Transforming the Smile Line
Lithium disilicate restorations offer opportunity to correct malocclusion while restoring esthetics
Nada Albatish, DDS
The longevity of restorative treatments is predicated on many factors, including the development of proper tooth form and occlusal function.1 An exaggerated curve of Spee is often present in patients with malocclusions and deep overbites2; if not corrected, it can lead to restoration fractures, adhesive failure, and other negative sequelae.3When extensive rehabilitation is required to reestablish dental function and smile esthetics, placing lithium disilicate restorations using an esthetic adhesive resin cement enables dentists to predictably correct malocclusion and appearance issues.
A 49-year-old man presented with old and failing composite restorations in his maxillary anterior teeth, intrinsic discoloration (ie, fluorosis), occlusal wear, and two missing mandibular incisors that led to space loss and a narrowed arch (Figure 1). A thorough examination was performed that emphasized the patient's visibly retroclined and over-erupted maxillary and mandibular incisors, deep bite, severely exaggerated curve of Spee, and roller-coaster occlusal plane (Figure 1). Esthetically, the patient demonstrated excessive mandibular tooth display, a low smile line, inadequate maxillary incisor display, and poor incisor and premolar arrangement in the smile line.
Orthodontic treatment was presented; however, the patient declined and opted to reestablish an ideal occlusion and correct his discolored and worn teeth using full-coverage crown restorations. The treatment plan involved extracoronal coverage in both arches and opening the vertical dimension of occlusion using a shortened dental arch concept.4,5
Functional Smile Design
Intraoral photographs were taken to digitally visualize a new occlusal plane and anterior maxillary esthetics (Figure 2). Impressions were taken, and models were articulated using an earless facebow (Kois Dento-Facial Analyzer, Panadent) and a centric relation bite record. A diagnostic wax-up was then completed. The case was designed in centric relation, and the mandibular restorations were designed for function against the esthetic maxillary tooth positions.
An intraoral mock-up was completed on the maxillary arch to demonstrate the proposed improved incisor and premolar length as well as the improved facial positions of teeth at the thickest mock-up dimensions. When designing the case, photographs and impressions of the mock-up were taken for laboratory use (Figure 3). All other records were also forwarded to the laboratory.
The preoperative models were mounted, and the distance between the cementoenamel junctions (CEJs) was determined to be 13.93 mm. Based on the proposed treatment plan, an enhanced wax-up was created, mounted on the articulator, and a new CEJ-to-CEJ distance of 16.05 mm was established.
Preparation and Provisionalization
Using a laboratory-fabricated putty matrix (Sil-Tech®Putty, Ivoclar Vivadent) of the wax-up, an intraoral mock-up was placed as a reduction guide prior to preparation. The matrix was also used to create chairside provisional restorations (Figure 4).
Next, 10 maxillary and six mandibular teeth were prepared for the full-coverage lithium disilicate restorations. Two mandibular anterior teeth were also prepared as abutments for a lithium disilicate bridge to replace the two missing incisors. To transfer the correct vertical dimension of occlusion to the laboratory, control bites were taken from the unprepared and mocked-up molars using an extra-hard bite registration material (Futar® D, Kettenbach GmbH). In addition, an anterior tripod was fabricated after tooth preparation.
After the chairside provisional restorations were made, they were temporarily cemented and finalized. The patient was dismissed and recalled after 1 month to approve the esthetics and function of the proposed restorations (Figure 5).
Final Delivery and Cementation
The final restorations were fabricated at the laboratory from medium translucency lithium disilicate ingots in shade BL3 (IPS e.max® Press MT, Ivoclar Vivadent).
After the provisional restorations were removed and the preparations cleaned, the final restorations were tried in, adding one at a time with a try-in paste in a light value shade (Variolink Esthetic Try-in Paste, Ivoclar Vivadent), to verify their color and fit (Figure 6). Upon patient approval, the restorations were removed, and the preparations were cleaned and dried.
Prior to final cementation, isolation was established with a slit rubber dam, and 00 gingival retraction cord was placed, using a hemostatic agent (Traxodent®, Premier) as needed. A universal cleaning paste (Ivoclean, Ivoclar Vivadent) was applied to the internal aspects of the restorations, left on for 20 seconds, and then rinsed and dried. Once cleaned, a primer (Monobond Plus, Ivoclar Vivadent) was applied to the internal surfaces of the restorations for 1 minute and lightly air-dried, an adhesive bonding agent (Adhese® Universal, Ivoclar Vivadent) was applied as a wetting agent, and the restorations were stored in a dark box until the teeth were treated for bonding.
Next, the preparations were etched, rinsed, dried, and desensitized (Telio® CS Desensitizer, Ivoclar Vivadent). After the adhesive bonding agent was scrubbed onto the preparation surfaces, the solvent was evaporated with warm air, and the adhesive was light-cured for 10 seconds from the occlusal aspect.
An esthetic adhesive resin cement in a light value shade (Variolink® Esthetic, Ivoclar Vivadent) was applied directly into the restorations, which were seated and tack cured into place for 1 second each (Figure 7). Any excess cement was removed from the gingival margins and interproximal spaces. Glycerin gel (Liquid Strip, Ivoclar Vivadent) was placed on the margins, and the restorations were fully light-cured for 10 seconds each from multiple aspects.
After the occlusion was checked, canine guidance confirmed, and any necessary ad---
justments completed, the restorations were polished using diamond polish and a brush (Abbott-Robinson® Brush, Keystone Industries) (Figure 8).
The author would like to acknowledge Gold Dust Dental Laboratory for its work on this case.
About the Author
Nada Albatish, DDS
Clinical Mastery Series
All Smiles Dental Centre
1. McIntyre F. Restoring esthetics and anterior guidance in worn anterior teeth: a conservative multidisciplinary approach. J Am Dent Assoc. 2000;131(9):1279-1283.
2. Kumar KP, Tamizharasi S. Significance of curve of Spee: an orthodontic review. J Pharm Bioallied Sci. 2012;4(Suppl 2):S323-S328.
3. Alex G. Is occlusion and comprehensive dentistry really that important? Inside Dent. 2007;3(2):32-40.
4. Witter DJ, van Palenstein Helderman WH, Creugers NH, et al. The shortened dental arch concept and its implications for oral health care. Community Dent Oral Epidemiol. 1999;27(4):249-258.
5. Käyser AF. Shortened dental arches and oral function. J Oral Rehabil. 1981;8(5):457-462.