**5.3 Polymer-based bone grafts**

 Polymer-based grafts can be broadly grouped as synthetic or natural polymerbased grafts and can further be classified as biodegradable and nonbiodegradable substitutes. This category of grafting materials is specifically utilized for dental implants, as they are found helpful in restoring of edentulous site in the lost tooth. In the case of long bone-related congenital defects, or cases requiring bone segment replacements after invasion of malignant tissues, polymer-based grafts (vascular fibulas) are found helpful in restoring skeletal integrity. Other polymers like chitosan, collagen, gelatin, and poly lactic acid (PLA) are reported to exhibit improved bone regeneration capabilities both *in vitro* and *in vivo* when combined with hyaluronic acid [64]. Another advantage shown by these materials is that of better bone-matrix interference since they also act as bio-mimetic, thus helping in deposition, precipitation, and enhancing formation of calcium phosphate [65]. The type of commercially available polymer-based bone graft substitute is mentioned in **Table 4**.
