Early implant loading in the atrophic posterior maxilla: 1-stage lateral versus crestal sinus lift and 8 mm hydroxyapatite-coated implants. A 5-year randomised controlled trial.

PURPOSE: To evaluate the efficacy of long implants (10-16 mm) inserted in maxillary sinuses augmented according to a lateral approach versus short (8 mm) implants placed in crestally augmented sinuses, early loaded after 45 days.

MATERIALS AND METHODS: Forty partially or fully edentulous patients having 3 to 6 mm of residual crestal height and at least 4 mm in thickness below the maxillary sinuses were randomised according to a parallel group design to receive either one to three 10 to 16 mm-long hydroxyapatite-coated implants (20 patients) after lateral sinus lifting with 50% an organic bovine (Bio-Oss) and 50% autogenous bone, or 8 mm implants (20 patients) after crestal sinus lifting with autogenous bone. Implants were submerged and left healing for 45 days before loading the implants. Within 1 week after abutment connection, implants were loaded with screw-retained full acrylic provisional prostheses. Definitive metal-ceramic prostheses were provisionally cemented 45 days after abutment connection. Outcome measures were prosthesis and implant failures, any complications, and radiographic periimplant marginal bone level changes. In addition, the stability of individual implants was assessed with Osstell and Periotest at abutment connection (baseline), and at 1 and 5 years after loading by blinded outcome assessors. All patients were followed up to 5 years after loading.

RESULTS: One patient dropped out (death) from the longer implant group. One implant failed in the short implant group versus 5 implants in 3 patients of the longer implant group. The difference was not statistically significant. Four complications occurred in 4 patients of the short implant group versus 8 complications in 7 patients of the long implant group, the difference being not statistically significantly different. However, the 2 major postoperative complications occurred in the longer implant group: 1 abscess, and 1 sinusitis that led to the complete failure of the treatment in 2 patients (4 implants lost). A total of 0.72 mm of peri-implant marginal bone was lost after 5 years at long implants and 0.41 mm at short implants, the difference between the two groups was statistically significant (P = 0.028). Osstell values increased and Periotest decreased over time and there were no differences between groups at any time points.

CONCLUSIONS: In atrophic maxillary sinuses with a residual bone height of 3 to 6 mm, 8 mm short implants placed in a simultaneously crestally lifted sinus might be a preferable choice than a 1-stage lateral sinus lift for placing longer implants since they appear to be associated with less morbidity. If these implants are placed with an insertion torque >35 Ncm and are joined together under the same prosthesis, they can be early loaded at 6 weeks.