Treatment for a Dental Crown Tooth Cap that Keeps Falling Out

This patient was a male in his mid-thirties with no significant medical history. Intra-oral and extra-oral exams were all within normal limits. When he presented into the office, his chief complaint was “My crown fell off.” Patient had PFM crown on #18 that was not retentive due to the lack of core tooth structure. He had this crown redone many times and the treatment would always fail since there was not enough physical tooth structure present. In addition, as observed in the photographs, the core build-up and prep was inadequate. The tooth was previously endodontically treated in another office.

As apparent in the periapical film of tooth #18, the RCT is satisfactory because the gutta percha filling material ends at the apex and there is no evidence of periapical pathology. In addition, there is sufficient amount of alveolar bone present to warrant restoration of the tooth. The patient agreed to the treatment plan of a gold cast post and core and a PFM crown. The purpose of the cast gold post and core is to retain the crown. Upon cautiously removing the old composite core, being careful not to pierce the pulp chamber, there were 4 canal orifices filled with gutta percha.

After the preparation for cast post and removal of gutta percha from distal buccal canal, a cast post impression was taken with impregum light and heavy body with the parapost system.  This allows for the hydrophilic impression material to flow into the canal while being stabilized by a plastic post to create an accurate pattern for the gold post. The canal was irrigated with sodium hypochlorite to reduce the likelihood of bacterial contamination and sealed with cotton and cavit until the next visit.

A 14 carat gold post with Kaitlyn loop (floss was threaded through during try-in to prevent swallowing or aspiration of the cast post) was created and ready for try-in and cementation. The post was cemented with powder and liquid Rely-X cement.

After post cementation, the final crown prep was refined with a chamfer margin design. Minor periodontal surgery was performed around the crown margin. In order to increase the retention of the new crown, a crown lengthening procedure was performed. An acrylic temporary was fabricated using the block technique. The temporary crown was cemented with Temp-Bond cement.

It was important to create a temporary that had a good anatomical contour and did not have any marginal deficiencies. Otherwise, the healing gingiva can grow over the margins, preventing proper seating of the final crown.The Final crown ready for cementation was created with a Kaitlyn loop attached to prevent aspiration or swallowing ligated with dental floss.

Crown try-in was followed up with a bitewing radiograph to confirm seating and marginal fit. There were no open margins in the radiograph and the crown was approved for final cementation. In addition, occlusion was also checked with articulating paper and adjusted prior and after final cementation.  Rely-X Cement was used for the final cementation of the PFM crown. The color and fit were confirmed with patient prior to cementation.

After cementation, the Kaitlyn loop was removed with a diamond bur.  Oral hygiene and proper home care instructions were reviewed with the patient. In completing this case, I learned about certain issues that a patient can present with when a fixed restoration fails. In this case, the tooth was able to be restored and the patient was confident that he would receive proper care at The Center For Special Dentistry, even though he had this particular crown replaced a number of times and they have all failed. The patient was told the reasons why this treatment was failing and the proper sequence of procedures that he would need to have in order to retain a new crown. Once he understood, he was more than happy to commit to the treatment plan.

L.R., New York University College of Dentistry

Categorised in: Dental Student Experiences

This post was written by Dr. Jeffrey Dorfman