Supra-Alveolar Bone Regeneration: Progress, Challenges, and Future Perspectives

Abstract

Periodontitis is a highly prevalent disease that damages the supporting tissues of a tooth, including the alveolar bone. Alveolar bone loss owing to periodontitis is broadly categorized as supra-alveolar and intra-alveolar bone loss. In intra-alveolar bone loss, the defect has an angular or oblique orientation to the long axis of the tooth in an apical direction. In contrast, the defect is perpendicular to the long axis of the tooth in supra-alveolar bone loss. Unlike intra-alveolar bone defects, supra-alveolar bone defects lack supporting adjacent space, which makes supra-alveolar bone regeneration more challenging. In addition, the limited availability of resources in terms of vascularity and underlying tissues is another obstacle to supra-alveolar bone regeneration. Currently, supra-alveolar bone loss is the least predictable periodontal defect type in regenerative periodontal therapy. In addition, supra-alveolar bone loss is much more common than other alveolar bone loss. Despite its prevalence, research on supra-alveolar bone regeneration remains sparse, indicating an unmet need for significant research efforts in this area. This review summarize recent advances, obstacles, and future directions in the field of supra-alveolar bone regeneration. We discuss the biomaterials, bioactive molecules, and cells that have been tested for supra-alveolar bone regeneration, followed by pre-clinical and clinical approaches employed in this field. Additionally, we highlight obstacles and present future directions that will propel supra-alveolar bone research forward.

Keywords: alveolar bone loss; dental materials; periodontitis; supra-alveolar bone; tissue regeneration.

Figure 1

Schematic representation of alveolar bone loss. (a) normal bone. (b) intraalveolar bone loss. (c) supra-alveolar bone loss. dotted black line: crest of alveolar bone; ab: alveolar bone.

Figure 2

Fabrication of hierarchical injectable nanofibrous microspheres for bone regeneration. BMP-2 is encapsulated into heparin-conjugated gelatin nanospheres, which are further immobilized in nanofibrous microspheres. Adapted from [97]. Copyright WILEY-VCH Verlag GmbH & Co.

Figure 3

(a) Surgical creation of a critical size supraalveolar periodontal defect. (b) Application of rhBMP-12/ACS. (c-d) Alveolar defects receiving rhBMP-12 (0.04 mg/ml)/ACS. (e-f) Alveolar defects receiving rhBMP-12 (0.2 mg/ml)/ACS. The green line specifies the level of the periodontal attachment and alveolar bone after surgical reduction. The coronal extension of the newly formed bone is denoted by green arrows in (c) and (d). A functionally oriented PDL is indicated by blue arrows in (e) and (f). Adapted from [43]., Copyright © John Wiley & Sons A/S.

Figure 4

Surgical reconstruction of the maxillary premolar teeth (a) Scaling and root planing of elevated flap. (b) Direct application of rhBMP-2/PGS (arrows) on the root-planed surface. (c) After the surgery gingival flaps are repositioned and sutured. (d) Healing after 12 weeks. H&E staining images of different groups. (e) Physiological saline/PGS was placed onto the root surface (f) rhBMP-2/PGS was placed on the root surface. (g) rhBMP-2/PGS with PGS membrane as a spacer was placed onto the root surface. C: residual cementum; NC: new cementum; NB: new bone; ARP: apical end of the root-planed surface. Adapted from [42]. Copyright © John Wiley & Sons A/S.

Figure 5

(a) Micro-CT images of bone defect sites with representative samples at 4 and 8 weeks after operation. White arrows indicate the baseline of the supra bone defect site. (b) Histological sections of bone defect sites with representative samples at 4 and 8 weeks after operation. Yellow dotted line indicates the original bone defect level. Scale bars 100 μm. Adapted from [45]. Copyright © 2019 The Authors. Journal of Periodontology published by Wiley Periodicals, Inc.

Figure 6

Transplantation of PDL-MSC sheets in a canine supra defect model. (a) Surgical creation of the critical defect. (b) Application of PDL-MSC sheets to the exposed root surfaces. (c-d) Placement of β-TCP constructs mixed with type I collagen over the roots wrapped with absorbable GTR membrane. (e-f) Graphical illustration of three-layered cell sheets and a PGA sheet and the transplanted site. Azan-staining of histological specimens (g–i) show alveolar bone regeneration in the control, autologous, and allogeneic groups, respectively. Black dotted rectangles in images (g–i) are enlarged in images (j–l), respectively., Adapted from [39]. Copyright © 2016, Mary Ann Liebert, Inc.

Figure 7

A combined approach to treat a patient with a severe alveolar defect. (a) Debridement of the extraction site, showing the extensive defect of the buccal wall. (b) Implant placement in the defect. (c, d) Placement of biomaterials construct (rhBMP-2/ACS, particulate bovine bone, autogenous bone, PRP) and the customized collagen barrier membrane into the defect. (e) The cone beam computed tomography (CBCT) image at 14 weeks. (f) The CBCT image at 12 months. Adapted from [30]. Copyright © John Wiley & Sons.

Figure 8

Treatment of supra-alveolar bone defect with a combination of open flap debridement (OFD), intramarrow penetration (IMP), and platelet-rich fibrin matrix (PRFM). (a) Pre-op radiography. (b) Probing pocket depth. (c) Incisions of the surgery. (d, e) Debridement and IMP. (f) Place IMP and PRFM in the bone defect. (g) Direct interrupted suture. (h) Probing pocket depth. (i) 9 months post-op radiography. Adapted from [48]. Copyright © Wolters Kluwer.

Figure 9

Treatment of periodontal supra-osseous defects using single flap and concentrate growth factors (CGF). (a) Cone-beam computed tomography (CBCT) image of the supra bony defect before surgery. (b, c) Incisions of the surgery and debridement of the defect. (d) CGF preparation. (e) Adding CGF in the bone defect area. (f) Horizontal internal mattress suture. (g) The photograph at day 21 after surgery. (h) The CBCT image at 6 months. Adapted from [153]. Copyright © ScienceDirect.