Restoring a Discolored Central Incisor with CAD/CAM
Stump management and material selection is key for favorable outcome
Dhaval Patel, DDS
Restoring a single discolored maxillary central incisor to a near mirror image of the contralateral tooth is a very difficult task when considering the biological, functional, esthetic, and material dimensions of the procedure. The task gets more difficult if the dentist chooses to complete the restoration chairside with CAD/CAM and without the help of a lab technician and layered ceramics. Stump management and cement and restorative material choice becomes key in ensuring a favorable outcome.
A 53-year-old man with a discolored maxillary left central incisor presented for treatment. He requested to make the tooth look as much as possible like his other front tooth (Figure 1). The maxillary left central incisor had been treated endodontically as a result of previous trauma when the patient was 16 years old. Further discoloration occurred as the patient grew older. The midline diastema was not a concern and the patient’s only desire was to have both the centrals match as close as possible. After discussing several treatment options that included orthodontia, composite bonding, and veneers, the patient chose to have the tooth restored with a porcelain crown that was fabricated with CAD/CAM same-day.
Tooth Preparation and Material Selection
An enameloplasty was completed on teeth Nos. 8 and 9 until the incisal edge length was acceptable to the patient (Figure 2). The left central incisor was prepped for a full coverage crown. The grayness around the cervical third and patches of discoloration in the middle third were noticeable at this point (Figure 3). Based on past experience, the options for what material to use in the final restoration were narrowed down to a few choices, including:
e.max® CAD LT (Ivoclar Vivadent, www.ivoclarvivadent.com): This would very easily block the dark stump but would not be able to give the incisor translucency to match the other central.
e.max CAD HT (Ivoclar Vivadent): This would look too gray, as it may not be able to block the dark stump but would get close enough for the incisal translucency.
IPS Empress® CAD Multi (Ivoclar Vivadent): If the dark stump could be masked with an opaque sealant, this material would achieve the best incisal translucency.
The IPS Empress was chosen, and while packable composite was used in the past to block stumps, it requires further preparation on the facial to prevent the composite layer from adding bulk. Therefore, Pink Opaque (Cosmedent®, www.cosmedent.com) was selected because it is easy to use and quickly neutralizes dark stains and unsightly dentition. It is indicated for unsightly dentition, such as non-vital teeth, tetracycline stained teeth, or teeth with metal posts and core. It gives you natural restorative results that are not overly opaque and can be used under composite or porcelain restorations. The facial surface of the preparation was etched for 15 seconds (35% phosphoric acid solution, Ultradent, www.ultradent.com), washed, and dried. The bonding agent was applied, air-dried, and light-cured. Pink Opaque was applied with a paintbrush all over the facial surface. It was then light-cured. This material blocked the gray and dark patches on the facial surface (Figure 4).
Scanning and Designing Process
The preparation, along with the adjacent teeth, was scanned in the upper arch folder using the Omnicam acquisition unit (Dentsply Sirona Dental, www.dentsplysirona.com) (Figure 5). The opposing lower anterior teeth were scanned in the lower arch folder. The patient was asked to bite in maximum intercuspation and the facial surfaces of the bite were scanned in the buccal bite folder. In the model phase, the left central incisor was marginated and the correct insertion axis was selected. The software then proposed a crown for the left central. This technique analyzes neighboring and adjacent teeth, and calculates and proposes a restoration design that fits the form and shapes of the other teeth in the arch—the more information available, the more successful the calculation. However, the restoration’s width, incisal edge position, and basic outline form designs did not match that of the right central. Several design tools, along with the grid, were used to make sure the left central matched the right central in terms of length, width, shape, and symmetry (Figure 6).