Digitizing Implant Treatment: Abutment Design, Fabrication, and Provisionalization

INTRODUCTION
Digital technologies that were once mainly used for traditional restorative or prosthodontic dentistry have made their way into implant dentistry. As a result, recent advancements in aesthetic materials and chairside CAD/CAM applications are leading dental professionals down a path of highly efficient and customized implant treatments.

Like other dental procedures, implant placement requires comprehensive diagnosis and careful planning.¹ Many implant procedures also require multiple appointments for placement and subsequent removal of implant components. This has been shown to compromise the mucosal barrier, cause additional bone remodeling to be necessary, and alter the position of connective tissue.² Therefore, placing the definitive abutment during initial surgery—described as “one abutment, one time”—has been proposed.^3,4 This approach is enabled through materials and innovations associated with today’s CAD/CAM technologies.

The following case demonstrates the possibilities that can be achieved today. Simultaneously, it reiterates our need to recognize that technology alone cannot overcome fundamental biology and principles of implant dentistry. Rather, progress is only made when the limits are pushed!

CASE REPORT
Diagnosis and Treatment Planning
A male patient presented for a routine new patient evaluation (Figure 1). His primary concern was discoloration of the central incisor (tooth No. 8). It had recently begun to resorb and was causing discomfort. He reported a history of trauma during his teenage years that necessitated endodontic therapy on teeth Nos. 8 to 10. Periapical radiographs revealed severe external resorption of these teeth (Figures 2 and 3).

It was determined that implant treatment would be appropriate. An alternative treatment could have been a bridge restoration. A 3-D CBCT radiograph (GALILEOS [Sirona Dental Systems]) was taken to properly evaluate the extent of resorption and confirm the potential for implant treatment (Figure 4). Since the buccal plate was intact and sufficient apical extension existed for primary stability, it was determined that implant placement was appropriate (Figure 5).

Implant treatment planning was completed utilizing a combination of digital impressions and 3-D CBCT radiography (Figure 6). It was determined that ideal implant placement could be achieved at the time of extraction. This idealized, virtual plan was implemented to fabricate a digital surgical guide to assist with implant placement. It is important to note that application of these technologies made it possible to accomplish this assessment and treatment planning during the patient’s initial visit. Furthermore, this digital technology ensured that all components of the implant system (ie, abutment and restoration) would be functional yet highly aesthetic.⁵

Figure 1. Preoperative view of the patient’s dentition.	Figure 2. A periapical radiograph revealed severe external root resorption of the maxillary incisors.
Figure 3. Close-up retracted view of the patient’s dentition.	Figure 4. A radiograph was necessary to determine the extent of root resorption and confirm the potential for implant placement.
Figure 5. A 3-D CBCT radiograph determined implant placement was possible.	Figure 6. Digital impressions and a maxillary radiographic view of the anticipated implant site were taken to ensure stability.

Clinical Protocol
The patient’s second appointment was the day of surgery. Tooth No. 8 was extracted utilizing an atraumatic technique (Figures 7 and 8). The socket was then debrided to remove remnant granulation tissue (Figure 9) because, when performing immediate implant placement, it is important to ensure complete removal of any residual tissue from the socket. Following tooth extraction, the implant (NobelActive RP [Nobel Biocare]) was placed utilizing guided surgery (Figure 10). The implant was hand-torqued to ensure that primary stability of at least 35 Ncm was achieved (Figure 11). By achieving this primary stability, immediate provisionalization would be possible.

Figure 7. At the second appointment, the patient presented for implant surgery.	Figure 8. The tooth was extracted using an atraumatic technique.
Figure 9. The socket was debrided to remove excess granulation tissue.	Figure 10. The implant (NobelActive RP [Nobel Biocare]) was placed using a surgical guide.
Figure 11. The implant was hand-torqued to achieve primary stability of 35 Ncm.	Figure 12. A digital implant level impression post was placed.

A digital design and fabrication process was employed to create the “provisional” implant-supported restoration. A digital implant-level impression post was placed onto the implant and scanned using the CEREC OmniCam (Sirona Dental Systems) (Figures 12 and 13). Within a few minutes, a digital (ie, virtual) implant-level model was created. With details of the preoperative tooth, tissue position, and implant location incorporated into this virtual model, an appropriate provisional implant restoration could be designed to ideal contours and support (Figure 14). Additionally, this digital process (eg, CEREC 4.2 chairside software) provided complete control over occlusion, ensuring that the restoration would not only be out of centric occlusion, but also excursive movements as well (Figure 15).

The proposed implant/abutment/restoration complex would consist of a hybrid screw-retained implant crown bonded with a universal cement (Multilink [Ivoclar Vivadent]) to a titanium base (TiBase [Sirona Dental Systems]). While dental implants have frequently been restored with cement-retained restorations,⁶ the residual cement that is often the by-product of such procedures has been linked with instances of peri-implantitis.⁷

The implant-supported provisional restoration was designed (Figure 16) and milled from a recently introduced lithium disilicate CAD/CAM abutment block (IPS e.max CAD Abutment [Ivoclar Vivadent]) (Figure 17). The basis for the selection of this material in this case was its ability to facilitate a better evaluation of color and shade characterizations for planning the definitive restoration. When fabricated with the proper emergence profile, this highly aesthetic material also allows for a natural appearance to be imparted.⁸ (A shade C2 of the A16 [LT] abutment block was selected.)
The provisional restoration was milled chairside using the lithium disilicate block (IPS e.max CAD), after which it was tried in the mouth to verify fit, contour, and aesthetics (Figure 18). IPS e.max CAD restorations demonstrate excellent long-term success and have been shown to be an effective selection for high-strength all-ceramic restorations.⁹ The restoration was removed, then crystallized and stained/glazed in a single oven cycle (Figures 17 to 19).

The provisional restoration was delivered to the mouth, after which it was tightened to 15 Ncm of torque in order to not disturb the implant (Figure 20). The shade for the definitive restoration would be determined upon completion of final healing (Figures 21 and 22).

Figure 13. The impression post was scanned with the CEREC OmniCam (Sirona Dental Systems).	Figure 14. A digital provisional restoration was designed in the software.
Figure 15. The restoration was designed with necessary contours and support relative to the surrounding dentition.	Figure 16. The virtual restoration was ready for milling.
Figure 17. The restoration was milled, contoured, and placed onto the TiBase (Sirona Dental Systems).	Figure 18. The restoration was tried in the mouth to verify fit and aesthetics.
Figure 19. The restoration was crystallized, stained, and glazed in a single oven cycle.	Figure 20. The provisional restoration was delivered.
Figure 21. Close-up retracted view of the final restoration that was placed after healing.	Figure 22. Close-up facial view of the final restoration that was placed after healing and based on the immediately placed provisional.

CLOSING COMMENTS
Technological advancements such as in-office CAD/CAM systems and digital radiography allow clinicians to provide patients with highly aesthetic implant restorations with greater predictability in less time. These technologies also facilitate healing and placement processes by eliminating unnecessary or disadvantageous steps in restorative procedures, as well as reducing the number of appointments, all of which greatly benefit patients.

References

1. Liddelow G, Klineberg I. Patient-related risk factors for implant therapy. A critique of pertinent literature. Aust Dent J. 2011;56:417-426.
2. Abrahamsson I, Berglundh T, Lindhe J. The mucosal barrier following abutment dis/reconnection. An experimental study in dogs. J Clin Periodontol. 1997;24:568-572.
3. Degidi M, Nardi D, Piattelli A. One abutment at one time: non-removal of an immediate abutment and its effect on bone healing around subcrestal tapered implants. Clin Oral Implants Res. 2011;22:1303-1307.
4. Canullo L, Bignozzi I, Cocchetto R, et al. Immediate positioning of a definitive abutment versus repeated abutment replacements in post-extractive implants: 3-year follow-up of a randomised multicentre clinical trial. Eur J Oral Implantol. 2010;3:285-296.
5. Khoury F, Happe A. Soft tissue management in oral implantology: a review of surgical techniques for shaping an esthetic and functional peri-implant soft tissue structure. Quintessence Int. 2000;31:483-499.
6. Wilson TG Jr. The positive relationship between excess cement and peri-implant disease: a prospective clinical endoscopic study. J Periodontol. 2009;80:1388-1392.
7. Santosa RE, Martin W, Morton D. Effects of a cementing technique in addition to luting agent on the uniaxial retention force of a single-tooth implant-supported restoration: an in vitro study. Int J Oral Maxillofac Implants. 2010;25:1145-1152.
8. IPS e.max CAD abutments among new innovations from Ivoclar Vivadent. Compend Contin Educ Dent. 2014;35:128.
9. Fasbinder DJ, Dennison JB, Heys D, et al. A clinical evaluation of chairside lithium disilicate CAD/CAM crowns: a two-year report. J Am Dent Assoc. 2010;141(suppl 2):10S-14S.

Dr. Agarwal, a 1999 graduate of University of Missouri-Kansas City, maintains a full-time private practice emphasizing aesthetic restorative and implant dentistry in Raleigh, NC. His work and practice has been featured in numerous consumer and dental publications. He has completed extensive continuing education with many dental leaders and regularly presents to study clubs and dental organizations nationally. Through his real-world approach to dentistry, practice enhancement, and balancing life, Dr. Agarwal has motivated dentists and energized team members to increase productivity and profitability. He can be reached via email at the address dra@raleighdentalarts.com or via the website raleighdentalarts.com.

Disclosure: Dr. Agarwal reports no disclosures.