Guest Editorial
Photomedicine and Laser Surgery Volume 32, Number 11, 2014 ª Mary Ann Liebert, Inc. Pp. 589–591 DOI: 10.1089/pho.2014.9855
Photodynamic Antimicrobial Chemotherapy as a Strategy for Dental Caries: Building a More Conservative Therapy in Restorative Dentistry Mary Anne S. Melo, DDS, MSc, PhD
D
ental caries, the most widespread disease affecting humans, is a worldwide challenge and economic burden.1 Its treatment has high cost implications both in monetary and biological (tooth cavity, pain, endodontic infections, and tooth loss) terms.2 Patients are susceptible to this disease throughout their lifetime. This disease forms through a complex interaction over time between acid-producing bacteria organized in biofilms, and fermentable carbohydrates that produce progressive demineralization of dental tissue.3 The elimination/reduction of cariogenic biofilm formation over the tooth surface as well the management of cavitated lesions in advanced stages are still challenging occurrences in everyday dental practice.4 The presence of cariogenic biofilm is closely related to the development of dental caries. Cariogenic bacteria produce acids that promote and increase lesion development by perpetuating the acidic environment represented by net mineral loss and carious lesion formation.5 The suppression of these disease-related micro-organisms is an important requirement for the prevention and therapy of dental caries.6 Streptococcus mutans remains deserving of detailed study, as an exemplar of an acidogenic, aciduric plaque bacterium, and because it shows a strong association with caries; however, the set of oral pathogens that form complex biofilms has so far been considered to be particularly difficult to suppress.7 For a sufficient elimination of bacteria organized in biofilms, high doses of antimicrobial drugs are needed that might lead to unfavorable side effects. For cavitated teeth in advanced stages, the traditional management has involved removal of all soft demineralized dentine before a filling is placed.8 The rationale for this has been to prevent further caries development caused by remaining bacteria in the demineralized inner layer. The difficulty with this approach is the imminent risk of pulp exposure during the caries excavation procedures, with damage to the nerve of the tooth.9 In addition, removal of all of the caries lesions has some disadvantages, including toothache and possibly weakening of the tooth structure.10 New scientific developments in cariology and diagnostic systems have shifted dentistry’s approach toward minimal intervention. Contemporary restorative dentistry has con-
sidered removing the infected layer of dentine, leaving the affected layer to preserve the integrity of the tooth. However, the total disinfection of the remaining dental tissue cannot be guaranteed. Eradication of bacterial pathogens related to dental caries with a noninvasive method is an important issue for oral care. Antimicrobial photodynamic therapy, also known as photodynamic antimicrobial chemotherapy (PACT), has entered the dentistry field as a well-suited avenue for the control of bacteria in oral plaque biofilms where there is relatively easy access for application of the photosensitizing (PS) agent and light sources to areas requiring treatment.11 Therefore, use of PACT as modality for the treatment of localized microbial infections following similar principles to those of photodynamic therapy (PDT) has gained greater attention with its applicability to different fields of dentistry such as periodontics, endodontics, and oral medicine.12 Large classes of micro-organisms, such as gram-positive and gram-negative bacteria, fungi, and viruses, including a large number of oral micro-organisms, have been effectively inactivated by PACT with a wide range of PS, both natural and synthetic, available with differing physicochemical makeup and light-absorption properties.13,14 Considering this, some investigators have also advocated the clinical application of PACT therapy as a possible adjunctive tool for a conservative approach for caries management in restorative dentistry, and to fight against cariogenic bacteria organized in biofilms that present increased resistance to conventional antibacterial treatment.15 Because of its specific mechanism of action, PACT offers the particular advantage of immediate bacterial reduction; a condition only reached by other approaches after the treatment stages of two visits with a long time interval between them (*3–6 months).10 PACT for caries-related bacteria has been characterized as a process in which micro-organisms are treated with a PS drug and then irradiated with low-intensity visible lights of the appropriate wavelength. Usually, red or blue light sources, such as noncoherent light-emitting diodes (LED) and low-intensity lasers, are used, because these wavelengths are compatible with the most used PS available in dentistry. These light sources are easily available and present other clinical applications in restorative dentistry.
Department of Endodontics, Prosthodontics and Operative Dentistry University of Maryland School of Dentistry, Baltimore, Maryland.
589
590
Blue LED is often used in restorative dentistry for photocuring of resin-based dental materials.16 A number of study groups have investigated the susceptibility of cariogenic species to photoinactivation. With this approach, gram-positive species such as S. mutans, Streptococcus sobrinus, various lactobacilli, and Actinomyces viscosus do appear to have their numbers greater reduced by more than tenfold by PACT when growing in liquid (planktonic) cultures and biofilms.17,18 The initial experience with PACT in carious tissue suggested positive response and prolonged control expressed by Williams et al. in a collagen matrix that resembled demineralized dentine19 and by Wilson et al. in extracted carious teeth.20 Our group experience with PACT reported the bacterial killing response of this approach using different in vitro and in situ models that expose dentin samples to the oral environment. The bacterial reduction using similar protocol [red LED; 94 J/cm2; toluidine blue O (TBO) at 100 lg mL - 1] are slightly minimized in carious substrate produced by these models reaching significant reduction ( > 3 log10).21–23 In view of promising pre-clinical results, in vivo studies have been suggested to support the bacterial reduction response obtained by PACT; however, relatively few in-depth studies have been published on this subject. Longo et al.24 reported that PACT promoted a mean reduction of 82% of total bacteria in the treated cavities using aluminumchloride-phthalocyanine associated with red laser. Guglielmi et al.25 showed a range of log reduction from 0.91 to 1.38 using methylene blue dye and a red low-power laser. A similar outcome was reported by a clinical trial underway that evaluated microbial outcome promoted by PACT in dental caries.26 Although the data from clinical trials cannot yet provide substantial evidence to support the effectiveness promoted by PACT, these studies identify challenges being faced to improve the performance of this therapy for caries management and oral biofilm inhibition. To promote the desired therapeutic effect, knowledge of both light and PS distribution through target-tooth substrate is essential for dental caries treatment.27 The depth of diffusion of the PS and the light certifying that they reach the full extent of carious tissue may influence the outcome. Moreover, the assignment of the appropriate light intensity (energy delivered) and PS dose (concentration, solubility, and polarity) to be used in each specific treatment would contribute to the development of an optimized practical protocol to be adopted for PACT in restorative dentistry. Notwithstanding these concerns, the information obtained can make possible investigative overcoming strategies and end-points for further research trials. Despite all of the abovementioned considerations, PACT is returning to its origins in microbiology and is offering an alternative treatment for destroying oral micro-organisms. PACT in contemporary restorative dentistry possesses a future related to its potential for one-step high-level disinfection of the tooth cavity, and has led to a plethora of publications and patent applications. The recent advances in pre-clinical research and the development of reliable in vivo data (animal, in situ models) and clinical trials under investigation continue to provide cautious optimism that an effective clinical decision support to PACT for dental caries
MELO
will eventually emerge. We expect to see more enhanced application of PACT to improve dental caries management in the years to come. References
1. United States Department of Health and Human Services, Centers for Disease Control and Prevention (2010). Oral health: preventing cavities, gum disease, tooth loss, and oral cancers: At a glance 2010. Available at: http://www .cdc.gov/chronicdisease/resources/publications/AAG/doh (Last accessed August 14, 2014). 2. United States Government Accountability Office (2008). Medicaid: extent of dental disease in children has not decreased and millions are estimated to have untreated tooth decay (GAO-08-1211). Available at http://www.gao.gov/ new.items/d081211 (Last accessed August 14, 2014). 3. Selwitz, R.H., Ismail, A.I., and Pitts, N.B. (2007). Dental caries. Lancet 369, 51–59. 4. Zarco, M.F., Vess, T.J., and Ginsburg G.S. (2012). The oral microbiome in health and disease and the potential impact on personalized dental medicine. Oral Dis. 18, 109–120. 5. Marsh, P.D. (2003). Are dental diseases examples of ecological catastrophes? Microbiology 149, 279–294. 6. De Soet, J.J., Nyvad, B., and Kilian, M. (2000). Strainrelated acid production by oral streptococci. Caries Res. 34, 486–490. 7. Kleinberg, I. (2002). A mixed-bacteria ecological approach to understanding the role of the oral bacteria in dental caries causation: an alternative to Streptococcus mutans and the specific-plaque hypothesis. Crit. Rev. Oral Biol. Med. 13, 108–125. 8. Bjørndal, L., and Kidd, E.A. (2005). The treatment of deep dentine caries lesions. Dent. Update 32, 402–413. 9. Ricketts, D., Lamont, T., Innes, N.P., Kidd, E., and Clarkson, J.E. (2013). Operative caries management in adults and children. Cochrane Database Syst. Rev. 3, CD003808. 10. Orhan, A.I., Oz, F.T., and Orhan, K. (2010). Pulp exposure occurrence and outcomes after 1- or 2-visit indirect pulp therapy vs complete caries removal in primary and permanent molars. Pediatr Dent. 32, 347–355. 11. Konopka, K., and Goslinski, T. (2007). Photodynamic therapy in dentistry. J. Dent. Res. 86, 694–707. 12. Komerik, N., and MacRobert, A.J. (2006). Photodynamic therapy as an alternative antimicrobial modality for oral infections. J. Environ. Pathol. Toxicol. Oncol. 25, 487–504. 13. Kharkwal, G.B., Sharma, S.K., Huang, Y.Y., Dai, T., and Hamblin, M.R. (2011). Photodynamic therapy for infections: clinical applications. Lasers Surg. Med. 43, 755–767. 14. Rolim, J.P.M.L., Melo, M.A.S., Guedes, S.F., Albuquerque-Filho, F.B., Souza, J.R., Nogueira, N.A.P., Zanin, I.C.J., and Rodrigues, L.K.A. (2012). The antimicrobial activity of photodynamic therapy against Streptococcus mutans using different photosensitizers. J. Photochem. Photobiol. 5, 40–46. 15. Arau´jo, N.C., Fontana, C.R., Bagnato, V.S., and Gerbi, M.E. (2014). Photodynamic antimicrobial therapy of curcumin in biofilms and carious dentine. Lasers Med. Sci. 29, 629–635. 16. Feuerstein, O. (2012). Light therapy: complementary antibacterial treatment of oral biofilm. Adv. Dent. Res. 24, 103–107. 17. Bevilacqua, I.M., Nicolau, R.A., Khouri, S., Brugnera, A. Jr., Teodoro, G.R., Zaˆngaro, R.A., and Pacheco, M.T. (2007). The impact of photodynamic therapy on the viability of Streptococcus mutans in a planktonic culture. Photomed. Laser Surg. 25, 513–518.
PACT AND DENTAL CARIES
18. Zanin, I.C.J., Goncalves, R.B., Brugnera, A. Jr., Hope, C.K., and Pratten, J. (2005). Susceptibility of Streptococcus mutans biofilms to photodynamic therapy: an in vitro study. J. Antimicrob. Chemother. 56, 324–330. 19. Williams, J.A., Pearson, G.J., Colles, M.J., and Wilson, M. (2003). The effect of variable energy input from a novel light source on the photoactivated bactericidal action of toluidine blue O on Streptococcus Mutans. Caries Res. 37, 190–193. 20. Wilson, M. (2004). Lethal photosensitisation of oral bacteria and its potential application in the photodynamic therapy of oral infections. Photochem. Photobiol. Sci. 3, 412–418. 21. Melo, M.A.S., De-Paula, D.M., Lima, J.P.M., Borges, F.M.C., Steiner-Oliveira, C., Nobre-Dos-Santos, M., Zanin, I.C.J., Barros, E.B., and Rodrigues, L.K.A. (2010). In vitro photodynamic antimicrobial chemotherapy in dentine contaminated by cariogenic bacteria. Laser Phys. 20, 1–10. 22. Lima, J.P.M., Sampaio De Melo, M.A., Borges, F.M., Teixeira, A.H., Steiner-Oliveira, C., Nobre Dos Santos, M., Rodrigues, L.K., and Zanin, I.C. (2009). Evaluation of the antimicrobial effect of photodynamic antimicrobial therapy in an in situ model of dentine caries. Eur. J. Oral Sci. 117, 568–574. 23. Monteiro-Oliveira, M.A., Rodrigues, L.K.A., Melo, M.A.S., and Nobre-dos-Santos, M. (2010). Photodynamic therapy effect in carious bovine dentin - an in vitro study. J. Oral Laser Appl. 29, 36. 24. Longo, J.P., Leal, S.C., Simioni, A.R., de Fa´tima Menezes Almeida-Santos, M., Tedesco, A.C., and Azevedo, R.B. (2012). Photodynamic therapy disinfection of carious tissue
591
mediated by aluminum-chloride-phthalocyanine entrapped in cationic liposomes: an in vitro and clinical study. Lasers Med. Sci. 27, 575–584. 25. Guglielmi, C.A., Simionato, M.R., Ramalho, K.M., Imparato, J.C.P., Pinheiro, S.L., and Luz, M.A.A.C. (2011). Clinical use of photodynamic antimicrobial chemotherapy for the treatment of deep carious lesions. J. Biomed. Opt. 16, 088003. 26. Borges, F.M.C., Melo, M.A.S., Lima, J.P.M., Zanin, I.C.J., Rodrigues, L.K.A., and Nobre-dos-santos, M. (2010). Evaluation of the effect of photodynamic antimicrobial therapy in dentin caries: a pilot in vivo study. SPIE Proc. 75490. 27. Melo, M.A., Rolim, J.P., Zanin, I.C., Silva, J.J., Paschoal, A.R., Ayala, A.P., and Rodrigues, L.K. (2013). A comparative study of the photosensitizer penetration into artificial caries lesions in dentin measured by the confocal Raman microscopy. Photochem. Photobiol. [Epub ahead of print]
Address correspondence to: Mary Anne S. Melo Department of Endodontics, Prosthodontics and Operative Dentistry University of Maryland School of Dentistry 650 W. Baltimore St. Baltimore, MD 21201 E-mail: [email protected]
Photomedicine and Laser Surgery Volume 32, Number 11, 2014 ª Mary Ann Liebert, Inc. Pp. 589–591 DOI: 10.1089/pho.2014.9855
Photodynamic Antimicrobial Chemotherapy as a Strategy for Dental Caries: Building a More Conservative Therapy in Restorative Dentistry Mary Anne S. Melo, DDS, MSc, PhD
D
ental caries, the most widespread disease affecting humans, is a worldwide challenge and economic burden.1 Its treatment has high cost implications both in monetary and biological (tooth cavity, pain, endodontic infections, and tooth loss) terms.2 Patients are susceptible to this disease throughout their lifetime. This disease forms through a complex interaction over time between acid-producing bacteria organized in biofilms, and fermentable carbohydrates that produce progressive demineralization of dental tissue.3 The elimination/reduction of cariogenic biofilm formation over the tooth surface as well the management of cavitated lesions in advanced stages are still challenging occurrences in everyday dental practice.4 The presence of cariogenic biofilm is closely related to the development of dental caries. Cariogenic bacteria produce acids that promote and increase lesion development by perpetuating the acidic environment represented by net mineral loss and carious lesion formation.5 The suppression of these disease-related micro-organisms is an important requirement for the prevention and therapy of dental caries.6 Streptococcus mutans remains deserving of detailed study, as an exemplar of an acidogenic, aciduric plaque bacterium, and because it shows a strong association with caries; however, the set of oral pathogens that form complex biofilms has so far been considered to be particularly difficult to suppress.7 For a sufficient elimination of bacteria organized in biofilms, high doses of antimicrobial drugs are needed that might lead to unfavorable side effects. For cavitated teeth in advanced stages, the traditional management has involved removal of all soft demineralized dentine before a filling is placed.8 The rationale for this has been to prevent further caries development caused by remaining bacteria in the demineralized inner layer. The difficulty with this approach is the imminent risk of pulp exposure during the caries excavation procedures, with damage to the nerve of the tooth.9 In addition, removal of all of the caries lesions has some disadvantages, including toothache and possibly weakening of the tooth structure.10 New scientific developments in cariology and diagnostic systems have shifted dentistry’s approach toward minimal intervention. Contemporary restorative dentistry has con-
sidered removing the infected layer of dentine, leaving the affected layer to preserve the integrity of the tooth. However, the total disinfection of the remaining dental tissue cannot be guaranteed. Eradication of bacterial pathogens related to dental caries with a noninvasive method is an important issue for oral care. Antimicrobial photodynamic therapy, also known as photodynamic antimicrobial chemotherapy (PACT), has entered the dentistry field as a well-suited avenue for the control of bacteria in oral plaque biofilms where there is relatively easy access for application of the photosensitizing (PS) agent and light sources to areas requiring treatment.11 Therefore, use of PACT as modality for the treatment of localized microbial infections following similar principles to those of photodynamic therapy (PDT) has gained greater attention with its applicability to different fields of dentistry such as periodontics, endodontics, and oral medicine.12 Large classes of micro-organisms, such as gram-positive and gram-negative bacteria, fungi, and viruses, including a large number of oral micro-organisms, have been effectively inactivated by PACT with a wide range of PS, both natural and synthetic, available with differing physicochemical makeup and light-absorption properties.13,14 Considering this, some investigators have also advocated the clinical application of PACT therapy as a possible adjunctive tool for a conservative approach for caries management in restorative dentistry, and to fight against cariogenic bacteria organized in biofilms that present increased resistance to conventional antibacterial treatment.15 Because of its specific mechanism of action, PACT offers the particular advantage of immediate bacterial reduction; a condition only reached by other approaches after the treatment stages of two visits with a long time interval between them (*3–6 months).10 PACT for caries-related bacteria has been characterized as a process in which micro-organisms are treated with a PS drug and then irradiated with low-intensity visible lights of the appropriate wavelength. Usually, red or blue light sources, such as noncoherent light-emitting diodes (LED) and low-intensity lasers, are used, because these wavelengths are compatible with the most used PS available in dentistry. These light sources are easily available and present other clinical applications in restorative dentistry.
Department of Endodontics, Prosthodontics and Operative Dentistry University of Maryland School of Dentistry, Baltimore, Maryland.
589
590
Blue LED is often used in restorative dentistry for photocuring of resin-based dental materials.16 A number of study groups have investigated the susceptibility of cariogenic species to photoinactivation. With this approach, gram-positive species such as S. mutans, Streptococcus sobrinus, various lactobacilli, and Actinomyces viscosus do appear to have their numbers greater reduced by more than tenfold by PACT when growing in liquid (planktonic) cultures and biofilms.17,18 The initial experience with PACT in carious tissue suggested positive response and prolonged control expressed by Williams et al. in a collagen matrix that resembled demineralized dentine19 and by Wilson et al. in extracted carious teeth.20 Our group experience with PACT reported the bacterial killing response of this approach using different in vitro and in situ models that expose dentin samples to the oral environment. The bacterial reduction using similar protocol [red LED; 94 J/cm2; toluidine blue O (TBO) at 100 lg mL - 1] are slightly minimized in carious substrate produced by these models reaching significant reduction ( > 3 log10).21–23 In view of promising pre-clinical results, in vivo studies have been suggested to support the bacterial reduction response obtained by PACT; however, relatively few in-depth studies have been published on this subject. Longo et al.24 reported that PACT promoted a mean reduction of 82% of total bacteria in the treated cavities using aluminumchloride-phthalocyanine associated with red laser. Guglielmi et al.25 showed a range of log reduction from 0.91 to 1.38 using methylene blue dye and a red low-power laser. A similar outcome was reported by a clinical trial underway that evaluated microbial outcome promoted by PACT in dental caries.26 Although the data from clinical trials cannot yet provide substantial evidence to support the effectiveness promoted by PACT, these studies identify challenges being faced to improve the performance of this therapy for caries management and oral biofilm inhibition. To promote the desired therapeutic effect, knowledge of both light and PS distribution through target-tooth substrate is essential for dental caries treatment.27 The depth of diffusion of the PS and the light certifying that they reach the full extent of carious tissue may influence the outcome. Moreover, the assignment of the appropriate light intensity (energy delivered) and PS dose (concentration, solubility, and polarity) to be used in each specific treatment would contribute to the development of an optimized practical protocol to be adopted for PACT in restorative dentistry. Notwithstanding these concerns, the information obtained can make possible investigative overcoming strategies and end-points for further research trials. Despite all of the abovementioned considerations, PACT is returning to its origins in microbiology and is offering an alternative treatment for destroying oral micro-organisms. PACT in contemporary restorative dentistry possesses a future related to its potential for one-step high-level disinfection of the tooth cavity, and has led to a plethora of publications and patent applications. The recent advances in pre-clinical research and the development of reliable in vivo data (animal, in situ models) and clinical trials under investigation continue to provide cautious optimism that an effective clinical decision support to PACT for dental caries
MELO
will eventually emerge. We expect to see more enhanced application of PACT to improve dental caries management in the years to come. References
1. United States Department of Health and Human Services, Centers for Disease Control and Prevention (2010). Oral health: preventing cavities, gum disease, tooth loss, and oral cancers: At a glance 2010. Available at: http://www .cdc.gov/chronicdisease/resources/publications/AAG/doh (Last accessed August 14, 2014). 2. United States Government Accountability Office (2008). Medicaid: extent of dental disease in children has not decreased and millions are estimated to have untreated tooth decay (GAO-08-1211). Available at http://www.gao.gov/ new.items/d081211 (Last accessed August 14, 2014). 3. Selwitz, R.H., Ismail, A.I., and Pitts, N.B. (2007). Dental caries. Lancet 369, 51–59. 4. Zarco, M.F., Vess, T.J., and Ginsburg G.S. (2012). The oral microbiome in health and disease and the potential impact on personalized dental medicine. Oral Dis. 18, 109–120. 5. Marsh, P.D. (2003). Are dental diseases examples of ecological catastrophes? Microbiology 149, 279–294. 6. De Soet, J.J., Nyvad, B., and Kilian, M. (2000). Strainrelated acid production by oral streptococci. Caries Res. 34, 486–490. 7. Kleinberg, I. (2002). A mixed-bacteria ecological approach to understanding the role of the oral bacteria in dental caries causation: an alternative to Streptococcus mutans and the specific-plaque hypothesis. Crit. Rev. Oral Biol. Med. 13, 108–125. 8. Bjørndal, L., and Kidd, E.A. (2005). The treatment of deep dentine caries lesions. Dent. Update 32, 402–413. 9. Ricketts, D., Lamont, T., Innes, N.P., Kidd, E., and Clarkson, J.E. (2013). Operative caries management in adults and children. Cochrane Database Syst. Rev. 3, CD003808. 10. Orhan, A.I., Oz, F.T., and Orhan, K. (2010). Pulp exposure occurrence and outcomes after 1- or 2-visit indirect pulp therapy vs complete caries removal in primary and permanent molars. Pediatr Dent. 32, 347–355. 11. Konopka, K., and Goslinski, T. (2007). Photodynamic therapy in dentistry. J. Dent. Res. 86, 694–707. 12. Komerik, N., and MacRobert, A.J. (2006). Photodynamic therapy as an alternative antimicrobial modality for oral infections. J. Environ. Pathol. Toxicol. Oncol. 25, 487–504. 13. Kharkwal, G.B., Sharma, S.K., Huang, Y.Y., Dai, T., and Hamblin, M.R. (2011). Photodynamic therapy for infections: clinical applications. Lasers Surg. Med. 43, 755–767. 14. Rolim, J.P.M.L., Melo, M.A.S., Guedes, S.F., Albuquerque-Filho, F.B., Souza, J.R., Nogueira, N.A.P., Zanin, I.C.J., and Rodrigues, L.K.A. (2012). The antimicrobial activity of photodynamic therapy against Streptococcus mutans using different photosensitizers. J. Photochem. Photobiol. 5, 40–46. 15. Arau´jo, N.C., Fontana, C.R., Bagnato, V.S., and Gerbi, M.E. (2014). Photodynamic antimicrobial therapy of curcumin in biofilms and carious dentine. Lasers Med. Sci. 29, 629–635. 16. Feuerstein, O. (2012). Light therapy: complementary antibacterial treatment of oral biofilm. Adv. Dent. Res. 24, 103–107. 17. Bevilacqua, I.M., Nicolau, R.A., Khouri, S., Brugnera, A. Jr., Teodoro, G.R., Zaˆngaro, R.A., and Pacheco, M.T. (2007). The impact of photodynamic therapy on the viability of Streptococcus mutans in a planktonic culture. Photomed. Laser Surg. 25, 513–518.
PACT AND DENTAL CARIES
18. Zanin, I.C.J., Goncalves, R.B., Brugnera, A. Jr., Hope, C.K., and Pratten, J. (2005). Susceptibility of Streptococcus mutans biofilms to photodynamic therapy: an in vitro study. J. Antimicrob. Chemother. 56, 324–330. 19. Williams, J.A., Pearson, G.J., Colles, M.J., and Wilson, M. (2003). The effect of variable energy input from a novel light source on the photoactivated bactericidal action of toluidine blue O on Streptococcus Mutans. Caries Res. 37, 190–193. 20. Wilson, M. (2004). Lethal photosensitisation of oral bacteria and its potential application in the photodynamic therapy of oral infections. Photochem. Photobiol. Sci. 3, 412–418. 21. Melo, M.A.S., De-Paula, D.M., Lima, J.P.M., Borges, F.M.C., Steiner-Oliveira, C., Nobre-Dos-Santos, M., Zanin, I.C.J., Barros, E.B., and Rodrigues, L.K.A. (2010). In vitro photodynamic antimicrobial chemotherapy in dentine contaminated by cariogenic bacteria. Laser Phys. 20, 1–10. 22. Lima, J.P.M., Sampaio De Melo, M.A., Borges, F.M., Teixeira, A.H., Steiner-Oliveira, C., Nobre Dos Santos, M., Rodrigues, L.K., and Zanin, I.C. (2009). Evaluation of the antimicrobial effect of photodynamic antimicrobial therapy in an in situ model of dentine caries. Eur. J. Oral Sci. 117, 568–574. 23. Monteiro-Oliveira, M.A., Rodrigues, L.K.A., Melo, M.A.S., and Nobre-dos-Santos, M. (2010). Photodynamic therapy effect in carious bovine dentin - an in vitro study. J. Oral Laser Appl. 29, 36. 24. Longo, J.P., Leal, S.C., Simioni, A.R., de Fa´tima Menezes Almeida-Santos, M., Tedesco, A.C., and Azevedo, R.B. (2012). Photodynamic therapy disinfection of carious tissue
591
mediated by aluminum-chloride-phthalocyanine entrapped in cationic liposomes: an in vitro and clinical study. Lasers Med. Sci. 27, 575–584. 25. Guglielmi, C.A., Simionato, M.R., Ramalho, K.M., Imparato, J.C.P., Pinheiro, S.L., and Luz, M.A.A.C. (2011). Clinical use of photodynamic antimicrobial chemotherapy for the treatment of deep carious lesions. J. Biomed. Opt. 16, 088003. 26. Borges, F.M.C., Melo, M.A.S., Lima, J.P.M., Zanin, I.C.J., Rodrigues, L.K.A., and Nobre-dos-santos, M. (2010). Evaluation of the effect of photodynamic antimicrobial therapy in dentin caries: a pilot in vivo study. SPIE Proc. 75490. 27. Melo, M.A., Rolim, J.P., Zanin, I.C., Silva, J.J., Paschoal, A.R., Ayala, A.P., and Rodrigues, L.K. (2013). A comparative study of the photosensitizer penetration into artificial caries lesions in dentin measured by the confocal Raman microscopy. Photochem. Photobiol. [Epub ahead of print]
Address correspondence to: Mary Anne S. Melo Department of Endodontics, Prosthodontics and Operative Dentistry University of Maryland School of Dentistry 650 W. Baltimore St. Baltimore, MD 21201 E-mail: [email protected]
