Which feature of the internal hex implant helps prevent screw loosening?

• A. Conical abutment thread form
• B. Spiralock abutment thread form
• C. Traditional screw mechanism
• D. Thread-locking adhesive

Answer: (B)

The spiralock abutment thread form is designed specifically to create a mechanical locking mechanism that resists loosening under load. The unique geometry of the spiralock threads provides a wedging effect that tightens as more torque is applied, enhancing stability during dynamic forces that occur during normal function, such as chewing. This design minimizes the potential for movement between the implant and the abutment, which is a primary cause of screw loosening over time.

In contrast, other designs may not offer this level of mechanical engagement. For instance, traditional screw mechanisms rely solely on the friction created by the threads, which may not be sufficient to prevent loosening if subjected to repetitive stresses. Similarly, conical abutment thread forms, while they do provide a tight fit, do not incorporate the specialized locking features that spiralock offers. Thread-locking adhesives can provide additional security; however, they introduce their own complications, such as potential degradation over time and the need for more complex removal if adjustments are necessary. Thus, the spiralock abutment thread form stands out as the most effective feature in preventing screw loosening.