Reduced Bone Neoformation in Smoking Rat’s Calvaria Grafted with Bone Ceramic| Stephy Publishers

 


                            SOJ Dental and Oral Disorder - (SOJDOD) | Stephy Publishers

Abstract

The impact of cigarette smoke on bone grafts in implantodontics has been discussed in the scientific literature. The present study aimed to evaluate bone repair in calvaria of rats after the performance of critical bone defects and graft of bone ceramic biomaterial in animals exposed or not to cigarette smoke. Bone defects of 5mm in diameter were made in parietal bone. Each defect was filled with Bone Ceramic biomaterial. Twenty rats were used and divided into 2groups: test, consisting of 10rats exposed to cigarette smoke; and a control group, consisting of 10rats not exposed to cigarette smoke. The animals were euthanized in the 4th postoperative week and bone tissue samples were extracted to perform the histometric analysis. The test group showed less bone neoformation, with statistical significance (p<0.05) when compared to the control group. We conclude that cigarette smoke had a negative influence on bone neoformation.

Keywords
Bone graft, Biomaterials, Bone ceramic, Cigarette smoke

Introduction
Bone tissue is a dynamic tissue which is under constant renewal in response to mechanical, nutritional and hormonal influences. Bone tissue metabolism is characterized by two antagonistic and concomitant events: the neoformation of bone tissue by osteoblasts and the resumption of existing bone tissue by osteoclasts, a mechanism known as bone remodeling. Bone matrix is a biological compound consisting of water, mineral, collagen and non-collagen macromolecules, which are referred to as non-collagenous proteins.2 Collagens, have a structural and morph genic role. In mineralized tissues, they interact with several non-collagenous proteins and provide a framework for accommodating mineral crystals. Non-collagenous proteins can be classified briefly into glycoproteins, proteoglycans, proteins derived from plasma, growth factors and other macromolecules. In addition to having a structural function, the bone matrix stores macromolecules that play roles in bio mineralization and cell-matrix interactions, which serve as a reservoir for growth factors and cytokines. When there is any bone injury, such signalling molecules are produced and released activating local bone regeneration.

The ability of the bone tissue to restore original structure and mechanical properties has limitations and may even fail, interrupting or preventing bone repair if vascular supply failure, mechanical instability, excessive defects and/or competing tissues with high capacity proliferative. However, there are some options that are available to promote and sustain bone neoformation, such as: osteoinduction by growth factors, osteoconduction by grafts and bone substitutes, transfer of stem cells or progenitor cells that differentiate into osteoblasts, osteogenic distraction, and guided bone regeneration. These options may be used isolated or combined.

Bone regeneration is commonly understood as the replacement of lost or deficient bone structure by elements of the same structural organization, so that the lost portion is completely restored in function and structure. Bone tissue has the potential to regenerate its original architecture and some basic conditions need to be present, such as ample blood supply and mechanical stability promoted by a solid base, that is, the pre-existing bone structure.5 However, in some defects, surgical procedures are necessary in which bone grafts assist bone repair.

Bone grafts are classified according to its origin (autogenously, allogeneic, xenogenous and alloplastic), the reaction against the host site (bio tolerable, bio inert, bioactive, resorb able), physical characteristics (inorganic, demineralized and fresh) and biological behaviour (osteogenic, osteoinductive, osteoconductive). The autogenously graft is the individual's own tissue. The allogeneic graft is the tissue of another individual of the same species, obtained in a bone bank, where cellular components are eliminated and the osteoinductive and osteoconductive properties are preserved. Xenografts are bone tissues originating from other species. Alloplastic are made from synthetic materials. A bone substitute is an osteoconductor if it conducts bone neoformation promoted by its support structure. Materials that have bone cells capable of promoting bone neoformation are called osteogenic. If they have the biological characteristic of inducing cell differentiation leading to the deposit of new bone, they are called osteoinductors.

Bone graft materials are used in reconstructive surgery to fill the defects, replace bone portions, increase bone size, facilitate or improve the repair of bone defects, provide mechanical support, and stabilize the blood clot. Bone filler must be safe, non-toxic and biocompatible and still be osteogenic, osteoconductive and osteoinductive. 8 The ideal bone substitute attracts the proliferation of new blood vessels and favours bone growth in the grafted region during the repair procedure and is gradually replaced by newly formed bone.


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