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research I I 25implants4_2013 cells,demonstratedwelldifferentiatedcapillaryvascu- larization was numerous in all NanoBone group speci- mens(Fig.4),whileitwasfeworabsentintheFisiograft group specimens. There was no evidence of acute or chronic inflammatory infiltrate in all sections of NanoBone group. Inflammatory cell infiltration within thenewbone,primarilymononuclearcellssuchaslym- phocytes and macrophages, was seen in all samples of theFisiograftgroup(Fig.5).Theinflammatorycellswere considered indicative of a significant inflammatory or immune response. Histologically, NanoBone granules exhibited adequate vascularization and high biocom- patibilitycomparabletoFisiograftbone,asindicatedby the fact that in NanoBone groups, signs of angiogene- sis and large vessels and cells could be observed in the centerofthetissue(Fig.4),whileFisiograftbonewasin- vadedbysmallvesselsandcells(Fig.5). _Discussion Bone substitutes act as space maintainers by pro- vidingascaffoldthatallowsthemtocolonizebybone- promoting cells and to replace by newly formed bone.2 One of the major challenges in the application of bone substitutesisadequatevascularisationandbiocompat- ibility3 and rapid vascularisation of the block graft is paramount for successful neo-osteogenesis.4 Our his- tological results showed that NanoBone architecture allows better vascularisation (Fig. 4), as well as coloni- sationofthebonegraftbythehostprogenitorcellsand promotestheosteoconductivepropertiesofthemate- rial. On the other hand, the Fisiograft samples showed lessvascularisation(smallvesselsandcells,Figs.5&6). Our histological results showed furthermore that in- flammatory cells infiltration within the new bone, pri- marily mononuclear cells such as lymphocytes and macrophages, was seen in all samples of Fisiograft group (Fig. 6). The inflammatory cells considered in- dicative of a significant inflammatory or immune re- sponse.Thisfindingisnotconsistentwiththefindingof Scaranoetal.,whostatedthatFisiograftisfreefromin- flammation effect.5 Our histological results showed that,intheNanoBonegroupspecimens,theNanoBone graft remnants were few and at the periphery of the specimens, ongoing resorption and surrounded by os- teoclasts.ThisisconsistentwithHeinemannetal.,who postulate that nanocristalline HA has osteoconductive and biomimetic properties and is integrated into the host’s physiological bone turn over at a very early stage.6,7 AnditisalsoconsistentwithCannoloetal.,who proposedthatthenewlyformedboneinNanoBonewas alreadyfoundatthreemonthsofhealingandnewtra- becularbonewasfoundatsixmonthsofhealing.8,9 Dur- ingimplantplacement,thequalityofgraftedbonewas evaluated clinically, especially during drilling and im- plant placement. In all NanoBone group patients, the grafted bone was firm and strongly in contact to the naturalbone(Fig.8).Copiousbleedingoccurredduring drillinginthegraftedbone(Fig.9).Thisisconsistentwith thehistologicalresultswhichshowedbettervasculari- sation, as well as colonisation of the bone graft by the host progenitor cells and promotes the osteoconduc- tive properties. We also noticed that, during crestal in- cision and flap reflection, it was difficult to dissect the mucosa over the augmented NanoBone block and we used a scalpel to dissect it. We refer that to an absence of the periosteum that covers the grafted NanoBone block. On the other hand, in Fisiograft group patients, thegraftedbonehadnostringcontacttonaturalbone andlittlebleedingoccuredduringdrillinginthegrafted site. _Conclusions NanoBone block (NanoBone, ARTOSS) showed fasterboneformation,bettervascularisation,aswellas colonisation of the bone and less inflammatory cells, while Fisiograft showed less vascularisation and nu- merous inflammatory cells. NanoBone graft degraded earlierthanFisiograft._ Fig. 9a–c_Showing copious bleeding during drilling in NanoBone graft six months after augmentation. Dr Omar Soliman PhD candidate Perioimplant dentistry Tel.:+20 1009634358, +20 1201005457 Omar.Soliman77@yahoo.com Prof.Dr Dr Mohamed Nassar Professor of Perioimplant dentistry Faculty of Dentistry,Tanta University,Egypt. Tel.:+20 1121522221 Prof_Nassar@yahoo.com _contact implants Fig. 9a Fig. 9b Fig. 9c