Biology and innovation. Keys to success in fixed prosthesis
Recently, a new modality in alveolar ridge preservation favoring the biological bases of bone healing has been described (Pramstraller et al. 2020). To discuss this technique, we talked to Prof. Leonardo Trombelli, director of research in periodontology at the University of Ferrara.
In the last decade, a multitude of techniques and materials for socket preservation have been introduced and published. In your opinion why haven’t we found a consensus about the best technique for ridge preservation?
Prof. Trombelli: Although a recent meta-analysis showed a significantly reduction in horizontal ridge dimension when a combination of a graft material (bovine bone particulate) plus socket sealing by a collagen membrane/sponge was used, the available data did not allow ranking the efficacy of different alveolar ridge preservation (ARP) approaches. This may at least in part be due to a wide heterogeneity of proposed techniques and devices used including flap management at suturing, chemical-physical characteristics of graft material, and additional socket sealing.
What are the short comings of the current commonly performed ARP approaches?
Prof. Trombelli: Although ARP procedures based on socket grafting can prevent up to a 30% of volume reduction in the coronal third, a limited effect was observed in the remaining middle-apical thirds. Moreover, grafting of the alveolus often results in the persistence of residual graft particles embedded into the newly formed bone with a delay in the rate of bone deposition and mineralization.
Recently you published a case report about a novel ARP modality. What is BARP? And what distinguishes this technique from other established ARP approaches?
Prof. Trombelli: Based on the previous considerations, we recently proposed a novel, simplified technique, namely the Biologically oriented Alveolar Ridge Preservation (BARP), that restricts socket grafting to the coronal portion of the socket (Fig. 1). Briefly, BARP is based on three layers of materials placed in the extraction socket: First a deep collagen layer filling the socket up to ≈4 to 5 mm from the most coronal extensions of the buccal and lingual crest to create a support for the coronal graft; Second a graft layer, placed on top of the apical collagen layer to fill the coronal part of the socket and third a superficial collagen layer, used to obtain socket sealing.
Fig. 1 modified from “A Simplified Procedure for Biologically-oriented Alveolar Ridge Preservation: Clinical and Histological Findings from a Case Report”. Pramstraller M, Farina R, Simonelli A, Götz W, Trombelli L., Clinical Advance in Periodontics. 2020.
Which are the main advantages of this technique (BARP)?
Prof. Trombelli: The clinical and histological observations derived from the published case and interim results from ongoing studies indicated three major advantages:
First, the deep collagen layer effectively supports the clot during the bone healing process. In the apical and central parts of the socket, abundant trabeculae of mature lamellar bone were evident, with minor signs of bone remodeling and minimal inflammation. Moreover, the deep collagen layer was able to maintain the graft particles confined to the coronal portion of the socket throughout the tissue maturation phase; Second the graft layer in the most coronal part of the socket limited the reduction in vertical and horizontal ridge dimensions. The magnitude of the effect was consistent with other studies where the use of the graft biomaterial was performed on the entire apico-coronal extension of the socket. Third, the superficial layer of collagen sponge used to stabilize clot and graft at socket entrance allowed a successful re-epithelialization of the area left intentionally exposed. This led to an unaltered apico-coronal dimension of the keratinized peri-implant mucosa.
What is the rationale behind the biomaterial choice for this technique?
Prof. Trombelli: The rationale of BARP is based on the optimization of the use of biomaterials while limiting the potential drawbacks from their application. In this respect, the selection of collafleece and cerabone has shown to be promising to ensure both stability of alveolar ridge dimensions and ideal conditions for bone healing process. We are currently validating our results in a prospective observational study and a randomized controlled trial.
A Simplified Procedure for Biologically‐oriented Alveolar Ridge Preservation: Clinical and Histological Findings From a Case Report
A recent systematic review failed to identify one approach for alveolar ridge preservation (ARP) with superior outcomes compared with the others. The present case report presents a novel, simplified technique for ARP, namely the Biologically‐oriented Alveolar Ridge Preservation (BARP), based on socket grafting and sealing.
After extraction of tooth #19, the socket was filled with a collagen sponge up to 4‐5 mm from the most coronal extension of the bone crest (deep collagen layer). A bovine‐derived xenograft was placed on top of the collagen sponge to fill the coronal part of the socket (graft layer). Socket sealing was then performed by placing a collagen sponge over the exposed portion of the graft (superficial collagen layer), and the wound healed by secondary intention. At implant insertion (4 months after ARP), limited reduction in bone width and no vertical change in ridge height were observed. Histological analysis of a biopsy specimen retrieved during implant site preparation showed a gradient ranging from interconnected trabeculae of mature, lamellar bone in the apical portion to cancellous bone incorporating a modest number of remodeled graft granules in the central portion. In the coronal portion, non‐mineralized tissue with sparse isles of newly formed cancellous bone and residual graft granules was found.
The present case report indicates that BARP might provide ideal conditions for preserving the pre‐existing alveolar ridge dimensions following tooth extraction while restricting any potential interference of the graft biomaterial with bone healing dynamics to the coronal part of the socket.