implants - international magazine of oral implantology

I research _Introduction Alveolar bone first forms when the Hertwig’s root sheath develops from the tooth germ. The alveolar bone does not form in the absence of primary or sec- ondary tooth development. The close relationship be- tween the tooth and the alveolar process continues throughoutlife.Wolff’sLaw(1892)statesthatbonere- modelsinrelationtotheforcesapplied.Everytimethe functionoftheboneismodified,adefinitechangeoc- curs in the internal architecture and external configu- ration. Bone needs stimulation to maintain its form and density. Roberts et al.1 report that a 4% strain to the skeletal system maintains bone and helps balance re- sorption and formation. When a tooth is lost, the lack ofstimulationtotheresidualbonecausesadecreasein trabeculaeandbonedensityinthearea,withlossinex- ternalwidthandheightofthebonevolume,andeven- tually leads to atrophic edentulous ridges. A primary reasontoconsiderdentalimplantsforreplacingmiss- ingteethisthemaintenanceofalveolarbone.Adental implant placed into the bone serves both as an anchor for the prosthetic device and as a means of preventive maintenance in dentistry. When stress and strain are appliedtothebonesurroundingtheimplant,thebone trabeculation decrease after tooth extraction is re- versed.Thereisanincreaseinbonetrabeculaeandden- sity once the dental implant has been placed and is functional.Inaddition,thedentalimplanthelpsmain- taintheoverallvolumeofthebone.2 Ridge augmentation is designed to widen ridges prior to implant placement. Various grafting proce- dures have been utilised for grafting an edentulous ridge, including an allograft, autogenous graft or xenograftwithorwithoutatitaniumreinforcedmem- brane, ridge splits, distraction osteogenesis, and onlay grafting with an autogenous or allograft bone block. Traditionally, onlay ridge augmentation has entailed the use of an autogenous graft from a separate intra- oral surgical area such as the ramus, chin or posterior ridge, or from extra-oral sites such as the tibia, iliac crest or ribs.3 The need for a second surgical site could beeliminatedwereagraftmaterialsuchasanallograft boneblockorNanoBoneblockbeshowntoprovidead- equate volume and quality of new bone in atrophic sites. Tissue engineering is an interdisciplinary field that applies the principles of engineering and life sci- encestothedevelopmentofbiologicalsubstitutesthat can replace, restore, or improve tissue function.4 One tissue-engineeringapproachistheuseof3-Dscaffolds toprovideasuitableenvironmentfortissueformation. Ideal scaffolds act as a guide supporting cell growth anddifferentiationandutilisethedepositionofregen- eratedtissue.5 Inbone-tissueengineering,thescaffold should be biocompatible, osteoconductive and os- teoinductive. The scaffold allows cells to attach and proliferate and to form an extracellular matrix. It should have an open and interconnected pore struc- ture(withaporosityof>90%)thatallowsnutrientsto Ridge augmentation for an atrophied posterior mandible—Part I NanoBone block versus allograft bone block Authors_Dr Omar Soliman, Prof. Dr Mohamed Nassar, Ass. Prof. Dr Mahmoud Shakal & Ass. Prof. Dr Eman Mohy El-din Megahed, Egypt 20 I implants1_2013 Fig. 1bFig. 1a