## 1 Introduction  
Dental implants are osseeintegrated structures that stably combine with the surrounding bone, so maintaining marginal bone is essential for implant treatment success and long-term stability [1]. Peri-implant bone loss is a multifactorial process that involves progressive bone loss caused by factors such as bone quality deterioration, surgical trauma, peri-implantitis, and occlusal overload [2; 3; 4]. A long-term follow-up study of implants revealed complications such as loss of marginal bone after the prosthetic stage [5]. These complications are caused by direct stress transmission due to the implant-bone interface and stress concentration due to differences in stiffness of the bone around the implant under various load conditions. Anatomically, unlike teeth, implants do not have a periodontal ligament, so stress is directly transferred to the bone around the implant [6]. Excessive stress leads to bone microcracks and negatively affects implant stability, leading to implant failure in the long term. Previous studies have shown that as peri-implant bone loss increases, the magnitude of stress within the implant increases [7; 8; 9]. Other studies have suggested that unfavorable stress distribution associated with peri-implant bone resorption may lead to vertical fractures of internally connected implants [10]. Bone quality can affect implant survival and surrounding bone maintenance [11]. It is important in high-risk patients with skeletal diseases characterized by decreased bone density and microstructural deterioration, such as osteoporosis [12; 13]. The results of implant treatment are within a predictable range in normal-quality bone, but it is difficult to obtain the same results in bone with low-quality bone. In previous studies, if the bone quality is poor during implant placement surgery, the risk of bone damage increases compared to normal bone [14]. [PERSON] et al. [15] reported that bone quality was the most important factor for implant selection and initial stability. [PERSON] et al. [16] reported that bone structure was the most important factor in selecting favorable patient treatment outcomes. Continuously monitoring and comparing marginal bone changes is essential to prevent implant failure and complications, and it can provide useful information when implanting low-quality bone. However, there is still a need for more research that continuously evaluates implant stability and marginal bone changes according to bone loss and bone quality in various clinical situations, and the results of existing studies are inconsistent. [PERSON] et al. [17] reported that deep implant insertion and short abutment were associated with greater marginal bone loss during the first 6 months after prosthesis loading. In contrast, [PERSON] et al. [18] evaluated clinical and radiographic changes in bone around implants inserted at various bone levels and reported that the apical position of the implant did not affect the ridge loss. In addition, [PERSON] et al. [19] summarized the factors influencing bone loss around implants and reported that low bone density was correlated with decreased implant stability and increased bone deformation. In contrast, [PERSON] et al. [20] summarized the influence of various potential risk factors on the incidence of late dental implant failure and reported that bone status (osteoporosis or osteopenia) was not significantly associated with late failure. The inconsistency in these research results is likely due to differences in study design, definition and assessment of bone quality, criteria for measuring implant stability, and analytical methods. In particular, there is a lack of a standardized approach to quantitatively assess the effect of bone quality on early implant stability and long-term marginal bone changes and the specific mechanisms by which the interaction between bone loss progression and bone quality affects the mechanical stress and strain distribution in the bone around implants have not been elucidated.