Marginal Gap and Screw Loosening in CAD/CAM Materials for Implant-Supported Fixed Partial Dentures: An In Vitro Study

Area of Science:

• Biomaterials Science
• Dental Materials
• Prosthodontics

Background:

• Material selection is critical for the long-term success of implant-supported fixed partial dentures (IS-FPDs).
• Understanding the relationship between material properties, marginal gap, and screw loosening is essential for optimizing IS-FPD design and fabrication.

Purpose of the Study:

• To compare the marginal gap and screw loosening of 3-unit IS-FPDs fabricated from different materials.
• To investigate the correlation between marginal gap and screw loosening in various material groups.

Main Methods:

• Fifty 3-unit IS-FPD frameworks were fabricated using CAD/CAM technology from zirconia (Zir), chrome-cobalt (Co-Cr), titanium (Ti), polyetheretherketone (PEEK), and polyetherketoneketone (PEKK).
• Marginal discrepancies were measured using scanning electron microscopy, and screw loosening was assessed with a digital torque device.
• Statistical analysis was performed using SPSS with a significance level of P<0.05.

Main Results:

• Significant differences in marginal gap were observed among all material groups (P<.001). PEEK exhibited the smallest marginal gap (67.22 ± 15.55 μm), while Co-Cr showed the largest (176.87 ± 88.34 μm).
• PEKK demonstrated the lowest screw loosening values for both molar (0.44% ± 0.73%) and premolar (0.06% ± 1.40%) abutments.
• No significant correlation was found between the marginal gap and screw loosening across the tested materials (P>.05).

Conclusions:

• Material selection plays a pivotal role in the clinical performance of IS-FPDs.
• PEEK material provides superior marginal adaptation, potentially minimizing microleakage.
• PEKK material enhances screw stability, which is crucial for reducing prosthetic complications.