Resorbable collagen membranes: histopathologic features

Objective. Resorbable collagen membranes (RCMs) are commonly used by oral surgeons, periodontists, and endodontists for multiple purposes. We report 6 cases of RCMs that did not resorb as expected and describe the histopathologic features. Study Design. Cases of an unusual fibrillar foreign material were noted in biopsy specimens curetted from bone. Hematoxylin-eosin and Masson trichrome stains were performed. Clinicians were contacted for detailed clinical information. Results. There were 3 men and 3 women. RCMs presented as hyalinized, paucicellular, delicate eosinophilic fibrils or a meshwork without a foreign body reaction. They were refractile and stained for Masson trichrome as expected. These RCMs persisted longer than expected (2-6 weeks) in 3 cases and may have retarded healing in 5 cases. Conclusions. Although RCM is supposed to be fairly rapidly resorbable, this material sometimes persists within wound sites without any obvious foreign body reaction and may retard healing.