Direct Implant Loading in the Edentulous Maxilla Using a Bone Density–Adapted Surgical Protocol and Primary Implant Stability Criteria for Inclusion

Abstract

Long healing periods and submerged implant placement are commonly used in the maxilla. This extends the time of oral handicap and makes the use of immediate loading protocols an attractive option. The current clinical literature on direct loading of dental implants in the maxilla is limited. The purpose of this prospective clinical study was to evaluate the clinical outcome and stability of directly loaded Brånemark System or Replace Select Tapered implants (Nobel Biocare AB, Göteborg, Sweden) after using a modified surgical protocol and inclusion by primary implant stability. In addition, a reference group treated according to a two-stage protocol was used for comparison. Twenty patients planned for prosthetic rehabilitation with implant-supported bridges in the edentulous maxilla participated in the study group. The final decision on immediate loading was made after implant placement using insertion torque and resonance frequency analysis (RFA) as acceptance criteria. All patients were included, and 123 oxidized implants (TiUnite, Nobel Biocare AB) were placed using a surgical protocol for enhanced primary stability. A screw-retained temporary bridge was delivered within 12 hours and a final bridge within 3 months of implant placement. The patients were monitored through clinical and radiographic follow-up examinations from implant placement to at least 12 months. Marginal bone level was measured at bridge delivery and after 12 months of loading. Additional RFA measurements were made after 6 months of loading. A reference group comprising 20 patients with 120 implants treated according to a two-stage protocol was used for comparison. One (0.8%) of the 123 implants in the study group failed, and no implant was lost in the reference group. The cumulative survival rates after 12 months of loading were thus 99.2% and 100% for immediate and delayed loading protocols, respectively. The marginal bone resorption was 0.78 (SD 0.9) in the study group and 0.91 (SD 1.04) in the reference group. RFA showed a mean value of 62.9 (SD 4.9) implant stability quotient (ISQ) at placement and 64.5 (SD 4.8) ISQ after 6 months for immediately loaded implants (not significant). The corresponding figures for the reference groups were 61.3 (SD 8.8) ISQ and 62.6 (SD 7.0) ISQ (not significant). There were no statistically significant differences between the groups at any time point. The use of six to seven implants for immediate loading of a fixed provisional bridge is a viable option for implant treatment of the edentulous maxilla, at least when good primary implant stability can be ensured.