The impact of two-socket preservation approaches on the soft and hard tissue healing: a short-term study in dogs

The present study was designed in the context of the uncertain circumstances related to the best therapeutic option for ridge preservation. The research aimed to investigate the quality of early healing processes developed in the former sockets preserved with a collagen matrix alone or associated with a bone substitute in comparison with naturally-healed sockets, using an animal model previously validated. In both quadrants of the mandible of two dogs, the distal sockets of the second and fourth premolars served as experimental sites. Two sockets healed naturally, three sockets were preserved with the collagen matrix and three sockets were preserved with the collagen matrix plus a bone substitute. After one month of healing, the samples were harvested and histologically processed. The soft tissue covering the preserved ridges displayed an obviously thicker epithelial layer containing mostly areas of parakeratinized epithelium alternating with keratinized ones in comparison with naturally-healed sockets. In the apical third of the sockets, a mature bone structure was recorded for all three types of post-extraction approaches. While in naturally-healed and collagen matrix-preserved specimens the central third of the sockets contained bone with a mature aspect, in collagen matrix plus bone substitute-preserved sockets an immature appearance was observed. In the external third of the sockets, only in matrix-preserved alveoli a well-developed cancellous bone was present. The bovine bone substitute seemed to delay hard tissue development. The use of the collagen matrix could be a clinical option to preserve post-extraction ridges especially when an improvement in soft tissue quality is desired.