What are dental crowns?

A crown is a type of indirect dental restoration, which completely caps or encircles a tooth or dental implant. Crowns are often needed when a large cavity threatens the ongoing health or structural integrity of a tooth.

They are shaped and coloured to look like natural teeth thereby serving an aesthetic and protective function. They are bonded to the tooth using a dental cement.

When one needs crown?

  • Severely break down tooth and it need coverage of al the cusps.
  • Endodontically treated tooth that has compromised structural integrity and under heavy occlusal forces.
  • Implants need crown to complete the prosthetic part.
  • Abutment tooth are crowned to support the bridges.
  • In case precision attachments are used for partial dentures, crowns with female part of attachment are fabricated on tooth next to edentulous span.
  • When patient desires to have his or her smile aesthetically improved and partial coverage (i.e., a veneer/laminate) is not an option for some reasons as in small crowns, bruxers and clenchers or long term orthodontic treatment is not feasible. 

What are the types of crowns?

As per the coverage of tooth:

  • Full crowns: that covers a tooth on all the surfaces.
  • Partial Crowns: 3/4th crown, 7/8th crown, ring crowns are sometimes used to preserve the natural teeth, to be aesthetically better or in case of limitation of tooth reductions. 
  • As per the material:

  • Full metal crowns: These are made of base metal alloys and are silver or dark in colour. These crowns can be made in precious metal alloys, but the cost of crown goes up substantially.
  • Porcelain-fused-to-metal crowns (PFMs): PFMs have a metal coping on which porcelain is fused in a high heat oven. The metal provides strong compression and tensile strength, and the porcelain gives the crown a white tooth-like appearance. The metal coping could be of base metal alloy or precious metal alloy. Only, disadvantage of these crowns is that sometimes a grey margin is visible nar the gums.
  • Metal free crowns: When no grey margin is desired, We recommend metal free or white metal crowns. Different materials available in this are silica reinforced, alumina or zirconia. These are made by using CAD/CAM technology.These are as strong as PFMs or full metal crowns and are aesthetically much more superior and pleasing.
  • Stainless steel crowns: SS crowns are preformed crowns used for deciduous teeth to restore function and to maintain the integrity of tooth.
  • Acrylic crown: these are generally temporary crowns used to restore the function and aesthetic till the final prosthesis is processed.
full-metal-crown PFM-crown

What is the procedure for making a crown?

As crown is an indirect restoration, it require more than 1 sitting to finalize the procedure.

1st sitting: Under local anaesthesia, tooth is prepared by reducing it from all sides making space for the material. A dental impression of a prepared tooth is taken to form a cast or model of your tooth.

This impression or cast goes to the laboratory to fabricate the final crown. A temporary crown is placed on the prepared tooth in the same sitting or the next day. There may be 1 or 2 visits involved for checking the fit and colour of the crown. When you are satisfied with the colour and the we are satisfied with the fit and occlusion of crown, it is sent for final polishing or glazing.

Final sitting: generally no anaesthesia is required at this sitting. Temporary crown is removed and final crown is cemented on the prepared tooth using luting cements. You are advised not to eat for few hours.

How to take care of your crowns?

  • Crowns become part of your tooth after luting. You should continue with your daily oral hygiene instructions as brushing and flossing.
  • You may be instructed to avoid food that sticks to the tooth and can pull the crown down.
  • If the crown comes out, you should visit a dentist at the earliest to cement it back on tooth.
  • A properly maintained crown can give a service of 15yr. plus in your mouth.