Comparison of retentive force and wear pattern of Locator® and ADD-TOC attachments combined with CAD-CAM milled bar

• Published in: The journal of advanced prosthodontics Vol. 14; no. 1; pp. 12 - 21
• Main Authors: Chae, Sung-Ki, Cho, Won-Tak, Choi, Jae-Won, Bae, Eun-Bin, Bae, Ji-Hyeon, Bae, Gang-Ho, Huh, Jung-Bo
• Format: Journal Article
• Language: English
• Published: Korea (South) The Korean Academy of Prosthodontics 01.02.2022; 대한치과보철학회
• Subjects: Original; 치의학; Zirconia prosthesis; Computer aided design and computer aided manufacturing (CAD-CAM); Bar attachment; Implant supported overdenture; Digital milled bar
• ISSN: 2005-7806; 2005-7814
• DOI: 10.4047/jap.2022.14.1.12

The purpose of this study was to investigate changes in retention and wear pattern of Locator® and ADD-TOC attachments on a digital milled bar by performing chewing simulation and repeated insertion/removal of prostheses in fully edentulous models. Locator (Locator®; Zest Anchors Inc., Escondido, CA, USA) was selected as the control group and ADD-TOC (ADD-TOC; PNUAdd Co., Ltd., Busan, Republic of Korea) as the experimental group. A CAD-CAM milled bar was mounted on a master model and 3 threaded holes for connecting a bar attachment was formed using a tap. Locator and ADD-TOC attachments were then attached to the milled bar. Simulated mastication and repeated insertion/removal were performed over 400,000 cyclic loadings and 1,080 insertions/removals, respectively. Wear patterns on deformed attachment were investigated by field emission scanning electron microscopy. For the ADD-TOC attachments, chewing simulation and repeated insertion/removal resulted in a mean initial retentive force of 24.43 ± 4.89 N, which were significantly lower than that of the Locator attachment, 34.33 ± 8.25 N ( < .05). Amounts of retention loss relative to baseline for the Locator and ADD-TOC attachments were 21.74 ± 7.07 and 8.98 ± 5.76 N ( < .05). CAD-CAM milled bar with the ADD-TOC attachment had a lower initial retentive force than the Locator attachment. However, the ADD-TOC attachment might be suitable for long-term use as it showed less deformation and had a higher retentive force after simulated mastication and insertion/removal repetitions.