TNFRSF11A and osteopetrosis: For the extrinsic origins, regardless of the way the bone remodeling is affected (e.g., a deficiency in RANKL/RANK inducing osteopetrosis [7,23,30,31,32,33] or overactivation in RANKL/RANK inducing osteolytic diseases [8,9]), in both cases root formation is touched.