Long-term clinical, microbiological and radiographic outcomes of Brånemark™ implants installed in augmented maxillary bone for fixed full-arch rehabilitation

Purpose: To document the long-term outcome of Brånemark implants installed in augmented maxillary bone and to identify parameters which are associated with peri-implant bone level. Material and methods: Patients of a periodontal practice who had been referred to a maxillofacial surgeon for iliac crest bone grafting in the atrophic maxilla were retrospectively recruited. Five months following grafting they received 7 to 8 turned Brånemark implants. Following submerged healing of another 5 months, implants were uncovered and restorative procedures for fixed rehabilitation were initiated 2 to 3 months thereafter. The primary outcome variable was bone level defined as the distance from the implant-abutment interface to the first visible bone-to-implant contact. Secondary outcome variables included plaque index, bleeding index, probing depth and levels of 40 species in subgingival plaque samples as identified by means of checkerboard DNA-DNA hybridization. Results: Nine out of 16 patients (8 females, 1 male; mean age 59) with 71 implants agreed to come in for evaluation after on average 9 years (SD 4; range 3 – 13) of function. One implant was deemed mobile at the time of inspection. Clinical conditions were acceptable with 11 % of the implants showing pockets ≥ 5 mm. Periodontopathogens were frequently and in high numbers encountered. Clinical parameters and bacterial levels were highly patient-dependent. The mean bone level was 2.30 mm (SD 1.53; range 0.00 – 6.95) with 23 % of the implants demonstrating advanced resorption (bone level > 3 mm). Regression analysis showed a significant association of the patient (p < 0.001) and plaque index (p = 0.007) with bone level. Conclusions: The long-term outcome of Brånemark implants installed in iliac crest augmented maxillary bone is acceptable, however advanced peri-implant bone loss is rather common and indicative of graft resorption. This phenomenon is patient-dependent and seems also associated with oral hygiene