spark erosion and implant dentistry

 Duluth MN

Electric Discharge Machining (EDM)

Electric Discharge Machining (EDM), also known as spark erosion, is a precision machining process that uses controlled electrical discharges to remove extremely small amounts of metal. Before today’s digital manufacturing methods became widely available, EDM offered prosthodontists a way to improve the precision and fit of metal implant frameworks after they were fabricated.

Spark erosion has a special place in the history of Dental Implant & Reconstructive Center. Dr. Douglas Erickson, the prosthodontist who founded this practice, incorporated EDM into his implant prosthodontic work. The practice’s original EDM machine has been preserved, along with clinical photographs demonstrating how the technology was used.

WHY WAS EDM IMPORTANT?

Restorations could be built from the implant level rather than from the abutment level. This provided greater control over the emergence profile—the way a restoration transitions from the implant through the gum tissue—and could improve the esthetic design of the restoration.

Building restorations from the implant level could also reduce the number of intermediate abutment components required. Fewer components could reduce the cost of fabricating the restoration and, ultimately, reduce expense to the patient.

EDM also helped compensate for small inaccuracies that could occur during traditional metal casting and the fusing of porcelain to metal substructures. The process allowed the mating surface of the implant restoration to be precisely refined after fabrication, improving the passive fit of a multi-implant framework.

This was particularly important for screw-retained implant restorations. Screw retention allows a restoration to be removed when maintenance or repair is needed. Improving passive fit could also help reduce mechanical complications such as screw loosening and screw fracture.

With EDM, the mating surface of an implant restoration could be finished to approximately 2–5 microns.

FROM THE PRACTICE ARCHIVES

The photographs below come from Dr. Erickson’s original educational materials and demonstrate the effect of spark erosion on the fit of an implant restoration.

Historical photographs demonstrating Electric Discharge Machining (EDM) at Dental Implant & Reconstructive Center.

References

Van Roekel NB. Prosthesis fabrication using electrical discharge machining. Int J Oral Maxillofac Implants. 1992;7(1):56-61.

Linehan AD, Windeler AS. Passive fit of implant-retained prosthetic superstructures improved by electric discharge machining. Journal of Prosthodontics. 1994;3(2):88-95. doi:10.1111/j.1532-849X.1994.tb00134.x.

Evans DB. Correcting the fit of implant-retained restorations by electric discharge machining. Journal of Prosthetic Dentistry. 1997;77(2):212-215. doi:10.1016/S0022-3913(97)70238-5.

Presotto AGC, Oliveira LV, Pisani MX, Barão VAR, Mesquita MF. Influence of spark erosion on the fit of screw-retained Co-Cr fixed complete denture frameworks veneered with different materials. Journal of Prosthetic Dentistry. 2018;119(5):797-803. doi:10.1016/j.prosdent.2017.07.003.