Horizontal bone grafting using equine-derived cancellous bone blocks is associated with severe complications: A prospective clinical and histological pilot study

Aims The aim of this prospective, clinical study was to evaluate the clinical performance and histological outcome of a new equine hydroxyapatite collagenated bone block (eHAC) for horizontal bone grafting prior to implant placement. Materials and Methods Five patients (two male/three female) with a mean age of 51.6 years (range 22-66 years) and a reduced horizontal bone width of the alveolar ridge (mean 3.5 mm) underwent horizontal bone grafting using eHAC at 10 grafting sites. Reentry was performed 6.9 months after the horizontal grafting procedure. Clinical follow-up (mean 28.9 month) considered width gain of the alveolar ridge, soft tissue healing, and complications. To evaluate graft incorporation, four additional patients underwent histological assessment of equine blocks adjacent to autologous blocks 3 and 6 months after grafting. Results The study was terminated after graft failure was observed in four of five patients. Mean horizontal bone width had increased by 3.6 +/- 1.22 mm. Three out of nine implants placed had to be removed due to graft failure. Histological evaluation revealed large amounts of soft connective tissue within the grafts (mean 67.3 +/- 9.5%). The proportion of new bone formation 3 months after the lateral grafting procedure revealed an average of 8.6%, compared to 11.4% after 6 to 7 months. Conclusion Lateral ridge grafting using eHAC achieved measurable horizontal width gain but revealed high rates of severe complications. Clinical Implications Within the limitations of this study, eHAC bone blocks cannot be recommended for horizontal bone grafting.