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. However, the possibility of placing dental implants is limited by the presence of adequate bone volume permitting their anchorage. Several bone grafting procedures have been developed to solve this problem. The missing bone can be taken from a donor site, transplanted where needed and then implants are placed. Major bone grafting operations have to be undertaken under general anaesthesia and patients have to be hospitalized for a few days. Some degree of morbidity related to the donor site must be expected and two to three surgical interventions are needed before the implants can be functionally used. Often patients have to wait more than 1 year before a denture can be fixed to the implants and the total cost of the treatment is high. However, the major problem is that about 25% of the implants placed in grafted bone fail. Zygomatic implants are long screw-shaped implants developed as an alternative to bone grafting. Zygomatic implants are inserted into the body of the zygomatic bone. Their main advantages are that bone grafting may not be needed and patients may be fitted with a fixed denture much sooner.

OBJECTIVES

To test the hypothesis of no difference in outcomes between zygomatic implants 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 Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE. We handsearched several dental journals. No language restrictions were applied. Personal contacts and manufacturers of dental implants were contacted to identify unpublished trials. Most recent search: February 2003.

SELECTION CRITERIA

Randomised controlled clinical trials (RCTs) on patients with severely resorbed maxillae who could not be rehabilitated with conventional dental implants, treated with zygomatic implants without bone grafts versus conventional dental implants with bone grafts or other procedures for bone augmentation with 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 the trials and data extraction were to be conducted in duplicate and independently by two reviewers. Results were to be expressed as random effects models using weighted mean differences for continuous outcomes and relative risk 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.

REVIEWER'S CONCLUSIONS: There is an urgent need for RCTs in this area, since zygomatic implants, if found to be at least as effective as other augmentation procedures, may involve major advantages for both patients and society.