In case 2, the clinical wound did not heal for 6 weeks after tooth extractions (see Figure 1), leading the clinician to perform a biopsy. Remnants of OsseoGuard membrane (Collagen Matrix Inc) were seen, as expected given that the reported resorption time is 6 months; but there was no evidence of new bone formation 6 weeks after the procedure. In general, reepithelialization occurs within 4 weeks, osteoid starts to fill the extraction socket by 2 to 4 weeks, woven bone by 8 weeks, and lamellar bone by 12 weeks.21, 22,23 and 24 Similarly, in cases 3, 4, and 5 there was persistence of CollaTape (Integra LifeSciences Corp) 8 weeks after extraction, 4 weeks after curettage of a KCOT, and 4 weeks after apicoectomy, respectively, although this membrane is reported to typically undergo resorption within 2 weeks. The biopsies did not show significant new bone formation, and this is particularly striking in case 3, which was evaluated 8 weeks after extraction.