Full-arch implant framework casting accuracy: preliminary in vitro observation for in vivo testing

Area of Science:

• Dental Materials Science
• Biomaterials Engineering
• Prosthodontics

Background:

• Fabrication of metal frameworks for osseointegrated implants requires high precision for passive fit.
• Conventional casting techniques often yield errors exceeding acceptable passive fit tolerances.
• Understanding the relationship between prosthesis fit and implant-tissue response is crucial.

Purpose of the Study:

• To determine the accuracy of torch casting full arch implant frameworks.
• To evaluate the precision of a high palladium alloy with a ringless phosphate-bonded investment technique.
• To assess casting errors against the passive fit requirement for osseointegrated implants.

Main Methods:

• Investigated three variables: completeness of mold fill, phosphate-bonded investment liquid concentrations, and investment mold shape.
• Measured horizontal and vertical distances on wax patterns and cast frameworks using a machinist's microscope.
• Utilized one-way analysis of variance to compare combined vertical and horizontal casting errors.

Main Results:

• No significant differences in casting accuracy were found among the tested groups (P > 0.05).
• Incomplete mold fill resulted in more porous castings but did not significantly affect mean error.
• The mean casting error (0.130 mm) was over ten times greater than the recommended passive fit requirement.

Conclusions:

• Conventional lost wax casting is imprecise and inaccurate for fabricating one-piece full arch implant frameworks.
• The technique fails to meet the critical passive fit requirement for osseointegrated implants.
• Further investigation into the consequences of misfitting prostheses on implants is ongoing.