16: Case Presentations

CHAPTER 16 Case Presentations

Quad Zygoma

Preliminary Presentation

Complete maxillary alveolar resorption results in lack of bony volume in zones I, II, and III. Retention of a removable prosthesis is not possible with the remaining maxillary basal bone. When the maxillary alveolus is completely resorbed, clinical examination reveals a flat palatal vault and absence of a maxillary vestibule. Patients are unable to function with their conventional complete dentures. Such patients present with a significantly thick denture base and a thick circumferential flange, confirming the presence of horizontal and vertical composite defects. Physiologic reconstruction of this group of debilitated patients requires adequate implant support to stabilize an implant-supported prosthesis. To enable prosthetic rehabilitation of such patients, Brånemark introduced the idea of using extensive onlay bone grafts in conjunction with bilateral sinus inlay grafts for placement of six implants. The Brånemark “horseshoe” graft requires hospitalization and harvesting of autogenous iliac bone from the patient. During the 6-month osseointegration period, the patient is unable to wear his or her denture, which is generally not well-received by patients. An alternative graftless approach uses four zygomatic implants. The placement of two zygomatic implants in each zygoma allows for fabrication of an implant-supported fixed maxillary prosthesis without bone grafting and can be accomplished in an office setting.

The implants are placed in a “stacked” manner, with the superior implant emerging at the cuspid position and the inferior implant emerging in the bicuspid position (Figures 16-1 and 16-2).

The preoperative panoramic radiograph demonstrates a lack of maxillary alveolar bone in all three zones. The surgical protocol for implant placement is very similar to the single zygoma implant protocol, with the exception that care must be taken to identify the most inferior lateral corner of the infraorbital rim. This reference is used while preparing the superior osteotomy to avoid penetration into the bony orbit. The implants are stabilized at 40 Ncm or greater. The two-stage protocol is followed by securing cover screws and submerging the implants for the 6-month osseointegration period (Figures 16-3 to 16-6).

During stage II surgery, 6 months after implant placement, osseointegration is confirmed and multiunit abutments are placed. The full denture is converted into a provisional fixed bridge using the same immediate-loading conversion protocol.

The completed fixed provisional is secured to the multiunit abutments and the patient’s occlusion is checked for bilateral group function. Radiographs taken after stage II surgery confirm complete seating of all components (Figures 16-7 to 16-9).

The soft tissues are allowed to heal for a period of 6 to 8 weeks prior to initiation of the fabrication steps for the final profile prosthesis (Figures 16-10 to 16-12).

Jan 7, 2015 | Posted by in Implantology | Comments Off on 16: Case Presentations
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