Cytoflex Barrier Membrane Clinical Evaluation Historical Background Guided tissue regeneration is a well established concept in the repair of oral bone defects. The exclusion of soft tissue epithelial and connective tissue cells from a bony defect, leading to enhanced bony repair is scientifically sound and has been proven clinically. Several types of membrane materials, including dense non-porous PTFE, porous expanded PTFE and certain resorbable membrane materials have been used in periodontal and oral surgery with success. Current evidence suggests that the physical blockade of cell migration is primarily responsible for the enhanced healing and regeneration. Porous-ePTFE (P-ePTFE) and Non-Porous-PTFE (NP-ePTFE) Many different membrane materials are currently available for clinical applications, including cellulose, collagen, polylactic acid, polyglycolic acid and lactide/glycolide copolymers and PTFE. Due to its superior biocompatibility and long history of use, the first generation, highly porous expanded PTFE membrane (P-ePTFE) has received the most attention in the literature. The large porosity of P-ePTFE allows tissue integration within the barrier membrane and minimizes early exposure due to sloughing off of thin flaps. However, P-ePTFE often results in the heavy accumulation of microorganisms within the interstices of the material when exposed to the oral environment. In addition, it is very difficult for surgeon to remove the highly tissue-integrated porous barrier membrane at the end of the guided tissue regeneration process. Recently, a dense, non-porous PTFE membrane (NP-PTFE) has been proposed as a superior barrier membrane for alveolar ridge preservation and reconstruction. The smooth, non-porous PTFE membrane precludes the connective tissue and cells from migrating into the bony defect, prevents the accumulation of micro-organisms within the membrane and allows for easy removal of the membrane material after tissue regeneration. Nonetheless, the dense PTFE is stiffer and its smooth surface is difficult for cells and tissue to attach, often resulting in early flap sloughing off and exposure. As an improvement, NP-PTFE is embossed with micro texture to encourage tissue and cell attachment. NP-PTFE had been approved and is commercially available for clinical applications. Page 1 of 9
Micro-Porous-ePTFE (MP-ePTFE) has developed Cytoflex, a micro-porous eptfe barrier membrane (MP-ePTFE), which exhibits the synergic advantages of both porous and non-porous PTFE membranes. The micro pores allow certain nutrients to pass through the barrier membrane, but block the ingrowths of connective tissue, cells and micro organisms. Micro- porosity also enhances the adhesion of host cells to MP-ePTFE membrane, while still permitting the barrier to be removed with ease after wound healing. Objective of the Clinical Study The purpose of this investigation is to evaluate the soft tissue response to a MP-ePTFE barrier membrane and clinically evaluate the bone and bone graft healing under such a membrane. Study Design and Method This study is designed to evaluate the general applicability of the MP-ePTFE barrier that may be encountered by a private dental surgeon on a routine basis. The study was performed by a periodontal surgeon (Wang, Kungchun) at his private practice. The MP-ePTFE membranes were used as a barrier membrane over human tooth extraction sockets, periodontal infrabony defects and in conjunction with dental implants. The MP-ePTFE membranes were used alone or together with the use of bone grafting particulates. The pre- and post- operative radiographs and photographs were recorded and compared to assess the safety, effectiveness and general applicability of the material. All of the surgical procedures were performed under local infiltration anesthesia. The exposed defect surfaces were carefully debrided and root planed using both hand and ultrasonic instruments. All granulation tissue was removed. The material was trimmed and draped over the bony margins of the defect to extend 2-4 mm beyond the bony margins. The mucoperiosteal flaps were then re-approximated and closed with 4-0 silk suture. If bone grafting particulates were used, the defect was first filled with the bone substitute and then the membrane material was draped over the bone graft substance. Patients were informed about the clinical procedures, the material used and the need to have the barrier removed. Results In all, a total of six patients (2 for extraction sites, 2 for periodontal defects and 2 in conjunction with dental implants) received Cytoflex membranes for bone regeneration. There was no incidence of postoperative wound infection, inflammation or pain at the defect Page 2 of 9
site. There were no membranes lost in the immediate postoperative period. The suture was removed approximately 7 days, postoperatively. There was no adverse tissue response to the implanted membrane. Epithelial migration over the exposed membrane was observed in several cases. Membranes were removed 3-6 weeks postoperatively depending on the individual amount of tissue overgrowth. At the time of removal, the membrane material was grasped with a small forceps and removed with a gentle tug. The soft tissue exhibited excellent response to the MP-ePTFE membranes used in this study. No inflammation, infection or adverse reactions that can be attributed to the membrane material were observed. The underlying tissue following 3 weeks or more of healing was found to resemble a dense, fibrous connective tissue which was in intimate contact with the inferior surface of the membrane. In the cases of extraction site reconstruction, there was no invagination, contraction, or collapse of the surrounding tissue as is seen in a conventionally treated extraction site. For patients that were treated with bone substitute and the placement of a MP-ePTFE membrane, the bone substitute particles appeared to be consolidated in the defect in a stroma of fibrous connective tissue following membrane removal. This technique resulted in the incorporation of a very high percentage of graft material when compared to conventional grafting techniques without the use of a barrier membrane. Discussion and Conclusions The material is very easy to use and conform to the wound margins due to its compliance and lack of material memory. During retrieval, the MP-ePTFE membrane can be easily removed with a gentle tug without damaging the surrounding and underlying tissue. This seems to confirm that there is no tissue penetration and integration within the MP-ePTFE membrane. In several cases, the membrane was exposed, but the exposed surface was cleaned during revisit and did not cause infection or inflammation. This appears to indicate that the bacteria and infectious agents are blocked by the micro porous barrier membrane. Overall, the use of MP-ePTFE membranes for oral surgery appears to be safe and effective as illustrated by the three cases given below. The barrier membrane appears to enhance the wound healing by protecting the underlying defects from physical and bacterial contact. Page 3 of 9
Case Report 1 Tooth extraction site treated with resorbable bone substitute and MP-ePTFE membrane. This case describes the wound healing response in a patient whose tooth extraction site was grafted with a bioglass (Unigraft ) bone substitute and then covered with a MP-ePTFE membrane. During the complicated surgical extraction, the buccal wall of bone was lost due to ankylosis of the tooth root. The defect site was gently packed with bioglass bone substitute following tooth extraction and curettage of the tooth socket. The MP-ePTFE membrane was placed as a barrier over the bone graft material. At 30 days, the membrane was removed and a dense fibrous connective tissue bed was observed under the membrane. The appearance of the dense, fibrous connective tissue is clinically identical to that observed following the removal of Gore-Tex augmentation material (P-ePTFE). This technique allows for the placement of bone graft material into the tooth socket and rebuilds the lost buccal plate without a loss of graft material. Page 4 of 9
Figure 1. Extraction in maxilla with loss of buccal wall of bone. Figure 4. MP-ePTFE barrier material and healing tissue at 30 days postoperatively. Figure 2. Extraction site packed with Unigraft bioglass bone substitutes. Figure 5. Clinical view at 30 days with barrier removed. There is a dense fibrous connective tissue bed which follows the contours of the barrier material. There is no collapse or concavity as would be expected in an untreated extraction site. Figure 3. MP-ePTFE membrane in situ. The margins of the material extend 2-3 mm beyond the margins of the defect. Page 5 of 9
Case Report 2 Treatment of severe periodontal defect with MP-ePTFE membrane. This case describes the use of MP-ePTFE in the treatment of a patient with a deep circumferential periodontal defect. The exposed root surfaces were carefully debrided and root planed using both hand and ultrasonic instruments. All granulation tissue was removed. MP-ePTFE membrane was placed over the bony margins and tucked under the mucoperiosteal flaps as a temporary barrier to protect the infrabony defect. The clinical view at 40 days after removal of barrier membrane is similar to that observed when the Gore-Tex membrane is removed. A 6-month postoperative radiograph shows significant regeneration of bony tissue emerging from the base of the defect. This case demonstrates the effectiveness of MP-ePTFE in the treatment of periodontal defects using guided tissue regeneration techniques. Page 6 of 9
Figure 1. Deep circumferential periodontal defect in the right maxilla Figure 4. Clinical view at 12 month post-operatively. Figure 2. Clinical view at 10 days postoperatively. Figure 5. Pre-surgical radiograph of a circumferential defect in the right maxilla. Figure 3. Clinical view at 40 days after removal of membrane. Figure 6. 6-month post-operative radiograph shows significant tissue regeneration at the base of the defect. Page 7 of 9
Case Report 3 Use of MP-ePTFE membrane in conjunction with placement of a titanium dental implant into a compromised extraction site. This case describes the clinical wound healing response in a patient in who was to receive a dental implant into a tooth extraction site immediately following extraction of the tooth. During the complicated extraction procedure, the buccal wall of bone was lost due to ankylosis of the tooth root. The case was treated with a MP-ePTFE membrane to prevent epithelial migration into the bony defect adjacent to the implant surface. The clinical results demonstrate that this material can prevent epithelial migration into bony defects. Page 8 of 9
Figure 1. Extraction site with loss of buccal wall, resulting in bony dehiscence. Figure 5. Clinical view at 21 days following membrane removal. Figure 2. Titanium implant in place. Figure 6. Clinical view of operative site 6-months postoperatively. Figure 3. MP-ePTFE membrane placed over dental implant and bony dehiscence. Figure 7. 6-months post-operative radiograph showing the titanium implant in place. Page 9 of 9