Alveolar Ridge Preservation in the Sheep Model

Abstract

Abstract

Post extraction remodelling of the alveolar ridge results in significant reduction in the width of the ridge, which may preclude the placement of dental implants. Alveolar ridge preservation (ARP) procedures have been shown to reduce these changes, and thus are desirable, especially when the buccal plate is partially missing. Bovine-derived xenografts with porcine collagen membrane (BX) are considered the “gold standard” against which novel ARP materials should be compared. Four equine collagen products developed for ARP were tested: membrane (CM), cone with/without biphasic phosphate particles (CC, CO), and cone with integrated membrane (CS).

Objectives

To compare four novel products against BX in a novel sheep mandibular extraction socket model with standardised buccal defect.

Methodology

In 11 animals, mandibular premolars were extracted and standardised 5x2 mm buccal dehiscence defects were created. The sockets were grafted (Latin-square allocation) with BX, CC, CS, CO, CO+CM or ungrafted control (CON). The animals were euthanised after 16 weeks. Socket healing, new bone formation and reduction in the alveolar ridge width were analysed in undemineralised sections.

Results

No distinctive pattern of healing was noted for any of the materials. BX particles were partially resorbed by osteoclast-like multinuclear cells. Remnants of equine collagen-based products were not observed. BX grafted sites, compared to CON, showed a threefold decrease in reduction of the alveolar ridge width (p=0.002). Width preservation achieved by equine collagen products compared to non-grafted controls was not statistically significant, however better results were observed in groups CS and CO+CM.

Conclusion

A challenging extraction socket model with buccal defects representative of a “real-life” clinical situation was created. The test materials did not preclude new bone formation and were completely resorbed during the healing period, whereas BX-grafted sites have shown only partial resorption of the graft. The test materials, unlike the “gold standard” BX, were unable to demonstrate significant width preservation, although the results suggested that barrier membranes play an important role in ARP procedures.