The zygomatic implant placement procedure does not require any adjunctive procedures. Furthermore, the ability to immediately use existing dentures and the lack of need for bone grafting and prolonged hospitalisation makes this treatment modality more acceptable to the patient. Four cases are reported that demonstrate the successful treatment of a severely atrophic maxilla with either a fixed prosthesis supported by two zygomatic and a minimum of three standard dental implants or an over-denture supported by two zygomatic and one standard dental implant.
According to Behnam aghabeigi Birmingham placement of dental implants in the posterior maxilla is often jeopardised by the size and extension of the sinus cavities and inadequate amounts of bone. Atrophic processes can be accelerated by removable dentures as well. Surgical procedures were therefore developed to elevate the floor of the sinus and fill the hereby created cavity with bone or a substitute material, in order to subsequently install dental implants. Autogenous bone, harvested from the iliac crest, remains the optimum bone grafting procedure including maxillary sinus augmentation techniques. In view of the extreme maxillary atrophy, the conventional surgical approach would have been maxillary augmentation with or without a titanium mesh and particulate cancellous bone marrow graft from the iliac bone. Another option could have been a Le Fort osteotomy with an interpositional iliac corticocancellous block graft.
Extraoral bone harvesting necessitates increased hospitalisation, financial costs, donor site morbidity and functional limitations. Moreover, there is up to 8.6%5 risk of complications following iliac crest bone graft harvesting. Even higher morbidity rates6 including pain (14%) and neurosensory deficits (26%) have been reported lately. Finally, unpredictable reduction in size of the bone graft, because of resorption, is a frequent finding.
The acceptance of this approach is low by both patients and clinicians due to the following reasons:
1. The psychological fear of being subjected to a relatively major surgical procedure
2. The need for hospitalisation and morbidity associated with a distant donor site, particularly the restricted mobility associated with an iliac bone graft
3. Inability to use the existing denture during the graft healing period. This precaution is intended to minimise graft resorption by eliminating transmission of occlusal loads to the grafted site during the healing phase
4. Increased costs of the procedure including the cost of hospital stay, use of in-patient operating facilities and a second surgical team for the bone harvest
5. Extended treatment time with delayed implant placement four to six months following the grafting procedure.
Simultaneous placement of dental implants at the time of bone grafting is avoided due to a lower success rate than delayed placement.
An alternative treatment for this group of patients is the zygomaticus implant, introduced by Branemark. The implant is a titanium endosteal implant ranging in length from 30 mm to 52.5 mm. The surgical procedure is carried out under general anaesthesia as described elsewhere.9 Briefly, following bilateral elevation of the buccal mucoperiosteal tissue, removal of the lateral sinus bony window posteriorly and reflection of the antral mucosal lining, two zygomatic implants are inserted engaging the dense bone of the body of zygomatic arch, emerging intraorally in the upper premolar region just palatal to the alveolar crest. Each implant is introduced into the second premolar area, traversing the maxillary sinus, and is placed into the body of the zygomatic bone.
Synchronous placement of a minimum of four dental implants in the canine and the central incisor maxillary area, allows for fabrication of fixed hybrid prosthesis. Alternatively, placement of two zygomatic implants and at least two standard dental implants at the pyriform buttresses allows construction of a bar to support a maxillary overdenture without the need for any bone grafting. In case more root form dental implants can be placed in the pre-maxilla a fixed prosthesis could be fabricated.
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