Comparison of autogenous and allograft bone rings in surgically created vertical bone defects around implants in a sheep model.

Abstract

The aim of this study was to compare autogenous and allograft bone rings in surgically created vertical bone defects. Four male, 1-year-old sheep were used in this study. In each sheep, eight vertical bone defects 7mm in diameter were created using trephine drill in the iliac wing. Autogenous and allograft bone rings 5mm in height and 7mm in diameter were used for vertical augmentation around implants. The study consisted of four groups according to the bone ring type and amount of vertical augmentation, autogenous 2mm, allograft 2mm, autogenous 4mm, and allograft 4mm. Two of the animals were sacrificed after 4months, and the remaining two animals were sacrificed after 8months. Undecalcified sections were prepared from harvested samples. Histological assessment and histomorphometric analysis were performed. Autogenous 2mm group showed higher values than allograft 2mm group, and autogenous 4mm group showed higher values than allograft 4mm group in terms of bone area and bone-to-implant contact (BIC) after 4months. However, allograft 2mm group showed higher bone area and BIC values than autogenous 2mm group after 8months. Also, autogenous 4mm and allograft 4mm groups showed comparable results after 8months. Allograft 2mm and allograft 4mm groups showed higher bone area and BIC values at 8months compared with 4months. Allograft bone ring looks promising in augmentation of surgically created vertical bone defects around implants after 8months of healing.