Bone Regeneration And Implantation Of Hydroxyapatite And Tricalcium Phosphate

Investigation of the appearance and distribution of bone morphogenetic protein 2/4 (BMP2/4), osteopontin (OP), osteocalcin (OC), osteoprotegerin (OPG) and human β defensin 2 (HBD2) in rabbit’s bone tissue three month after implantation of different biomaterials. 

Methods:

Six Californian rabbits were used in the study. Material was obtained from the right side of lower jaw after implantation of hydroxyapatite/tricalcium phosphate (HAP/TCP) burned under 1150⁰C and 1000⁰C, tricalcium phosphate (TCP) burned under 1000⁰C and 1150⁰C, hydroxyapatite (HAP) burned under 1000⁰C. All implanted materials were manufactured at the Riga Biomaterial Innovation and development centre of Riga Technical University. The left side of jaw was considered as a control tissue. Experimental and control tissue were processed for routine morphological study and immunohistochemical detection of OC, OP, BMP2/4, OPG and hBD-2. Semi-quantitative counting method was used for the assessment of relative amount of immunohistochemically positive cells. 

Results: The highest expression of OC and OP was detected in tissue with HAP. Expression of OC and OP was less extent in control tissue than in experimental tissue with other materials, too. Although, expression of OPG was moderate in tissue by using of pure HAP. Expression of OC, OP and OPG was less extent, but equally with control tissue in bone tissue using HAP/TCP burned under 1000⁰C, while expression of BMP2/4 was higher. HBD2 positive osteocytes in other experimental material and in control tissue were not noticed at all. 

Conclusions:

Prevalence of OC, OP and OPG consisting osteocytes in the experimental tissue three month after implantation indicates possible bone regeneration stimulated by pure HAP implant. Lack of HBD2 positive osteocytes and variable amount of OPG positive osteocytes at the experimental side possibly associates with decreased activity of osteocytes and disturbance of bone antimicrobial defence during formation process of biocompatibility between HAP, TCP, HAP/TCP and supportive tissue.