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Journal of Oral Science & Rehabilitation Issue 01/2015

22 Volume 1 | Issue 1/2015 Journal of Oral Science & Rehabilitation β-TC P b ov in e b iph a s ic bi o mate r i al i ncre ase s bo ne f o rmati o n i n do g mo de l Cortical defect closure: All groups showed a re- duction inthe defect size in comparisonwiththe eight-week study time. Test B showed the high- est defect closure (86.11 ± 1.9%). Test A showed increased closure (78.23 ± 1.2%) in comparison with the eight-week study time, and the control group showed the lowest amount of defect clo- sure (26.45 ± 1.5%). Both test groups showed significantdefectclosureincomparisonwiththe controlgroup(p< 0.05;Table3). Residual material: Test B showed a higher per- centage of residual material (39.41 ± 1.3%) in comparison with Test A (35.78 ± 2.9%) and the controlgroup(p< 0.05;Table3). Connective tissue: Connective tissue was the highest in the control group (71.65 ± 1.6%), and was lower in Tests A and B (p < 0.05; Table 3 & Figs.4d–f). Newbone: New bone was observed at the centre ofthedefectandatthebordersinTestsAandB;in the control group, no new bone formation was found.Thehighestamountofnewbonewasfound inTestB,followedbyTestA(p< 0.05;Table3). Discussion The purpose ofthe present work was to evaluate the benefits of incorporating 3% silicon into the compositionofabiphasicsyntheticgraftmaterial ofHA/β-TCP, used in critical-size defects in dogs’ post-extraction defects. The current dog model haspreviouslybeenusedinseveralexperimentsin our laboratory to study various aspects of socket healing.4–6 In the studies referred to, woven bone startedtoforminthefreshextractionsocketafter one week of healing and after four weeks the socket was largely filled with woven bone (about 90%ofthesocket). In our present study, cortical defect closure was evaluated by histological and histomorpho- metric tests at eight and 12 weeks. Excellent de- fectclosureinbothtestgroupswithgraftmaterial granulessurroundedbynewbonewasfound. The present experiment demonstrated that the early healing of an extraction socket grafted withHA/β-TCPplus3%siliconinvolvednewbone formationandacoagulumwasreplacedbyapro- visional granulation tissue matrix in which new wovenbonecouldbeformed.Thebiphasicbioma- terialwas apparently involved in this process. HA granules were occupied by large active multi- nucleated cells that most likely removed calcium andphosphateionsfromthesmallgranulesofthe biomaterial.Thus,inthegraftedsites,substantial amounts of newlyformed bone could onlybe de- tectedintheapicalportionofthesocketwherethe graft material was absent. In the remaining por- tionsofthegraftedsockets,amildlyinflamedpro- visional matrix surrounded the majority of the 4BONEXBMgranules. Thepresentresultsagreewiththoseobtained by El Backly et al., who compared the effects of platelet-rich plasma and a silicon-stabilized HA/β-TCPscaffoldonhealingcritical-sizedefects in rabbit calvaria, evaluating healing at four, eight and16weeks.24 Inthe nongrafted control sites, large amounts of woven bone had formed in most compartments of the socket. This finding is in agreement with observations from similar experiments that in- vestigated tissue modeling and remodeling in extraction sockets, as well as in mechanically produceddefectsinthealveolarridgeindogs.4,5 Most ofthe graft particles present inthetest sites were surrounded by either a dense provi- sionalmatrixornewlyformedwovenbone,espe- ciallyinthetest grouptreatedwith 4BONE XBM plus 3% silicon. Most of the 4BONE XBM gran- uleswereindirectcontactwithimmaturewoven bone. The present study used CT and resin-em- bedded histology to evaluate healing evolution. The results showed that the silicon-stabilized Histomorphometry Cortical defect closure Residual material Connective tissue New bone 12 weeks (Mean ± S.D.) (Mean ± S.D.) (Mean ± S.D.) (Mean ± S.D.) Controla 26.45 ± 1.5% — 71.65 ± 1.6%*b,c 27.54 ± 2.1% Test Ab 78.23 ± 1.2% 34.36 ± 1.1% 14.28 ± 1.9% 53.29 ± 1.7%*a Test Bc 86.11 ± 1.9%*b,a 36.24 ± 1.8%*b,a 10.37 ± 1.6% 58.92 ± 0.8%*a * Statistical significance was set at p < 0.05. Table 3Table 3 Histomorphometry in 12 weeks. Post hoc multiple comparisons showed that defect closure and residual material were higher for Test B, connective tissue was higher for the control group, and new bone formation was higher for Tests A and B in comparison with the control group.

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