title: Antimicrobial photodynamic therapy of S. mutans biofilms attached to relevant dental materials.
abstract: Antimicrobial Photodynamic therapy (aPDT) has demonstrated efficacy in situations where conventional antibiotic therapies can be challenged such as biofilms, gram-negative bacteria, and antimicrobial resistant organisms. Surface characteristics can affect biofilm adherence and integrity and so may modify the effectiveness of aPDT. This study investigates the killing efficacy of aPDT on S. mutans biofilms grown on relevant dental substrata, examining the killing efficacy and specifically the effects of aPDT on the biofilm matrix architecture.
  
  
  
  S. mutans (NCTC 10449) was grown in 48 hours biofilms on different substrata, specifically glass, titanium, and denture acrylic. During aPDT assays, the biofilms were treated with a purpurin based sensitizer ([25 ug/ml] in DMSO) for 30 minutes, then exposed to a 664 nm diode laser at light doses of 15, 30, and 45 J/cm2. Colony forming unit assays were performed to determine survival following treatment. Controls for comparison in survival assays consisted of (No light/No PS; No light/PS; and No light/DMSO). MAIR-IR spectroscopy analysis was performed to investigate aPDT effects on biofilm composition before and after jet impingement.
  
  
  
  Survival was greatly reduced in the biofilm cultures following the aPDT assays. All light doses achieved a greater then 3-log inactivation on 48 hours biofilms grown on polished denture acrylic. The higher light doses (45 and 30 J) achieved greater than 3-log inactivation in 48 hours biofilms grown on glass. The higher light doses (30 and 45 J/cm2) produced a 2-log inactivation in 48 hours biofilms grown on titanium. Multiple attenuated internal reflection infrared (MAIR-IR) spectroscopy data demonstrates enhanced loss of exopolysaccharide (EPS) and Amide in the aPDT treated biofilms following jet impingement.
  
  
  
  Antimicrobial PDT experiments using a purpurin based sensitizer and laser light doses of 15, 30, and 45 J/cm2, against S. mutans biofilm grown on different surfaces, show the effectiveness of this therapy. In CFU survival assays, a dose response to the laser is evident. While considerable disinfection was achieved on all surfaces compared to the controls, not all surfaces could be disinfected equally. MAIR-IR spectroscopy showed that aPDT groups lost more EPS and Amide versus controls, suggesting aPDT induced biofilm embrittlement, which was revealed by jet impingement. With demonstrated efficacy against various microbes and on different substrata, antimicrobial aPDT shows potential for clinical application in biofilm-mediated diseases such as peri-implantitis and periodontitis. Lasers Surg. Med. 48:995-1005, 2016. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Department of Oral and Maxillofacial Surgery, University at Buffalo School of Dental Medicine, 3435 Main St, Buffalo, New York, 14214.
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Zoccolillo
authors.affiliation: Department of Oral and Maxillofacial Surgery, University at Buffalo School of Dental Medicine, 3435 Main St, Buffalo, New York, 14214.
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Rogers
authors.affiliation: Department of Oral and Maxillofacial Surgery, University at Buffalo School of Dental Medicine, 3435 Main St, Buffalo, New York, 14214.
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Mang
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects*; D003764:Dental Materials; D050296:Microbial Viability / Q000187:drug effects*; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000494:pharmacology*; D013295:Streptococcus mutans / Q000187:drug effects* / Q000502:physiology
chemical_list: D000900:Anti-Bacterial Agents; D003764:Dental Materials; D017319:Photosensitizing Agents
keywords: antimicrobial photodynamic therapy; dental acrylic; titanium