Use of guided tissue regeneration has been documented by Waldrop and Semba [71]. This method uses an absorbable gelatin membrane, allogenic bone graft material, and a nonresorbable expanded polytetrafluoroethylene (ePTFE) membrane. After flap reflection, an absorbable gelatin membrane is placed over the OAF with its edges on the bony margins of the perforation, which serve as a barrier for the bone graft material and prevent displacement of the graft material into the antrum and sinus epithelial cell migration. A layer of allogenic bone graft material is put on the membrane. The nonresorbable ePTFE membrane is used to cover the bone graft material, and the soft tissue flap is placed over the membrane. This membrane promotes selective cell population with subsequent regeneration. Eight weeks after insertion, the barrier membrane is removed. After removal of the inner aspect of the flap adjacent to the ePTFE membrane, the mucoperiosteal flap is replaced. Closure of the OAF was clinically confirmed by bone formation, although this was not confirmed histologically. One of the disadvantages of this technique is the need for an additional surgery to remove the nonresorbable ePTFE membrane. A further disadvantage is the need for a full-thickness flap. Götzfried and Kaduk developed an alternative procedure to close OAFs without surgical intervention [72]. According to the investigators, prolamin occlusion gel is directly injected into the perforation and hardens within a few minutes to form a barrier. One week later, granulation tissue is formed and the prolamin gel completely dissolves after 2 to 3 weeks [72]. This technique proved to be well tolerated by patients and results in fewer postoperative complaints compared with other procedures [68]. The disadvantage of this technique is chiefly its high material cost. Additionally, the technique is less appropriate for closure of OAFs greater than 3 mm [68].

Biostimulation with laser light for closure of OAFs was suggested by Grzesiak-Janas and Janas [73]. In this method, 61 patients were subjected to 3 cycles of extraoral and intraoral irradiation with a CTL 1106 biostimulative laser of 30-mW power with a tip-emitting light of 830-nm wavelength for 10.5 min and for four consecutive days. The researchers demonstrated a complete closure of OAFs. This technique eliminates the need for a surgical procedure. The technique has the disadvantage of being expensive and requires many visits to accomplish complete closure.