Contemporary Concepts in Osseointegration of Dental Implants: A Review

Table 1

Chronology of cellular and molecular events of osseointegration after implant placement.

Timeline after implant placement	Cellular/molecular event
1^st day	(i) Secretion of growth factors by water molecules and platelet absorption at the site of implant placed [15]; (ii) Nondifferentiated osteoblasts stick to the implant surface through the aid of fibronectin [16]; (iii) Migration of pluripotent mesenchymal cells along the implant surface, with their function dependent on the local oxygen tension and regulatory growth factors, which are further dependent on the position of implant and angiogenesis [17, 18]
2^ndday	(i) Local ischemia and necrosis toward the center of the implant site due to the capillary breakdown [19]; (ii) Neutrophils become the predominant cells, followed by macrophages becoming dominant, forming clots and tissue necrosis
3^rd day	(i) Activation of Runx2 and Op (osteoblast-related transcription factors) by the cells around the implant [4]
4^th day	(i) Necrotic bone resorption and the formation of some bone-implant interface [20]
5^th day	(i) Evidence of new bone formation and initiation of mineralization and matrix remodeling as indicated by the alkaline phosphatase activity [4]
7^th day	(i) Recognizable bone matrix cohesion on surface of implant [4]; (ii) Bone-to-implant contact attained is 35.8% [21]
16^th day	(i) Implant surface becomes entirely coated with mineralized tissues, osteoid, and dense matrix [20]
28^th day	(i) Complete binding of bone along the implant surface formation of a volume of tissue layer comprised of collagen fibers and osteoblasts adjacent to the implants; alignment of collagen fibers running parallel to the implant’s surface. Bone-to-implant contact of 46.3% is reached [21]; (ii) Bone regeneration: (i) Contact osteogenesis: from implant surface towards the bone (30% faster shaping of bone); as a response to the implant surface’s physicochemical properties [9, 19]; (ii) Distant osteogenesis: from the margin of bone to the surface of the implant; de nova formed bone is of woven type [9, 19]
End of the 12^th week	(i) Establishment of a mature lamellar bone connection with the titanium surface leading to uniformity of bone formed on the implant’s surface [20]