d e n t a l m a t e r i a l s 2 9 ( 2 0 1 3 ) 656–665 Available online at www.sciencedirect.com jo ur nal ho me pag e: www.intl.elsevierhealth.com/journals/dema Controlled release of metronidazole from composite poly--caprolactone/alginate (PCL/alginate) rings for dental implants Shih-Feng Lan a , Timilehin Kehinde c , Xiangming Zhang a , Sharukh Khajotia a,b , David W. Schmidtke a,c , Binil Starly a,d,* a Bioengineering Center, University of Oklahoma, Norman, OK 73019, USA b College of Dentistry, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73117, USA c School of Chemical, Biological and Materials Engineering, University of Oklahoma, Norman, OK 73019, USA d School of Industrial & Systems Engineering, University of Oklahoma, Norman, OK 73019, USA a r t i c l e i n f o Article history: Received 28 August 2012 Received in revised form 21 December 2012 Accepted 11 March 2013 Keywords: Localized drug delivery Dental implants Poly--caprolactone Alginate Solvent casting Metronidazole a b s t r a c t Objective. Dental implants provide support for dental crowns and bridges by serving as abut- ments for the replacement of missing teeth. To prevent bacterial accumulation and growth at the site of implantation, solutions such as systemic antibiotics and localized delivery of bactericidal agents are often employed. The objective of this study was to demonstrate a novel method of controlled localized delivery of antibacterial agents to an implant site using a biodegradable custom fabricated ring. Methods. The study involved incorporating a model antibacterial agent (metronidazole) into custom designed poly--caprolactone/alginate (PCL/alginate) composite rings to produce the intended controlled release profile. The rings can be designed to fit around the body of any root form dental implants of various diameters, shapes and sizes. Results. In vitro release studies indicate that pure (100%) alginate rings exhibited an expected burst release of metronidazole in the first few hours, whereas Alginate/PCL composite rings produced a medium burst release followed by a sustained release for a period greater than 4 weeks. By varying the PCL/alginate weight ratios, we have shown that we can control the amount of antibacterial agents released to provide the minimal inhibitory concentra- tion (MIC) needed for adequate protection. The fabricated composite rings have achieved a 50% antibacterial agent release profile over the first 48 h and the remaining amount slowly released over the remainder of the study period. The PCL/alginate agent release characteris- tic fits the Ritger–Peppas model indicating a diffusion-based mechanism during the 30-day study period. Significance. The developed system demonstrates a controllable drug release profile and the potential for the ring to inhibit bacterial biofilm growth for the prevention of diseases such as peri-implantitis resulting from bacterial infection at the implant site. © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved. ∗ Corresponding author at: School of Industrial Engineering, 202 West Boyd Street, Room 116B, University of Oklahoma, Norman, OK 73019, USA. Tel.: +1 405 325 3725; fax: +1 405 3257555. E-mail address: starlyb@ou.edu (B. Starly). 0109-5641/$ – see front matter © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.dental.2013.03.014