Ensuring Accurate All-on-X Restorations: Addressing Screw Channel and Prosthetic Screw Challenges
Precision is essential in All-on-X (AOX) dental restorations to ensure the long-term success and durability of the prosthesis. Two significant challenges that can compromise AOX restorations are inadequate surgical and prosthetic planning and execution, as well as discrepancies in the screw channels.
Screw Channel Discrepancies and Their Impact
Due to digital workflows, Zirconia restorations without Ti-bases have become the norm. They rely on specially designed screws that engage directly with the zirconia. Any minor discrepancy in the screw channel can lead to improper screw seating, increasing the risk of breakage and loosening under pressure. Although formal studies are limited, logic suggests that poorly fitting screws may contribute to this issue. Some clinicians are reverting to Ti-bases to avoid screw breakage, but this introduces another concern: Ti-base debonding. Accurate screw channel preparation is crucial to mitigate these issues, ensuring proper fit during try-in and final delivery, and reducing immediate complications related to poor screw fit.
Prosthetic Screw Complications in AOX Restorations
A study found that prosthetic screw complications, including breakage, loosening, and thread wear, occurred in approximately 13.7% of AOX cases. These complications are often linked to factors such:
Incorrect Vertical Dimension: Recording inadequate occlusion, or lack of passive fit in the prosthetic structure.
Mechanical Overload: Insufficient anterior-posterior (A-P) spread can overload specific implants, leading to bone loss and prosthetic failure.
Material and Design Considerations: While zirconia offers durability, precise fabrication is essential to prevent complications. Acrylic prostheses, though less durable, may also face issues like fractures and detachment.
Hygiene and Maintenance: Poor hygiene around the prosthesis can cause mucositis and peri-implantitis, which indirectly affect prosthetic screw stability.
These factors can be easily addressed with proper case planning and thorough patient education. However, the challenges posed by various new screw designs and discrepancies in the access screw channel have remained unresolved—until now. We believe we have successfully addressed this issue.
The Challenge of Screw Channel Debris
Zirconia and PMMA, commonly used in AOX restorations, often leave debris in the screw channel during the milling sintering or printing process. This debris can prevent proper screw seating, leading to fit issues, frustration, and potential damage.
Why Verification and Cleaning Matter
A clear screw channel ensures the screw travels passively through the restoration for proper alignment and a secure fit. Without proper verification and cleaning, the risk of screw jamming, misalignment, and breakage increases significantly.
Available in color-coded sets that ensure seamless integration with popular screw systems: Dess, Powerball, Rosen, and Vortex screws.
Tools Designed for Precision
The AOX ClearPath™ Toolset was developed after completing thousands of restorations, gathering extensive feedback from our customers, and collaborating with numerous respected laboratories and AOX key opinion leaders. This tool set addresses these challenges with two essential instruments:
Screwdriver Extension: Verifies that the screw channel is clear and properly aligned. Any obstruction indicates the need for further attention.
Reamer: Removes residual debris from the screw channel, ensuring a smooth and accurate path for the screw.
In summary, while screw complications in AOX restorations are relatively infrequent, they pose significant challenges when they occur. Addressing both screw channel preparation and prosthetic screw integrity through careful planning, precise execution, and regular maintenance is essential for successful, long-term outcomes.