Photodynamic therapy with two different photosensitizers as a supplement to instrumentation/irrigation procedures in promoting intracanal reduction of Enterococcus faecalis.
BACKGROUND
This in vitro study aimed to investigate the antibacterial effects of photodynamic therapy (PDT) with methylene blue (MB) or toluidine blue (TB) (both at 15 microg/mL) as a supplement to instrumentation/irrigation of root canals experimentally contaminated with Enterococcus faecalis.


METHODS
Seventy extracted teeth had their root canals contaminated with an endodontic strain of E. faecalis for 7 days, instrumented with nickel-titanium instruments and irrigated either with 2.5% NaOCl or with 0.85% NaCl, and then randomly distributed into four experimental groups: MB/NaOCl (PDT with MB and NaOCl as the irrigant), TB/NaOCl (PDT with TB and NaOCl as the irrigant), MB/NaCl (PDT with MB and NaCl as the irrigant), and TB/NaCl (PDT with TB and NaCl as the irrigant). For PDT, the photosensitizer remained in the canal for 2 minutes before exposed to red light emitted from a diode laser for 4 minutes. Samples were taken before and after instrumentation/irrigation and following the specific PDT procedure for each group, plated onto Mitis-salivarius agar and the colony forming units counted.


RESULTS
Regardless of the irrigant used (NaOCl or NaCl), instrumentation significantly reduced bacterial counts in comparison to the baseline (p < 0.001). NaOCl as the irrigant was significantly more effective than NaCl, and this difference persisted after PDT, irrespective of the photosensitizer used (p < 0.05). PDT with either MB or TB did not significantly enhance disinfection after chemomechanical preparation using NaOCl as irrigant (p > 0.05). No significant differences were observed between the two photosensitizers (p > 0.05).


CONCLUSIONS
These in vitro results suggest that PDT with either MB or TB may not exert a significant supplemental effect to instrumentation/irrigation procedures with regard to intracanal disinfection. Further adjustments in the PDT protocol may be required to enhance predictability in bacterial elimination before clinical use is recommended.
Souza
Letícia C
LC
Department of Endodontics, Faculty of Dentistry, Estácio de Sá University, Rio de Janeiro, Brazil.
Brito
Patrícia R R
PR
de Oliveira
Julio C Machado
JC
Alves
Flávio R F
FR
Moreira
Edson J L
EJ
Sampaio-Filho
Hélio R
HR
Rôças
Isabela N
IN
Siqueira
José F
JF
D015169:Colony Count, Microbial; D003131:Combined Modality Therapy; D003786:Dental Pulp Cavity / Q000382:microbiology* / Q000528:radiation effects; D004203:Disinfection / Q000295:instrumentation / Q000379:methods; D013293:Enterococcus faecalis / Q000528:radiation effects*; D006801:Humans; D008751:Methylene Blue / Q000627:therapeutic use; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000627:therapeutic use*; D012388:Root Canal Irrigants / Q000627:therapeutic use; D018915:Root Canal Preparation / Q000379:methods*; D012965:Sodium Chloride / Q000627:therapeutic use; D012973:Sodium Hypochlorite / Q000627:therapeutic use; D018709:Statistics, Nonparametric; D014048:Tolonium Chloride / Q000627:therapeutic use
D017319:Photosensitizing Agents; D012388:Root Canal Irrigants; D014048:Tolonium Chloride; D012965:Sodium Chloride; D012973:Sodium Hypochlorite; D008751:Methylene Blue