624 | wileyonlinelibrary.com/journal/jcpe J Clin Periodontol. 2018;45:624–634. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd 1 | INTRODUCTION Alveolar bone resorption after tooth loss or extraction can lead to insufficient bone volume, which negatively affects the prognosis of dental implants (Ashman, 2000; Esposito, Grusovin, Coulthard, & Worthington, 2006). Traditionally, bony defects have been classified according to anatomical deficiency as follows: horizontal, vertical or combinations. Vertical ridge augmentation has been reported to be successful, but with a low degree of predictability and a rather high complication rate (Esposito et al., 2009; Rocchietta, Fontana, & Simion, 2008). More predictable results have been obtained with horizontal bone augmentation (Donos, Mardas, & Chadha, 2008; Kuchler & von Arx, 2014). In addition, similar clinical and radiological results have been reported for implants placed with bone augmen- tation compared with those completely placed into pristine bone (Benic, Bernasconi, Jung, & Hämmerle, 2017). Numerous techniques have been described to reconstruct de- ficient alveolar ridges (Buser et al., 2002; Esposito et al., 2009). In the simultaneous treatment approach, guided bone regeneration (GBR) is associated with superior outcomes when compared to other procedures and has become the treatment of choice to provide optimal bone support for dental implants (Aghaloo & Moy, 2007; Accepted: 1 February 2018 DOI: 10.1111/jcpe.12877 CLINICAL INNOVATION REPORT Leucocyte- and platelet-rich fibrin block for bone augmentation procedure: A proof-of-concept study Simone Cortellini 1,2 | Ana B. Castro 1,2 | Andy Temmerman 1,2 | Jeroen Van Dessel 3 | Nelson Pinto 1,4 | Reinhilde Jacobs 3,5 | Marc Quirynen 1,2 1 Department of Oral Health Sciences, Section of Periodontology, KU Leuven, Leuven, Belgium 2 Dentistry, University Hospitals, KU Leuven, Leuven, Belgium 3 Department of Imaging and Pathology, Faculty of Medicine, OMFS-IMPATH Research Group, KU Leuven, Leuven, Belgium 4 Faculty of Dentistry, Postgraduate Implant Program, University of the Andes, Santiago, Chile 5 Oral and Maxillofacial Surgery, University Hospitals Leuven, Leuven, Belgium Correspondence Simone Cortellini, Department of Oral Health Sciences, Section of Periodontology, KU Leuven & Dentistry, University Hospitals, KU Leuven, Leuven, Belgium. Email: simone.cortellini@kuleuven.be Funding information The Section of Periodontology (KU Leuven) received unrestricted research grants from GC Europe N.V. (chair in bioregeneration) and Intra-Lock International Inc. (chair in optimized osseointegration). Jeroen Van Dessel is a researcher supported by Research Foundation Flanders (FWO). Abstract Aim: The objective of this proof-of-concept study was to investigate the effects of a new guided bone regeneration technique with a tissue engineering approach. Materials and Methods: This single cohort observational study evaluated the out- come of the leucocyte- and platelet-rich fibrin (L-PRF) Block for horizontal bone aug- mentation in the maxilla. The L-PRF Block is prepared by mixing a particulated biomaterial with chopped L-PRF membranes at a 50:50 ratio and adding liquid fi- brinogen to glue all together. Horizontal augmentation was assessed linearly and volumetrically immediately after surgery and 5–8 months later by matching consecu- tive cone beam computed tomography (CBCTs). Results: Ten patients (mean age of 50.7 years [±17.2]) representing 15 sites with hori- zontal alveolar deficiencies were included. Superimposition of pre-operative and posthealing CBCT scans showed an average linear horizontal bone gain of 4.6 mm (±2.3), 5.3 mm (±1.2) and 4.4 mm (±2.3), measured at 2, 6 and 10 mm from the alveo- lar crest, respectively. The volumetric gain was 1.05 cm 3 (±0.7) on average. The re- sorption rate after 5–8 months was 15.6% (±6.7) on average. Conclusions: L-PRF Block may be a suitable technique to augment deficient alveolar ridges. KEYWORDS bone augmentation, bone substitutes, bone volume, guided bone regeneration, leucocyte- and platelet-rich fibrin, leucocyte- and platelet-rich fibrin block, platelet concentrate, tissue engineering