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ePaper created 2014-07-29, 09:08:59 | version 1.30.01
I research 10 I implants2_2014 tomorphometrical analysis was on the characterisa- tion of the cellular response to the bone-substitute material, its stability and the vascularisation of the implantation bed. Thehistologicalanalysisshowedthetriphasicbio- materialremaininginabulk-likestructurewithanin- ner core and an outer ring for up to 30 days. A wall of vessel-rich granulation tissue was formed at the tis- sue-biomaterialinterfaceontheouterwall,whichthe initial degradation seemed to originate from. The aqueoussolutionseemedtoholdthebonesubstitute materialintheinnercoreandpreventitfromearlyin- growth of connective tissue. At the end of the study periodtheinnerregionbecomesinvadedbymorede- grading cells, which penetrated towards the -TCP granules.-TCPisawell-establishedbonesubstitute material which is highly biocompatible, cellular degradability and supports osseointegration and os- teoconduction.3-6 Therefore, the analysis of the pure solid -TCP granules showed early invading of the biomaterial granules by mono- and multinucleated phagocytes,i.e.,macrophagesandgiantcellsfromthe peri-implanttissue.Itisknown,thatthesecellsareex- pressed in the foreign body response and take part in the biomaterial degradation process.8 The histomorphometric analysis of the extracted and processed samples revealed significantly higher vascularisation within the paste-like triphasic -TCP group compared to the pure -TCP group. This in- creased vascularisation started in the outer core and wasinitiatedbymultinucleatedgiantcellswithinthe implantation bed.8,9 By physicochemical changes in material charac- teristics, such as size, porosity and shape, synthetic bonesubstitutecanbeindividuallytailoredtoachieve an optimal level of inflammation and vascularisation in order to regulate bone tissue regeneration.9,39 Origin of the bone substitute material as well as production and processing parameters, such as sin- teringtemperature,playanimportantroleinmaterial stability.Hydroxyapatite(HA)isknowntobemoresta- ble than -TCP.3-5 Fast degradation results in the risk ofconnectivetissueingrowthintheimplantationbed of -TCP augmentation material, which might com- promise osteoconduction. Another approach to en- large material stability is the here presented combi- nationof-TCP,MethylcelluloseandHyaluronicacid, which leads to a divided inner and outer structure of the biomaterial and inhibits the connective tissue in- growth between the granules in the inner core. The conceptofapaste-likematerialcombinesnotonlythe advantagesofdifferentmaterialclasses,butalsosim- plifies the augmentation process by a minimally-in- vasiveinsertion.Cellulose,usedinthisstudyasaque- Fig. 5_The tissue reaction to the triphasic bone-substitute material at day 60 after implantation; a) total scan of the implant area (H&E staining, total scan, 100x magnification); b) the remaining granulation tissue, i.e., vessels (red arrows), macrophages and multinucleated giant cells (arrow heads); (Movat’s pentachrome staining, 400x magnifi- cation; scale bar = 100 µm); c) only TRAP-negative giant cells (arrow heads) were detectable at this time point (CT = connective tissue, TCP = β-TCP granules) (TRAP staining, 200x magnification; scale bar = 100 µm). Fig. 6_The immuno- and histochemical analysis of the cellular degradation of the triphasic bone-sub- stitute material; a) overview of the implantation bed at day 60. (arrows: macrophages; arrow heads: multinu- cleated giant cells; ED-1 staining, 400x magnification); b) higher magnification showing a single multinucleated giant cell (arrow heads; ED-1 staining, 600x magnifica- tion; scale bar = 100 µm); c and d) The implantation bed at day 60, in which mononucleated (arrows) and multinu- cleated giant cells (arrow heads) were involved in the cellular degradation of the β-TCP granules (black granules) (Von Kossa/Safranin-O staining); C: 200x magnification; D: 600x magnification; scale bar = 100 µm). Fig. 7_The tissue reaction to the -TCP granules used in the control group; a) implantation bed at day 10. (arrows: tissue ingrowth covering approximately half the area of the implantation bed; H&E staining, total scan, 100x magnification); b) implantation bed at day 15. (asterisks: granulation tissue divided by bridges of connective tissue; H&E staining, total scan, 100x magnification); c) implantation bed at day 30. (asterisks: fragmenta- tion within single islands by connective tissue bridges; H&E staining, total scan, 100x magnifica- tion); d) implantation bed at day 60. Almost complete degradation of the -TCP granules (H&E staining, total scan, 100x magnification). Fig. 5a Fig. 5b Fig. 5c Fig. 6a Fig. 6b Fig. 6c Fig. 6d Fig. 7a Fig. 7b Fig. 7c Fig. 7d