Effects of Photodynamic Process (PDP) in Implant Osseointegration: A Histologic and Histometric Study in Dogs Paulo Esteves Pinto Faria, DDS, MS, PhD;* Daniela Nair Borges Felipucci, DDS, MS; † Andreza Ribeiro Simioni, MS, PhD; ‡ Fernando Lucas Primo, MS, PhD; § Antonio Cláudio Tedesco, MS, PhD; ¶ Luiz Antonio Salata, DDS, MS, PhD** ABSTRACT Background: The combination between photosensitivity substances with laser or light-emitting diode (LED) form the photodynamic therapy basis that consists of photosensitivity drug activated by low-frequency light. This mechanism is used in soft tissue healing process to improve the oxygen tension leading to a fast revascularization. Purpose: The objective of this study was to evaluate the effects of photosensitivity drugs activated through LED on osseointegration process. Materials and Methods: Eight mongrel dogs underwent implant therapy in four mandibular bone defects using 5.0 mm trephine drill on each side of the mandible. The defects were randomly filled up with (1) Nano emulsion, (2) liposome, (3) blood clot, and (4) autogenous bone. LED with visible and infrared light were applied after 48/72 postoperative hours on four dogs and after 96/120 postoperative hours in the other four dogs. All the animals were euthanized at 15 days after surgery. Ground sections slides were prepared from the experimental site for histomorphometry and histological analysis. Results: No difference was detected in the following parameters: bone-implant contact, bone inside the defect and crest level on LED 48/72. Significant difference was detected inside the defect when filled with autogenous bone (p = .0238) on LED 96/120. When LED 48/72 and LED 96/120 were compared, significant higher bone formation was detected when auto- genous bone on bone-implant contact (p = .0043) and bone inside the defect (p = .0008) was used. Conclusion: The use of photosensitivity drugs activated by LED demonstrated a tendency to stimulate bone formation, similar to autogenous bone graft on later time point. KEY WORDS: bone healing and osseointegration, photodynamic therapy INTRODUCTION Several clinical and experimental studies 1–11 reported the potential acceleration of tissue regeneration using light amplification by stimulated emission of radia- tion (laser) or light-emitting diode (LED) irradiation devices, both operating at low-energy intensity. In vitro studies using low-intensity lasers result in bone matrix formation for osteoblast cultures, 4,12 and proliferation and maturation of human osteoblasts. 13 Furthermore, experimental studies in vivo suggested that photo- dynamic therapy (PDT) accelerated bone healing in *Associate professor, Oral and Maxillofacial Surgery, School of Den- tistry of the University of Ribeirão Preto, São Paulo, Brazil; † doctorate fellow, Department of Dental Materials and Prosthodontics, Faculty of Dentistry of Ribeirão Preto, University of São Paulo, São Paulo, Brazil; ‡ doctorate fellow, Institute of Research and Development, Laboratory of Organic Synthesis, University of Paraíba Valley, São José dos Campos, Brazil; § doctorate fellow, Department of Chemistry, Faculty of Philosophy and Science at Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil; ¶ full professor, Department of Chemis- try, Group of Photobiology and Photo Medicine, Faculty of Philoso- phy and Science at Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil; **associate professor, Department of Oral and Maxil- lofacial Surgery and Periodontics, Faculty of Dentistry, University of São Paulo, Ribeirão Preto, Brazil Corresponding Author: Prof. Luiz A. Salata, Faculty of Dentistry, University of São Paulo at Ribeirão Preto, Av. do Café, S/N – Campus USP, 14040-904, Ribeirão Preto, São Paulo, Brazil; e-mail: lasalata@forp.usp.br © 2014 Wiley Periodicals, Inc. DOI 10.1111/cid.12204 1