An inlay is an intracoronary restoration and an onlay is a combination of an intracoronary and an extracoronary restoration. With the onlay, one or more nodules are covered, but unlike a crown, not all surfaces are completely ground. Metal (gold, palladium), porcelain or composite are used as materials. The inlay and onlay are made outside the mouth after a print has been made (see images below).
The method for manufacturing the metal, porcelain and composite inlay and onlay in the indirect manner is roughly the same as for the full crown. The preparation form must be divergent, that is, the preparation on the bottom is narrower than on the outline. Bumps are also ground on the onlay. For the porcelain and composite inlay and onlay, the outline should be in the glaze as much as possible, since acid-etching technique is used in cementing. The preparation must also be somewhat more complete (see image below).
After preparation and draining, only those parts of the outline are made visible that are subgingival due to sulcus widening. The temporary provision can be made by making a situation print of alginate before preparation. After preparation, the alginate impression at the prepared element is filled with self-polymerizing resin and placed over the element as described in the crowning procedure. A ball of thick synthetic resin can also be placed over the preparation. The still deformable synthetic resin is modeled in shape as much as possible. After hardening, the emergency facility is finished with stones and discs and then cemented. The cementing of a metal inlay and onlay is done in the same way as with a metal crown.
Adhesive techniques are used for securing the porcelain and composite restoration. The preparation is etched and the in and onlay are placed with a thin-liquid composite. For a strong bond between the porcelain and the bonding composite, the restoration must be etched into the mouth after fitting.
Labial porcelain veneer
Porcelain shields can be made in the laboratory to mask discolored or deformed front elements or to correct minor tooth abnormalities, which are fixed to the buccal surface using the etching bonding technique (labial veneer or facing). The procedure is similar to that for the porcelain in- and onlay.
It is usually necessary to grind the buccal plane approximately 1.5 mm. Color determination follows after a spray print. In a subsequent session, the facing is fixed in the manner previously described (see figure below).