Guided Bone Regeneration: Novel Use of Fixation Screws as an Alternative to Using the Buccoapical Periosteum for Membrane Stabilization With Sutures—Two Case Reports

A key requirement to achieving successful guided bone regeneration (GBR) is the stabilization of the graft-membrane complex ("PASS" principles).^1-4 The use of membrane fixation screws, tacks, and periosteal biting sutures for this purpose has been discussed and recommended in the literature.^5-9 Procedures involving tacks or screws, however, can pose complex challenges and be technique sensitive, especially when direct fixation of a membrane is required.^10,11 Alternatively, periosteal stabilizing sutures can provide stabilization without the need for tacks or screws, but several drawbacks are associated with this technique as well. These include the presence of anatomic limitations in the area of the mental nerve as significant periosteal dissection is required as well as potential loss of tension in the stabilization sutures when completing primary closure.⁷

The aim of this article is to present a new technique that uses membrane fixation screws that serve as anchors for membrane stabilization sutures without the need for periosteal dissection and biting of the buccoapical periosteum. Demonstrated through two representative case reports, this technique may be a viable alternative when there is a desire to avoid the complexities of periosteal suturing and direct membrane fixation using tacks or screws.

This technique for stabilizing the graft-membrane complex utilizes stabilization sutures that are anchored to apical fixation screws as opposed to the buccoapical periosteum. The technique is performed in the following manner (Figure 1): First, using a 15c blade, a mid-crestal incision is made at the edentulous site along with one or two vertical releasing incisions that are one to two teeth wider than the defect being treated. Full-thickness reflection is then performed to elevate the flap beyond the margin of the defect. The recipient site is then prepared by placing intra-marrow decortications to expose the medullary blood supply, and a periosteal releasing incision is completed to reduce tension in the flap and allow for tension-free primary closure.¹² At this point, autogenous bone can be harvested locally or from a secondary site and mixed with allograft or xenograft to improve the regenerative potential of the procedure.^13,14

Three-millimeter (3 mm) membrane fixation screws are then placed using a contra-angle driver at a torque of 5 Ncm. Sufficient apical pressure is required to allow for engagement and fixation of the screws into the cortical bone while leaving the head of the screws 0.5 mm to 1 mm above the buccal aspect of the residual ridge. The screws should be placed 3 mm to 5 mm beyond the margin of the defect being regenerated and may be placed at multiple points along the mesiodistal dimension of the defect.

Next, the particulated bone graft is carefully adapted to the defect. A resorbable suture is then secured around the most lateral fixation screw with a single loop and subsequent knot, with care taken to leave the short tail at least 1 cm to 2 cm long. A resorbable collagen membrane is then prepared according to the manufacturer's recommended protocol, trimmed, and adapted to completely contain the bone graft to the defect. The initial suture that is anchored to the most lateral apical first screw is placed over the collagen membrane, entering through the palatal flap from inside to outside. The suture re-enters the palatal flap from outside to inside (epithelium to periosteum) 5 mm to 7 mm lateral to the initial palatal bite and is finally tied to the remaining free end of the suture to complete the first stabilization suture. The suture is then positioned over the medial aspect of the membrane and looped around the second fixation screw, laid over the membrane once again, and exited through the lingual flap from inside to outside (periosteum to epithelium) 5 mm to 7 mm distal from its original entrance point. The same process is repeated for each of the apical fixation screws that have been placed to ensure graft containment and sufficient stabilization of the graft to the defect.

Ultimately, primary closure is obtained in the normal fashion utilizing multiple horizontal mattress sutures to release tension on the flap margin and allow for dual-layer closure, followed by multiple single interrupted sutures along the length of the flap.^7,15 The site is left to heal for a sufficient time based on the grafting material used. Because the fixation screws are manufactured in a biocompatible titanium alloy, their retrieval during implant surgery is not required.¹⁶ A variety of commercially available fixation screws and/or membrane tacks may be used for this technique.

A 63-year-old woman with a non-contributory medical history presented for rehabilitation of her mandibular left quadrant; this included an edentulous mandibular left first and second molar, and a failing second premolar and third molar, with the latter being mesially inclined due to the premature loss of the second molar (Figure 2 and Figure 3). The case was planned for extraction of the failing teeth with simultaneous ridge augmentation extending over the defect area from the second molar to the first premolar with a bone replacement graft and a resorbable collagen membrane.

Following administration of adequate anesthesia, a sulcular incision was placed at the mandibular left third molar and the first and second premolars, with a crestal incision at the edentulous sites that bisected the available keratinized gingiva. Extraction of the third molar and second premolar was then completed, and the sockets were meticulously debrided of all granulomatous tissue followed by copious irrigation with saline solution.

Intra-marrow penetrations into the buccal plate were then performed using a 3-mm round carbide bur (Figure 4). Autogenous bone was harvested from the oblique line of the mandibular ascending ramus with a disposable bone scraper. In the recipient site, a single periosteal releasing incision was performed followed by stretching of the subperiosteal fiber bundles to facilitate flap advancement and obtain tension-free primary closure.

Prior to positioning of the bone graft and the adaptation of the membrane to the defect, several 3-mm membrane fixation screws (Pro-fix^™, Osteogenics, osteogenics.com) were secured at the apical extent of the defect to be grafted (Figure 4). These screws were inserted using the protocol described above and placed with care to avoid accidental penetration of anatomical structures such as the roots of adjacent teeth and the inferior alveolar nerve canal. Care was taken to place an anterior screw medial to the margin of the defect, a second screw was inserted distal to the defect, and a third screw was placed at the apical extent of the defect, midway between the extent of the defect mesiodistally.

Following placement of the anchoring micro screws, the autogenous bone was combined with an equal amount of 70:30 mineralized/demineralized cortical allograft (OraGRAFT^® MD 70/30, Lifenet Health, lifenethealth.org) and adapted to the confines of the defect. A sugar crosslinked collagen membrane (Ossix^® Plus, Datum Dental, datumdental.com) was placed over the defect to contain the bone graft to the site. In this case, two membranes were used: one was adapted over the buccal occlusal line angle, while the second membrane was adapted over the lingual occlusal line angle. At this time, a resorbable monofilament suture (Resorba^® Glycolon^®, RESORBA Medical GmbH, resorba.com) was utilized to initiate stabilization by entering through the lingual flap from outside to inside (epithelium to periosteum), 5 mm to 7 mm from the gingival margin, as previously described. This suture was then positioned over the medial aspect of the membrane and looped around the most anterior fixation screw, laid over the membrane once again, and exited through the lingual flap from inside to outside (periosteum to epithelium) 5 mm to 7 mm distal from its original entrance point (Figure 5 and Figure 6).

Thereafter, the suture was tied off. Care was taken to place the bites of the lingual flap at least 7 mm from the flap margin to allow for eventual dual-layered closure with horizontal mattress and single interrupted sutures. The same procedure was repeated along the length of the defect to ensure sufficient stabilization of the membrane over the composite bone graft. Once stabilization was completed, dual-layer primary closure was performed (Figure 7). This was accomplished by placing two horizontal mattress sutures 7 mm to 10 mm apart to reduce tension at the flap margins and evert them. Finally, single simple interrupted sutures were evenly distributed 5 mm from the flap margin along the length of the flap.

The patient presented for postoperative evaluation at 2 weeks and again at 6 weeks. Both appointments evidenced optimal maintenance of primary closure with no signs of pain, swelling, or infection. All sutures were left to resorb without additional intervention.

At 22 weeks following the initial bone grafting procedure (Figure 8), placement of implant fixtures was planned. A cone-beam computed tomography (CBCT) scan was acquired, and a significant increase was noted in the width of the alveolar ridge and adequate bone height and width to support implant placement (Figure 9). Upon re-entry, it was noted that complete defect fill had been obtained and implants were able to be placed in the ideal prosthetic position without the need for additional bone grafting. Local anesthesia was then administered, and a crestal incision was placed bisecting the available keratinized gingiva and a full-thickness flap was reflected. Measurements with a calibrated periodontal probe revealed an increase in the ridge width at the mandibular left second premolar and first molar sites of 7 mm and 10 mm, respectively. Implants (Astra Tech EV, Dentsply Sirona, dentsplysirona.com), 4.2 mm x 11 mm and 4.8 mm x 11 mm, respectively (Figure 10), were placed following the manufacturer's recommended protocol, and healing abutments were hand-tightened. The healing abutments were secured on the implants and a connective tissue graft was harvested from the palate and adapted to the buccal contour. The area was sutured with simple interrupted resorbable sutures (Resorba Glycolon). The implants were restored with single-unit screw-retained ceramic crowns 6 months later (Figure 11).

A 45-year-old woman with a non-contributory medical history presented for replacement of her maxillary right lateral incisor. After flap release, a severe horizontal ridge deficiency with a residual bone width of 3 mm to 4 mm was revealed, confirming the CBCT findings (Figure 12 and Figure 13).

The recipient site was prepared as described previously, and a single apical fixation screw was placed beyond the apical extent of the defect (Figure 14). In this case, a 50:50 combination of autogenous and allogenous composite graft (OraGRAFT MD 70/30) was obtained and adapted to the defect. In addition, a laminar plate was used to confine the bone graft to the defect and provide additional stability of the graft-membrane complex (Figure 15). A single stabilization suture was then wrapped around the apical fixation screw and anchored to the palatal flap in a similar fashion as described above. An additional fixation screw was placed a few millimeters apically to the first one to completely confine the defect. The initial screw was left in as it provided some initial stability of the laminar plate, helping to prevent it from inadvertently moving in the apical direction. Primary closure was obtained using the same protocol as described above, and the patient was discharged for recovery.

A CBCT was acquired prior to re-entry at 6 months and displayed adequate bone height and width to support implant placement (Figure 16). Full flap reflection revealed a significant increase in the width of the alveolar ridge at the site (Figure 17 and Figure 18). Implant placement (Straumann^® Bone Level Tapered Implant, 3.3 mm x 12 mm, Straumann, straumann.com) was completed and a customized healing abutment was hand-tightened to help create an ideal emergence profile (Figure 19). The implant was restored with a screw-retained ceramic crown 4 months after implant placement (Figure 20).

The use of the periosteal-anchored stabilization suture technique presents with several limitations,¹⁷ mostly associated with the dissection required for the stabilization of the sutures in the apical areas of the buccal flap.¹⁸ First, inherent anatomical risks exist, such as the presence of the mental nerve and branches of the infraorbital nerve around the canine-premolar maxillary area.¹⁹ Additionally, insufficient separation of the buccal flap from the apical periosteum will cause the stabilization sutures to loosen, reducing the stability of the graft-membrane complex.¹⁸ Furthermore, following placement of an initial periosteal biting suture that secures the membrane, there may not be sufficient access for subsequent periosteal biting sutures. Therefore, the periosteal stabilization suture can be considered a technique-sensitive approach.²⁰

In general, periosteal stabilizing sutures may allow for adequate stabilization of bone graft material when the membrane being used is not suitable for fixation with tacks or screws.⁷ For larger defects, sugar crosslinked collagen membranes, fascia-derived membranes, and similar matrices with low tensile strength often used as barrier methods in GBR procedures may lack stability, leading to graft migration and membrane collapse. These resorbable membranes, therefore, become ill-suited for fixation with tacks or screws²¹ as the tension release of the flap and process of obtaining dual-layer closure may inadvertently cause a loss in tension of periosteal stabilization sutures.⁷ Moreover, the placement of stabilizing sutures that bite the buccoapical periosteum is technique sensitive and often presents some anatomic limitations.⁷

In this report of two case presentations, the placement of membrane fixation screws apical and lateral to the defect prior to adaptation of the bone graft and membrane allowed for significantly improved stabilization with sutures compared to the previously described periosteal biting sutures.⁷ Although an apically secured fixation could potentially result in less bone width at the neck of the implants, the additional anchorage provided by the apical screws provided better control over the bone graft positioning and stabilization. The favorable GBR outcomes observed in these two cases facilitated implant placement at prosthetically driven positions, suggesting that screws used as anchors for stabilization sutures might be a preferable option to periosteal sutures when resorbable collagen membranes are used, preserving the integrity of the resorbable membrane prior to final closure. It is also suggested that special care should be taken to reduce related risks to the procedure, such as perforation of the roots or lesion of the alveolar canal nerve or perforation of the sinus buccal wall in the maxilla.

Because of the lack of comparative studies of this novel technique compared to traditional stabilization methods, the authors recommend careful deliberation when choosing to follow this approach. Further research on this membrane stabilization technique is needed to render this approach as safe and predictable as other previously described techniques.²²

The use of membrane fixation screws or tacks as anchors for stabilization sutures is presented as an alternative approach to secure a resorbable barrier membrane over a particulate bone graft. This hybrid technique addresses some of the limitations associated with current techniques. These limitations include the need for a resorbable membrane with significant tensile strength to resist tearing and distortion during the stabilization period, as well as the risk of losing tension in the stabilization sutures when achieving tension-free soft-tissue closure with periosteal sutures, thereby increasing technique sensitivity.

Instead of relying on the apical periosteum, the presented technique requires less flap dissection and allows for tension-free primary closure without the risk of losing tension in the stabilization sutures. This hybrid technique shows promise as an alternative to previously described techniques, but further studies are needed to validate this claim.

The authors declare no conflicts of interest.

Matthew J. Fien, DDS
Co-Medical Director, International Dentistry Research Group, Palma de Mallorca, Spain; Private Practice, Fort Lauderdale, Florida

Israel Puterman, DMD, MSD
Co-Medical Director, International Dentistry Research Group, Palma de Mallorca, Spain; Private Practice, Chevy Chase, Maryland

Juan Mesquida, DDS
Co-founder, Co-Medical Director, International Dentistry Research Group, Palma de Mallorca, Spain; Private Practice, Palma de Mallorca, Spain

Ignacio Ginebreda, DDS
Co-Medical Director, International Dentistry Research Group, Palma de Mallorca, Spain; Private Practice, Barcelona, Spain

Guillermo Bauza, PhD
Co-founder, Research Director, International Dentistry Research Group, Palma de Mallorca, Spain; Honorary Lecturer, Faculty of Medicine, Health and Life Science, Swansea University, Swansea, Wales; Private Practice, Palma de Mallorca, Spain