Bacterial and Candida albicans adhesion on rapid prototyping-produced 3D-scaffolds manufactured as bone replacement materials A. Al-Ahmad, 1 M. Wiedmann-Al-Ahmad, 2 C. Carvalho, 3 M. Lang, 1 M. Follo, 4 G. Braun, 1 A. Wittmer, 5 R. Mu ¨ lhaupt, 3 E. Hellwig 1 1 Department of Operative Dentistry and Periodontology, Albert Ludwigs University, Freiburg, Germany 2 Department of Oral and Maxillofacial Surgery, Albert Ludwigs University, Freiburg, Germany 3 Freiburg Material Research Center and Institute for Macromolecular Chemistry, Albert Ludwigs University, Freiburg, Germany 4 Department of Hematology and Oncology, Albert-Ludwigs-University, Freiburg, Germany 5 Institute for Medical Microbiology and Hygiene, Albert Ludwigs University, Freiburg, Germany Received 15 June 2007; revised 2 October 2007; accepted 18 October 2007 Published online 28 January 2008 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/jbm.a.31832 Abstract: Rapid prototyping (RP)-produced scaffolds are gaining increasing importance in scaffold-guided tissue engineering. Microbial adhesion on the surface of replacement materials has a strong influence on healing and long-term outcome. Consequently, it is important to exam- ine the adherence of microorganisms on RP-produced scaf- folds. This research focussed on manufacturing of scaffolds by 3D-bioplotting and examination of their microbial adhe- sion characteristics. Tricalciumphosphate (TCP), calcium/so- dium alginate, and poly(lactide-co-glycolic acid) (PLGA) constructs were produced and used to study the adhesion of dental pathogens. Six oral bacterial strains, one Candida strain and human saliva were used for the adhesion studies. The number of colony forming units (CFU) were deter- mined and scanning electron microscopy (SEM) and confo- cal laser scanning microscopy (CLSM) were performed. Microorganisms adhered to all scaffolds. All strains, except for Streptococcus oralis, adhered best to PLGA scaffolds. Streptococcus oralis adhered to each of the biomaterials equally. Streptococcus mutans and Enterococcus faecalis adhered best to PLGA scaffolds, followed by alginate and TCP. Prevotella nigrescens, Porphyromonas gingivalis, Strepto- coccus sanguis, and Candida albicans showed the highest adherence to PLGA, followed by TCP and alginate. In contrast, the microorganisms of saliva adhered significantly better to TCP, followed by PLGA and alginate. SEM obser- vations correlated with the results of the CFU determina- tions. CLSM detected bacteria within deeper sheets of alginate. In conclusion, because of the high adherence rate of oral pathogens to the scaffolds, the application of these biomaterials for bone replacement in oral surgery could result in biomaterial-related infections. Strategies to decrease microbial adherence and to prevent infections due to oral pathogens are discussed. Ó 2008 Wiley Periodicals, Inc. J Biomed Mater Res 87A: 933–943, 2008 Key words: rapid prototyping; tissue engineering; bacterial colonization; dental pathogens; saliva INTRODUCTION The field of scaffold-guided tissue or bone engi- neering has rapidly developed in recent years. This method offers a promising new approach in recon- structive surgery. The loss of bone due to congenital or acquired pathology, such as trauma, tumor, or infection can be reconstructed by the use of vitalised biomaterials (cell/scaffold constructs). The scaffolds have to be biocompatible, biodegradable, and should also have good bone replacement properties. Addi- tionally, the scaffold material should enhance cell attachment, proliferation, and the expression of the native phenotype. However, at the same time it should reduce the extent and the kinetics of bacterial adhesion. 1,2 This is of primary importance because during surgical procedures the RP-produced scaf- folds which should be applied in patients could be exposed to bacteria from saliva or dental plaque. Thus, the scaffolds should have surfaces with pro- perties which are antimicrobial or which limit bacte- rial adhesion. Bacterial adhesion and colonization on scaffold surfaces can lead to foreign body infections or directly to the degradation of the scaffold by pro- teolytic bacterial enzymes and consequently to the failure of the replacement material. 3 Hung et al. 4 Correspondence to: A. Al-Ahmad; e-mail: ali.al-ahmad@ uniklinik-freiburg.de Ó 2008 Wiley Periodicals, Inc.