Solution for the Challenging Implant

In the aesthetic region of the anterior maxilla restoring a single-tooth implant can be a demanding challenge to the clinician. In such cases the dental implant is the sole restoration for the arch, and the clinician is faced with the challenge to mimic what is naturally present versus recreating the best possible restoration via modification of the existing dentition.^1,2 For a singular aesthetic zone restoration to be considered a success, the dental implant needs not only to be osseointegrated in the appropriate position, but also restored in a manner in which the implant crown blends in harmoniously with its natural neighbors in form and function.^1-4
The increasing growth in ceramics in dentistry is reflective of the escalating de-mand for better cosmetics.^3,5,6 Today’s dentist is challenged daily to deliver not only a functional product, but also a product that imitates, or in select cases actually im-proves, the natural condition of a person’s dentition. Duplicating the natural dentition begins with proper placement of the dental implant, continues with the correct emergence profile, and finishes with a restoration that seamlessly incorporates natural anatomy into the replacement tooth restoration. Because the implant is subgingival, the type of implant is of less importance than the abutment. For the restoration to be an in-conspicuous success the color, contour, and material of the abutment must imitate the emergence profile of the natural dentition^.2

CASE REPORTS

Case 1

Figure 1. Fractured tooth No. 7.	Figure 2. Dental implant placed immediately after extraction.
Figure 3. Panorex of dental implant.	Figure 4. Model with Atlantis Zirconium Custom Abutment.
Figure 5. Atlantis Custom Abutment on dental implant.	Figure 6. Final restoration.

Figure 7. Final restoration in occlusion.

The patient was a healthy 23-year-old male who initially presented to the author’s office on referral from his general dentist with a fracture of endodontically treated tooth No. 7 (Figure 1). After consultation, the patient elected to have tooth No. 7 extracted, followed by the immediate placement of a dental implant at position No. 7.
While the patient was under general anesthesia, tooth No. 7 was atraumatically extracted and a 3.7 x 16 mm internal hex dental implant (Zimmer Dental) was immediately placed in the extraction socket (Figures 2 and 3). A cover screw was appropriately placed. The wound was closed without tension with 3-0 silk and the patient was given appropriate antibiotics and analgesics postoperatively. He was seen frequently in the month immediately following the surgery, and no complications were noted.
Six months later the implant was uncovered under local anesthesia and a healing abutment was placed. Reverse torque testing at this appointment measured 40 N/cm². Two weeks later polyvinylsiloxane impressions (Impregum Penta Soft, 3M ESPE) of the upper (closed tray) and lower arches were taken. A bite registration (Blu-Mousse, Parkell) was also taken at the same appointment. All impressions were sent to Atlantis Components for fabrication of a Zirconia custom abutment (Figure 4). A lab processed provisional restoration for the abutment was fabricated at a local lab. Three weeks after the impressions were taken a custom Zirconia abutment was delivered and restored with the provisional restoration out of occlusion (Figure 5). Two weeks later the final restoration was placed by the general dentist after the abutment was torqued into place to 35 N/cm² (Figures 6 and 7).

Case 2

Figure 8. Dental implants in maxilla.	Figure 9. Panorex of dental implants.
Figure 10. Atlantis Custom Zirconia abutments on model.	Figure 11. Atlantis Custom Zirconium Abutment (No. 7) on implant.
Figure 12. Atlantis Custom Zirconium Abutment (No. 10) on implant.	Figure 13. Provisional restorations on abutments in maxilla.
Figure 14. Final restoration No. 7.	Figure 15. Final restoration No. 10.

The patient was a healthy 16-year-old female who presented to the author’s office for dental implant reconstruction to address congenitally missing lateral incisors. After review of a panorex radiograph and Simplant (Materialise) computed tomography scan, a custom surgiguide was generated from the virtual placement of 2 dental implants in the Simplant program.
While the patient was under general anesthesia two 3.7 x 13 mm implants (Zimmer Dental) were placed using the custom surgi-guide in sequence (Figures 8 and 9). A cover screw was placed on each implant. Appropriate antibiotic and analgesics were given to the patient for postoperative care. The pa-tient was followed for 8 months without event.
Eight months after placement the implants were uncovered and reverse torque testing was performed. The torque value of implants at positions No. 7 and No. 10 measured 35 N/cm² each. Impressions were taken with polyvinylsiloxane material (Impregum Penta Soft) of the upper and lower arches. A bite registration (Blu-Mousse) was also taken at the same appointment. Impressions and bite registration were sent to the Atlantis Corporation for fabrication of custom Zirconia abutments (Figure 10). A suitable healing abutment was placed on each implant.
At the next appointment the custom Atlantis Zirconia abutments were placed on each implant, torqued into place, and restored with provisional restorations (Figures 11 to 13). One month later the patient received her final restorations (Figures 14 and 15).

DISCUSSION

The titanium abutment is considered the standard method for restoring dental implants. Titanium is well tolerated by oral tissue, has excellent strength properties, and can be manufactured inexpensively. Drawbacks to employing titanium abutments in the aesthetic zone include the likelihood of the patient showing the titanium as the soft tissue retracts over time. In the aesthetic zone titanium’s dark color often shows through the thin mucosa, producing a blue/grey shadow that compromises the aesthetics of the final product.^1,7,8
Ceramic abutments, made of either densely sintered high purity alumina (AL203) ceramic or yuridium oxide stabilized zirconium oxide (ZRO₂) offer the restoring clinician an alternative to titanium. Like titanium, these ceramics possess adequate strength to withstand the forces of mastication, demonstrate excellent biocompatibility, have reasonable wear characteristics, and are relatively easy to work with.^2,4 Additionally, their white or near white color eliminates the blue/gray shadow for a more aesthetic restoration.^2,4,9
The increasing growth in ceramics in dentistry is reflective of the increasing demand for better cosmetics.5,6 Both AL₂O₃ and ZRO₂ represent a significant advancement in dental implant abutments by permitting the dentist to deliver a quality restoration with aesthetics far above that which can be attained by titanium, even in more difficult cases. Aluminum oxide is reported to offer excellent aesthetics due to its natural tooth color properties. Zirconium oxide’s most desirable characteristic is its strength. In multiple studies its flexural strength more than twice exceeds that of aluminum oxide. These same studies claim its high flexural strength (over 700 Newtons) is a product of the higher density and smaller particle size of zirconium oxide versus aluminium oxide.^4-7,10
Both aluminum oxide and zirconium oxide abutments demonstrate superior biocompatibility. One study by Remondini et al¹¹ reported that zirconium poly crystals stabilized with yttrium accumulated fewer bacteria than titanium.
In 1996 Atlantis Components patented a CAD/CAM design and integrated machining processes to fabricate patient-specific precision milled abutments from a single block of titanium.⁸ Recently, Atlantis expanded their CAD/CAM designs to include a custom abutment made from zirconium. Like their titanium counterparts, an Atlantis zirconium abutment milled from a single block of material to patient-specific dimensions produces a custom aesthetic abutment while at the same time providing an abutment of sufficient strength to withstand the forces of mastication. The CAD/CAM customization of the abutment allows for proper emergence profile, spacial design, axillo-angulation, and occlusal clearance.⁵ These properties save valuable time for the restorative dentist while delivering the most aesthetically pleasing product available.

References

Dr. Whitesides is a graduate of the Medical College of Georgia School of Dentistry. After completing his dental degree he participated in a one-year GPR at Maimonides Medical Center in New York. In 1997 he completed his Oral and Maxillofacial surgery training at the University of Maryland Medical Systems in Baltimore. He is currently in private practice at Atlanta Oral and Facial Surgery in Atlanta, Georgia. He can be reached at drmac@bellsouth.net.