Nowadays, dental implants have become very popular among patients and dentists due to high success rate in replacement of missing few or full set of teeth in respect of the old process of bridge which requires grinding of healthy neighboring natural teeth or removable plates which used to be unstable/poorly retained. The neighboring teeth involved in bridging process used to be lost due to grinding, caries, overloading and pyorrhea. Dental implants are screw shaped cylindrical devices placed in jaw bone after drilling osteotomy of appropriate size in jaw bone. Main stream dental implants are made-up of cp-titanium due to the fact that titanium has high affinity for oxygen and readily forms an oxide layer on its surface which provides it self- passivation capacity. Professor Per-Ingvar Branemark after his initial investigation where he found that the titanium gets united to the bone gave the term osseointegration. Moreover, titanium is a tough material i.e. it’s a good combination of ductility and strength with modulous of elasticity closest to bone.

Usually the dental implant takes more than three months to get strongly united (osseointegrated) with jaw bohe to be able to sustain -masticatory loads so that there is no gaping on the interface and crestal bone loss is minimal on application of loads. Long waiting time is highly inconvenient to patients. Several efforts have been made worldwide to expedite the process of osseointegration between the implants and jaw bone; however, they are associated with one or other problem in functioning because of corrosion, chipping and resorption of the coatings used on implants and lead to peri-implant problems. There is profound scope to increase on implants and lead to peri-implant problems. There is profound scope to increase biocompatibility and corrosion resistance of implants to allow more bone formation on implant surface to enhance anchorage to bone. The dental implants are usually placed following two surgical and prosthetic protocols.

In case of single stage surgery the gum is incised and reflected after giving local anesthesia to make area numb. The drilling is done in bone to prepare an osteotomy by sharp, sterile drills of gradually increasing diameter under copious irrigation to avoid the heating of tissues and denaturation of tissue proteins to keep osteoblasts alive and in healthy state. The osteotomy is always of lesser diameter than the implant diameter and this disparity corroborate with thread depth of implant so that the implant gets inserted and achieve initial stability. In this single stage modality one part of implant (abutment/healing cap) transits through the gum. This extension into the mouth is liable to application of forces due to tongue, cheek, lip and food from outset. These early loading forces can lead to micro movements at interface and result in compromised osseo-integration of implant.

In case of two stage surgery the initial steps like incision, flap raising and drilling is same and in similar manner disparity of diameter is kept for initial stability. However, the implant is submerged beneath the gum during suturing and no part of implant projects trans-gingival. Thus the implant remains away from any forces from outset to avoid any movement at interface and achieve undisturbed healing to achieve better osseo-integration i.e. more bone to implant contact.

Generally, 3-6 months healing period is given to the implant so that the osseointegration has achieved optimum level. Thereafter, the gum is incised from top of implant and a healing cap or abutment is attached to fix the prosthesis. This technique has drawback that a second surgery is to be performed. Titanium surfaces have been physically and chemically modified to improve corrosion because the corrosion products can lead to deleterious events in vicinity of implant and may reach to vital structure and cause systemic problems as well. Oral cavity is having changing PH, changing temperature, cyclic loading of more than 100 N and electrolyte with active anions like chloride and fluoride. Schiflf N et al, Adya et al and Lautensch!ager EP et al have explored how significant is the corrosion behavior of titanium. Micron to nanometer scale roughness along with surface energy and wettability are so important factors to increase the adsorption of body fluid, small/large molecular weight proteins, celt attachment, cell spreading, cell differentiation. gene expression, hydroxy-apatite production and ultimately osseointegration of implant.

Guehennec L, Buser Daniel, Elias CN and Jindal S have worked on these aspects. Thomson LA et a! have described that diamond like carbon coating on steel implants is stable, abrasion resistant and impervious and, by cell culture studies, found it suitable biomaterial for orthopedic implants where very heavy compound forces are withstood. Dowling DP et al deposited diamond like carbon coatings on austenite stainless steel by saddle field source deposition system and they conducted both in vitro studies with fibroblasts, in vivo tests in sheep and found the material to be biocompatible. Wear resistance of these femoral heads was significantly higher in femoral heads thus the tribological properties were also better. Thomson LA et al have also found diamond like carbon as biocompatible in their experiments mouse macrophages and fibroblasts.

Poon RWY et al have formed a TiC coating on NiTi to prevent the leaching of Ni which has deleterious effect on tissues; TiC was showed to be biocompatib!e with osteoblasts by these workers. Viteri VS et al reveal that there is always a local and systematic response to the implanted material, doesn’t matter how biocompatible/inert was the material, these always initiate a reaction for adaptation to the environment. Antsiferov VN et al used atmospheric plasma spraying and argon-arc padding for making TiC (not carbon) on titanium. The layer was observed as non-stoichiometric titanium carbide improving strength of titanium implant. An implant prototype was created for improved articular surface. Dentoalveolar implants were prepared by incorporation of titanium in carbon for replacement of lost jaw parts due to trauma or malignancy. Zhu Y et al created carbide (TiC) layer (not Carbon) on its surface to improve the abrasion resistance by heating in hydrocarbon atmosphere (benzene) at a temperature of 1000 1400°C using high frequency induction heating method. Vicker’s harness number turned 4000 which is good for preventing abrasion but otherwise is a disadvantage. Carbon compounds have been usually classified as ceramics due to their chemical inertness and due to lack of ductility.

These materials are good conductors of heat and electricity and are biocompatible thus they have been used in dental and orthopedics. Vitredent implant system became popular in 1970s but due to designs, material and high clinical failure were discontinued.

Need of present investigation

Carbon is principle constituent element of human body and carbon has shown high biocompatibility to the cells. Implants made from pure carbon have several advantages over other biomaterials. Carbon has unique biological inertia, corrosion resistance, fatigue properties, plasticity, moreover, non toxic & non carcinogenic. Its modulus of elasticity and conductivity is similar to bony tissues. Carbon implants have proven to be highly biocompatible, although, these are not tough materials (good combination of ductility and strength) as is titanium. The principle purpose of present investigation was to invent a procedure by which a new biomaterial (cp-Ti with eraphene like coating) which possess the properties of both the commercially pure titanium

(cp-Ti) and carbon. Thus a titanium surface has been carbonized by using pure graphene by a novel procedure described below.

Procedure of carbonization:

The cp-Ti was used for this study and not Ni-Ti or Ti6A14V because component dements leach out and are harmful to local and remote tissues. The cp-Ti samples were 2mm thick and were sectioned with a hacksaw and the sides were smoothened by mechanical polishing. Samples were mechanically polished with emery paper of 1/0 to 4/0 grades and finally on sylvet cloth, mounted on a polishing wheel, using suspension of alumina powder in water as abrasive, in the

Department of Metallurgical Engineering, IIT (BHU). The samples were cleaned in water using ultrasonic cleaner for 8 minutes and then washed with acetone. The samples were air dried and kept in desiccators. The titanium sample was kept in quartz tubular furnace for carbonizing. The tube was first evacuated using rotary pump in the order of 10 ^-2 torr and then the sample was heated upto the desired temperature of 300°C, 400°C, 600°C and 650°C at a constant heating rate of 20° per minute. When the growth temperature was reached hexane as a liquid precursor for carbon was introduced/injected into the growth chamber for 10 minutes and then after completion of process the furnace was allowed to cool to the room temperature. Throughout the whole process the hydrogen gas was flown at a constant flow rate of 40 SCCM. The samples were removed with clean twizzer and kept in desiccators followed by the desired characterization.