This indicates that (i) the biopsy procedure may in no case have involved the walls of the extraction site or (ii) after >6 months of healing the bundle bone had been resorbed and replaced with lamellar bone or bone marrow. The fact that bundle bone gradually may disappear following tooth removal is in agreement with findings from experiments in dogs (Cardaropoli et al. 2003; Araujo & Lindhe 2005) who studied socket healing during a 4- to 6-month period. In the early phase of healing, periodontal ligament fibers as well as bundle bone occurred in the lateral walls of the socket. During the process of modeling and remodeling, however, the bun- dle bone disappeared and was eventually replaced with bone marrow. It is suggested that the loss of function and disappearance of the periodontal ligament fibers and the bundle bone following tooth extraction may play a crucial role for the resorption and diminution of the residual ridge. This assumption is in agreement with Sennerby et al. (1988) who stated that the loss of ridge dimension “could be described as a resorptive atrophy, a fundamen- tal and physiologic reaction to loss of function and inactivity.”