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References

Schwartz RS, Robbins JW. Post placement and restoration of endodontically treated teeth: a literature review. J Endod. 2004; 30:289-301
Trope M, Ray HL. Resistance to fracture of endodontically treated roots. Oral Surg Oral Med Oral Pathol. 1992; 73:99-102
Trabert KC, Caput AA, Abou-Rass M. Tooth fracture a comparison of endodontic and restorative treatments. J Endod. 1978; 4:341-345
Sorensen JA, Martinoff JT. Intracoronal reinforcement and coronal coverage: a study of endodontically treated teeth. J Prosthet Dent. 1984; 51:781-784
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Technique tips – constructing a provisional crown for a broken down tooth

From Volume 44, Issue 8, September 2017 | Pages 796-797

Authors

Raj Dubal

BDS, MFDS, MClin Dent(Pros), MRD(Rest), PGCertDentEd, FDS, ISFE (Rest Dent)

Specialty Trainee in Restorative Dentistry, St George's University Hospitals NHS Foundation Trust, Blackshaw Road, London SW17 0QT, UK

Articles by Raj Dubal

Article

Cuspal coverage restorations are indicated for teeth which have been endodontically treated,1,2,3,4 or have been structurally compromised either due to large restorations4 being present within them or some traumatic incident. Such compromised teeth can benefit from cuspal coverage restorations as these can help to protect the tooth from further fractures which may render the tooth unrestorable.4 The destruction of marginal ridges, extensive restorations, or the presence of visible cracks can help to highlight the potentially structurally compromised tooth.4,5

Provisional restorations are an essential part of the treatment pathway for teeth which have been prepared for a cuspal coverage restoration. They are indispensible as they can contribute to providing interim protection for the residual preparation,6 limit microbial leakage into the endodontic space via the dentinal tubules,⁷ prevent sensitivity and pulpal inflammation and prevent undesirable movement of adjacent and opposing teeth. Well-constructed provisional restorations can also be valuable in aiding resolution of inflamed periodontal tissues so that definitive impressions can be recorded with the tissues in a healthy and stable condition. It is not uncommon to have to prepare broken down teeth to receive a crown and the limited quantity of tooth structure initially can make it challenging to construct a well-fitting and contoured provisional restoration. This short article describes an effective way to construct a well-fitting, appropriately contoured provisional crown quickly and cost-effectively.

A 57-year-old patient was seen within our department for dental assessment of the UR7. He had been diagnosed with multiple myeloma and had a 6-year history of intra-venous bisphosphonate (Zometa®) administration. As a function of this, extraction of teeth was avoided due to the high risk of medication-related osteonecrosis of the jaws. The UR6 had been endodontically treated and restored by means of a partial coverage gold crown two months previously. The UR7 had suffered a buccal wall fracture, and had previously been restored with an extensive amalgam restoration. A number of failed attempts had been previously made to restore the tooth adhesively using direct composite resin, and eventually it had been decided by the patient's dentist to leave the tooth as it was. Clinically, the UR7 was carious and a considerable quantity of mature plaque had accumulated on it. The patient had complained of difficult access for oral hygiene measures. Following oral hygiene instruction and discussion with the patient, it was decided to provide a partial coverage gold crown (Figure 1).

Figure 1. The quantity of tooth structure of UR7 remaining prior to cementation of the crown on the UR6.

Following caries removal in the UR7 under local anaesthesia, petroleum jelly was applied to the occlusal surfaces of the opposing teeth. A zinc polycarboxylate provisional restorative material was used to build-up the UR7 tooth to an acceptable anatomical form. The margins and tooth form were fashioned using a flat plastic, and the patient was guided to occlude in the intercuspal position (ICP). He was then instructed to perform left and right excursive and protrusive mandibular movements from the ICP. This allowed for the construction of a functionally generated occlusal morphology which, when incorporated into the provisional restoration, would prevent dislodging or premature debonding. During establishment of the crown and occlusal morphology, excess and displaced material was removed using a flat plastic (Figure 2). Once the material had set, an alginate impression was recorded of the tooth form and this was kept in a damp sealed bag (Figure 3). The provisional restoration in the coronal portion of the tooth was removed and the cuspal coverage preparation on the UR7 was completed (Figure 4).

Figure 2. The form of the provisional material on the UR7.
Figure 3. The alginate impression of the built-up UR7.
Figure 4. UR7 following preparation for a cuspal coverage restoration.

The alginate impression was retrieved and any water was removed from the impression surface using air from a 3-in-1 syringe. An autocatalytic temporary crown and bridge material was injected into the tooth space in the alginate impression corresponding to the UR7, and the impression was located and seated back into the mouth. A small amount of provisional crown and bridge material was injected onto the instrument tray to monitor setting. Having partially set, the impression tray was removed from the mouth and the provisional crown was retained on the preparation. Should the provisional crown have been present within the alginate impression upon withdrawal, this could be removed using fine nosed dental forceps and relocated back on the tooth. The occlusion and excursive movements were at this point checked and confirmed. The patient was instructed to maintain his occlusion in ICP until the provisional material had set and the excess material was removed using a flat plastic.

Once fully set, the provisional restoration was removed from the tooth preparation using a flat plastic. A small excavator can also be used but damage to the margins must be avoided. Any minor imperfections can either be polished out or added to using light-cured flowable composite resin. The restoration was subsequently cemented onto the preparation using a provisional crown cement, and the excess was removed. The marginal interface was gently polished using a rubber composite polishing burr and a light occlusal contact was confirmed in ICP. Conformity to the existing lateral excursive and protrusive movements was confirmed using occlusal indicator paper of different colours from that used for the ICP confirmation. Following confirmation of the occlusion, the occlusal markings where polished off the provisional crown (Figure 5).

Figure 5. The retentive and functional provisional crown on the UR7.

The importance of provisional restorations has been reported in the literature and the impact of interim undesirable consequences can be considerable. These can ultimately lead to loss of vitality of the tooth or catastrophic fracture of the preparation. It is highly recommended that provisional restorations be placed whenever a cuspal coverage preparation is performed. This article describes the technical steps in facilitating provisional restoration construction in a challenging clinical scenario.