The combination of bovine bone matrix with collagen shows good results in bone and volume preservation after tooth extraction. To determine the ideal time to apply an implant after augmentation with Bio-Oss Collagen and to observe if there are differences in the age of the patients and the sex, the aim of this randomized controlled clinical trial was to compare the post-extraction changes in angiogenic and osteogenic aspects during spontaneous bone regeneration with those during socket preservation using Bio-Oss Collagen. Sixty-six patients were included in this study. After 8-12 weeks, bone biopsies were embedded in paraffin and histological and immune-histological investigated. Using qRT-PCR bone (Alpl, Bglap, Runx2) and angiogenic markers (VEGF, caveolin-1) were identified. The histomorphometric analysis of all examined samples showed no differences between treated and untreated sockets, but a tissue compression. After classification in bone regeneration stages, more samples with woven bone were present in treated sockets than in controls. The Alpl expression correlates with increase in mature bone tissue. In treated sockets a significant decrease in CD34 and caveolin-1 protein expression was found. Additionally, a significant increase of Runx2 and VEGF mRNA was detected in patients younger than 50 years. Thus, all specimens showed ossification in different stages after eight weeks of healing. The treated group gives an earlier stage of ossification than controls, but produces densified tissue with greater volume fraction. It can be assumed that successful implant placement in Bio-Oss Collagen augmented extraction sockets is possible after eight weeks of bone healing.
Keywords: Bone augmentation; Graft material; Histomorphometry; qRT-PCR.
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