Reconstruction of the Posterior Maxilla Following Total Loss of Crestal Bone Support
Sascha A. Jovanovic, DDS, MS
A 45-year-old white male patient presented with an
edentulous posterior left maxilla (Figure 1). The patient was a nonsmoker and
in good health. The medical history of the patient did not demonstrate any
contraindications but revealed that he had undergone questionable extraction of
the maxillary left premolars, molars, and all supporting alveolar
substructures. As a result of this treatment, the patient exhibited an exposed
sinus cavity, covered only by the mucoperiosteal flap. No prospect for
satisfactory prosthetic rehabilitation was evident.
The patient desired the fabrication of a fixed prosthesis
that would restore posterior function, aesthetics, and health. The treatment
plan mandated diagnostic evaluation that included radiographs, models, and
laboratory waxups. The surgical and restorative plans required the staging of
the clinical procedures. The initial phase necessitated a surgical
reconstruction of the posterior maxilla with a bone graft. The placement of
implants was scheduled for the second surgical phase. The third phase of the
treatment included the exposure of the implant fixtures, soft tissue
management, and the initiation of the restorative procedures.
In the initial phase of the clinical procedure, full
mucoperiosteal flaps were elevated, revealing the crestal opening in the sinus
cavity. The Schneiderian membrane was also elevated (Figure 2). A resorbable
membrane was placed onto the Schneiderian epithelium to prevent trauma during
the placement of the bone graft (Figure 3). A monocortical bone block was
harvested from the patient’s symphysis. In addition, a particulate autogenous
bone graft and 2 cc of demineralized freeze-dried bone (DFDB) (500 µm to 1000
µm), were utilized as bone grafting materials. The bone grafts were placed in
layers into the sinus cavity. The DFDB mixture was placed into the remote
regions of the sinus cavity where no implant placement was planned. The
particulate autogenous bone was placed into the anticipated implant sites, and
the monocortical bone block was wedged into the crestal bone defect (Figure 4).
The complete grafted site was covered with a nonresorbable expanded
polytetrafluoroethylene membrane to allow for stabilization of the blood clot
around the bone graft, to prevent resorption of the bone graft, and prevent
soft tissue cells from invading the site (Figure 5).
Following an uneventful healing period of 8 months (Figure 6), the site was reopened and the membrane was removed. Once full-thickness
buccal flap elevation and membrane removal were accomplished, complete
incorporation of the bone graft was noted and the closure of the crestal bone
defect was observed (Figure 7). Radiographic analysis revealed sufficient bone
height and density to support 3 titanium standard screw type dental implants of
13-mm length. The implants were placed, utilizing a modified surgical procedure
that included the use of a smaller (2.85 mm) twist drill, no tapping of the
bone site, and a 3.75-mm standard titanium implant (Figure 8). While the
quality of the bone density was determined to be type III to IV, adequate
implant stability was achieved (> 20 N/cm).
Following a 6-month uneventful healing period, abutment
connection surgery was planned. A periapical radiograph taken at the conclusion
of the healing period indicated good bone density, maintenance of crestal bone
level, and no radiolucencies around the implant fixtures (Figure 9). A
split-thickness flap was elevated toward the buccal aspect to increase the
quantity of keratinized attached tissue surrounding the implants (Figure 10).
The healing abutments were connected, and the soft tissue was permitted to heal
undisturbed for 2 months.
Following the completion of soft tissue maturation, attached
keratinized tissue was observed surrounding the 3 implants (Figure 11), and the
restorative phase was initiated. Once implant impression taking, bite
registration, and abutment selection was completed, three individual copings
were fabricated and placed onto the implants (Figure 12). A metal
superstructure was subsequently fabricated and fitted and adjusted to the
individual copings intraorally (Figure 13). The one-piece metal substructure
was subsequently finished with porcelain and cemented to the individual copings
(Figure 14). No screw access holes were evident on the occlusal aspect, and the
definitive restoration demonstrated an optimal emergence profile and
satisfactory aesthetic and functional results (Figure 15).
The prosthesis was in function for 1 year, at which time the
patient was recalled for follow-up evaluation. Periapical radiographs
demonstrated the restoration of the posterior maxilla and normal density of the
bone surrounding the implants and in the sinus cavity (Figure 16).
Implant placement may be performed in challenging intraoral
sites. In treatment sites (eg, the posterior mandible) that do not demonstrate
suitable hard and soft tissue support for implant placement, the clinician may
augment the existing tissue with bone grafts, guided bone regeneration, soft
tissue management, or a combination of these treatment modalities. In addition,
moderate bone quality requires a modified implant surgical procedure to enhance
implant stability. These procedures offer a technique-sensitive, yet
efficacious, means of restoring tissue for suitable implant restoration. When
the clinician adheres to clinical parameters based on biological principles
such as a sufficient blood supply, selective proliferation of cells, and
appropriate bone graft and barrier membrane, and an uneventful healing period,
these restorative treatments may be utilized to effectively rehabilitate
partially and fully edentulous patients.
Have a case study of your own? Submit it to us!