Nanoapatite and organoapatite implants in bone: Histology and ultrastructure of the interface

Abstract

This article reports on the reaction of bone to a new family of nanocrystalline hydroxyapatite biomaterials with crystal sizes similar to those of human bone. Pure nanoapatite cylinders and organoapatite cylinders containing a synthetic nanopeptide were analyzed 28 days after implantation into the spongy bone of Chinchilla rabbits. The experimental techniques used for analysis were light microscopy, scanning electron microscopy, and transmission electron microscopy. Both implant types were well incorporated, and interface events were found to be similar to those observed on human bone surfaces with regard to resorption by osteoclast-like cells and bone formation by osteoblasts. Different types of giant cells were observed resorbing the outermost surfaces of implants. There seemed to be both dissolution of the implant and particulate biodegradation leading to less dense implant regions near the interface, whereas the bulk of the implants remained denser. Transmission electron micrographs revealed that bone bonding occurred with and without an afibrillar intervening layer. Given the biologic reaction observed, these implant materials should be suitable for bone replacement and the organoapatite form could be useful for additional functions such as the release of drugs and optimized release of antibiotics, growth factors, or other substances. The organic component can also be used to control physical properties in a bony implantation bed.

Nanodimensional and Nanocrystalline Calcium Orthophosphates

“…Both implant types were well incorporated and interface events were found to be similar to those observed on human bone surfaces with regard to resorption by osteoclast-like cells and bone formation by osteoblasts. That study revealed a suitability of such materials for both bone replacement and drug release purposes [606]. Similar results were obtained in other studies [607,608].…”

“…Already in 1990-s, implants prepared from nanodimensional apatites, as well as biocomposites of nanodimensional apatite with organic compounds were tested in vivo [606][607][608]. Cylinders made of both pure nanodimensional apatite and organoapatite containing a synthetic peptide were analyzed 28 days after implantation into spongy bones of Chinchilla rabbits.…”

“…However, it is presented in the titles of several publications, namely Refs. [606,629,653,667]. In a slightly modified form, the term "nano-apatite" is presented in the titles of several other publications, namely Refs.…”

“…[89,100,226,511,631,735,789]. Furthermore, similar terms "nano-HA" [103,575,608,659,681,692], "nano-hydroxyapatite"[42, 87,91,92,96,97,102,119,190,191,294,295,314,338,451,459,486,492,578,583,606,627,628,641,664,666,677,682,685,687,693,698,701,703,705,770,773], nano-fluorapatite [104,684] and "nanohydrox...…”

Osteoblast reaction at the interface between surface-active materials and bonein vivo: A study usingin situ hybridization

“…1 Bioactive materials are classified into surface-active materials and resorbable materials. 2 Surface-active materials bond to bone through an apatite layer formed on the material surface after implantation, [1][2][3][4][5] and it is assumed that the velocity of layer formation correlates with bioactivity. 1,[6][7][8] However, how the formation of the apatite layer affects bioactivity is poorly understood.…”