The three-dimensional casting distortion of five implant-supported frameworks.

Area of Science:

• Dental Materials Science
• Biomaterials Engineering
• Prosthodontics

Background:

• Accurate fit of implant-supported prostheses is crucial for long-term success.
• Conventional casting techniques are widely used for fabricating titanium implant frameworks.
• Titanium frameworks require high precision to ensure passive fit on implant abutments.

Purpose of the Study:

• To evaluate the three-dimensional (3D) distortion in conventionally cast, full-arch, screw-retained titanium implant frameworks.
• To determine if the casting accuracy meets the clinical requirement for passive fit.

Main Methods:

• Fabrication of five wax patterns on a multi-unit brass analog cast.
• Utilizing the lost-wax technique for one-piece titanium casting.
• Measurement of 3D distortion using a reflex microscope.

Main Results:

• Significant distortion was observed between wax patterns and final titanium castings.
• Casting distortion ranged from 416 to 477 micrometers, exceeding the 150 micrometers limit for passive fit.
• Maximal distortion occurred at terminal implant abutments and in vertical dimensions, with inconsistent patterns.

Conclusions:

• Conventional casting of titanium implant frameworks results in unacceptable levels of 3D distortion.
• The inherent variables in the conventional casting process make achieving passive fit for titanium frameworks highly improbable.
• Alternative fabrication methods may be necessary to meet the precision demands for implant prosthetics.