳥 沙久良 (清水沙久良) 日本歯科大学, 生命歯学部, 助教 (20804074)
• Project Period (FY): 2018-04-01 – 2022-03-31
• Keywords: CAD/CAM / CAD/CAM冠 / 機械的嵌合力 / 接着歯学 / 被着面処理

Outline of Final Research Achievements

The inner surface of the crown milled using CAD/CAM system is provided with a "groove (Micro Retentive Groove, hereafter MRG)" that provides an undercut to maximize the mechanical bonding behavior. We constructed a machining program that can be demonstrated and the crown debonding can be reduced. From the results, it was clarified that the highest adhesive strength was obtained when the depth of MRG was 100 μm, and that the effect was observed regardless of the type of luting material tested. In addition, the evaluation of the crown shape, it was clarified that it is most effective MRG design was that with 40 μm cement space, and a depth of 100 μm MRG milled in the center of the crown height on the inner surface. Three MRGs are recommended for maximum bonding effect.

Free Research Field

歯科理工学

Academic Significance and Societal Importance of the Research Achievements

金属価格の高騰からレジンブロックから切削加工されたCAD/CAM冠の需要が大幅に躍進している．そのCAD/CAM冠の装着にはクラウン内面に対して装着直前のアルミナブラスト処理とシラン処理が必須となっている．また，装着材料には接着性レジンセメントが推奨されていることから，装着時には多くの煩雑な前処理が必要となっている．本研究の結果から，クラウン製作時，冠内面に100μmのMRGを3本付与するだけで，クラウン内面への前処理が必要なくなり，装着術式の簡便化が可能となった．このことから，テクニカルエラーの低減も期待でき，安全な医療を国民に提供可能となったと考える．