All-ceramic resin-bonded bridges. A 3-dimensional finite-element analysis study

Area of Science:

• Dental Materials Science
• Biomaterials Engineering
• Prosthodontics

Background:

• Resin-bonded fixed partial dentures (FPD) with metal frameworks present aesthetic and biocompatibility issues.
• Aluminum oxide (Al2O3) ceramic, such as In-Ceram, offers a potential alternative for all-ceramic FPD frameworks.
• New preparation designs are needed to accommodate ceramic wings and ensure adequate inter-occlusal space.

Purpose of the Study:

• To investigate the impact of load orientation (45° and 60°) on stress distribution in all-ceramic resin-bonded FPDs.
• To evaluate how interproximal connector design influences stress concentration in ceramic bridges.
• To determine optimal design parameters for In-Ceram resin-bonded FPDs to prevent fracture.

Main Methods:

• Development of a 3-dimensional finite-element model simulating the anatomical conditions of an FPD.
• Application of a 250 N biting force oriented in the oro-buccal direction at a specific loading point.
• Analysis of stress distribution under varying load angles and interproximal connector designs (height, separation, edge rounding).

Main Results:

• Stress increased significantly with a 60° biting force angle compared to 45°.
• Smaller interdental connectors (3mm) and greater separation led to high stresses (up to 534 MPa).
• Larger connectors (4mm), rounded edges, and less separation substantially reduced stress (down to 143 MPa).

Conclusions:

• All-ceramic resin-bonded FPDs using In-Ceram require a minimum connector height of 4mm for clinical viability.
• Rounded interproximal edges and minimal interdental separation are critical design elements for reducing stress and enhancing longevity.
• Optimized connector design is essential to ensure the tensile strength of In-Ceram (340-400 MPa) is not exceeded.