Bone regeneration using an equine cortical membrane: a retrospective study

OBJECTIVES Implant-supported prosthetic rehabilitation in the aesthetic area requires an adequate reconstruction of hard and soft tissues. This reconstruction can be achieved by means of the guided bone regeneration (GBR) technique, which involves the positioning of a membrane between the soft tissues and the osteoconducting graft, which in turns is placed on the receiving site. The membrane acts as a mechanical barrier between the cells that will regenerate the bone tissue and those that will repair the gingival tissues. It aims to protect bone defects and to prevent the alveolar site from being invaded by connective tissue. Moreover, it stabilizes the graft and prevents micro-movements that could hinder the process of bone regeneration. In the past, some authors have successfully used homologous bone membranes made of thin, partially demineralized bone plates. Despite positive clinical results, their use was discontinued, possibly because of their homologous origin and the consequent availability issues and high costs associated. The authors of this article have been using since a long time a similar membrane, but with equine origin, which currently still lacks a significant body of evidence. To partially close this knowledge gap, the present study reports the outcome of a retrospective midterm analysis regarding the use of this type of membrane in implant positioning interventions and the associated guided bone regeneration. MATERIALS AND METHODS Clinical records of patients to whom at least one implant was in-serted concurrently with a guided bone regeneration intervention were selected. Implant success was assessed by means of the criteria defined by Albrektsson and Zarb. When available, histological and tomographic (CBCT) data were also qualitatively analyzed. RESULTS 17 patients aged between 36 and 67 years (average 53.7 +/- 9.2) were selected, for a total of 24 implants placed.The average followup was 38.1 +/- 3.7 months. Two implants failed, for an implant success rate of 87.5%. 7 membrane samples were histologically analyzed at an average time after surgery of 4.3 +/- 1.2 months: all the portions considered were still occlusive. Six CBCT scans showed the formation of a cortical bone layer in the graft area. CONCLUSIONS Cortical equine membranes appear to possess a long persistence and barrier effect, and to undergo remodeling in the medium term, hence allowing the formation of a cortical tissue layer similar to that physiologically present in the alveolar process. CLINICAL SIGNIFICANCE When treating few-wall, large bone defects according to a Guided Bone Regeneration (GBR) approach, the oral surgeon - expecting a slow regeneration kinetic might want to use the membrane described in the present study, given its long permanence and barrier-effect.