## 1 Introduction  
Dental implants are used as a permanent substitution for natural teeth for oral rehabilitation when dedentulous patients have no other alternative to replace the tooth at the edentulate site. With advances in modern dental implantology, dental implants are fabricated using various materials, and new surgical techniques have been proposed to increase the success rate of dental implant treatment [1; 2; 3]. Metallic materials have gradually become the most widely used materials for dental implants owing to their stable mechanical property, high corrosion resistance, and suitable biocompatibility [4; 5]. Despite these advantages of metallic materials, the incomplete osseointegration between the implant surface and transplanted site remains a critical problem after dental implant treatment [2; 6]. [PERSON] [7] proposed an ideal osseointegration period of 3-6 months after a successful implant operation; however, patients have to endure masticatory difficulty during the osseointegration period. Moreover, the soft tissue and bone are more susceptible to periodontitis during this time, which stimulates inflammation and bone loss, requiring antibiotic treatment and may ultimately result in implant failure [8]. [PERSON] [9] revealed that the risks of peri-implant mucositis are about 80% in patients and the risks of peri-implantitis are about 28-56% in patients, following dental implant surgery. Therefore, it is a challenge to develop an ideal dental implant that can effectively promote osseointegration while suppressing bacterial biofilm formation and activity. Surface treatment of a dental implant is regarded as an essential process to control the structural property, and several commercial dental implants have been developed with various surface modifications, including plasma spraying, resorbable blasted media, acid etching, and oxidation [2; 10; 11]. The advantages of surface treatment include: (i) improvement of the mechanical fixation of the implant during placement, (ii) proper structure formation for blood clot maintenance, and (iii) promotion of bone healing [12]. These surface modifications can accelerate osseointegration along with preventing biofilm formation [13; 14]. In addition, different biochemical materials, including proteins, drugs, and biomolecules, have gradually been used to improve local delivery on the surface of a metallic implant [15; 16; 17]. [PERSON] et al. [18] investigated the effects of a growth factor-loaded titanium implant on osseointegration. Bone morphogenetic protein (BMP) is the key factor for inducing differentiation into osteoblasts to promote bone regeneration. Using an immersion technique, BMPs at various concentrations were successfully loaded onto the surfaces of a titanium implant that was sand-blasted with large grit and acid-etched, and the optimal concentrations of BMPs (0.5 and 1.0 mg/mL) were found to be effective for inducing bone regeneration and osseointegration in a beagle dog model. In addition to this study, various other traditional approaches (i.e., structural and biochemical treatments) have been proposed to improve the functions of a dental titanium implant. Graphene is regarded as a new carbon-based nanomaterial on the threshold of the silicon age, and its potential for various fields has been widely acknowledged, including chemical, biomedical, environmental, and electrical fields [19; 20]. In our previous research, we used graphene as a stem cell culture substrate [21; 22]. Human adipose-derived stem cells (hASCs) were cultured on a graphene film, and the affinity of hASCs on the graphene film was induced under the fluid shear stress of a rocking culture system. The differentiation of hASCs into specific lineages, including osteogenic, adipogenic, and epithelial lineages, was strongly promoted in the presence of graphene. In addition, human mesenchymal stem cells (hMSCs) were cultured on graphene-incorporated chitosan substrates with various concentrations of graphene [22].