## 4 Discussion  
The decision as to which donor site would be chosen for the reconstruction depended on the bone defect size and location [10]. The DCIA flap bone's vertical volume is much greater, allowing for the reconstruction to have the original height of the mandible. Additionally, the implant placement can be performed without creating unfavorable implant-to-crown ratios [10]. The DCIA flap has been demonstrated to be very reliable for the reconstruction of maxilla-mandibular complex defects following the ablation of lesions. The DCIA flap offers optimal bone shape for maxilla reconstruction, which could form a facial bone buttress or orbital rim. It is also important to be able to make a curvature for mandibular reconstruction. In the DCIA flap, the anterior superior iliac spine is similar to the angle of the jaw, the anterior inferior iliac spine is similar to the head of the condyle, and the iliac crest is similar to the lower border of the mandible. Thus, the DCIA flap, which provides advantages for the reconstruction of the maxilla-mandibular complex, has become the flap of choice [16]. The DCIA flap provides a large amount of tissue compared with other flaps [16]. The DCIA flap has favorable bone height and width for implant placement, compared with the fibular flap, allowing for the reconstruction to have the original bone height of the maxilla-mandibular complex. The fibular flap can be applied, which needs the long bone segment for the reconstruction of the mandible. One of the disadvantage of the fibular flap is the small diameter of the grafted bone. In edentulous patients with defects in the mandible, the graft bone height might be sufficient to reconstruct the alveolar bone ridge and support facial contour. However, vertical discrepancies were observed between the teeth bearing and the grafted fibula [10,17]. In some studies, the microvascular fibular flap was validated as a recipient site for dental implants [18]. In several studies, a lack of vestibular and granular soft tissue at the implant site was observed due to an abnormal occlusal relationship between the maxilla and mandible after mandibular reconstruction, a vertical discrepancy between the grafted and teeth bearing areas, and a lack of keratinized tissue [19]. Furthermore, the retention of implants can be difficult because of the limited graft bone height [10]. This allows the surgeon to determine the height and width of the bone component [16]. After the reconstruction by the DCIA flap, implant placement can be performed without creating unfavorable crown-implant ratios [14]. An early study demonstrated that the C/I ratio was a more sensitive indicator of implant failure than the residual bone height [20]. Accordingly, a C/I ratio between 0.5 and 1 was proposed for the prevention of peri-implant bone stress, marginal bone loss, and eventual implant failure [21, 22, 23]. Conversely, another study reported that the C/I ratio of 889 single tooth implants was 1.3 on average [24]. In this study, it was confirmed that the crown to implant ratio was 1.26, which was close to the ideal ratio suggested in the previous study. Of the 41 implants placed in 13 patients in this study, 39 implants excluding 2 implants were followed up continuously through radiologic examination after the final prosthesis. Of the 39 implants that completed the final prosthesis, marginal bone loss was not observed. One implant showed the soft tissue swelling around the implant. Implant success was defined in implantology as follows: no pain, mobility, peri-implant radiolucency. For implant success, peripheral bone loss for the first year should be less than 1 mm and should subsequently be no more than 0.2 mm [25,26]. In this study, all of the 39 implants showed no sign of peripheral bone loss, but peripheral gingival swelling and pain were observed. The corresponding implants were removed due to the risk of peri-implant mucositis.