Introduction: The closure of post extraction gingival defects has not been studied in depth, although their achievement is of great importance in certain situations, such as prior to radiotherapy treatment in patients with oral cancer. The aim of this study is to assess the influence of bone substitutes on the time of closure of post extraction gingival defects. Materials and Methods: 22 patients underwent two symmetrical dental extractions. Using a split mouth model, with random assignment to one or other group, one was considered a control group (no filling with any type of material post extraction), whereas the other was considered the experimental group (filling with bone substitute and calcium sulphate post extraction). Gingival closure and healing were assessed in the first group at 2, 3, 4 and 6 weeks after extraction. Results: No differences were seen between both groups in gingival health. Gingival closure was greater and faster in the experimental group than in the control group, and was statistically significant in the first and second week after extraction (1st week, control: 19.63mm2 ± 2.52 - experimental: 11.76mm2 ± 2.40 - p < 0.05) (2nd week, control: 15.09mm2 ± 2.77 - experimental: 7.98mm2 ± 1.99 - p < 0.05), although these differences evened out during subsequent periods. No medical accidents were seen and tolerance to treatment was good in both groups. Discussion: According to our data, the use of filling material allows a faster initial gingival closure of the socket post extraction. However, we must assess the cost of intervention, with the aim of applying it in situations in which it may be of significant advantage (for example, patients that will undergo radiotherapy treatment), or in cases in which the use of these materials is justified due to other reasons in addition to the one mentioned (such as maintenance of bone crest architecture for implant restoration).