Biomodulative Effects of Visible and IR Laser Light on the Healing of Cutaneous Wounds of Nourished and Undernourished Wistar Rats Antonio Luiz Barbosa Pinheiro, Ph.D., MDentSci, D.D.S., 1,2 Gyselle Cynthia Silva Meireles, Ph.D., 1 Carolina Montagn Carvalho, Ph.D., 1 Luciana Maria Pedreira Ramalho, Ph.D., 2 and Jean Nunes dos Santos, Ph.D. 2 Abstract Aim: We evaluated histologically the differences in the healing of cutaneous wounds on nourished or under- nourished rats following laser phototherapy (LPT) (20 or 40 J=cm 2 ). Background: Wound healing occurs due to a competitive mechanism between the synthesis and lysis of collagen. Any factor that increases the lysis or reduces the synthesis of collagen may change the healing process. Nutritional deficiencies have a great effect on wound healing. Methods: Fifty nourished or undernourished Wistar rats had one standardized wound created on the dorsum and were divided into 10 subgroups: Control (standard diet); Control [Northeastern Brazilian basic diet (DBR)]; Standard diet þ LPT (l635 nm; spatial average energy fluence (SAEF) 20 J=cm 2 ); Standard diet þ LPT (l635 nm; SAEF 40 J=cm 2 ); Standard diet þ LPT (l780 nm; SAEF 20 J=cm 2 ); Standard diet þ LPT (l780 nm; SAEF 40 J=cm 2 ); DBR þ LPT (l635 nm; SAEF 20 J=cm 2 ); DBR þ LPT (l635 nm; SAEF 40 J=cm 2 ); DBR þ LPT (l780 nm; SAEF 20 J=cm 2 ); DBR þ LPT (l780 nm; SAEF 40 J=cm 2 ). The first application of the treatment was carried out immediately and repeated daily for seven days. The specimens were routinely processed to wax, cut, stained with H&E and Sirius Red stains, and analyzed using light microscopy. The analyses included re-epithelization, inflammatory infiltrate, and fibroblastic proliferation. Sirius Red stained slides were used to perform descriptive analyses of the collagen fibers. Results: The results showed that LPT with l635 wavelength was more effective for the treatment of undernourished subjects, treated with either LPT with l730 nm with SAEF of 20 J=cm 2 or l780 nm with SAEF of 40 J=cm 2 . Conclusion: Nutritional status influenced the progression of the healing process as well as the quality of the healed tissue. In addition, the use of both wavelengths resulted in a positive biomodulatory effect on both nourished and undernourished subjects. Introduction A wound represents the interruption, anatomical or functional, of the continuity of a given tissue that is fol- lowed by damage or cellular death. Wound healing happens due to a competitive mechanism between the synthesis and lysis of collagen. Because of that, any factor that increases the lysis or reduces the synthesis of collagen may result in chan- ges in the healing process. 1 The factors that affect healing may be divided into sys- temic or local; in other words, those factors that influence the inflammatory response. 2 Nutritional deficiencies, including Ca, Mg, K, Zn, Mg, Fe, Cu, I, Cr, active enzymes, antioxidants, vitamins, minerals, and amino acids, have a great effect on wound healing by changing tissue regeneration through in- terference with inflammatory reactions and immunological function at any point of the healing process. 3 It has been shown that delayed healing may occur in subjects with de- ficiency in any one of the essential nutrients. 4,5 However, this situation reverts to normality upon the introduction of a diet with appropriate levels of nutrients. 1 Laser phototherapy (LPT) is used in many biomedical applications to promote tissue regeneration, and it has been shown to possess several advantages, including the control of pain, stimulation of the healing process, anti-inflammatory action, increase in the production of collagen, increase in fi- broblastic proliferation, and increase in local microvascul- arization. 6,7 1 Laser Center, School of Dentistry, Federal University of Bahia, Salvador, BA, Brazil. 2 Departament of Propedeutica and Clinica Integrada, School of Dentistry, Federal University of Bahia, Salvador, BA, Brazil. Photomedicine and Laser Surgery Volume 27, Number 6, 2009 ª Mary Ann Liebert, Inc. Pp. 947–957 DOI: 10.1089=pho.2009.2607 947