# Microstructural Evaluation of Dental Implant Success Using Micro-CT: A Comprehensive Review
## 3 Critical Bone Microstructure Parameters for Implant Success
Sp is a measure of the distance between the trabeculae, which are the small rod-like structures within the spongy bone. As Tb. Sp increases, the bone becomes less dense and more porous. This results in a reduction of the bone material available to support and distribute mechanical loads, leading to a weakening of the bone and an increased risk of fractures. In conditions such as osteoporosis, increased trabecular separation is a common finding, indicating a reduction in bone strength and an increased risk of fracture [51; 52; 53]. Tb. Sp is a pivotal parameter in the evaluation of the microarchitecture of trabecular bone, which is especially pertinent in the context of dental implants. Tb. Sp is a measure of the distance between the trabeculae, which are the small rod-like structures that are characteristic of spongy bone. An elevated Tb. Sp value indicates an increased presence of voids or gaps within the bone, resulting in elevated bone porosity. This consequently leads to a reduction in the quantity of solid bone material available to support the implant. An augmented Tb. Sp value results in a less dense bone structure, which compromises its capacity to withstand mechanical loads. For dental implants, this is of paramount importance, as the implant necessitates a robust and stable foundation to function effectively [54]. From the observations with 3D imaging, the results showed an increase or positive correlation in implant stabilization on Tb. Th and Tb. N, while the Tb. Sp values decreased or correlated negatively with implant stability. This indicates that the smaller the gap between the trabeculae, the denser the bone conditions are, so it is possible that the bone bond to the implant is stronger [55]. BS/TV reflects the complexity of the bone surface in relation to the total volume, while connectivity density describes the degree of interconnection of trabecular structures per unit volume [39]. The in vivo study by [PERSON] et al. (2021) testing a novel implant versus a control implant showed that an increase in BS/TV was positively correlated with increased time to new bone formation around the implant in both the novel and control implants [56]. There is a positive correlation between BV/TV and connectivity density. A denser bone volume will have a higher connectivity density value. This correlation is also similar to BS/TV. This result was obtained in a study by [PERSON] et al. (2024) [57]. This correlation also has similarities to BS/TV [39]. The DA index is an index that describes the anisotropy orientation of the bone geometry with a value range of 0 to 1 (0 < DA < 1). A value of 0 indicates that the trabecular orientation is highly isotropic, and a value of 1 indicates that it is highly anisotropic [57]. The DA index is a commonly used measure of bone stiffness and strength [58]. [PERSON] et al. (2024) found that there are significant differences between osteoporodic and non-osteoporotic bone. The results of osteoporotic bone have a trabecular structure in the longitudinal direction [57]. The SMI analysis is an index for the representation of the architecture of the trabecular bone in the form of plates or rods [59]. This index uses a range of values between 0 and 3 [60]. [PERSON] et al. (2020) noted that one of the causes of implant failure is marginal bone loss. In this condition, there is a very significant difference, one of which is characterized by an increase in the SMI value so that many plate shapes are visible or appear more regular in the trabecular structure in this area [61]. Tb. Pf represents a proxy measure of trabecular connectivity within a given region or volume of interest (VOI). The resulting measure value provides an illustration of bone connectivity. There is a close correlation between the change value of Tb. Pf and the SMI value with interpretation and relevance to the dental implant. This is typically associated with augmented bone strength and resilience, thereby suggesting superior support and enhanced osseointegration potential in the vicinity of the implant [41].