SHORT IMPLANTS VERSUS BONE AUGMENTATION AND LONGER IMPLANTS IN ATROPHIC MAXILLAE. FIVE-YEAR POST-LOADING RESULTS OF A RANDOMISED CONTROLLED TRIAL

PURPOSE. To evaluate whether short (5 to 8.5 mm) dental implants could be a suitable alternative to longer (at least 11.5 mm long) implants for supporting dental prostheses placed in atrophic fully edentulous maxillae augmented with autogenous bone.

MATERIALS AND METHODS. Twenty-eight patients with fully edentulous atrophic maxillae having 5 to 9 mm of residual crestal bone height at least 5 mm thick, as measured on CT scans, were randomised into two groups, either to receive four to eight short (5 to 8.5 mm) implants (15 patients) or autogenous bone from the iliac crest to allow the placement of at least 11.5 mm-long implants (13 patients). Both bone blocks and windows at lifted maxillary sinuses were covered with rigid resorbable barriers. Grafts were left to heal for 4 months before placing implants, which were submerged. After 4 months, provisional reinforced acrylic prostheses or bar-retained overdentures were delivered. Provisional prostheses were replaced after 4 months by definitive screw-retained metal-resin cross-arch restorations. Outcome measures were: augmentation, prosthesis or implant failures, any complications, peri-implant marginal bone level changes, and patient satisfaction. Patients were followed-up until 5 years after loading.

RESULTS. All patients could be rehabilitated with implant-supported prostheses, but four patients dropped-out from the augmentation group and three from the short implant group. One bilateral sinus lift procedure failed due to infection, though short implants could be placed. Four implants failed in four patients from the augmentation group versus three short implants in three patients (Fisher’s exact test P = 0.6500; difference in proportions = -0.17; 95% CI -0.51 to 0.21). No prosthesis failed. Significantly more complications occurred in augmented patients: 12 complications occurred in nine augmented patients versus one complication in the short implant group (Fisher’s exact test P = 0.0003; difference in proportions = -0.82; 95% CI -0.97 to -0.41). Periapical radiographs of only four patients were readable, so no bone level could be measured at 5 years after loading. With the exception of three patients from the augmentation group, who were only partially satisfied with function, all remaining patients were fully satisfied with the treatment (P = 0.0957); all would have the treatment again.

CONCLUSIONS. This study showed that in patients with fully edentulous atrophic maxillae, short implants can be a preferable alternative to longer implants placed in bone augmented with autogenous bone, the treatment being less invasive, cheaper, faster and associated with fewer complications.