DENTAL IMPLANTS Amoxicillin Administrations and Its Influence on Bone Repair Around Osseointegrated Implants Gabriela Giro, PhD, * Joon In, PhD,y Lukasz Witek, MS,z Rodrigo Granato, PhD,x Charles Marin, PhD,k Paulo G. Coelho, PhD,{ Juliana Cama Ramacciato, PhD,# and Rog erio Hel  adio Lopes Motta, PhD ** Purpose: The objective of this study was to evaluate the influence of 4 different amoxicillin administra- tion protocols on osseointegration of dental implants. Materials and Methods: Thirty-five Wistar rats received an implant in the right tibia and were divided into 5 groups (n = 7): the control group (G1), a group that received a single dose of amoxicillin suspension (40 mg/kg) hour before surgery (G2), a group that received amoxicillin suspension 1 hour before surgery and a 10-mg/kg dose every 12 hours for 3 days (G3), a group that received amoxicillin suspension 1 hour before surgery and a 10-mg/kg dose every 12 hours for 5 days (G4), and a group that received amoxicillin suspension 1 hour before surgery and a 10-mg/kg dose every 12 hours for 7 days (G5). The animals were sacrificed by anesthesia overdose 28 days after implant placement. The samples were retrieved for bone-to- implant contact (BIC) and bone area fraction occupancy (BAFO) analyses. Results: BIC analysis indicated 3 different statistical groups: G1 plus G2, G3, and G4 plus G5. There was no statistical difference between G1 and G2 or between G4 and G5. G3 presented lower values, with sta- tistical difference for G1 plus G2 and G4 plus G5. Also, a statistical difference was found between G1 plus G2 and G4 plus G5. For BAFO evaluation, no statistical difference was found for the experimental groups. Conclusion: The results of this study suggest that prolonged use of amoxicillin might have a negative effect on bone formation around implants. Ó 2014 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 72:305.e1-305.e5, 2014 For decades, dental implants have been widely used, with high success rates, to replace missing teeth. 1,2 However, implant failures can occur, and some factors, such as bacterial contamination during implant insertion, can cause early dental implant failure. 3,4 The contamination of the implant surface by bacterial biofilms during surgical procedures can lead to an inflammatory process of the hard and soft tissues, thus decreasing the implant success rate. 5 Likewise, infections around biomaterials are very difficult to treat and nearly all *Post Doctoral Fellow, Department of Periodontology and Oral Implantology, Dental Research Division, University of Guarulhos, Guarulhos, SP, Brazil. yPh.D. Graduate Student, Department of Pharmacology, Anesthesiology and Therapeutics, S~ ao Leopoldo Mandic Dental School, Campinas, SP, Brazil. zPh.D. Graduate Student, School of Chemical Engineering, Oklahoma State University, Stillwater, OK. xProfessor, Postgraduate Program in Dentistry, School of Health Sciences, Unigranrio University, Duque de Caxias, RJ, Brazil. kProfessor, Postgraduate Program in Dentistry, School of Health Sciences, Unigranrio University, Duque de Caxias, RJ, Brazil. {Director for Research, Department of Periodontology and Implant Dentistry; Assistant Professor of Biomaterials and Biomimetics, NewYork University College of Dentistry, New York, New York. #Professor, Department of Pharmacology, Anesthesiology and Therapeutics, S~ ao Leopoldo Mandic Dental School, Campinas, SP, Brazil. **Professor, Department of Pharmacology, Anesthesiology and Therapeutics, S~ ao Leopoldo Mandic Dental School, Campinas, SP, Brazil. Address correspondence and reprint requests to Dr Giro: Rua Car- los Gomes 2557, Araraquara, SP, Brazil; e-mail: gabi.giro@gmail.com Received June 11 2013 Accepted October 21 2013 Ó 2014 American Association of Oral and Maxillofacial Surgeons 0278-2391/13/01325-6$36.00/0 http://dx.doi.org/10.1016/j.joms.2013.10.013 305.e1