The fixed implant prosthesis

What “fixed” actually means

The prosthesis is one piece with the implants. You do not take it out at night, you never handle it: it stays in the mouth and is brushed where it sits.

That is what brings it closest to a natural dentition — and what also makes it more demanding to keep clean, since you cannot wash it outside the mouth.

Three designs, by extent

• One missing tooth: one implant, one abutment, one crown — leaving the neighbours untouched
• Several adjacent teeth: two implants carrying a bridge, rather than one implant per tooth
• A full arch: four to six implants supporting a fixed bridge

The number of implants is not decided in advance: it follows from the bone volume measured on 3D imaging and from how chewing forces are distributed.

From impression to fitting

• Digital impression of the implant and neighbouring teeth
• Computer-aided design of the abutment and crown
• Milling of the piece from a ceramic block
• Try-in, check of the contact point and the bite
• Assembly — screwed where the angle allows, cemented otherwise

A screwed assembly is preferred whenever possible: it can be taken off for a check or a repair, where a cemented one has to be cut through.

Setting the bite matters more than it seems

A natural tooth is suspended in its socket by a ligament that cushions shocks and signals overload. An implant is ankylosed in bone: it does not move, and it gives no warning.

The prosthesis is therefore set slightly clear of the contact made by the neighbouring teeth. Even a minimal overload is paid for in loosened screws, fractured ceramic, or marginal bone loss.

Upkeep determines how long it lasts

An implant does not decay, but the tissue around it becomes inflamed just as a gum does: that is peri-implantitis, and it costs bone around the whole assembly.

Under a full bridge, passing interdental brushes or a specific floss beneath the fitting surface is not optional: that is where plaque gathers, out of reach of a toothbrush.