Tenting screw-assisted membranes alveolar ridge augmentation in the anterior mandible.

Abstract

Background: Vertical ridge augmentation with a guided bone regeneration procedure in the anterior mandible requires membrane lingual stabilization. Until now, the only predictable way was the use of titanium-reinforced dense polytetrafluoroethylene (TR-dPTFE) membranes stabilized with self-drilling screws, which require large flaps for both placement and removal. This case report introduces a technique that does not require any membrane lingual fixation.

Methods: A tenting screw was placed in the middle of an anterior mandibular defect. A small TR-dPTFE membrane was bent 90° to take an L shape and be positioned crestally and lingually to the defect. Then, a larger collagen membrane (CM) was sutured with absorbable stitches to its more lingual and apical part. The TR-dPTFE membrane was stabilized on top of the tenting screw with its cap screw. A mixture of autogenous and porcine bone in a 1:1 ratio filled the defect. Then, the CM was moved toward the buccal side and stabilized with pins. After 8 months, the site was re-opened, the TR-dPTFE membrane and the tenting screw were removed with a small lingual envelope flap, two implants were inserted in the augmented bone and healing abutments applied.

Results: A screw-retained bridge was delivered 6 weeks after implant insertion and the 2.5-year follow-up showed perfectly maintained hard and soft tissues.

Conclusions: The stabilization of both membranes to the tenting screw reduced morbidity at re-entry avoiding a large lingual flap, while CM allowed graft revascularization from the periosteum, and resulted in optimal quality of the regenerated bone.

Key points: Titanium-reinforced dense polytetrafluoroethylene (TR-dPTFE) membranes require stabilization with pins or screws at the recipient site and large flaps for both placement and removal. On the lingual side of the anterior mandible the use of miniscrews is difficult and invasive, while the use of a tenting screw, placed vertically in the middle of the defect, allows for a simple and easy membrane stabilization and removal. Two membranes are utilized: a small TR-dPTFE membrane, that is stabilized to the tenting screw with its cap screw, and that does not allow to a collagen membrane (CM), that is sutured to the TR-PTFE membrane to cover the exposed part of the defect, to collapse over the bone deficiency. The CM, that covers the majority of the defect, after its biodegradation, allows graft revascularization from the periosteum, and results in optimal quality of the regenerated bone.

Plain language summary: Vertical bone defects of the jaws require bone augmentation procedures to allow the correct implants insertion to rehabilitate the masticatory function and aesthetics of patients. Among these techniques, guided bone regeneration is one of the most widely used. This technique is based on the use of non-absorbable titanium-reinforced dense polytetrafluoroethylene (TR-dPTFE) barrier membranes whose titanium frame allows them to be given a shape and not collapse onto the underlying bone defect. Since these membranes require screw stabilization to the recipient bone, large flaps must be performed to place and remove them. A technique is proposed that simplifies the positioning of the TR-dPTFE membrane, with the application of a tenting screw positioned in the center of the bone defect to which the membrane is stabilized. This procedure eliminates the need to place screws on the lingual side and the execution of a large lingual flap for its removal at the time of surgical re-entry. Furthermore, a re-absorbable collagen membrane is sutured to the TR-dPTFE membrane, the extension of which is limited to the crestal and lingual part, to cover the buccal part and the entire defect, improving the maturation of the bone graft inserted below the two membranes.