Dental implants have become an established prosthodontic treatment for missing teeth, with survival rates now exceeding 97%. The most popular current method of bone quality assessment is that developed by Lekholm and Zarb, who introduced a scale that ranges from 1–4 and is based on a radiographic assessment and the sensation of resistance experienced by the surgeon when preparing the implant site. However, the initial studies excluded patients with type IV bone (“soft” bone), in whom implant treatment was considered more likely to fail earlier.

Recent review has reported that implants placed in patients with systemic osteoporosis did not present higher failure rates than those placed in patients without osteoporosis. Furthermore, there are no data that contraindicate the use of dental implants in patients with osteoporosis, even though a correlation has been found between skeletal bone density and jawbone density.

In orthopedic surgery, osteoporosis is characterized by compromised bone strength that predisposes a patient to an increased risk of fracture; this suggests that both bone quality and bone mineral density (BMD) contribute to the risk of fracture. Bone quality, defined as “the sum of all characteristics of bone that influence the bone’s resistance to fracture”, is independent of BMD. Bone quality is determined by the characteristics of the bone matrix, including the microarchitecture, bone turnover, accumulation of microdamage, degree of calcification, and collagen content. Many clinical studies have indicated that the increase in BMD following treatment with anti-resorptive drugs does not reflect the proportional reduction in relative fracture risk, which suggests that bone quality plays an important role in bone strength. In a consensus statement issued by the National Institutes of Health, bone quality was defined more specifically by bone architecture, bone turnover, bone mineralization, and the accumulation of microdamage.

Research on bone turnover markers (BTMs) has increased considerably over the past decade. The use of BTMs as a method of biochemically monitoring bone metabolism requires measurement of the enzymes and proteins released during bone formation and measurement of the degradation products produced during bone resorption. Various biochemical markers are now available that allow specific and sensitive assessments of the rates of skeletal bone formation and resorption. Previous studies reported significant declines in areal BMD measured by DXA of the total hip and ultradistal radius and high levels of both formative and resorptive markers were associated with reduced BMD measured by CT at the total hip, but not at the lumbar spine.

However, in implant dentistry, bone quality is still considered to be equivalent to radiographically assessed bone density. The paradigm of bone quality has shifted from density-based assessments to structural evaluations of bone; however, clarifying bone quality from structural evaluations has remained challenging in implant dentistry because devices suitable for accurate evaluations of bone structure have yet to be developed. Therefore, we focused on BTM values as a clinical indicator of bone quality and hypothesized that patients with abnormal BTM value may have an abnormal jawbone quality, which may affect the prognosis of the implant.

The purpose of this study was to determine whether the BTM values are reflected in jawbone condition by evaluating the relationship at baseline and during follow-up in patients with prosthodontic implants.