Background The formation of a hard-tissue bridge covering the tooth extraction socket is termed corticalization. In dogs this process takes >60d, however, this process has hardly been investigated in humans. Recent reports have indicated increased primary implant stability and reduced bone strain after immediate implant loading in the presence of a (thick) cortical layer, thus, knowledge of the timeframe between tooth extraction and hard-tissue bridging of the extraction socket appears clinically relevant in some situations. Aim/Hypothesis To determine the timeframe between tooth extraction and radiographically detectable corticalization of the socket in humans and to evaluate the possible impact of various factors on this process, e.g., history of periodontitis, smoking status, systemic disease, medications, etc. Material and Methods Two-hundred-fifty patients with a CT scan μ 8804, 36 months after tooth extraction and without any manipulation at the extraction site were included. Three orthoradial multiplanar reconstruction slices per extraction socket were scored, by a single calibrated examiner, regarding the degree of corticalization as: (a) healed, i.e., complete/continuous corticalization of the socket entrance, or (b) non-healed. Thereafter, each extraction socket was classified as (1) non-corticalized, i.e., all 3 slices classified as non-healed, (2) partially corticalized, i.e., 1 or 2 slices classified as non-healed, or (3) corticalized, i.e., all 3 slices classified as healed (Figure 1). The possible effect of several independent parameters, i.e., age, gender, timeframe between tooth extraction and CT scan, tooth type, periodontal status, gap dimension, smoking status, presence of any systemic disease, and medication intake, on the corticalization status was statistically evaluated. Results Three to 6 months after tooth extraction, 27% of the sockets were judged as non-corticalized, and 53% were judged as partially corticalized. After 9 to 12 months, >80% of the sockets were corticalized, but some non-corticalized sockets were detected up to 15 months post-extraction (Figure 2). Each additional month after tooth extraction contributed significantly to higher likelihood of a corticalized socket (OR 1.645, 95% CIs 1.471–1.841, P < 0.001). Periodontal attachment loss of μ 8805, 75% significantly prolonged corticalization time, i.e., teeth with <75% attachment loss were judged more often as corticalized (OR 1.984, 95% CIs 1.011–3.896, P = 0.047). No other independent variable had a significant effect on corticalization status. Conclusions and Clinical Implications Three to 6 months after tooth extraction one out of 4 sockets was still completely non corticalized, and only 9 to 12 months after tooth extraction complete corticalization was observed in about 80% of the sockets. The results, indicating a considerably long timeframe until corticalization of extraction sockets, imply that in cases where immediate loading requiring high primary implant stability is considered, waiting μ 8805,9 months post-extraction appears advisable.