**Abstract**

Several diseases and medical treatments have been found to affect bone quality over decades. Bone mass characteristics summarized in bone mineral density (BMD), geometry, microarchitecture, and mechanical properties are the main parameters permitting to assess the quality of bone. Clinically, the diagnosis of bone diseases and the prediction of bone fracture are largely based on the BMD values. Thus, the investigation of how diseases and treatments alter the BMD value is primordial to anticipate additional treatment for the patient. In this chapter, we summarize the main research studies investigating diseases and treatments' effects on bone quality and more specifically on BMD.

**Keywords:** bone mineral density, osteoporosis, bone diseases, medical treatments, bone remodeling
