INTRODUCTION Bone is a dynamic organ that can regenerate and bone grafting is a dynamic phenomenon. The two types of bone grafts frequently used in are autografts and allografts. Autograft bone is transplanted from another part of the recipient’s body.[1] Autologous bone remains the gold standard, but requires a second surgical site that can result in additional pain and complications, is limited in quantity and increases the cost of the procedure. The bone grafted from genetically non identical members of the same species is known as Allograft bone. Its advantage is that it obviates the morbidity with donor-site complications and is readily available in the desired size, shape and quantity. Fresh-frozen or demineralized freeze-dried allograft bone has also been used, however due to rapid rate of resorption does not make it ideal for large bony defects. Recently, xenograft materials are gaining more popularity with good success rate as bone graft substitutes. These grafts are procured from one individual and transplanted into another individual of a different species and are usually derived from porcine, coral, and bovine sources[1].

Collagen as an osteoconductive material is due to its osteoconductive property and when it is used in combination with osteoinductive carriers like hydroxyapatite or tricalcium phosphate. These composites are mixed with autologous bone marrow which subsequently provides osteoprogenitor cells and other growth factors.[1] Hydroxyapatite is a biocompatible ceramic produced through a high temperature reaction and is highly crystalline form of calcium phosphate. The nominal composition of this mixture is Ca10 (PO4)6 (OH) 2 with a calcium-to phosphate atomic ratio of 1.67. The most unique property of this material is chemical similarity with the mineralized phase of bone; this

 

Bone formation, graft incorporation varies with each. HA in ceramic and crystalline form is slow in resorption and bone formation, where as non-ceramic, non-crystalline form is fast in resorption and in bone formation. A three-dimensional collagen-HAP (CHAP) nanocomposite scaffold was prepared by co-precipitation method (phosphoric acid solution mixed with collagen molecules and calcium hydroxide solution) through a self-organization process, which was then freeze- dried to create pores followed by a dehydrothermal crosslinking.[3]

Indeed, both collagen type I and hydroxyapatite were found to enhance osteoblast differentiation (Xie et al., 2004), but combined together, they were shown to accelerate osteogenesis. A composite matrix when embedded with human-like osteoblast cells, showed better osteoconductive properties compared to monolithic HA and produced calcification of identical bone matrix (Serre et al., 1993; Wang et al., 1995). In addition, Col-HA composites proved to be biocompatible both in humans and in animals (Serre et al., 1993; Scabbia and Trombelli, 2004). These composites also behaved mechanically in a superior way to the individual components. The ductile properties of collagen help to increase the poor fracture toughness of hydroxyapatites. The addition of a calcium/ phosphate compound to collagen sheets gave higher stability, increased the resistance to three-dimensional swelling compared to the collagen reference (Yamauchi et al. 2004) and enhanced their mechanical ‘wet’ properties (Lawson and Czernuszka, 1998).[4]

The BH particles incorporated with a porcine type-I collagen matrix (BHC) can be stabilized without dissipation like a hard sponge, which allow to adapt and condense into the irregular defects. When it gets wet, it is softened and has favorable manageability. A number of preclinical and clinical studies indicated that BHC grafting enhanced periodontal regeneration in periodontal intrabony defects[5]

Recently, Surgiwear has developed xenograft in the name of G-Graftâ„¢ It is natural Hydroxyapatite with natural collagen and with naturally occurring trabecular pattern. It is very useful for bone repair and replenishment. G-Graftâ„¢ is made of natural low crystalline Hydroxyapatite with collagen. It is available in form of granules, dowels and blocks. The shape can be changed by using Gigli saw and bone nibblers.[1]

Wahl DA et al. proposed that, the composite of Hydroxyapatite & Collagen (G-Grafâ„¢) may lead to earlier bone regeneration & greater density of the mature bone. Araujo M et al. in a study also found that de novo hard tissue formation after 3 months, particularly in the cortical region of the extraction site using of hydroxyapatite /collagen composite

(Bio-Oss Collagen) on healing of an extraction socket of dogs. Johnson KD et al, in a study reported that Collagen hydroxyapatite composite was better in comparison to tricalcium phosphate and hydroxyapatite used alone , in healing 2.5 cm bony defect created surgically in a canine radius model.[2]

Although hydroxyapatite is the most widely studied stiff scaffold material, the frequency of its clinical use is less than 10% of all bone grafting procedures due to its unstable fixation and insufficient interaction with host tissues. Instead, hydroxyapatite composites (e.g., hydroxyapatite plus collagen derivatives) have been developed to mimic biochemical and biomechanical properties of natural bone in order to enhance osteointegration and graft healing for potential biomedical applications.

The rapidly evolving technology enables the development of biomimetic nanocomposite biomaterials that fulfil the current requirements of an improved bone scaffold.Dentistry Section Three biologic processes are involved in new bone formation within a bone graft - Osteogenesis, Osteoconduction and Osteoinduction. The main purpose of this present study was to radiologically assess and compare the regenerative potential of hydroxyapatite with Collagen (G-Graftâ„¢) & hydroxyapatite (G-Boneâ„¢).