A 47-year-old male patient was a regular attendee with an uneventful past medical history. He had sought advice
because he was unhappy with his smile. His main complaint was the crown on the upper left central incisor. This tooth had a history of multiple fillings, root canal treatment and a subsequent restoration with a metal-ceramic crown which had been provided more than 20 years ago. Over the years, the patient’s teeth had changed in colour and the crown became more noticeable. The patient was aware of a significant amount of tooth wear on the remaining upper teeth, but declined any restorative treatments to address this. He was also offered, but declined, teeth whitening.
Assessment and diagnosis
During a clinical evaluation, a low smile line was noted. There were no other significant extra-oral findings.
On an aesthetic assessment, a satisfactory position of the incisal edge was noted. It was decided that a diagnostic wax-up would not facilitate the fabrication of the new crown. A common complaint of patients with a single long standing crown is discolouration due to recession of a gingival margin, which was observed in this case. A loss of a distal interdental papilla was also noted, but there was no active periodontal disease. A diagnosis of an aesthetically failing long standing metal-ceramic crown on the upper left central incisor was made.
First visit
After careful removal of the metalceramic crown, the underlying core structure was assessed and found to be satisfactory with signs of minor leakage.
Tooth preparation was refined. The finishing line was positioned 0.3-0.5mm subgingivally on a buccal aspect. Preparation for an all-ceramic crown requires smooth finishing line and rounded edges, to avoid internal stresses within the coping.
As the gingivae were in a good condition, a working impression was taken with polyvinyl-siloxane impression material (heavy and light body) using a single stage technique and a double-cord retraction.
A well-fitting temporary crown was made with Bis-Acryl temporary material (3M ESPE Protemp 4 Temporisation Material) using pre-operative silicone index. Preoperative and preparation shade photographs were taken for the shade communication with the dental technician.
Second visit
The temporary crown was removed and the preparation was cleaned with pumice. A final all-ceramic crown was tried in. The marginal fit, occlusion and inter-proximal contacts were checked and found to be satisfactory. An excellent colour match was achieved and this was confirmed with the patient. The allceramic crown was cemented with resin-modified glass-ionomer cement.
Discussion and outcome
The restoration of a single central incisor is a challenging procedure and requires very close cooperation between the patient, dentist and dental technician.
The patient’s high expectations can be hard to meet. What may appear to be an easy exercise can require multiple visits to the dentist and technician and this must be discussed with the patient at the outset. It is usually necessary for the patient to visit the technician during the fabrication of the anterior crown.
Digital dental photography has had a significant impact on improving communication between the dentist and the technician. However, it cannot always be relied upon for shade communication when restoring single incisor. Colour calibrated dental photography is a very powerful tool for communication of the shade with the dental technician.
The clinician should not only create optimum preparation design and soft tissue condition, but should also provide the technician with certain information necessary to facilitate construction of a crown. This includes such parameters as incisal edge position and contour, pre-operative shade, shade of the prepared tooth and occlusal factors that can affect material selection.
The shade of the underlying tooth structure can have significant effect on material selection for a future restoration. All-ceramic crowns with opaque cores (alumina based, nonetchable cores) offer good alternatives to conventional metal-ceramic crowns, both in terms of aesthetic outcomes and strength.
Alumina-based crowns allow non-adhesive cementation. This can be advantageous in the cases with subgingival preparation and difficult application of the rubber dam for the isolation from moisture.
In the presented case the new restoration was fabricated in two clinical visits and one laboratory visit.
An excellent aesthetic outcome was achieved. This was result of a mastery work by the dental technician and good
communication between the dentist and the technician.