**6. Mode of application**

The growth factors are the naturally occurring molecules responsible for completing the healing process. However, there are instances where the systemic, metabolic or local compromise of the patient can lead to inadequacy of these factors, delaying or inhibiting healing.

In solution to these problems, many in vitro and animal studies have been conducted to determine the potency of added growth factors on the healing sites. The most important criteria of clinical use of these molecules must always be biocompatibility, biodegradability, hydrophilicity, and modulation of the osteoinductive response.

The various BMP carriers and delivery systems used in studies include collagen sponge, hyaluronan sponge, polylactic acid, polylactic-polyglycolic acid, fibrin glue, xenograft, and demineralized freeze-dried bone allograft [73, 74].

Orthopedic studies also show the use of polylactide-coated implants as local delivery mechanisms for IGF-1, TGF-b1, and BMP-2. These studies have shown predictable with favorable results on fracture healing. Adding to advantage is absence of systemic side effects and more effective delivery than systemic delivery of growth factors [75].

## **7. Futuristic approach**

Tissue engineering was initiated with the aim of developing genetically engineered autologous cells and tissues without causing donor site morbidity. Although growth factors are naturally occurring molecules, a laboratory made tissue engineered component would definitely aid in faster healing of tissues even in the compromised cases.

Holy et al. suggested a recent biomimetic strategy to engineer bone. This is conducted by involving autologous osteogenic cells that are seeded, in vitro on a biodegradable polymer scaffold that mimics the architecture of trabecular bone to create a scaffold-cell hybrid called a tissue engineering construct [76].

Growth factor delivery mechanism in-vivo, makes use of Gene therapy approaches. This is used with BMPs that elicit osteoinductive and bone healing effects [77, 78].

Given the complex osteogenic cascade of bone regeneration at implant development site, a combination of different BMPs and other angiogenic growth factors shall definitely improve the success rates of dental implants, particularly at compromised host sites.

Advances in growth factor vector design, gene regulation, and tissue targeting are in their infancy which will soon establish themselves or future human clinical trials and eventual use in daily dental and surgical practice.
