Safety and performance of a novel collagenated xenogeneic bone block for lateral alveolar crest augmentation for staged implant placement.

OBJECTIVES: To evaluate the performance and safety of placing a collagenated xenogeneic bone block (CXBB) graft for the lateral bone augmentation of the alveolar crest prior to implant placement. MATERIAL & METHODS: In patients with single or multiple tooth gaps and a severe horizontal collapse of the alveolar ridge, a ridge augmentation procedure was performed using CXBB fixated with osteosynthesis screws to the atrophic bone crest and complemented with deproteinized bovine bone mineral particles (DBBM) and a native bilayer collagen membrane (NBCM). Patients were examined with CBCT prior to and 24 weeks after the augmentation. Twenty-six weeks postoperatively, a re-entry procedure was performed to evaluate the bone width and availability for adequate implant placement. RESULTS: Fifteen patients received 28 CXBB, and in 13 patients, a re-entry procedure was performed. Eleven patients (84.6%) gained enough bone volume for implant insertion without additional contouring or secondary bone augmentation. The mean crest width at baseline was 2.83 mm (SD 0.57), and the mean crest width at re-entry was 6.90 mm (SD 1.22), with a mean ridge width increase of 4.12 mm (SD 1.32). Soft tissue dehiscence occurred during the follow-up in 5 of 14 patients (35.7%) at various time points. In addition, there was a high incidence of early implant loss (30.8% [patient-based]). CONCLUSIONS: CXBB achieved significant horizontal crestal width gains allowing a secondary implant placement in the majority of the patients. However, the occurrence of soft tissue dehiscence may notably affect the outcome of the subsequent implant therapy.

Histomorphometric and immunohistochemical evaluation of collagen containing xenogeneic bone blocks used for lateral bone augmentation in staged implant placement.

BACKGROUND: The osteoconductive properties of collagen containing xenogeneic bone blocks (CCXBB) remain unclear. The aim of this prospective single-arm clinical study was to assess the histological outcomes of CCXBB blocks used as bone replacement grafts for lateral bone augmentation procedures. METHODS: In 15 patients with severe horizontal alveolar ridge resorption, lateral augmentation procedures were performed using CCXBB as bone replacement grafts. Twenty-six weeks postoperatively, a re-entry procedure was performed to evaluate the bone width for adequate implant placement and two histological specimens were retrieved from each patient, one being processed for ground sectioning and the other for decalcified paraffin-included sections. In non-decalcified sections, the relative proportions occupied by bone, biomaterials, and connective tissue present in the biopsies were identified. In de-calcified sections, structures and cells positive for osteopontin (OPN), tartrate-resistant acid phosphatase activity (TRAP), osteocalcin (OSC), and alkaline phosphatase (ALP) were assessed. RESULTS: Soft tissue dehiscence occurred during the follow-up in 5 out of 15 patients (33.3%). The mean crest width at baseline was 2.78 mm (SD 0.57) and the mean crest width at re-entry was 6.90 mm (SD 1.22), with a mean ridge width increase of 4.12 mm (SD 1.32). Twenty-six bone biopsies were obtained from 13 patients. Histomorphometric analysis showed a mean of 26.90% (SD 12.21) of mineralized vital bone (MVB), 21.37% (SD 7.36) of residual CCXBB, 47.13% (SD 19.15) of non-mineralized tissue, and 0.92% of DBBM. The immunohistochemical analysis revealed a large number of OPN-positive cells 8.12% (SD 4.73), a lower proportion of TRAP positive multinuclear cells 5.09% (SD 4.91), OSC-positive cells 4.09% (SD 4.34), and a limited amount of ALP positive cells 1.63% (SD 2). CONCLUSIONS: CCXBB achieved significant horizontal crestal width allowing for staged implant placement in most of the patients. In light of the histological outcomes and implant failures, special attention must be placed to prevent soft tissue dehiscence when CCXBB is used in severe atrophic alveolar crests.