Interventions for replacing missing teeth: dental implants in zygomatic bone for the rehabilitation of the severely deficient edentulous maxilla.

BACKGROUND: Dental implants are used for replacing missing teeth. Placing dental implants is limited by the presence of adequate bone volume permitting their anchorage. Several bone augmentation procedures have been developed to solve this problem. Zygomatic implants are long screw-shaped implants developed as a partial or complete alternative to bone augmentation procedures for the severely atrophic maxilla. One to three zygomatic implants can be inserted through the posterior alveolar crest and maxillary sinus to engage the body of the zygomatic bone. A couple of conventional dental implants are also needed in the frontal region of the maxilla to stabilize the prosthesis. The potential main advantages of zygomatic implants could be that in some situations bone grafting may not be needed and a fixed denture could be fitted sooner. Another specific indication for using zygomatic implants could be the need of maxillary reconstruction after maxillectomy in cancer patients.
OBJECTIVES: To test the hypothesis of no difference in outcomes between zygomatic implants with and without bone augmenting procedures in comparison with conventional dental implants in augmented bone for severely resorbed maxillae. SEARCH STRATEGY: We searched the Cochrane Oral Health Group's Trial Register, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE. We handsearched several dental journals. No language restrictions were applied. Personal contacts and all known zygomatic implant manufacturers were contacted to identify unpublished trials. Most recent search: May 2005. SELECTION CRITERIA: Randomised controlled clinical trials (RCTs) including patients with severely resorbed maxillae who could not be rehabilitated with conventional dental implants, treated with zygomatic implants with and without bone grafts versus patients treated with conventional dental implants in conjunction with bone augmentation procedures having a follow up of at least 1 year. Outcome measures considered were: prosthesis and implant failures, side effects, patient satisfaction and cost effectiveness. DATA COLLECTION AND ANALYSIS: Screening of eligible studies, assessment of the methodological quality of trials and data extraction were to be conducted in duplicate and independently by two authors. Results were to be expressed as random-effects models using weighted mean differences for continuous outcomes and risk ratio for dichotomous outcomes with 95% confidence interval. Heterogeneity was to be investigated including both clinical and methodological factors. MAIN
RESULTS: No RCTs or controlled clinical trials (CCTs) were identified. AUTHORS'
CONCLUSIONS: There is the need for RCTs in this area to assess whether zygomatic implants offer some advantages over alternative bone augmentation techniques for treating atrophic maxillae.