'Lamina External Graft Overlay': The Use of Segmented Xenogenic Bone Sheets in the Reconstruction of 3D Bone Defects.

Guided bone regeneration (GBR) has represented a challenge for clinicians in the past 30 years, and the literature has well described many different surgical options such as d-PTFE membranes, titanium grids, or autogenous bone harvested from the posterior mandible. All of the previously mentioned techniques have shown a high rate of complications but, in the last decade, a new membrane made of xenogenic bone was introduced. Most of the publications regarding its application report very few and mild complications. In this article we will suggest a new application using segmented xenogenic bone sheets instead of autogenous bone to correct severe ridge deformity. Background and Objectives: Xenogenic bone sheets have been studied extensively over the past decade and have proven effective, with a very low rate of complications when used to reconstruct bone atrophies. The technique presented in this paper aims to reduce morbidity, avoid the need for intra-oral graft harvesting, and minimize both surgical time and post-operative discomfort. Materials and Methods: Xenogenic bone sheets of equine origin were used to reconstruct severe 3D bone defects in five patients requiring dental implants. The segmentation of the sheet allowed the operator to rebuild the missing bone walls and achieve optimal anatomy without compromise. Furthermore, using different sizes and thicknesses of the bone sheets allowed safe procedures preventing early exposure of the membranes. CBCT of the defects before and after 8 months of healing were measured with Exocad software to assess the volumetric gain. Histological analysis performed on one site showed integration of the bone lamina and live bone underneath. Results: In all five cases evaluated the ridge deformities were successfully corrected and all patients' implants have functioned for more than two years to date. The average horizontal bone gain in these five cases was 6.18 mm (±1.19 mm) while the vertical gain was 9.70 mm (±2.39 mm). Conclusions: This new application of flex cortical sheets simplifies the surgical procedure for both operator and patient, reduces morbidity and post-operative complications, and shows promising signs for resolving complex 3D bone reconstructions.