Zirconia Crown Prep Guide

Step-by-step placement protocol for KTR pediatric zirconia crowns. Select your crown type below.

Anterior crown preparation for primary incisors

|~20 min9 steps0/9 completed

Preparation

1.Select the crown before you begin the preparation, not after.
2.Hold candidate sizes against the unprepped tooth and compare size, shape, and contour.
3.Step up or down a size until one clearly matches the original tooth better than its neighbors.
4.Set the selected crown aside for try-in after the preparation is complete.

Tips

Selecting first gives you a reference for how much structure to remove.

Anterior crowns come in sizes 1-6 for each position. Having the sizes on either side of your pick ready reduces chair time.

Caution

Primary incisors are thin. Stay at the incisal edge and avoid over-reduction toward the pulp.

1.Switch to the pencil-shaped flame-tipped diamond bur.
2.Reduce the interproximal surfaces where contact exists with the adjacent teeth.
3.Take only what is needed to separate the contacts before moving to the chamfer.

Caution

Protect adjacent teeth during proximal slicing.

1.Switch to the diamond 016 chamfer bur once the contacts are separated.
2.Carry the reduction subgingivally around the entire tooth.
3.Hold the bur along the long axis of the tooth to produce a properly tapered preparation.
4.Watch the tissue roll away from the tooth rather than tear as you prep.

Tips

A round-shaped diamond or chamfer bur is preferred here. It allows subgingival prep with minimal tissue tear and minimal hemorrhage.

Caution

Do not leave a margin or ledge. A marginal ledge will prevent the crown from seating.

1.Go back to the football diamond bur and remove part of the cingulum area.
2.Use the same bur to slightly round off the rough edges of the preparation.
3.Confirm the finished reduction: about 2mm at the incisal edge and a smooth circular reduction around the entire tooth.
4.Verify there are no margins and no ledges anywhere on the preparation.

Caution

If marginal ledges are present, the crown will not seat properly. Remove them before try-in.

Fitting

1.Try in the crown you selected before beginning the preparation.
2.The crown should seat passively, without force.
3.Check that the incisal edge lines up with the incisal edge of the adjacent tooth.
4.Check that the marginal ridge lines up and the crown matches the size, shape, and contour of the adjacent tooth.
5.If the crown is noticeably too large, move down a size and try again.

Tips

A passive fit means the crown drops into place and stays aligned. If you have to push it on, it is the wrong size or a ledge remains.

Cementation

1.Clean the prepared tooth and prepare it for cementation.
2.Hand mix a pure glass ionomer cement to a thick, almost putty-like consistency.
3.Fill the crown with cement.
4.Seat the crown, making sure it is seated properly and seated fully.

Tips

Ketac glass ionomer as a luting agent has produced the best results, though any cement can be used for placement.

The thick putty-like mix helps hold the crown in correct position and keeps moisture and hemorrhage from re-entering the crown.

Caution

Moisture or hemorrhage inside the crown can cause staining to show through the zirconia.

Finishing

1.Use an explorer to clean excess cement from the proximal spaces.
2.Check the lingual as well and remove any excess cement there.
3.With a thick, putty-like mix you can remove excess almost immediately once the crown is fully seated.
4.If the mix came out runny, let it sit a minute or two before removing excess.
5.Verify the final result. The lingual should sit 1-2mm under the gingiva for a natural aesthetic finish.