In Vitro Evaluation of Retention of Double-Crown Prostheses Connecting Natural Teeth and Implants. A Comparative Analysis of Zirconia, PEKK, and Cobalt Chromium Materials for Primary and Secondary Crowns

Sarah Zaman Sahib Awad, Postgraduate student, Department of removable prosthodontics, Faculty of Dentistry, Mansoura University, EgyptFollow
Khloud Ezzat Mourad, Lecturer, Department of removable prosthodontics, Faculty of Dentistry, Mansoura University, Egypt
Ahmed Sameh AbdElaziz Ismail, Lecturer, Department of production and Mechanical design, Faculty of Engineering, Mansoura University, Egypt
Aisha Zakaria Hashem Mostafa, Professor, Department of removable prosthodontics, Faculty of Dentistry, Mansoura University, Egypt

Article Type

Original Article

Section/Category

Restorative Dentistry

Abstract

Purpose Objective: To assess and compare the retention performance of different material combinations—Zirconia, PEKK, and Cobalt-Chromium—over time using insertionremoval tests simulating one year of use. Materials and Methods: Nine mandibular polyurethane models with two canines and two dummy implants (first molar area) were used. Three groups of double-crown prostheses were fabricated, differing in materials used for both primary and secondary crowns: Zirconia, PEKK, and Cobalt-Chromium. All crowns were CAD/CAM-designed. Retention was tested using a Universal Testing Machine, with each overdenture subjected to 1,440 insertionremoval cycles to simulate one year. Final retention forces were measured and analyzed using SPSS v23, with significance set at P < 0.05. Results: Zirconia prostheses showed significantly lower retention than PEKK and CoCr (P = 0.0001). Although PEKK had higher retention than CoCr, the difference was not significant at baseline (P = 0.090). After simulated one-year use, all materials showed a reduction in retention. Zirconia remained significantly lower in retention compared to PEKK (P = 0.0001) and CoCr (P = 0.001), while PEKK showed significantly higher retention than CoCr (P = 0.015). Conclusion: All materials maintained clinically acceptable retention. PEKK provided the highest retention, followed by Cobalt-Chromium, while Zirconia showed the lowest. Retention decreased in all groups after one year of simulated use.

Keywords

Double-crown prosthesis; Telescopic crowns; Tooth-implant-supported prosthesis; PEKK; Zirconia

How to Cite This Article

Awad S , Mourad K , Ismail A , Mostafa A . In Vitro Evaluation of Retention of Double-Crown Prostheses Connecting Natural Teeth and Implants. A Comparative Analysis of Zirconia, PEKK, and Cobalt Chromium Materials for Primary and Secondary Crowns. Mans J Dent. 2025; 12(4):
Available at: https://doi.org/10.61793/2812-5479.1165