implants - international magazine of oral implantology International Edition

research I osteoblastscanbesomewhatmotileviatheprocessof endocytosisalongascaffoldlikefibrin. Theprocessofendocytosisismerelythetransferof cell membrane from the retreating edge of the cell, through the cytoplasm as a vesicle, to the advancing edge to reform a cell membrane and thus increase the cellularsurfaceareaattheadvancingedge.Thismech- anism slowly advances the cell and allows it to secrete itsproductintheprocess.Inthiscase,theproductisos- teoidonthefibrinnetwork.Thiscellularregenerationis often referred as phase 1 bone regeneration or woven bone phase. By the time it is nearly complete (4 to 6 weeks), sufficient osteoid production and mineraliza- tion have occurred to permit graft function. At this stage, the bone has formed without going through a chondroblasticphaseandhistologicallyappearsasran- dom cellular bone that a pathologist would refer to as wovenbone. Phase2:Boneregeneration1 The cellular bone regeneration that has occurred in phase1producesthisdisorganizedwovenbonethatis structurally sound but not the degree of mature bone. The random organization and hypercellular nature of this bone is similar to that seen in fracture callus. This bone will undergo an obligatory resorption and re- placementtypeofremodeling.Eventually,itisreplaced by phase 2 bones, which is less cellular, more mineral- izedandstructurallymoreorganizedintolamellarbone. Thereplacementofphase1byphase2bone(woven bone by lamellar bone), like all bone remodelling, is ini- tiatedbyosteoclast.Osteoclastsarefusedmonocellular cells that arrive at the graft site through the newly de- Figs. 2a–d_X400, H&E stained section showing new bone formation. Fig. 2a Fig. 2b Fig. 2c Fig. 2d 4,0 x 5,0mm 4,5 x 6,0mm 5,0 x 5,0mm 6,0 x 5,7mm 6,0 x 5,0mm 5,0 x 6,0mm www.bicon.de.com Since 1985 5,0 x 6,0mm 6,0 x 8,0mm 5,0 x 6,0mm 5,0 x 5,0mm 6,0 x 5,7mm 4,5 x 6,0mm 5,0 x 5,0mm 4,5 x 6,0mm 5,0 x 5,0mm 5,0 x 6,0mm 6,0 x 5,7mm 14 Years 6,0 x 5,7mm 14 Years 0 x 5,4 mm0,5 e 1985Sinc Simple»e 1985 .dte Lporun EociB 1.rtstpuaH reubnehcueB19455 ner nyamreG 56)0(94+enohP 34 002818 mo.cnoic@byanmreg m om.cde.oncib.www AD