A randomized, controlled, multicentre clinical trial of post-extraction alveolar ridge preservation

Abstract

Aim: To compare the effectiveness of two-ridge preservation treatments.

Materials and methods: Forty subjects with extraction sockets exhibiting substantial buccal dehiscences were enrolled and randomized across 10 standardized centres. Treatments were demineralized allograft plus reconstituted and cross-linked collagen membrane (DFDBA + RECXC) or deproteinized bovine bone mineral with collagen plus native, bilayer collagen membrane (DBBMC + NBCM). Socket dimensions were recorded at baseline and 6 months. Wound closure and soft tissue inflammation were followed post-operatively, and biopsies were retrieved for histomorphometric analysis at 6 months.

Results: Primary endpoint: at 6 months, extraction socket horizontal measures were significantly greater for DBBMC + NBCM (average 1.76 mm greater, p = 0.0256). Secondary and Exploratory endpoints: (1) lingual and buccal vertical bone changes were not significantly different between the two treatment modalities, (2) histomorphometric % new bone and % new bone + graft were not significantly different, but significantly more graft remnants remained for DBBMC; (3) at 1 month, incision line gaps were significantly greater and more incision lines remained open for DFDBA + RECXC; (4) higher inflammation at 1 week tended to correlate with lower ridge preservation results; and (5) deeper socket morphologies with thinner bony walls correlated with better ridge preservation. Thirty-seven of 40 sites had sufficient ridge dimension for implant placement at 6 months; the remainder were DFDBA + RECXC sites.

Conclusion: DBBMC + NBCM provided better soft tissue healing and ridge preservation for implant placement. Deeper extraction sockets with higher and more intact bony walls responded more favourably to ridge preservation therapy.

Keywords: collagen membrane; demineralized allograft; extraction; guided bone regeneration; private practice; randomized controlled trial; ridge preservation; xenogeneic graft.

© 2016 The Authors. Journal of Clinical Periodontology Published by John Wiley & Sons Ltd.

Figures

Figure 1

(a) Baseline extraction socket measures insured that buccal wall mesial‐distal and vertical dehiscences were at least 1/3 of the overall extraction socket dimensions. (b & c) Measuring stents were fabricated from 0.020” thermoplastic and registered on adjacent teeth. The stents included three indexing holes for measuring ridge buccal‐lingual width, vertical height to the lingual wall and vertical height to the buccal wall.

Figure 2

Left column DFDBA + RECXC and right column DBBMC + NBCM. Top to bottom; original extraction socket illustrating extent of vertical and mesial‐distal dehiscences, graft placement, membrane coverage, closure, soft tissue appearance at 6 months, ridge preservation at 6 months.

Figure 3

Complete trephine biopsy sections (original magnification 50x, azure II and pararosaniline) for DFDBA + RECXC (left pair) and DBBMC + NBCM (right pair), showing both original staining and digital labelling for histomorphometry. (Note that the split in the DBBMC + NBCM section was artifactual.) Yellow lines in the lateral regions delineate old bone (OB) from new bone (NB) and define the healing area of the defects, which were further labelled for the following tissue types: (1) red for NB not in contact with graft, (2) pink for NB in contact with graft. Dark blue for DFDBA not in contact with NB, and light blue for DFDBA in contact with NB. Light green for DBBMC not in contact with NB, and dark green for DBBMC in contact with NB (composite overview scans, individual microphotographs original magnification x50).

Figure 4

(a) DFDBA graft prior to implantation showing different degrees of mineralization within the “virgin” grafting material: fully mineralized bone (mDB), partially demineralized bone (pDB), and almost completely demineralized bone (dDB), including osteocyte lacunae (OL) empty or filled with organic material. (b) Six month biopsy showing remineralization of DFDBA: demineralized DFDBA (dDB), mineralized DFDBA (mDB), remineralized DFDBA (rDB), and “island”‐like calcified structures (I) in the remineralization zone. (c) Resorption (R) of DFDBA by osteoclast (OC) – a phenomenon not observed with DBBMC. (d) Original, native bone (OB) with DBBMC (BB) embedded in connective tissue (CT) or in newly formed bone (NB). (e) A possible vascular channel in DBBMC within the coronal portion of the biopsy. (f) Woven new bone (wNB) with tightly integrated DBBMC (BB) granules forms a dense trabecular network; loose connective tissue is free of inflammation and densely vascularized.