Do collagen membranes with different thickness-related mechanical properties affect the outcomes of lateral bone augmentation? An immunohistochemical analysis.

OBJECTIVES

This study evaluated immunohistochemical profiles associated with guided bone regeneration (GBR) using collagen membranes with different thickness-related mechanical properties to characterize membrane-related biological responses during lateral bone augmentation.

METHODS

Standardized mandibular defects in beagle dogs were grafted with bone substitutes and covered with one of two collagen membranes with different thickness-related mechanical properties or left uncovered. At 8 and 16 weeks, tissues were analyzed for markers associated with osteogenesis (ALP), vascular/perivascular and myofibroblast-associated responses (α-SMA), inflammation-related cell profiles (iNOS and CD206), and bone remodeling (TRAP, Cathepsin K, and collagen type I).

RESULTS

At 8 weeks, the FM group showed a trend toward higher numbers of CD206-positive cells in the coronal region. iNOS-positive cells did not differ significantly among groups in any region. However, most macrophage-related outcomes were not statistically significant. The SM group exhibited significantly greater collagen type I deposition, particularly in deeper regions, although this appeared to represent early unmineralized matrix rather than enhanced bone formation. TRAP-positive cells were more frequently observed in membrane-covered groups at both time points, mainly around biomaterials, suggesting remodeling-related activity. ALP, α-SMA, and Cathepsin K showed no significant intergroup differences. At 16 weeks, most immunohistochemical differences had diminished across all groups.

CONCLUSIONS

Collagen membranes with different thickness-related mechanical properties were associated with distinct early tissue responses during GBR healing. The FM group showed trends toward increased CD206-positive cells, whereas the SM group exhibited greater early collagen type I deposition. Because most inflammation-related outcomes were not statistically significant, these findings should be interpreted cautiously and considered exploratory.