Guided Bone Regeneration in the Posterior Mandible Using a Resorbable Metal Magnesium Membrane and Fixation Screws: A Case Report

Abstract

Background: Due to bone loss, implant placement in the posterior mandible is often impossible without prior augentative procedures. The reconstruction of bone defects with horizontal and vertical components using particulated bone grafts requires the placement of a mechanically stable structure for stabilization of the grafting material. Although titanium-reinforced membranes and titanium meshes have been shown to be effective in this indication, the necessity of their removal, often in a separate surgical procedure, is seen as a disadvantage. Since the introduction of a new resorbable magnesium metal membrane and fixation screw, a mechanically stable and resorbable system might provide an alternative option for guided bone regeneration (GBR) in the posterior mandible. Case Presentation: A 61-year-old patient was presented with large edentulous areas in all posterior regions and requested fixed dentures in Areas 34-36. Tooth 33 was extracted and treated with an immediate implantation of a ceramic implant, whereas Positions 34-36 were treated with a two-stage approach. The site was augmented horizontally, with a slight vertical component using autologous and allogenic bone and a new completely resorbable magnesium metal membrane and fixation screw. During the initial healing period, the patient reported a tingling sensation at the site of the augmentation. This is an observation that is specific to the magnesium products and is potentially caused by the release of hydrogen gas as the metal degrades and is resorbed. Upon re-entry at 3 months, it was clinically observed that there was a very dense and vascularized bone that was sufficient for placing two 5.5 × 10 mm ceramic dental implants. Conclusion: A completely resorbable magnesium membrane and fixation screw were able to support the bony regeneration in a large GBR situation in the posterior mandible. Due to the use of a new material for GBR, different clinical observations were made compared to the standard material choices.

Keywords: biodegradable; bone regeneration; magnesium fixation screws; magnesium membrane; staged GBR.

Figure 1

(a) Initial OPG showing a large defect between Sites 34 and 37, (b) CBCT of defect site, (c) CBCT image of the apical lesion in Site 33, and (d–f) CBCT perspectives of defect site demonstrating severe bone loss.

Figure 2

Augmentation procedure using the magnesium membrane. (a) Exposure of the defect showing the initial situation. (b) The cortical bone is perforated in multiple places to improve blood flow into the augmentation site. (c) The defect site is augmented with a mix of allograft, autogenous bone, and liquid PRGF in a 1:1:1 ratio, after which additional PRGF is positioned on top. (d) The magnesium membrane is cut and bent into shape prior to its placement over the defect. (e, f) The membrane is secured on both the lingual and the buccal sides using magnesium fixation screws.

Figure 3

Soft tissue healing over the augmentation. (a) Wound closure using a continuous seam stitch; (b) wound control, 3 weeks post-op; (c) 3 months post-op, prior to re-entry and dental implant placement.

Figure 4

OPG taken immediately after the augmentation procedure.

Figure 5

(a) Re-entry after 3 months; (b) placement of two 5.5-mm-diameter ceramic implants in Positions 35 and 36; (c) control OPG taken after implant placement.

Figure 6

One-year follow-up after implant placement. (a) Frontal view clinical photograph, (b) CBCT showing distortion due to the presence of artifacts caused by the ceramic implants, (c) CBCT cross-sectional view of defect site prior to augmentation, and (d) CBCT cross-sectional view of defect at 1-year follow-up.