Histomorphometric evaluation of an immediately loaded implant retrieved from human mandible after 2 years

The aim of the present study was to evaluate the interplay between microstructure and function of the bone around an immediately loaded implant retrieved from human maxilla after 23 months due to fracture. A spiral implant of 3.3 mm x 15 mm was placed in a male 53 years old in the anterior region of the mandible bone (4.1) and it was processed for histology. The specimen was analyzed under the confocal scanning laser microscope (CSLM) and brightfield light microscope (LM) equipped with circularly polarized light (CPL). The BIC rate was 76.7± 4.9 (mean ±SD). Many cement lines indicates an high remodeling rate of the bone. The transverse collagen fiber orientation (CFO) (mean ±SD) under the lower flank of the thread near the tread tip was 55.2 ± 4.8 x 104 pixel while the longitudinal CFO was 45.8 ± 2.3 x 104 pixel (P<.05). In the inter-threads region the transverse CFO (mean ±SD) was 36.4 ± 2.4 x 104 pixel while the longitudinal CFO was 65.6 ± 6.5 x 104 pixel (P<.05). The osteocytes numbers (mean ±SD) was 205 ± 45 in the peri-implant bone and 144 ± 53 in the native bone (P=.007). After 2-years of loading the SLA spiral implant was well osseointegrated but still surrounded by woven bone. The osteocytes density was significantly higher in the peri-implant bone than in the native bone. The transverse collagen fibers were significantly associated with the lower flank of the implant threads, while the longitudinal collagen fibers were more represented in the straight surface of the implant. The implant fracture was correlated to crestal bone resorbing and subsequent fatigue yielding.