Achieving desired cosmetic results that are durable and aesthetically pleasing has long been a challenge for dentists. Once metal-free restorations became the norm and no longer the exception, a number of ceramic solutions and resin alternatives emerged that provided material strength for crowns and bridges, but did not provide optimal aesthetic results. Others were cosmetically pleasing but required replacement after a short time.
The advent of computer-aided design/computer-aided manufacturing (CAD/CAM) technology brought a new restorative option to dentists. Since then, all-ceramic crowns have become popular among patients, providing desirable properties such as transluceny and high flexural strength.
One challenge a patient presented with in our office was a desire to restore his teeth with a material that could successfully perform on 2 levels: (1) the restoration needed to be of high aesthetic quality, since so many front teeth were involved, and (2) the restoration required a material that could provide more than adequate strength to be able to withstand the patient’s grinding habit.
This article describes the materials and treatment used to meet the patient’s needs.
CASE REPORT
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| Figure 1. The patient’s chief complaint was about extreme wear to his remaining teeth. |
A 59-year-old male Caucasian in good overall health presented for comprehensive dental care. His chief complaint was extreme wear of his remaining teeth, and he suffered from extreme loss of tooth structure, with some teeth broken down to the gum line (Figure 1). The patient was completely symptom free with respect to TMD and periodontal breakdown and was able to chew and eat whatever he wanted. However, he admitted eating more slowly and cautiously due to his worn teeth.
EVALUATION/TREATMENT PLAN
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| Figure 2. TENS unit with a facial plate bite registration. |
Upon thorough clinical examination, it was apparent that the patient was an extreme clencher and bruxer as well as a possible Delta stage bruxer. Full-mouth radiographs were taken in addition to full periodontal probing, models, and a full set of digital diagnostic photos. Several bite registrations were taken, along with facial measurements, using the Tru-Byte Facial Denture Tooth Guide (DENTSPLY). Measurements were taken from the maxillary central dental enamel junction (DEJ) to the mandibular central DEJ. (This is known as a Shimbashi measurement, which is used to determine the vertical component of occlusion during closure and was first described by Hank Shimbashi.) An inadequate DEJ to DEJ measurement of 9 mm was recorded (Figure 2).
A case presentation was done at a subsequent visit, where our office outlines extensive, full-mouth rehabilitation. One of the first challenges was to determine the proper vertical dimension of occlusion, as so much tooth structure had been worn or abraded away. A full neuromuscular approach was taken using electro-sonography, muscle EMGs, and jaw tracking. A 2-hour Transcutaneous Electro Neuro Stimulation (TENS, Myotronics-Noromed) session helped relax the muscles of mastication to the level where an accurate, balanced, neuromuscular bite registration could be obtained. It should be noted that this relaxed neuromuscular position was opened both vertically and down and forward of his centric occlusal position. The new Shimbashi measurement was now 17 mm. A full-mouth wax-up was accomplished, and Sil-Tech matrices (Ivoclar Vivadent) were made to use as a fixed orthotic device, as the patient was insistent about not wearing a removable orthotic device.
At a subsequent appointment, a fixed neuromuscular orthotic was placed on the patient’s maxillary and mandibular teeth. Coronoplasty was accomplished to keep the device on the proper neuromuscular trajectory. An immediate im-provement was noted in his appearance, and the patient reported over the next 2 months that he was much more comfortable chewing.
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| Figure 3. Patient’s provisionals at the corrected vertical dimension. |
Full-mouth rehabilitation was done at yet another appointment. Rules, tools, and strategies for this type of single-appointment rehabilitation, as taught by the Las Vegas Institute, were followed. The entire mouth was prepped and impressions were taken. The patient underwent laser recontouring for the gingival tissues, and provisional restorations were fabricated using a bisacryl provisional material (Figure 3).
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| Figure 4. Shade tabs were placed against both the patient’s natural dentition and the prepared teeth. |
Shade selection was done using digital photography, with shade tabs placed against both the patient’s natural dentition and the prepared teeth (Figure 4). This information was conveyed to the laboratory. Incisal-to-gingival single-tooth and central-to-lateral-to-cuspid color progression was done by the master ceramist Moshe Mizrachi, CDT, at Mizrachi Dental Lab. This achieved a more natural result and produced a case that was both aesthetically pleasing and age-appropriate. This enabled the final ceramics to mimic natural teeth better.
MATERIALS
Lava Crowns and Bridges system (3M ESPE) was chosen as the restorative material, as it would provide both highly desirable aesthetic results and the strength and reliability necessary for this case. The Lava system is a CAD/CAM technology for all-ceramic crowns and bridges and is relatively easy to integrate into any practice. In addition, the technology helps dentists achieve highly desired aesthetic results without altering their crown and bridge technique.
The system’s framework ceramic comprises zirconia, which provides strength characteristics and support that rival some alloy substructures, and is supplemented by a specially designed veneer ceramic for final aesthetic form. The frameworks are fabricated utilizing CAD/CAM procedures (scanning, computer-aided framework design and milling) on pre-sintered zirconia blanks. The frameworks, the sizes of which have been digitally calculated and increased to compensate for shrinkage during sintering in a special, high-temperature furnace, are used to produce high-strength restorations with an excellent fit. In fact, the Lava system’s high strength values and high fracture toughness allow a framework/coping thickness of 0.5 mm as well as reduced subgingival margins. Eight different framework shades allow for natural tooth matching and better translucency. Final ceramic layering is done traditionally, which yields a highly aesthetic finished restoration.
CLINICAL PROCEDURE
Approximately 4 weeks following rehabilitation, the Lava restorations were completed. The patient was anesthetized, and the provisional materials were removed. The units were disinfected with Consepsis (Ultradent). Enamel etching was done at the cavosurface margins of the prepared teeth with 37% phosphoric acid. This was done for 10 to 12 seconds to secure a better marginal fit. The interiors of the Lava units were acid-etched to clean the internal surfaces, then treated with Co-jet bond-en-hancing particles (3M ESPE).
The units were seated using RelyX Unicem Self-Adhesive Universal Resin Cement (3M ESPE). Excess cement was easily removed following seating because of the seamless margins.
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| Figure 5. Final restorations delivered one month post-op. Notice improved aesthetic and functional result. |
Final coronoplasty (equilibration) was done over several appointments using Scan 12 (neuromuscular computerized equipment on the K7 from Myotronics-Noromed) and a Tekscan occlusal analysis program. Final polishing was done with the Brasseler Porcelain Polishing System, and the final glaze was added back with diamond paste (George Taub Products, Figure 5).
CONCLUSION
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| Figure 6. Pre-op, full-face image. | Figure 7. The patient was very pleased with his new smile. |
The patient in this case was extremely pleased with the precise fit and natural and beautiful look of his new smile (Figures 6 and 7). The Lava Crowns and Bridges system provided a metal-free option that offered aesthetics without compromising strength. Despite the patient’s history of grinding and parafunctional activity, his restorations continue to perform.
Acknowledgment
The author would like to thank Moshe Mizrachi, CDT, owner of Mizrachi Dental Lab, for the fabrication of the restorations used in this article.
Dr. Weiner is a graduate of the University of Maryland School of Dentistry. Currently he works in a prosthodontic-style private practice in the San Diego, Calif area. He has attended numerous continuums on advanced aesthetics and comprehensive full-mouth rehabilitation. He is a member of the ADA, AACD, California Dental Association, and Academy of Laser Dentistry. He also is a graduate of the Las Vegas Institute and has many other dental affiliations. He has presented programs nationally on both restorative and laser comprehensive dental care. He can be reached at (619) 670-5571 or rsdental@netscape.net.
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