Strain development in 3-unit implant-supported CAD/CAM restorations

Area of Science:

• Dental prosthetics
• Biomaterials engineering
• Digital dentistry

Background:

• Achieving passive fit in implant-supported restorations is challenging with current fabrication methods.
• Strain development during superstructure fabrication can compromise restoration longevity and implant stability.

Purpose of the Study:

• To compare strain development in computer-aided design/computer-aided manufacturing (CAD/CAM) fixed partial dentures (FPDs) fabricated from optical impressions versus conventionally fabricated FPDs.
• To evaluate the passive fit of CAD/CAM-generated FPDs in implant-supported restorations.

Main Methods:

• A measurement model with two implants was used, with strain gauges placed mesially and distally.
• Three groups of FPDs were fabricated: conventional (repositioning impression), conventional (pick-up impression), and CAD/CAM (optical impression).
• Strain development during FPD fixation was recorded and analyzed using multivariate analysis of variance (MANOVA).

Main Results:

• CAD/CAM-fabricated FPDs exhibited significantly lower strain development compared to those made from pick-up impressions (P = .01).
• No significant difference in strain development was found between CAD/CAM FPDs and those made from repositioning impressions (P = .19).
• Conventionally fabricated FPDs showed no significant difference in strain development between the two impression techniques (P = .07).

Conclusions:

• Restorations fabricated using optical impressions achieve a passive fit comparable to conventional methods.
• CAD/CAM technology offers a promising approach to minimize strain in implant-supported FPDs.
• This study supports the use of optical impressions for fabricating passive-fitting implant restorations.