Exploring prosthetic screw rupture in titanium and zirconia superstructures under various conditions

The fastening mechanics of prosthetic screws under various conditions is crucial to the maintenance of dental implants. This study comprehensively explores the prosthetic screw rupture in titanium (Ti) and zirconia (ZrO₂) superstructures under wet and dry conditions. Superstructures were fabricated using digital technology and subjected to tightening torque trials. Experimental results suggested that the implications of the conventionally recommended torque of 15 N•cm differ significantly between dry and wet environments. Both Ti and ZrO₂ exhibited preloads of >30 N•cm under dry conditions; however, differences emerged under wet conditions. In addition, screw rupture posed a prominent clinical challenge -particularly during long-term cyclic loading. Notably, the ZrO₂ superstructures exhibited a greater resistance to breaking torque than that of Ti. This study underscores the importance of reevaluating torque recommendations with consideration to the distinct characteristics of Ti and ZrO₂ in diverse environments.