Fixed prosthodontics

Crowns, bridges (fixed dentures), inlays, onlays, and veneers are some examples of indirect dental restorations.

Fixed prosthodontics can be used to reconstruct single or many teeth, spanning tooth loss areas.

Traditionally, crown and bridge work requires more than one visit, and the extra time necessary for the procedure can be a drawback; nevertheless, the improved benefits of such an intervention will generally outweigh these factors.

If the tooth is to be restored with a full gold crown, the restoration need only be .5 mm in thickness (as gold is very strong), and therefore, a minimum of only .5 mm of space needs to be made for the crown to be placed.

If porcelain is to be applied to the gold crown, an additional minimum of 1 mm of tooth structure needs to be removed to allow for a sufficient thickness of the porcelain to be applied, thus bringing the total tooth reduction to minimally 1.5 mm.

This can be accomplished with a pin-retained direct restoration, such as amalgam or a resin-like fluorocore, or in more severe cases, may require a post and core.

Conversely, too much taper will severely limit the grip that the crown has while on the prepared tooth, thus contributing to the failure of the restoration.

This margin will be the future continual line of tooth-to-restoration contact and should be a smooth, well-defined delineation so that the restoration, no matter how it is fabricated, can be properly adapted and not allow for any openings visible to the naked eye.

Tucker method of gold inlay and onlay restoration produces tooth-to-restoration adaptation of potentially only 2 nm (confirmed by scanning electron microscopy), less than the diameter of a single bacterium.

There is the chamfer, which is popular with full gold restorations, which effectively removes the smallest amount of tooth structure.

When using a shoulder preparation, the dentist adds a bevel; the shoulder-bevel margin serves to effectively decrease the tooth-to-restoration distance upon final cementation of the restoration.

This has been established through multiple experiments as a mandatory continuous circumferential height of 2 mm; any less provides for a significantly higher failure rate of endodontically treated crown-restored teeth.

Traditionally, the teeth to be crowned are prepared by a dentist, and records are given to a dental technician to construct the prosthesis.

A bridge may also refer to a single-piece multiple-unit fixed partial denture (numerous single-unit crowns either cast or fused together).

The screw-retained restoration can be easily removed which allows to repair or examine the soft tissue and direct visualization of the implant.

This eliminates the potential complications associated with excess residual cement—often difficult to completely remove with a cement-retained crown.