They are prefabricated crown forms that are adapted to individual teeth and cemented with a biocompatible luting agent. 

History

• Introduced in 1947, by Rocky mountain company. 
• Familiarized by Humphrey and Engel in 1950s.
• Crown preparation was suggested by Mink and Bennet. 

Classification 

According to composition: 

• 18/8 austenitic stainless steel 
• Nickel- chromium crown 

According to position:

• Crown for posterior teeth 
• Crown for anterior teeth 

According to trimming: 

• Untrimmed crowns
• Pretrimmed crowns 

Objectives

• To achieve biologically compatible, masticatorily competent and clinically acceptable restoration. 
• To maintain the form and function where possible. 

Indications

• Extensive caries. 
• Rampant caries. 
• Recurrent caries. 
• Post pulp therapy. 
• Inherited or acquired enamel defects.
• Intermediate restorations.
• Severe bruxism.
• Abutment teeth to prosthesis.
• As a part of Space maintainer. 

Contraindications

• Primary molars close to exfoliation 
• Primary molars with more than half the roots resorbed 
• Teeth that exhibit mobility 
• Teeth which are not restorable 
• Patients with known nickel allergy 

Armamentarium

• Crown cutting burs – pear shaped, tapering fissure, needle shaped, smoothening burs. 
• Pliers – Hoe pliers, No 114 Johnson contouring pliers, No 417 crimping plier, No 112 Ball and socket plier. 
• Scaler or any sharp instrument 
• Crown and bridge scissors
• Crown seater and remover
• Stone and finishing bur
• For cementation – luting cement, glass slab, spatula
• Miscellaneous – Articulating paper, wax sheet, marking pencil 

Procedure 

• Select the crown according to mesio distal diameter, proper occlusal height
• Pick the crown with sterile tweezer 
• Evaluate the occlusion 
• Administer local anesthesia 
• Occlusal reduction of 1.0 to 1.5mm with pear shaped head
• Proximal reduction with needle shaped bur to beak contact and establish taper
• Reduce and round off all line angles with finishing burs
• Verify occlusion and proximal contacts
• Try the crown on the tooth
• Check the gingival margin, any excess needs to be trimmed
• Smoothen the edges with finishing burs
• Contour the crown
• Crimping of the crown in gingival third
• Finish the margins of crown
• Mix and load luting cement on the crown
• Seat the crown and ask the patient to bite firmly
• Remove excess cement 

Article by Dr. Siri P. B.