Fatigue Resistance of Custom Made Resin-Ceramic, One-Piece and Two-Piece Implant Abutment/Crown : (In Vitro Study) /

Abstract

In recent years, social emphasis on esthetics and general appearance has reached an all-time high focus. Every practitioner is now faced with patients that care more about the appearance of their teeth than the actual treatment plan presented. The increased demand for esthetics by both patients and clinicians has revolutionized the treatment procedures taken in dental practice. High awareness and research was implemented towards conservatism and dental practice is now focusing on minimally invasive techniques in all procedures undertaken. Dental Implants are now the cornerstone for restoration of missing teeth and oral rehabilitation. Showing a 95-97% success rate of single implant-supported restorations.1 Providing favorable biomechanical properties, titanium implants and abutments are the golden standard for implant-supported restorations2. However, this causes an esthetic disadvantage, especially in highly esthetic zones. Titanium abutments cause an unnatural bluish-gray appearance to the surrounding soft tissue, specifically around thin layered gingiva. Therefore a tooth-colored abutment is needed to provide acceptable esthetics. For this reason several types of esthetic all ceramic abutments were introduced, offering a variety of tooth-colored shades and stains to accommodate a metal-free natural and esthetic look. In comparison to titanium abutments, ceramic abutments are more aesthetic with less, yet acceptable strength. 3–5 The introduction of Computer Aided Design/Computed Aided Manufacturing (CAD/CAM) technologies in the 1980s provided access to a standardized manufacturing process. Offering a more predictable, accurate and reproducible restoration with reduced production cost. As a result, a new generation of ceramic and composite materials was introduced to the market, opening the door for various uses and restorative designs to be introduced in dental practice.6 CAD/CAM materials (ceramics & zirconia) were tested and used for various prosthetic restorative modalities, including crown and implant abutments. Due to the brittle nature of ceramics, the abutments were shown to exhibit high stress propagation and concentration on their respective implants and bone specifically in high load areas such as posterior teeth. They also cause abrasion to the opposing dentition. The highly condensed particle nature of zirconia while exhibiting high strength and acceptable mechanical properties, they still provided an esthetic complication due to their dull opaque shade.7,8 Composite resin material, on the other hand, suffer from increased material wear, loss of surface polish, and color instability. Most recently, a new polymer infiltrated hybrid ceramic material has been developed by several companies for CAD/CAM application. Specifically, the VITA Company produced the VITA ENAMIC CAD/CAM blocks. The material is composed of a porous feldspathic ceramic mesh infiltrated by an acrylic polymer network material, providing mechanical properties similar to natural tooth properties. To the best of our knowledge, the hybrid ceramic material was not tested as an implant abutment. The fatigue behavior and the fracture resistance of the material as an implant supported abutment is unknown and was not investigated yet.