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.
