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ePaper created 2015-11-17, 15:11:47 | version 1.38.0
42 Volume 1 | Issue 1/2015 Journal of Oral Science & Rehabilitation Immunohistochemical osteopontin expression in bone xenograft in clinical series of maxillary sinus lift Abstract Ob jec tive Theobjectivesofthisstudyweretoexamineosteopontin(OPN) expression in bone and anorganic bovine bone (ABB) in maxil- lary sinus grafts after six months of healing and to study its re- lationship to morphological and immunohistochemical results andto patientvariables and habits. Ma teria ls a n d m eth od s Forty maxillary sinus lift procedures were performed in 40 con- secutive patients. Bone cores were obtained from implant re- ceptor sites at implant placement for histological, morphomet- ricandimmunohistochemicalstudies. Res ults Histomorphometric analysis found 32.75 ± 14.0% vital bone, 39.49 ± 17.4%connectivetissue,and27.75 ± 21.8%remnantABB particles. OPN expression was diffuse in 77.5% (31/40) of ABB samplesandfocalin22.5%(9/40);itwasdiffusein80%(8/10)of pristine bone samples and focal in 20% (2/10). OPN immuno- stainingofABBparticleswasintensein45%ofmaxillarysinuslift biopsies, moderate in 27.5%, mild in 10%, and absent in 17.5%. OPNexpressionwasmainlydetectedattheinterstitialboundary ofbonewithABBparticlesandwithinosteocytelacunaeandbone canaliculi. C on c lus ion Immunohistochemical expression of OPN is related to bone remodeling and maturation changes in maxillary sinus lift pro- cedureswithABB xenograft. Keyword s Anorganic bovine bone, bone remodeling, intrasinus graft, im- munohistochemistry, osteopontin. Os teopon tin expres s io n i n ano rgani c bovi ne bo ne Introduction Osteopontin (OPN) human gene contains seven exons, spans ∼11.1 kb, and maps to the long arm ofchromosome 4 (4q13).1, 2 OPN is expressed by a single-copy gene as a ∼34 kDa3 nascent pro- tein that is extensively modified by post- translational events; it is secreted as a noncol- lagenous acidic bone matrix of single-chain phosphoglycoproteins with diverse functions, including cell-binding activity4 and angiogene- sis.5 OPN has calcium-binding properties and is expressed bycells in awidevarietyoftissues, in- cluding bone, tooth and cartilage, and in acti- vatedmacrophagesandlymphocytes.6 Data are available on the structure, location and properties of OPN, but the biological func- tion of this protein in bone remains uncertain. OPN influences bone homeostasis by different mechanisms. This polypeptide chain undergoes extensive post-translational modifications, in- cluding glycosylation, phosphorylation and sul- fation, and the precise modification pattern de- pends on the species and tissues in which the protein is synthesized.7 The functional signifi- canceofpost-translationalmodificationsinOPN ispoorlyunderstood. Bone remodeling is a regulated process in which removal via osteoclasts is followed by boneformationviaosteoblasts.8 Thepresenceof OPN has traditionally been interpreted as an in- dicator of bone formation. In bone, OPN is pro- duced by osteoblastic cells at various stages of differentiation,9 including differentiated osteo- blasts, and by osteocytes.10, 11 The protein is pri- marily made by cells of osteoblastic lineage, and itisalsoexpressedbyfibroblasticcellsinembry- onicstroma12 andatwound-healingsites.13 OPN isfoundinsituinosteoblastsandaccumulatesin mineralized bone matrix during endochondral