Test Methods of The Retentive Force of Attachment System for Dental Implants

Objectives: Dental implant attachments are shown that various retention characteristics are commonly used to retain overdentures of dental implants. The purpose of this study was to evaluate the change in the retentive force of four implant attachment systems during simulation of insertion-removal cycles in artificial oral environment and to suggest the test methods of the retentive force of attachment system for dental implants.
Methods: Locator^® (Clear, HIOSSEN), EZ-LOCK (SELA405SR, SAMWON DMP), O-ring attachments (TS stud, Osstem implant) were embedded in a custom-manufactured Ti-alloy jig and Magnetic attachment (Magfit SX, Aichi Steel) were embedded in acrylic resin block. Each 10 attachments were connected abutments and implant fixture (TSIIISA, Osstem implant). The specimens were evaluated by insert-removal cyclic testing and retentive force testing with an Instron^® universal testing machine. Retention force were obtained four times (0, 750, 1500 and after 2,250 cycles) by simulating the clinical service in artificial saliva at 37 °C and measured with tensile strength at 5 mm min⁻¹ and load cell of 100 N. Retention force are an average of five measurements taken at each interval.
Results: Significant retention loss was observed in a three attachment systems upon completion of the 2,250 cycles of insertion and removal cycle, compared to the initial retentive force (P<0.05) except for magnetic attachments.
A comparison of the initial retentive force revealed the highest value for Locator, followed by the EZ-LOCK, O-ring and Magnetic attachments. Also, Locator showed the highest retentive loss, followed by O-ring, EZ-LOCK and Magnetic attachments after 2,250 cycles. The retentive force and retentive loss of magnetic attachments is markedly less than the others attachments. (P<0.05)
Conclusions: The results of this study were to standardize the test methods of retentive force of attachment system for dental implant. Also, this study will provide information of the selection of attachment system for patients.