Richmond Crown Notes

Richmond crown

It is an old type of crown with a dowel and a gold crown cast or soldered with a porcelain veneer facing.

Richmond Crown Indication

As a bridge retainer on the pulpless anterior tooth.

Read And Learn More: Fixed Partial Denture Short Essay Question And Answers

Parts of Richmond crown

Facing
Porcelain.

Coping

• Metal cap fitted on a root face
• Dowel extends into the root canal.

Steps in preparation

Preparation of tooth
Diamond stones are used to drill holes labiolingually through the crown 3 mm above the highest level of the crest of gingival tissues.

Root pre-operational
The part of the tooth in which a series of holes were placed is broken off and the face of the root is prepared.

Labial plane
Is prepared to slope gingivally terminating 1 mm above the labial crest of gingival tissue.

Lingual plane

• Prepared sloping in a cervical direction lying in the horizontal plane and terminating 3 mm above the lingual crest of gingival tissue
• Unsupported enamel margins are removed by files.

Measuring the face of the root
A wire is used to measure the circumference of the root cap required.

Construction of cap

• Direct method:
  Prepared tooth by fitting an axial band on which the cap is soldered
• Indirect method
  Cap swaged from a single piece of metal.

Richmond Crown Direct method

• The measured wire is cut and straightened and the measurement is transferred to a gold plate.
• The height of the band is from the gingival margin to the highest point on root preparation.
• The plate is made in a ring form with both ends joined and soldered.
• The soldered band is placed on root preparation and made to fit the ferrule margin cervically
• After many adjustments, the band is fitted well till it parallels the curvature of gum tissue.

Placement of band at gingival margin

• The margin of the band should be marked at the labial and lingual aspects and lowered into the crest of gum 0.75–0.5 mm short of the preparation till the marked area on the band.
• The height of the band is reduced by 2 mm above the crest of the gingival tissue.

Gold cap soldered
The band is removed from the tooth and the gold plate is soldered to the incisal end.

Dowel Placement

• After a clasp metal dowel is placed in the root canal, the opening of the canal is countersunk 0.5 mm.
• The cap is burnished into the countersunk area and the dowel is forced through the cap into the root canal.
• The dowel extends 2–3 mm above the root cap.
• The dowel and cap are stuck with sticky wax in the countersunk area.
• After the sticky wax is cooled the dowel cap unit is removed, invested, and soldered.
• The solder fills the countersunk area and the cap is united to the dowel and this is referred to as coping.

Richmond Crown indirect method

• After wire measurement, the copper band matrix is fitted and a modeling compound impression is made.
• Impression is boxed and an amalgam die is prepared.
• Heat-treated gold plate with its softness is swaged onto the die with finger pressure or wood piece to adapt well.
• The cap is placed on the prepared tooth and united to the dowel by soldering.

Preparation of models

• Impressions are made, and a wax wafer bite is taken.
• Before pouring the cast the inside of the copings and sides of the dowel are flowed with a thin layer of wax.
• The wax should not be flown to the inside of the root cap and gingival margins of the root cap.
• After the cast is retrieved, flame is applied to the region of the coping, this removes the thin layer of wax, and the coping is also removed from the cast.
• After the entire wax is removed the coping is lubricated and placed back on the model.

Selection of facing

• A correct shade porcelain facing with the adequate length and height is selected.
• The facing is ground to fit the gingival margin accurately.
• The lingual aspect is hollowed out and the facial aspect contacts the root cap in a line.

Incisal bevel

• After grinding to the correct shape and size the incisal edge is beveled to a 45° angle with a lingual surface.

Trial

• The facing is placed into the coping with soft wax to check the alignment
• Once the fit is confirmed assembling is done.

Assembling
The entire coping and backing of the face are covered with wax, invested, and soldered or cast.

Variation

Steele interchangeable facing: Is a replaceable facing, that can be cast or soldered.