Endosseous Implants Restored With All-Ceramic Single-Unit Restorations in the Aesthetic Zone

A fixed partial denture with natural teeth as abutments was historically the only alternative for a fixed restoration in the partially edentulous patient. In many of these situations, the natural teeth that served as abutments were in pristine condition. With the introduction of dental implants, the possibility of multiple single-unit restorations is achievable as long as the treatment option preserves bone and does not compromise healthy teeth.
The predictability and success of implant treatment has been well documented for both completely edentulous and partially edentulous patients.1-5 With the increase in our patients’ aesthetic awareness, the introduction of new and improved restorative materials including all-ceramic restorations,6 provides an additional tool to better achieve the aesthetic demands. More recently, ceramic implant abutments have been introduced that are helpful in achieving excellent aesthetics.
The most important requirement for implant-supported restorations is osseointegration of the dental implant. This process can be affected by quality of the bone, surgical technique, patient habits, etc. Nonaxial loading during function can contribute to loss of osseointegration; this loading can be the product of different causes, but is primarily due to incorrect implant localization and angulations.7

SURGICAL GUIDES

Fabrication of surgical guides for the correct placement of an endosseous implant is imperative to avoid aesthetic, functional, and phonetic complications.8,9 The use of 2-dimensional radiography (including panoramic, periapical, and bite-wing radiographs) may not allow the dentist to adequately assess the form and density of the bone at the recipient site. However, the dentist typically fabricates the surgical guide using a mounted cast and these radiographs. An ample variety of designs and techniques exist for the fabrication of surgical guides. These range from simple ones made from thermoplastic vacuumed formed guides10-12 that merely provide information for the desired location of the dental implant, to more complex guides fabricated from computed tomography (CT) scans and computer aided design (CAD)/computer-aided manufacturing (CAM) technology that provide information on the location, angulations, and depth information for every single drill necessary for the placement of an endosseous implant, as well as for the placement of the implant itself.
Depending on the complexity of the case, different surgical guides can be chosen. The use of CT scans combined with CAD/CAM technology for the fabrication of surgical guides provides a guide for the exact positioning of the implant. This technology also provides us with the knowledge that is needed to fabricate implant components such as abutments, temporary, or definitive restorations—prior to surgery.

CAD DESIGNED IMPLANT ABUTMENTS

Computer designed and generated implant abutments have also changed the restorative protocols for implant dentistry. The Procera design software (3D CAD) offers the opportunity to develop implant abutments from zirconia and other materials. Through this portion of the software, the user can custom design abutments and fixed restorations using all-ceramic materials that potentially offer better aesthetic results when compared to the more classic metal-ceramic restorations.
Customized abutments from several materials may be fabricated with the 3D CAD technique in the following manner: A screw with a graduated pin for determining the height of the abutments is placed into the implant replica (embedded) in the master cast to visualize and align the computer image with the master cast. The design software enables the alteration of the body of the abutment, its angle, height, width, taper, gingival margin height, and emergence angle. The completed abutment design is represented on the screen and then transmitted electronically to the production facility where it is milled. The implant abutment is delivered within 4 days of sending the order.13-15
The software enables the practitioner to fabricate individualized implant components with the desired height, width, and contour. These components are biocompatible, and successfully mimic the appearance of natural teeth.16-18 This article will now describe the fabrication of 2 all-ceramic single unit restorations on 2 endosseous implants in the aesthetic zone, 4-month postimmediate-provisionalization.

Figure 1. Preoperative photo.	Figure 2. Provisional restorations in place.
Figure 3. Implant placed in the correct position. (After 4 months of healing with the provisional restorations in place).	Figure 4. Impression copings in place.
Figure 5. Customized zirconia abutments.	Figure 6. Final restorations.

Figure 7. Final restorations.

A complete medical examination was performed, as well as the review of the medical history. There were no medical findings that would contraindicate any dental care, including elective surgery.
Immediate provisionalization over 2 external hexagon implants (Bränemark, Nobel Biocare) 4.0 mm x 13 mm in the position of the maxillary left central incisor, and a 3.3 mm x 13 mm implant in the area of the maxillary left lateral incisor was achieved (Figure 2).
After 4 months the provisional restorations and the provisional custom abutments were removed (Figure 3). The provisional restorations (worn for that 4-month period) aided in the contouring of the soft tissue, as well as providing the patient with a realistic idea of the final restorations. A custom tray (Triad; DENTSPLY International) was then used to make a closed-tray implant-level impression of the external hexagon endosseous implants after placing the impression copings (Nobel Biocare AB) and verifying them radiographically for fit (Figure 4). Next, an impression was taken using a vinyl polysiloxane (VPS) material (Extrude [Kerr Corp]). The impression of the opposing arch was taken using hydrocolloid impression material (Jeltrate [DENTSPLY]) and poured with a Type V gypsum stone (DieKeen [Heraeus Kulzer]). Using a pink VPS material (Gingitech [Ivoclar Vivadent]) to first create a soft-tissue moulage, the maxillary impression was then poured with a Type V gypsum material (Die-Keen [Heraeus Kulzer]).
Interocclusal bite records and a face-bow transfer were taken utilizing occlusal registration wax (Aluwax Dental Products) and base plate wax (Truwax [DENTSPLY]). These records were then transferred to a semi-adjustable articulator (Hanau WideView [Water Pik Technologies]).
Two custom zirconia abutments were designed with the 3-D CAD (Procera [Nobel Biocare]) using the double-scan technique. The abutments were then digitized with a touch-probe scanner (Procera Piccolo [Nobel Biocare]), and the copings were also fabricated in zirconia. Veneering porcelain (NobelRondo [Nobel Biocare]) was then applied and fired by the dental ceramist to complete the aesthetic portion of the crowns.
At the insertion appointment, the provisional custom abutments were removed and the new ceramic abutments were secured in place at 35-Ncm torque (Figure 5). The fit was verified radiographically. Next, the access openings were filled with wax, and the all-ceramic crowns were placed onto the abutments to verify marginal integrity, occlusal relationships, and aesthetics. The all-ceramic restorations were cemented onto the zirconia custom abutments using provisional cement marketed for the use with dental implants restorations (Premier Dental Implant Cement [Premier Dental Products]) (Figures 6 and 7).
In routine follow-up (hygiene) visits that have spanned over 2 years, no adjustments have been required.

DISCUSSION

The use of endosseous implants has revolutionized the dental world, providing a great variety of options for restoring the partially and completely edentulous patients. This treatment option has proven to be an excellent alternative for replacing single or multiple teeth. When indicated, the use of ceramic abutments and all-ceramic crowns provides restorative success over time as well as excellent aesthetics.
The use of 3-D CAD technology has greatly contributed to the predictability of these restorations. The selection of treatment modalities has always been a dilemma. In the past few years, with the increased use of dental implants, this dilemma has become of greater concern due to the wider selection of treatments, including the possibility of treating the edentulous patients with single unit restorations on implants.

CONCLUSION

In this article, a case was presented in which the maxillary left central and left lateral incisors were replaced with implants, followed by immediate restoration with zirconia abutments and a provisional restoration.
The placement of endosseous implants in edentulous areas has proven to be an excellent alternative for replacing single or multiple teeth. After providing adequate time for osseointegration, remodeling of the bone, and desirable changes in the architecture of the soft tissue, single unit all-ceramic restorations were placed providing both excellent function and aesthetics for the patient.

References

Dr. Abbo earned his dental degree from the Santa Maria University in Caracas, Venezuela in 2002. He completed a 3-year Master Program in Prosthodontics at the University of Michigan in 2006 and was then appointed Clinical Lecturer for their Prosthodonic Department. While teaching, he practiced dentistry in a private dental practice, as well as in the University Prosthodontic clinic for a period of 2 years. He has published numerous articles in various dental journals, and has lectured and conducted workshops both nationally and internationally. His topics of interest have included dental implants, all-ceramic restorations, and aesthetics. Currently, Dr. Abbo owns a private practice in the area of North Miami Beach, Florida, has state-of-the-art technology and is committed to excellence—providing his patients with optimum dental care in a warm and caring environment. He can be reached at bill@drabbo.com or bill_abbo@hotmail.com.

Dr. Abbo did not report any disclosures.