Insight 86 — A Crown That Has Stayed on Temporary Cement for a Year: Should It Be Recemented with Definitive Cement?

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Clinical Explanation

For a patient whose crown we cemented with temporary cement and which also had a good fit, if the crown still has not come off a year later, do we need to remove it and cement it with definitive cement?

Answer

An implant crown, no. But a crown on a natural tooth should be removed, because the temporary cement under it may have washed out, and that condition sets the stage for recurrent caries. A crown that has stayed on a tooth for a year does not necessarily mean the cement under it is intact.

In my own practice, if a temporarily cemented crown on a tooth does not come off with a light tap, I give the patient an appointment two months later, and at that visit the crown usually comes off.

Question

In a screw-cement-retained restoration, do you cement the crown with definitive or temporary cement at the delivery appointment?

Answer

A screw-cement-retained restoration is one in which the crown is cemented onto the abutment, but the access hole to the abutment screw is open through the occlusal surface of the crown; that is, a combination of a cement-retained and a screw-retained restoration that has the advantages of both, and if needed the crown and abutment assembly can be removed by loosening the screw.

My own approach is to cement the crown with temporary cement first in these restorations too, even though I have access to the screw. The aim is that if there is a force such as an inappropriate occlusal contact that I did not detect at the delivery appointment or that slipped past me, it reveals itself through debonding of the crown. Repeated crown loss in this situation is a diagnostic pattern for me, telling me that I need to look for a factor that has not yet been corrected.

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