Osteotome sinus floor elevation using Choukroun's platelet-rich fibrin as grafting material: A 1-year prospective pilot study with microthreaded implants

Objectives. The aim of this prospective study was to document, radiographically, changes in the apical bone levels on microthreaded implants placed in subsinus residual bone height, according to a bone-added osteotome sinus floor elevation technique with platelet-rich fibrin (PRF) as grafting material. Study design. Implants were placed using PRF as grafting material in the bone-added osteotome sinus floor elevation (BAOSFE) technique. The survival rate at abutment tightening (6 to 12 weeks of healing) and at 1 year was calculated. The radiographic analysis determined on consecutive radiographs: 1) the mean residual bone height (RBH) under the maxillary sinus at implant placement; and 2) the change in endosinus bone level. Mean and standard deviation were used to assess the endosinus bone changes in the mesial and distal implant sides at 1 year. Results. Between December 2004 and June 2005, 20 consecutive patients were included in the study after bone height measurement by periapical radiographs. Patients included 14 women (70%) and 6 men (30%) with a mean age of 54.8 +/- 11.1 years, range 35 to 73 years; they were treated with 35 Astra Tech implants (Astra Tech Dental Implant System; Astra Tech, Molndal, Sweden) fulfilling the inclusion criteria. The mean healing time before abutment tightening was 8.3 +/- 1.4 weeks (range 6-12 weeks); by this time, 1 implant was mobile and was removed. At 1 year, all implants were clinically stable and the definitive prostheses were in function, resulting in a survival rate of 97.1%. Nineteen implants (55%) were 11 mm long, 6 implants (17%) were 9 mm, 5 implants (14%) were 8 mm, and 5 implants (14%) were 13 mm. The RBH was measured after implant placement on the radiographs on both implant sides. The mean RBH was 6.5 +/- 1.7 mm: 6.3 +/- 1.3 on the mesial side and 6.7 +/- 2.0 mm on the distal side. Measurements of the changes in the endosinus level on the mesial and distal sides showed that all implants gained endosinus bone. The mean endosinus gain was 3.2 +/- 1.5 mm: 3.5 +/- 1.4 mm on the mesial side and 2.9 +/- 1.6 mm on the distal side. The lowest bone gain was 0.9 mm and 0.1 mm on the mesial and distal sides, respectively. The highest gain was 5.8 mm and 5.2 mm on the mesial and distal sides, respectively. Conclusions. The BAOSFE procedure with PRF as grafting material can lead to an endosinus bone gain. Despite a limited RBH, a healing period of 2-3 months was found to be sufficient to resist a torque of 25 N.cm applied during abutment tightening. At 1 year, formation of a new recognizable bone structure delimiting the sinus floor was identified radiologically and led to a predictable implant function.