With Implants - Mini-Implant Overdenture The way that the spark erosion prosthesis is locked into place is with small latches (see photo at left) that rotate into a slot which is milled into the bar attached to the implants (see X-ray on previous page) that stays in the patient's mouth. Since the bar and framework fit very accurately together, once the latch is engaged, the prosthesis feels like a fixed bridge and is extremely stable.