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ePaper created 2014-12-05, 15:38:45 | version 1.33.01
I 19 industry report _ bonebuilder technology I cone beam4_2014 associated with pronounced and long-term neurological symptoms. _Allografts Alternatively, allogenic bone (from human donor tissue, known as an allograft) may be applied to avoid the additional risks that come with harvesting autologous bone. Due to its physiological structure, allogenic bone pro- vides an ideal matrix for revascularisation and newboneformation.Sinceitisfullyresorbable, itsupportsnaturalboneremodelling.Moreover, allografts are biocompatible and, like auto- grafts,donotinduceimmunologicalreactions.1 Histological studies of the final stages of graft incorporation identified no difference between allografts and autografts.2, 3 The allogenic bone tissue originates from living donorswhoareundergoingtotalhipreplace- ment surgery and are willing to donate their femoral heads to support the supply of bone graftmaterialformedicaluse.Donorshaveto meet high standard criteria in terms of their healthstatusinordertobeselected;systemic and neurological diseases, acute or chronic infections, and existing or past malignancies are only a few of the exclusion criteria. Everysingledonorundergoesserologicaltesting to detect the presence of virus antigens by nucleic acid testing (NAT). The donated tissue is processed in a multi-level cleaning process, which removes organiccomponentsandnon-collagenousproteins from the mineral phase of the bone. This process is also validated for its effectiveness to reliably in- activate potentially present viruses and bacteria. Theuniqueprocessingofthedonortissuepreserves the natural collagen content of the allograft bone, rendering the material with increased flexibility, simplehandling,andwithmorepotentialapplications, compared to synthetic or bovine bone substitutes. _Classical onlay block grafting The most important application for allografts is onlayblockgrafting;inthe3-Dreconstructionoflarge defects,theblockallograftensuresthenecessaryvol- umestabilityduringgraftincorporation.However,itis crucial during this initial phase of vascularisation and graft incorporation to establish the largest possible contactareabetweentheblockandthelocalbonebed. During conventional block grafting, a standard- ised square block has to be manually modified for adaptation to the surface of the local bone during the surgical procedure. to the alveolar ridge required in order to achieve stable implant positioning (patient data provided by Dr Markus Schlee, Forchheim, Germany). Figs. 7–10_Complex reconstruction of the maxillary ridge by digital backward planning— from superconstruction to customised bone blocks (patient data provided by Masoud Memari, Budapest, Hungary). Figs. 11 & 12_Digital simulation of the milling process after import of the *.stl .le in the CNC-milling machine. Fig. 10Fig. 9 Fig. 8Fig. 7 Fig. 12Fig. 11 CBE0414_18-21_Buchaeckert 28.11.14 11:36 Seite 2 CBE0414_18-21_Buchaeckert 28.11.1411:36 Seite 2