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Cementable Full-Arch BruxZir® Bridge Over Custom Abutments

Cementable Full-Arch BruxZir® Bridge Over Custom Abutments

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by Ara Nazarian, DDS, DICOI

Due to advancements in prosthetic materials, treatment protocols, digital dentistry and CAD/CAM technology, fully edentulous patients now have a wide range of restorative options when they make the life-changing decision to undergo dental implant therapy. From removable overdentures to fixed full-arch restorations, today’s implant practitioners have the clinical flexibility to provide effective treatment for virtually any case, whatever the oral health, anatomical characteristics and finances of the patient.

For patients who are indicated for such treatment, a fixed restoration affords the highest level of prosthetic stability, function, and comfort.1 Traditionally, this has been prescribed in the form of the screw-retained acrylic hybrid denture. In recent years, however, the monolithic zirconia full-arch implant prosthesis has been surging in popularity. This type of restoration permanently attaches to the implants in the manner of the screw-retained hybrid denture, but has been finding favor among practitioners due to the long-term durability of BruxZir® Solid Zirconia.

For patients who present with sufficient bone volume, the cementable full-arch BruxZir bridge over custom abutments offers another excellent option. Unlike screw-retained full-arch restorations, this type of prosthesis does not typically include gingival areas and is essentially a collection of crowns spanning the length of the edentulous arch. The result is a fixed bridge that emerges from the soft tissue in a manner that looks and feels like natural teeth. Because CAD-designed custom abutments are used, the gingival margins and prosthetic positioning established contribute to an exceptionally lifelike restoration.

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Figures 1a–1c: The concept of the cementable full-arch BruxZir bridge over custom abutments is inspired by the full-arch restoration over natural tooth abutments illustrated in this case.

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Figures 1a–1c: The concept of the cementable full-arch BruxZir bridge over custom abutments is inspired by the full-arch restoration over natural tooth abutments illustrated in this case.

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Figures 1a–1c: The concept of the cementable full-arch BruxZir bridge over custom abutments is inspired by the full-arch restoration over natural tooth abutments illustrated in this case.

The result is a fixed bridge that emerges from the soft tissue in a manner that looks and feels like natural teeth.

This approach takes the concept of a traditional full-arch monolithic zirconia bridge over natural tooth abutments and applies it to fully edentulous patients (Figs. 1a–1c). In addition to the wax setup process common to other full-arch implant prostheses, the restorative protocol includes a try-in bridge that grants the clinician and patient a preview of the proposed restoration, as well as an opportunity to make any needed adjustments before the final prosthesis is milled. These cases typically qualify for large case protocol pricing, meaning that the entire restoration, including custom abutments and the final bridge, can be provided at a cost comparable to that of the screw-retained BruxZir Full-Arch Implant Prosthesis.

Because the bridge is fabricated from monolithic zirconia, there is an unrivaled level of durability, freeing the patient and practitioner from concerns of wear, chipping and fractures. Yet despite the strength of BruxZir Solid Zirconia, the material is biocompatible and wear-friendly to opposing dentition, making it an optimal choice whether opposed by natural teeth or a dental prosthesis.2 Note that the restoration can be a roundhouse prosthesis or broken down into short-span bridges.

The following outlines the basic parameters for the diagnostic, surgical and restorative phases of treatment for the cementable full-arch BruxZir bridge over Inclusive® Custom Abutments. Various cases will illustrate the means through which a predictable outcome is achieved, providing patients with a highly esthetic restoration that is sure to stand the test of time.

Initial Consultation and Diagnosis

When a patient presents with an edentulous arch or non-restorable dentition as a result of severe caries, periodontal disease or other dental conditions, the patient has a full range of treatment options, from the traditional denture, to the implant overdenture, to the fixed full-arch restoration. In the author’s experience, most patients will elect for implant treatment once they are apprised of the benefits, including prevention of bone loss, superior function, preservation of facial esthetics, and a higher quality of life.3-5 Further, fixed full-arch restorations afford the highest rates of patient satisfaction, and explaining this information can help obtain acceptance of such treatment despite the higher cost.1

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Figures 2a–2d: A comparison of a cementable full-arch BruxZir restoration (2a, 2b) and a screw-retained BruxZir Full-Arch Implant Prosthesis (2c, 2d) illustrates the contrast in prosthetic width and height, making the cement-retained version an excellent option for patients with plenty of bone and soft tissue.

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Figures 2a–2d: A comparison of a cementable full-arch BruxZir restoration (2a, 2b) and a screw-retained BruxZir Full-Arch Implant Prosthesis (2c, 2d) illustrates the contrast in prosthetic width and height, making the cement-retained version an excellent option for patients with plenty of bone and soft tissue.

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Figures 2a–2d: A comparison of a cementable full-arch BruxZir restoration (2a, 2b) and a screw-retained BruxZir Full-Arch Implant Prosthesis (2c, 2d) illustrates the contrast in prosthetic width and height, making the cement-retained version an excellent option for patients with plenty of bone and soft tissue.

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Figures 2a–2d: A comparison of a cementable full-arch BruxZir restoration (2a, 2b) and a screw-retained BruxZir Full-Arch Implant Prosthesis (2c, 2d) illustrates the contrast in prosthetic width and height, making the cement-retained version an excellent option for patients with plenty of bone and soft tissue.

Like most full-arch implant restorations, determining whether the cementable full-arch BruxZir bridge is indicated for an individual case depends upon the patient’s anatomy, bone quality and quantity, and oral health. Because this type of prosthesis has less width and height than a screw-retained full-arch restoration, it is an appealing option for patients who have ample bone volume and soft tissue, and thus do not require gingival areas in the final prosthesis to establish proper esthetics (Figs. 2a–2d).

In terms of Dr. Carl Misch’s classifications of fixed prosthetics, the cementable full-arch BruxZir bridge is indicated for FP1 (Fixed-Prosthesis-1) cases, in which the patient’s anatomy allows for a restoration that emerges directly from the soft tissue like natural teeth.6 It is also indicated for FP2 cases, in which the prosthetic teeth are designed slightly longer, but are not in the esthetic zone and thus do not require the addition of gingival areas to the prosthesis.

Although this prosthesis type is indicated in limited FP3 situations, in which pink gingival areas are needed to recreate soft tissue, a screw-retained option such as the BruxZir Full-Arch Implant Prosthesis is typically a more suitable solution. Also, if the bone of the edentulous ridge necessitates placement of the implants significantly toward the lingual, screw-retention is required in many cases, as it can be extremely difficult under such circumstances to place the implants in proper alignment with the incisal edges of the restoration, which is required for a cementable bridge.

Thus, the cementable full-arch BruxZir bridge is most commonly indicated for patients who present with non-restorable dentition, have been without their natural dentition for a limited time, or previously received implants relatively shortly after the loss of their teeth (Figs. 3a, 3b). These patients usually have a quantity of bone and soft tissue that is well-suited to a cementable full-arch restoration, particularly in cases of immediate extraction and implant placement. This solution can also be an excellent option for heavy bruxers or grinders, who are especially prone to breaking acrylic appliances and thus stand to benefit from the long-term durability inherent to monolithic zirconia (Figs. 4a–4d).

Treatment Protocol

Prior to surgical intervention, a records appointment is recommended in which upper and lower impressions and a bite registration are taken. These can be used to produce diagnostic models that aid the treatment planning process, as well as any interim dentures or provisional restorations needed for the healing phase. This appointment also affords the opportunity to have patient consent forms completed in advance of treatment.

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Figures 5a, 5b: The implants were placed immediately following teeth extraction in this case, preserving the buccal plate, bone volume and soft tissue.

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Figures 5a, 5b: The implants were placed immediately following teeth extraction in this case, preserving the buccal plate, bone volume and soft tissue.

At the surgical appointment, a minimum of six implants should be placed to support the full-arch prosthesis, as there should be no more than two pontics between each custom abutment. When there is sufficient bone volume, it can be advantageous to place eight or more implants in order to distribute the occlusal load as evenly as possible around the arch. In full-arch extraction cases, placing implants immediately following teeth removal can help facilitate patient acceptance of treatment, as it reduces the total number of surgical appointments (Figs. 5a, 5b). Further, this approach facilitates excellent bone healing and remodeling.7

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Figures 6a, 6b: Examples of maxillary and mandibular BioTemps provisionals, which help establish esthetic soft-tissue margins while serving as a functional appliance for the patient during the healing or restorative phases of treatment.

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Figures 6a, 6b: Examples of maxillary and mandibular BioTemps provisionals, which help establish esthetic soft-tissue margins while serving as a functional appliance for the patient during the healing or restorative phases of treatment.

Once the implants have been placed, an immediate denture can be delivered by performing a soft reline and seating the appliance over the healing abutments. When indicated by sufficient primary implant stability, provisionalization with a full-arch BioTemps® prosthesis (Glidewell Laboratories; Newport Beach, Calif.) affords many benefits, including a patient “test drive” of the prosthesis and training of the soft-tissue contours and margins, which enhances the emergence profile of the eventual restoration (Figs. 6a, 6b). This temporary bridge can be provided on the day of surgery or after some healing has occurred, and appeals to patients because it provides them with a fixed prosthesis in advance of the final restoration.

Following a healing period of approximately three to five months, the patient returns for the restorative phase of treatment. The patient’s appliance is removed and the health of the soft tissue and osseointegration of the implants are assessed (Fig. 7). After verifying sufficient tissue healing and implant stability, transfer posts are seated, and a closed- or open-tray final impression is taken of the edentulous arch (Fig. 8). An opposing impression and a bite registration are also taken, as well as an impression of the patient’s existing appliance. The case is submitted with a completed Rx and any special instructions for the restoration. At the clinician’s discretion, diagnostic models or photos can be sent along with the final impression to clarify the requested prosthetic design.

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Figure 7: Example of healthy soft tissue four months after implant placement. In this case, a total of eight implants were placed freehand into fresh extraction sites, facilitating tissue preservation that would maximize the esthetics of the restoration.

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Figure 8: Open-tray final impression being taken for a cementable BruxZir bridge. The master cast produced from this impression would be used in the production of the wax rim, setup and try-in bridge.

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Figure 9: Although cementable full-arch BruxZir bridges do not typically include gingival areas, the lab produces a wax rim and setup to ensure proper esthetics, function, jaw relations and occlusion.

Even though this is a cementable restoration over custom abutments, wax rims and setups are required in order to ensure accurate jaw relations, vertical dimension, tooth arrangement, occlusion and other design considerations crucial to an accurate restoration. From the final impressions, the lab fabricates master models, which are first utilized to create the wax rim needed to record the jaw relationship (Fig. 9).

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Figure 10: After obtaining the jaw relation records, a bite registration is taken with the wax rim in place.

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Figure 11: The lab produces a wax setup that is used to ensure proper esthetics, function, jaw relations, tooth arrangement and occlusion.

At the next appointment, the wax rim is attached to the implants through temporary cylinders, and jaw relation records are obtained using standard denture technique. Once the vertical dimension of occlusion (VDO) and centric relationship have been determined, a bite registration is taken (Fig. 10). The lab then produces a wax setup, which is tried in to verify the jaw relationship, occlusion, esthetics and function (Fig. 11). Following approval of the setup, the case is returned to the lab, and the prosthetic designs for the custom abutments and cementable full-arch BruxZir bridge are determined.

First, the lab scans the master model, approved wax setup and articulated models to generate the data needed for the digital design. Using dental CAD software, the custom abutments are designed on the virtual model in tandem with the cementable full-arch BruxZir bridge (Figs. 12a–12d). This precise design process ensures that the custom abutments support both the soft tissue and the prosthesis in the most esthetic manner possible. The custom abutments are milled from the digital design file and seated on the master model to verify the fit (Fig. 13). Then, the lab fabricates a try-in bridge so the prosthetic design can be confirmed before the final restoration is milled from monolithic zirconia. Note that, as requested, the lab can produce a duplicate of the try-in appliance from BioTemps material, which can be worn by the patient for an interim to verify the esthetics and function in real life situations.

Next, the patient returns for try-in of the custom abutments and verification of the prosthetic design via the try-in bridge. After removing the patient’s healing abutments or provisional appliance, the custom abutments are seated using the lab-provided acrylic delivery jigs (Figs. 14a–14c). Next, the try-in bridge is seated over the custom abutments and evaluated to confirm the shape, size, emergence profile, midline, incisal edges, contours, gingival margins, occlusion and esthetics.

Any necessary adjustments are made directly to the try-in bridge, which ultimately serves as a blueprint for the final BruxZir restoration. If the occlusion, VDO or midline requires adjustment, a new bite registration is taken so the lab can ensure a well-fitting final restoration. When adjustments are needed, the try-in bridge is returned to the lab, and the modifications are implemented into the digital design prior to fabrication of the final restoration (Figs. 15a–15d). In cases where no adjustments are needed, the lab can simply produce the final restoration from the CAD design file used to fabricate the try-in bridge.

As requested, the lab can produce a duplicate of the try-in appliance from BioTemps material, which can be worn by the patient for an interim to verify the esthetics and function in real life situations.

At the final delivery appointment, the custom abutments are again tightened into place, with radiography used to confirm complete seating. Then, the final full-arch BruxZir prosthesis is seated over the custom abutments and checked for proper fit, occlusion and esthetics. Adjustments at this point are uncommon and are typically minor, as the prosthetic design has already been verified and fine-tuned through the wax-setup process and try-in bridge (Figs. 16a, 16b). Lastly, the prosthesis is cemented over the custom abutments, with care taken to remove any cement residue. For clinicians concerned about retrievability, the final BruxZir bridge can be attached using a strong temporary adhesive such as Retrieve™ implant cement (Parkell, Inc.; Edgewood, N.Y.).

Conclusion

The cementable full-arch BruxZir bridge over custom abutments affords implant practitioners yet another prosthetic option in the treatment of the fully edentulous. When patients present with sufficient bone volume, a prosthesis can be delivered that closely resembles natural dentition, with a monolithic construction that ensures long-term durability (Figs. 17a, 17b). The restorative workflow is straightforward, with several layers of verification that help ensure a predictable outcome.

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Figures 17a, 17b: The combination of custom abutments and BruxZir Solid Zirconia produces a restoration with a natural emergence profile and exceptional long-term durability.

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Figures 17a, 17b: The combination of custom abutments and BruxZir Solid Zirconia produces a restoration with a natural emergence profile and exceptional long-term durability.

References

  1. Brennan M, Houston F, O’Sullivan M, O’Connell B. Patient satisfaction and oral health-related quality of life outcomes of implant overdentures and fixed complete dentures. Int J Oral Maxillofac Implants. 2010 Jul-Aug;25(4):791-800.
  2. Clinicians Report. Jun 2014;7(6).
  3. Kordatzis K, Wright PS, Meijer HJ. Posterior mandibular residual ridge resorption in patients with conventional dentures and implant overdentures. Int J Oral Maxillofac Implants. 2003 May-Jun;18(3):447-52.
  4. Covani U, Cornelini R, Calvo JL, Tonelli P, Barone A. Bone remodeling around implants placed in fresh extraction sockets. Int J Periodontics Restorative Dent. 2010 Dec;30(6):601-7.
  5. Harris D, Höfer S, O’Boyle CA, Sheridan S, Marley J, Benington IC, Clifford T, Houston F, O’Connell B. A comparison of implant-retained mandibular overdentures and conventional dentures on quality of life in edentulous patients: a randomized, prospective, within-subject controlled clinical trial. Clin Oral Implants Res. 2013 Jan;24(1):96-103.
  6. Misch CE. Contemporary implant dentistry. 3rd ed. St. Louis: Mosby; 2007.
  7. Peñarrocha-Diago MA, Maestre-Ferrín L, Demarchi CL, Peñarrocha-Oltra D, Peñarrocha-Diago M. Immediate versus nonimmediate placement of implants for full-arch fixed restorations: a preliminary study. J Oral Maxillofac Surg. 2011 Jan;69(1):154-9.
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