In an engaging presentation at the EAO Digital Days, Benedikt Spies, Chair of the Department of Prosthetic Dentistry in Freiburg, Germany, explored the survival and technical complications associated with zirconia oral implants. Spies provided a comprehensive overview, addressing implant stability, handling complications, prosthodontic issues, and survival rates of ceramic-supported restorations.
The Relevance of Ceramic Implants Spies began by questioning the significance of ceramic implants. According to the EAO Delphi study, most experts believe that both ceramic and titanium implants will be prevalent in the next decade. However, zirconia, a common ceramic material, is prone to stress-induced local and environmental phase transformation. The impact of this on implant stability remains uncertain. Studies have shown that phase transformation can occur, potentially increasing implant stability. Spies presented data indicating that the fracture load of zirconia implants, even after aging and loading, remained well above clinical danger zones.
One-Piece and Two-Piece Implants Focusing on one-piece implants, Spies highlighted that both alumina-toughened zirconia and yttria-stabilized zirconia (Y-TZP) showed impressive stability after extensive testing, including 60 days of water aging at 85 degrees and 10 million loading cycles. Both materials maintained fracture loads far from the clinical danger zone, making them suitable for clinical application.
For two-piece implants, Spies discussed a design featuring a zirconia implant, zirconia abutment, and a carbon fiber-reinforced screw. Compared to titanium and titanium-zirconium alloy implants, this system demonstrated comparable stability. Another two-piece design used Y-TZP for the implant, polyetheretherketone (PEEK) for the abutment, and a titanium screw. However, PEEK abutments showed displacement under loading, indicating that PEEK might not be the best material choice.
Handling and Clinical Complications One-piece implants present challenges in positioning, especially in areas with scalloped bony crests. Spies emphasized the flexibility of two-piece systems, which allow for digitization during surgery and the option for screw-retained provisional or final restorations. However, data on two-piece zirconia implants remain limited. A study published this year provided promising 18-month data for two-piece zirconia implants, but more long-term research is needed.
Predictable Installation and Clinical Procedures Spies shared a clinical case involving the placement of ceramic implants in the upper maxilla using guided surgery. By combining intraoral scanning with CBCT data, the team achieved ideal implant positioning. The guided fit system, which guides the handpiece rather than the drill, allowed for precise parallel insertion of the implants. This method ensures proper placement without the need for gingival retraction cords, even for deep-seated implants.
Performance of Ceramic-Supported Restorations Spies presented four studies evaluating different zirconia-supported restorations:
Thin Zirconia Copings with Thick Veneering: Resulted in compromised survival and high chipping rates. Improved Frameworks with Even Veneering: Showed better survival but still experienced minor chipping. Monolithic Crowns: Demonstrated high survival rates with minimal chipping. Overpressed Bridges: High survival rates but significant chipping. Comparing these results to titanium implants, Spies noted that chipping rates for veneered zirconia reconstructions were higher, though not statistically significant. Monolithic reconstructions consistently showed reduced chipping, making them the preferred choice.
Cementation Technique To minimize peri-implant inflammation caused by excess cement, Spies recommended a venting technique. This method involves pre-cementing crowns to laboratory abutments and using a palatally located venting hole, significantly reducing excess cement.
Conclusion Spies concluded that standard diameter one-piece ceramic implants are stable enough for clinical use. However, careful selection and literature review are essential when choosing two-piece systems. Digital workflows facilitate the use of one-piece implants, while monolithic reconstructions are preferred to reduce chipping. Ceramic-supported crowns and bridges exhibit high survival rates, but chipping remains a concern.
Benedikt Spies' presentation underscores the complexities and potential of ceramic implants in modern dentistry. His insights highlight the importance of ongoing research and careful material selection to ensure optimal patient outcomes.