A New Implant Approach by Dr. Bobby Birdi

With this new system, dentists should be able to place implant-supported restorations just weeks after placing the implants

by Dr. Bobby Birdi

The timing of implant restoration and restorative design have not changed tremendously over the past 30 years with regard to immediate implant placement cases. We have seen the advent of immediate implant placement—and even immediate provisional restorations—but clinicians still wait 12–24 weeks before feeling comfortable placing a definitive restoration to allow for predictable implant integration. This leads to patients having to wait months to get their final implant-supported restorations.

How long a clinician waits to place a definitive restoration on a recently placed dental implant is a multifactorial decision specific to each case. However, doctors have been taught that the healing of a dental implant osteotomy involves a decrease in the initial stability of the dental implant during the healing process. This is related to how an osteotomy has been prepared for decades, involving the use of burs spinning at a high RPM, under copious irrigation, cutting the bone to make the osteotomy—a process that has not changed much since the first screw-type dental implant was placed by Dr. Per-Ingvar Brånemark in 1965.

As a result, the heat generation and trauma involved in classically preparing an osteotomy causes the implant stability to “dip” during Weeks 3–5 after the implant has been placed. The implant stability then increases to the final stability level, achieving osseointegration at Week 8 or more. As a result, most clinicians elect to routinely wait three or four months after implant placement to load the implant with a definitive restoration.

However, a new innovation in osteotomy preparation, the OsseoShaper instrument from Nobel Biocare, prepares an osteotomy at a very low RPM and with no irrigation. This leads to much less heat generation in creating the osteotomy, which is thought to decrease the prevalence of an implant stability “dip” during the healing process. Furthermore, this tool leaves a vital bone coagulum in the osteotomy, which would be available to contact with the implant at the time of implant placement. As a result, clinicians may be able to predictably place definitive implant-supported restorations just weeks after surgical implant placement.

The case here showcases the Nobel Biocare N1 system (Fig. 1), which has a unique design and is packaged with an OsseoShaper instrument specific to each implant to prepare the osteotomy in the most atraumatic fashion to date.

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The patient was a long-standing patient of the clinic and had received many other successful implant-supported restorations that had been created using conventional osteotomy preparation and loading times. She was informed of the innovations available with the N1 implant system and was eager to have it used in her treatment, because she loved the idea of having her final crown placed in a much shorter time than had been involved with her other implants.

Atraumatic extraction and innovative osteotomy preparation
On the surgical date, the area was locally anesthetised and the tooth was extracted atraumatically using a flapless microsurgical approach (Figs. 5 and 6). The implant osteotomy was then initiated using an innovative OsseoDirector instrument from Nobel Biocare (Fig. 7), which allows for efficient bone cutting in both apical and horizontal directions as needed.

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A directional indicator was then placed and a periapical radiograph taken to evaluate the trajectory of the proposed implant placement (Figs. 8 and 9). Upon approval of the projected trajectory, I opened a 4-by-11-mm N1 implant package, which included an OsseoShaper tool (Figs. 10 and 11) to prepare the final custom osteotomy to receive the implant.

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The tool is run at very low rpm (40–60) with no irrigation. Like a bone-tapping tool, it is run forward until the osteotomy is prepared to the desired depth; then, it is then reversed out, leaving behind a vital bone coagulum. By drilling just once with a bur (OsseoDirector) conventionally and then using the OsseoShaper instrument to prepare the final osteotomy, repeated drilling of the bone is avoided, which helps avoid continuous bone heating and trauma.

Implant and abutment placement
A xenograft (Creos Xenogain, Nobel Biocare) mixed with high-concentration PRP was placed into the socket with a piece of leukocyte-platelet-rich fibrin. This was followed by the implant, which has an ultrahydrophilic, multizone anodized TiUltra surface and a Tri-Oval crestal conical connection, a shape that better mimics the shape of a single-rooted tooth.

The N1 implant was placed 3 mm apical and 2–3 mm palatal from the proposed gingival zenith of the desired restoration. Care was also taken to place the implant with the flat side of the Tri-Oval to the buccal aspect of the socket (Fig. 12). An initial stability of >35 Ncm was attained from the implant placement, then bone milling was completed using a specific mill for this implant system. This step removes any bone or tissue above the implant connection that would interfere with the seating of the prosthetic components.

Studies have indicated that if we can minimize the exposure of the implant connection to the oral cavity, the implant bone and tissue results will be more predictable and have less variation; thus, a “one abutment, one time” concept has been conceptualized to seal the implant/abutment connection at the time of surgical placement or Stage 2 uncovery. Because of the customization and the need for an implant-level impression to create a final restoration with a custom emergence profile, this concept has been difficult to adopt with most implant systems.

However, the N1 Base (Fig. 13) is placed into the Tri-Oval connection at the time of implant placement (or Stage 2 uncovery) and is never taken out again; the final implant restoration is fabricated to screw into this base. This allows for the implant/abutment connection to be sealed off at the time of initial exposure. In this case, a 1.75-mm-tall N1 Base with a Xeal anodized surface was placed into the implant immediately after initial implant placement, then was torqued to specifications (20 Ncm). Then all restorative work was completed to fit onto the base. (Fig. 14)

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Placement of immediate provisional restoration and final impression
After the base was placed into the implant and torqued to specifications, a screw-retained provisional crown was fabricated chairside using conventional restorative materials and a provisional abutment (Figs. 15 and 16). A closedtray impression of the base was then taken to create the future final restoration (Fig. 17). The access hole for the provisional crown was filled with PVS impression material, and a final periapical radiograph was taken (Fig. 18).

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Delivery of final screw-retained crown, plus a one-year follow-up
At a postoperative appointment two weeks after the implant placement surgery, a single suture was removed and the surgical site was evaluated. Soft-tissue healing in the area was exceptional for the two-week mark, and the patient noted almost no discomfort during the healing period (Fig. 19). The provisional crown was removed and the tissues were again inspected; great health and healing were evident (Fig. 20).

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The N1 Base was again torqued to specifications (20 NCm) to evaluate stability of the implant, and no issues were found. The final screw-retained monolithic zirconia (ZirCad Prime, Ivoclar Vivadent) was seated onto the N1 Base and torqued to specifications (20 Ncm). Occlusion, proximal contacts, contours and aesthetics were all evaluated. After all these factors were approved by the patient, the access hole of the final crown was filled with Teflon tape and flowable composite (Tetric EvoFlow, Ivoclar, Figs. 21 and 22). A final periapical radiograph (Fig. 23) was then taken.

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The stability and healing of the implant site was monitored over the next six months and then the patient was seen at a one-year follow-up, at which time another periapical radiograph and photo were taken. Bone and tissue levels were ideal, and the patient was very happy with the overall result (Figs. 24–26).

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Conclusion
Implant site preparation has been a stagnant field of implant dentistry for many years. Conventional osteotomy preparation continues to be used throughout the industry. However, this case demonstrates the benefits of an innovative, minimally invasive way to prepare an osteotomy that may lead to increased reliability and decreased variability in our results, and may greatly decrease final loading times.

Dr. Bobby Birdi earned his dental degree from the University of Saskatchewan and postgraduate specialty training in both periodontics and prosthodontics from the University of Minnesota. He is a fellow of the Royal College of Dentists of Canada, and a diplomate of both the American Board of Periodontology and the American Board of Prosthodontics. Birdi is one of the few board-certified dual specialists in periodontics and prosthodontics in North America, and the first and only specialist in the world to attain board certification in these two specialties in both the U.S. and Canada. He is the co-founder of the Digital Dentistry Institute, a global learning organization for dentists, and the founder of the BC Perio Dental Health & Implant Centres in Vancouver, one of the largest and most technologically advanced multispecialty dental centers in Canada.