Surgical Procedures
Placement of four NDIs (1.8 mm x 14 mm) (ANEW®, Dentatus, www.dentatus.com) guided by a CAD/CAM surgical template (iGuide, Midwest Dental Arts, www.midwestdentalarts.com) was performed without flap elevation (Figure 4 and Figure 5). A single 1.4-mm pilot drill (CePo®, Dentatus) was used to prepare the osteotomy under copious irrigation at 1000 RPMs. The four NDIs were subsequently inserted at low speed (30 RPM) in position Nos. 7 through 9 and 12 (Figure 6 and Figure 7). Primary stability was tested with a torque driver and found to be sufficient for immediately loading the implants. Following placement of the NDIs, the patient’s provisional restoration was connected chairside.
The design of the ANEW implants allowed fabrication of a screw-retained fixed restoration that was retrievable. Four openings were drilled in the patient’s acrylic prosthesis to ensure proper fit. A coping was attached to each of the four NDIs and secured in place with a screw cap. This coping assembly was then processed into the partial restoration using a self-curing acrylic resin (Bosworth TrueRepair®, Keystone Industries, www.keystoneindustries.com). The access holes for the screws were blocked with cotton pellets and sealed with off-color resin for easy re-access (Figure 8).
The bone augmentation procedure was performed 2 months following implant placement. The patient was given a prescription of amoxicillin 2000 mg 1 hour prior to surgery. Because of the large dimension of the horizontal defect, both allogeneic bone block grafts and autogenous bone blocks, harvested from the right ascending mandibular ramus, were used. Crestal and intrasulcular incisions were made in the regions of teeth Nos. 6 through 15 around all teeth and NDIs. The autogenous bone block was sectioned in two pieces and shaped to eliminate sharp corners. After decortication, the two segments were fixated using two screws (OsteoMed, www.osteomed.com) in the region of missing teeth Nos. 7 through 10. The allogeneic bone block, which was also shaped, was fixated after decortication with two screws on the buccal aspect of missing teeth Nos. 10 through 12. The spaces were filled with particulate allogeneic graft (Puros Cancellous Particulate Allograft®, Zimmer Dental, www.zimmerdental.com) to obtain a homogenous surface (Figure 9). The grafted area was covered with two resorbable collagen membranes (Bio-Gide®, Geistlich Pharma, www.geistlich-pharma.com) that were stabilized with five tacks (truFIX, ACE Surgical, www.acesurgical.com) (Figure 10). A periosteal releasing incision was made to achieve tension-free closure using resorbable sutures (Coated Vicryl® 4.0, Ethicon, www.ethicon.com). To prevent transmucosal pressure on the tissues, which may have interfered with the healing process and the integration of the bone grafts, the buccal flange of the provisional was trimmed (Figure 11). Following surgery, amoxicillin 500 mg TID for 10 days and chlorhexidine 0.12% mouthrinse (Peridex™, 3M ESPE, www.3MESPE.com) BID for 2 weeks were prescribed. The healing process was uneventful.
Five months later, the block grafts appeared well integrated, and no signs of inflammation or bone resorption were noted. Two of the four NDIs (Nos. 7 and 12) were retained as planned and supported the provisional, while the other two (Nos. 8 and 9) were removed and replaced with three standard-diameter implants (3.5 mm x 13 mm) (Zimmer Dental) in sites Nos. 8, 9, and 11. Healing abutments were connected to these three implants (Figure 12). Due to a partial resorption of the allogeneic block graft, implant No. 11 was placed slightly more apical than Nos. 8 and 9, and a guided bone regeneration procedure was performed simultaneously using particulate allogeneic graft (Puros Cancellous Particulate Allograft) and a resorbable collagen membrane (Bio-Gide). The flap was sutured with absorbable 4-0 chromic gut sutures (Ethicon). The augmented area was submerged while implants Nos. 8 and 9 and their healing abutments were left exposed (Figure 13). The provisional was relined with TrueRepair to close the access holes through which NDIs Nos. 8 and 9 had been connected to the restoration and to cover the two non-submerged healing abutments. At this stage, the provisional remained connected and supported only by two NDIs (Nos. 7 and 12).
Four months later, a new provisional, supported by all five implants, was delivered (Figure 14). Once the healing of the soft tissues was completed, the final impression was taken and the final restoration was delivered (Figure 15).
Follow-up
Eleven years later, the patient, who lived in London, returned to the New York University periodontology and implant dentistry department for follow-up. Radiographic evaluation demonstrated complete implant integration with no bone resorption around either the standard-diameter implants or the NDIs (Figure 16). One of the titanium tacks that secured the membrane had remained above the No. 7 NDI. Because the tack was well tolerated with no hard- or soft-tissue pathology, it was allowed to remain in place. Clinically, no signs of soft-tissue inflammation were noted (Figure 17 and Figure 18), and the patient reported complete satisfaction with the function and esthetics of his fixed restoration.
Discussion
Implant treatment in an extremely atrophic maxilla is challenging for clinicians and requires careful evaluation, planning, and execution to achieve long-term success and fully satisfy the patient’s expectations. The surgeon, restorative dentist, and laboratory technician must work in collaboration to achieve the desired outcome.
In the present case, the patient’s desire was to replace his removable partial denture with a fixed restoration. Oftentimes, patients do not tolerate removable prostheses well, especially when the tooth loss was sudden and caused by trauma or hopeless teeth need to be removed. Furthermore, when augmentation procedures are necessary, regardless of the final restorative options, protecting the grafted area and maintaining graft immobilization are essential to achieve success.14 Using a fixed provisional restoration is usually preferable, but many times this entails preparing healthy teeth to function as abutments. Another option is to immediately load the implants; however, this risks complications and failure when implants are placed in augmented sites.
