Novel silk protein barrier membranes for guided bone regeneration Ralf Smeets, 1* Christine Knabe, 2* Andreas Kolk, 3 Michael Rheinnecker, 4 Alexander Gr € obe, 1 Max Heiland, 1 Rolf Zehbe, 5 Manuela Sachse, 2 Christian Große-Siestrup, 4 Michael W€ oltje, 6* Henning Hanken 1* 1 Department of Oral and Maxillofacial Surgery, University Medical Center Hamburg-Eppendorf, Hamburg, Germany 2 Department of Experimental Orofacial Medicine, Philipps University Marburg, Marburg, Germany 3 Department of Oral- and Cranio-Maxillofacial Surgery, Klinikum rechts der Isar der Technischen Universit€ at M€ unchen, Munich, Germany 4 Spintec Engineering GmbH, Kurbrunnenstraße 22, 52066 Aachen, Germany 5 BLS Laboratories GmbH, Berlin, Germany 6 Institute of Textile Machinery and High Performance Material Technology, Technische Universit€ at Dresden, 01069 Dresden, Germany Received 15 October 2015; revised 30 August 2016; accepted 12 September 2016 Published online 00 Month 2016 in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/jbm.b.33795 Abstract: This study assesses the biocompatibility of novel silk protein membranes with and without modification, and evalu- ates their effect on facilitating bone formation and defect repair in guided bone regeneration. Two calvarian bone defects 12 mm in diameter were created in each of a total of 38 rabbits. Four different types of membranes, (silk-, hydroxyapatite- modified silk-, b-TCP-modified silk- and commonly clinically used collagen-membranes) were implanted to cover one of the two defects in each animal. Histologic analysis did not show any adverse tissue reactions in any of the defect sites indicating good biocompatibility of all silk protein membranes. Histomor- phometric and histologic evaluation revealed that collagen and b-TCP modified silk membranes supported bone formation (collagen: bone area fraction p 5 0.025; significant; b-TCP modi- fied silk membranes bone area fraction: p 5 0.24, not signifi- cant), guided bone regeneration and defect bridging. The bone, which had formed in defects covered by b-TCP modified silk membranes, displayed a more advanced stage of bone tissue maturation with restoration of the original calvarial bone micro- architecture when compared to the bone which had formed in defects, for which any of the other test membranes were used. Micro-CT analysis did not reveal any differences in the amount of bone formation between defects with and without mem- branes. In contrast to the collagen membranes, b-TCP modified silk membranes were visible in all cases and may therefore be advantageous for further supporting bone formation beyond 10 weeks and preventing soft tissue ingrowth from the periphery. V C 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 00B: 000–000, 2016. Key Words: guided bone regeneration, bone defect, silk, membrane, alveolar ridge augmentation How to cite this article: Smeets R, Knabe C, Kolk A, Rheinnecker M, Gr € obe A, Heiland M, Zehbe R, Sachse, M, Große-Siestrup C, W€ oltje M, Hanken H. 2016. Novel silk protein barrier membranes for guided bone regeneration. J Biomed Mater Res Part B 2016:00B:000–000. INTRODUCTION Due to the resorptive processes following tooth extraction, site development and reconstruction or augmentation of the alveolar ridges is frequently required before dental implan- tation. 1,2 The principle of guided bone regeneration, 3 which utilizes barrier membranes, has become a well stabilized procedure for lateral alveolar ridge augmentation. 4 A barrier membrane prevents migration of soft tissue cells and col- lapse of surrounding soft tissues into the defect cavity, and therefore serves as a space-maintaining device, which facili- tates bone ingrowth from the defect margins. 3,5–7 Generally, an ideal barrier membrane should be biocom- patible, occlusive, mechanically stable, and degradable. 8–10 However, biodegradable membranes often do not possess sufficient mechanical strength for preventing membrane col- lapse into the defect cavity. In addition, there is the risk of disease transmission with membranes of animal origin. In this context, silk represents a novel type of material that meets all properties required for barrier membranes. Silk has excellent mechanical strength without any associated risk of disease transmission of mammalian origin. An addi- tional advantage of silk barrier membranes is the possibility of surface modification by integration of calcium phosphate- based bone grafting materials such as hydroxyapatite and ß- TCP (ß-tricalcium phosphate). Both HA and b-TCP are well- known synthetic bioceramic bone grafting materials which are highly biocompatible, biodegradable, nonimmunogenic, and osteoconductive. 11 Various products made of HA, b-TCP *These authors contributed equally to the study. Correspondence to: R. Smeets; e-mail: r.smeets@uke.de V C 2016 WILEY PERIODICALS, INC. 1