Article Options
Categories


Search


Advanced Search



This service is provided on D[e]nt Publishing standard Terms and Conditions. Please read our Privacy Policy. To enquire about a licence to reproduce material from endodonticsjournal.com and/or JofER, click here.
This website is published by D[e]nt Publishing Ltd, Phoenix AZ, US.
D[e]nt Publishing is part of the specialist publishing group Oral Science & Business Media Inc.

Creative Commons License


Recent Articles RSS:
Subscribe to recent articles RSS
or Subscribe to Email.

Blog RSS:
Subscribe to blog RSS
or Subscribe to Email.


Azerbaycan Saytlari

 »  Home  »  Endodontic Articles 3  »  An in vitro comparison of the bactericidal efficacy of lethal photosensitization or sodium hyphochlorite irrigation on Streptococcus intermedius biofilms in root canals
An in vitro comparison of the bactericidal efficacy of lethal photosensitization or sodium hyphochlorite irrigation on Streptococcus intermedius biofilms in root canals
Results - Discussion - References.



Results.
The teeth ( n = 17) with S. intermedius biofilms receiving no experimental treatment served as baseline controls, the mean number of viable bacteria recovered from them was 1.62 10 8 CFU/canal (Table 1).
The individual and combined effect of TBO and laser light on the viability of S. intermedius biofilms are also presented in Table 1. ‘TBO only’ treatment and ‘laser light only’ treatment, both had mild bactericidal effects. A maximum of 3 log 10 viable bacterial reduction was observed with TBO (100 gmL –1 ) or laser light (120 s [4.2 J] and 600 s [21 J] ).
The combined effect of TBO and laser was bactericidal but could not achieve 100% bacterial kill. A maximum reduction of 5 log 10 of viable bacteria was achieved with 100 g mL –1 TBO and 600 s (21 J) laser dose compared to baseline control.
In stark contrast, no viable bacteria could be recovered from any teeth with S. intermedius biofilms treated with 3% NaOCl for 10 min. Even the most effective combination of TBO and laser dose applied at the access cavity could not compete in effectiveness with 3% NaOCl.

Discussion.
The S. intermedius strain used in the study was isolated from an infected root canal in our laboratory. S. intermedius is a Gram positive, facultative anaerobe and has previously been identified in coronal and apical parts of infected root canals (Baumgartner & Falkler 1991, Sundqvist 1992), deep layers of root dentine (Ando & Hoshino 1990), acute apical abscesses (Lewis et al . 1986), and root-filled canals with persistent infections (Sundqvist et al . 1998). In addition, the choice was also influenced by the ease of growth and laboratory manipulation of this strain.
Previous studies on effectiveness of lethal photosensitization have focused mainly on bacterial suspensions (Wilson et al . 1992, 1993). Their effect on bacterial biofilms has rarely been investigated and most of these have been performed on single-species biofilms grown on nitrocellulose discs (Dobson & Wilson 1992, Poh et al . 2000). The laboratory extracted tooth model, with a S. intermedius biofilm coating the root canal used in this study, simulated the in vivo situation a little more closely. However, the single-species biofilm used is not representative of the polymicrobial infection encountered in the root canal (Nair 1987, Molven et al . 1991). Unpublished work in our laboratory attempting to create a simple polymicrobial biofilm has proved unpredictable and certainly not reproducible thus far. It was therefore decided to select one of the commonly isolated species likely to adhere to dentine and representative of those species more resistant to treatment. A series of pilot studies were carried out to establish the protocol for this model, including confirmation of the biofilm by SEM. The canals of all teeth were prepared to an apical size 25 with a 10% taper in order to allow accurate sampling and quantification of bactericidal effects, as well as to achieve a degree of standardization. The introduction of fibre optics into the canal was considered but not adopted in the first instance, as application at the access cavity is clinically straightforward, and experimentally avoids displacement of TBO and mechanical interference (not the subject of test) of the biofilm. Having shown the effectiveness of lethal photosensitization of a nitrocellulose disc biofilm model (Poh et al. 2000), the aim of the present study was to test the hypothesis that the structure of teeth would aid light transmission (Odor et al. 1996) and allow the reproduction of previous success in nitrocellulose-borne biofilms, in the current tooth model.
In this study, irradiation with He–Ne laser alone had no consistent bactericidal effect on S. intermedius biofilm. These data were in agreement with others (Wilson et al. 1992, 1993, Dobson & Wilson 1992, Sarkar & Wilson 1993, Burns et al. 1993) who investigated the effects of He–Ne laser on bacterial suspensions. TBO with an absorption maxima (632.2 nm) closest to the wavelength of the radiation emitted by the He–Ne laser (632.8 nm) has been shown to be an effective photosensitizer for He–Ne laser mediated killing (Wilson et al. 1992, Dobson & Wilson 1992). It was noted that TBO gave a bluish tinge to teeth after treatment but the discolouration could be easily removed with EDTA irrigation. The results of the present study have shown that the combined effect of TBO and He–Ne laser was bactericidal to the S. intermedius biofilm but not effective enough to achieve sterility even with a combination of high TBO concentration (100 gml–1) and laser dose (600 s, 428.6 J cm–2). Dobson & Wilson (1992) reported successful kills of periodonto-pathogenic species biofilms (Streptococcus sanguis, Actinobacillus actinomycetemcomitans, Fusobacterium nucleatum and Porphyromonas gingivalis) using low concentrations of TBO (50 gmL–1) and low doses of He–Ne laser light (30 s, 16.5 J cm–2). The difference in results could be explained by variations in the sensitivities of different bacterial species or indeed different properties of biofilms grown on agar plates compared to those on root canal walls. Low concentrations of TBO (<50 gmL–1) had no bactericidal effect on S. intermedius biofilms, but when they were incubated with 100 gmL–1 TBO for 30 s, a 3 log10 reduction in viable bacteria was observed. Previous reports have shown that some planktonically grown periodontal pathogen suspensions were sensitive to 25 and 50 gmL–1 of TBO (Wilson et al. 1993, Sarkar & Wilson 1993, Burns et al. 1993) but Actinomyces viscosus and Streptococcus mutans were significantly more resistant (Burns et al. 1993). Lethal photosensitization using a low power laser in an infected tooth model in the present study produced similar results to that of irradiation with higher power lasers (Nd:YAG, Nd:YAP, diode, CO2, Er:YAG) which have also achieved various degrees of bacterial killing but not to the extent of achieving sterility (Hardee et al. 1994, Fegan & Steiman 1995, Goodis et al. 1995, Gutknecht et al. 1996, Blum et al. 1997, Moritz et al. 1997, Ramsköld et al. 1997, Le Goff et al. 1999, Mehl et al. 1999). The inconsistent trends evident in bacterial killing with increasing TBO concentration and laser light dose could be attributed to the variation in root canal morphology. The anatomy could impact on this mode of treatment at two levels. First, the manner of interaction of the bacteria with individual root canal systems could result in variable biofilm properties. Secondly, the anticipated circumvention of anatomical complexities by light transmission appears to be confounded; whether this is a function of actual hindrance of light transmission, lack of penetration of TBO or lack of generation and dispersal of free radicals is unclear. Lethal photosensitization could not compete with NaOCl (3% v/v) in achieving consistent 100% bacterial kills in this study. This is however, different from treatment of polymicrobial infections, where NaOCl may not be so effective (Byström & Sundqvist 1981, 1983). The results of this study reinforce the use of NaOCl irrigation in root canal treatment because of its bactericidal effect, as well as its ability to denature bacterial toxins (Safavi & Nichols 1994) and dissolve organic tissues (Baumgartner & Cuenin 1992).
A major advantage of lethal photosensitization in treating root canal infections is the absence of thermal side-effects in the tissues surrounding the roots, as associated with the use of high power lasers. The anticipated benefits of ‘access’ of laser light and photosensitizer were more limited than hypothesized. Further studies are necessary to determine the penetration of photosensitizers into the complex root canal anatomy and the range of activity of ‘free radicals’. Moreover, refinement of the laser delivery system by introduction of the laser beam into the root canal and/or increased energy delivery may be needed to achieve a better antimicrobial effect. Overall the lethal photosensitization of single-species biofilms grown in a tooth model was interestingly effective considering delivery of the light dose at the access cavity, but ultimately not comparable to the conventional use of 3% NaOCl. The method may have potential, either as a modification of the current application or used as an adjunct to conventional approaches.

References.

Ando N, Hoshino E (1990) Predominate obligate anaerobes invading the deep layers of root canals dentine. International Endodontic Journal 23, 20-7.
Bahcall J, Howard P, Miserendino L, Walia H (1992) Preliminary investigation of the histological effects of laser endodontic treatment on the periradicular tissues in dogs. Journal of Endodontics 18, 47-51.
Baumgartner JC, Cuenin PR (1992) Efficacy of several concentrations of sodium hypochlorite for root canal irrigation. Journal of Endodontics 18, 605-12.
Baumgartner JC, Falkler WA Jr (1991) Bacteria in the apical 5 mm of infected root canals. Journal of Endodontics 17, 380-3.
Berkiten M, Berkiten R, Okar I (2000) Comparative evaluation of antibacterial effects of Nd: YAG laser irradiation in root canals and dentinal tubules. Journal of Endodontics 26, 268- 70.
Blum J-Y, Michailesco P, Abadie MJM (1997) An evaluation of the bactericidal effect of the Nd: YAP laser. Journal of Endodontics 23, 583-5.
Burns T, Wilson M, Pearson GJ (1993) Sensitisation of cariogenic bacteria to killing by light from a helium-neon laser. Journal of Medical Microbiology 38, 401-5.
Burns T, Wilson M, Pearson GJ (1995) Effect of Dentine and Collagen on the lethal photosensitisation of Streptococcus mutans. Caries Research 29, 192-7.
Bystr?m A, Sundqvist G (1981) Bacteriologic evaluation of the efficacy of mechanical root canal instrumentation in endodontic therapy. Scandanavian Journal of Dental Research 89, 321-8.
Bystr?m A, Sundqvist G (1983) Bacteriologic evaluation of the effect of 0.5 per cent sodium hypochlorite in endodontic therapy. Oral Surgery, Oral Medicine and Oral Pathology 55, 307-12.
Dobson J, Wilson M (1992) Sensitization of oral bacteria in biofilms to killing by light from a low-power laser. Archives of Oral Biology 37, 883-7.
Fegan SE, Steiman HR (1995) Comparative evaluation of the antibacterial effects of intracanal Nd: YAG laser irradiation: an in vitro study. Journal of Endodontics 21, 415-7.
Goodis H, White J, Yee B, Marshall S, Marshall G (1995) Sterilization of root canal spaces using an Nd: YAG laser, in vitro. Proceeding of International Society for Optical Engineering 2394, 154-9.
Grigoratos D, Knowles J, Ng Y-L, Gulabivala K (2001) Effect of exposing dentine to sodium hypochlorite and calcium hydroxide on its flexural strength and elastic modulus. International Endodontic Journal 34, 113-9.
Gutknecht N, Moritz A, Conrads G, Sievert T, Lampert F (1996) Bactericidal effect of the Nd-YAG laser in in vitro root canals. Journal of Clinical Laser Medicine and Surgery 14, 77-80.
Haapasalo M, ?rstavik D (1987) In vitro infection and disinfection of dentinal tubules. Journal of Dental Research 66, 1375-9.
Hardee MW, Miserendino LJ, Kos W, Walia H (1994) Evaluation of the antibacterial effects of intracanal Nd: YAG laser irradiation. Journal of Endodontics 20, 377-80.
Horiba N, Maekawa Y, Matsumoto T, Nakamura H (1990) A study of the distribution of endotoxin in the dentinal wall of infected root canals. Journal of Endodontics 16, 331-4.
Kakehashi S, Stanley HR, Fitzgerald RJ (1965) The effects of surgical exposures of dental pulps in germ free and conventional laboratory rats. Oral Surgery, Oral Medicine and Oral Pathology 20, 340-9.
Kimura Y, Wilder-Smith P (2000) Matsumoto Lasers in endodontics: a review. International Endodontic Journal 33, 173-85.
Le Goff A, Dautel-Morazin A, Guigand M, Vulcain J-M, Bonnaure-Mallet M (1999) An evaluation of the CO2 laser for endodontic disinfection. Journal of Endodontics 25, 105-8.
Lewis MAO, MacFarlane TW, McGowan DA (1986) Quantitative bacteriology of acute dento-alveolar abscesses. Journal of Medical Microbiology 21, 101-4.
Lussi A, Messerli L, Hotz P, Grosrey J (1995) A new non- instrumental technique for cleaning and root filling canals. International Endodontic Journal 28, 1-6.
Mehl A, Folwaczny M, Haffner C, Hickel R (1999) Bactericidal effects of 2.94 ?m Er: YAG-Laser radiation in dental root canals. Journal of Endodontics 25, 490-3.
Millward TA, Wilson M (1989) The effect of chlorhexidine on Streptococcus sanguis biofilms. Microbios 58, 155-64.
Molven O, Olsen I, Kerekes K (1991) SEM of bacteria in the apical part of root canals in permanent teeth with periapical lesions. Endodontics and Dental Traumatology 7, 226-9.
Moritz A, Gutknecht N, Goharkhay K, Schoop U, Wernisch J, Spoerr W (1997) In vitro irradiation of infected root canals with a diode laser: results of microbiologic, infrared spectrometric, and stain penetration examinations. Quintessence International 28, 205-9.
Moshonov J, ?rstavik D, Yamauchi S, Pettiette M, Trope M (1995) Nd: YAG. laser irradiation in root canal disinfection. Endodontics and Dental Traumatology 11, 220-4.
Nair PRN (1987) Light and electron microscope studies of root canal flora and periapical lesions. Journal of Endodontics 13, 29-39.
Nichols WW (1991) Biofilms, antibiotics and penetration. Reviews in Medical Microbiology 2, 177-81.
Odor TM, Watson TF, Pitt Ford TR, McDonald F (1996) Pattern of transmission of laser light in teeth. International Endodontic Journal 29, 228-34.
Poh Y-J, Ng Y-L, Spratt D, Gulabivala K, Bhatti M (2000) Lethal photosensitisation of root canal Fusobacterium nucleatum isolates. International Endodontic Journal 33, 74 (abstract).
Ramsk?ld LO, Fong CD, Stromberg T (1997) Thermal effects and antibacterial properties of energy level required to sterilized stained root canals with an Nd: YAG laser. Journal of Endodontics 23, 96-100.
Rooney J, Midda M, Leeming J (1994) A laboratory investigation of the bactericidal effect of a Nd: YAG laser. British Dental Journal 176, 61-4.
Safavi KE, Nichols FC (1994) Alteration of biological properties of bacterial lipopolysaccharide by calcium hydroxide treatment. Journal of Endodontics 20, 76-8.
Sarkar S, Wilson M (1993) Lethal photosensitization of bacteria in subgingival plaque from patients with chronic periodontitis. Journal of Periodontal Research 28, 204-10.
Shovelton DS (1964) The presence and distribution of microorganisms within non-vital teeth. British Dental Journal 117, 101-7.
Sim TPC, Knowles JC, Ng Y-L, Shelton J, Gulabivala K (2001) Effect of sodium hypochlorite on mechanical properties of dentine and tooth surface strain. International Endodontic Journal 34, 120-32.
Sj?gren U, H?gglund B, Sundqvist G, Wing K (1990) Factors affecting the long-term results of endodontic treatment. Journal of Endodontics 16, 498-503.
Smith CS, Setchell DJ, Harty FJ (1993) Factors affecting the success of conventional root canal therapy - a five-year retrospective study. International Endodontic Journal 26, 321- 33.
Spratt DA, Pratten J, Wilson M, Gulabivala K (2001) An in vitro evaluation of the antimicrobial efficacy of irrigants on biofilms of root canal isolates. International Endodontic Journal 34, 300-7.
Sunde PT, Tronstad L, Eribe ER, Lind PO, Olsen I (2000) Assessmant of periradicular microbiota by DNA-DNA hybridisation. Endodontics and Dental Traumatology 16, 191-6.
Sundqvist G (1992) Associations between microbial species in dental root canal infections. Oral Microbiology and Immunology 7, 257-62.
Sundqvist G, Figdor D, Persson S, Sjogren U (1998) Microbiological analysis of teeth with failed endodontic treatment and the outcome of conservative re-treatment. Oral Surgery, Oral Medicine and Oral Pathology 85, 86-93.
Syed SA, Loesche WJ (1972) Survival of human dental plaque flora in various transport media. Applied Microbiology 24, 638-44.
Tarsi R, Corbin B, Pruzzo C, Muzzarelli RA (1998) Effect of lowmolecular- weight chitosans on the adhesive properties of oral streptococci. Oral Microbiology and Immunology 13, 217-24.
Thilo BE, Baehni P, Holz J (1986) Dark-field observation of the bacterial distribution in root canals following pulp necrosis. Journal of Endodontics 12, 202-5.
Vigil GV, Wayman BE, Dazey SE, Fowler CB, Bradley DV Jr (1997) Identification and antibiotic sensitivity of bacteria isolated from periapical lesions. Journal of Endodontics 23, 110-4.
Wada M, Takase T, Nakamura K, Arisue K, Nagahama F, Yamazaki M (1998) Clinical study of a refractory apical periodontitis treated by apicectomy. Part 1. Root canal morphology of resected apex. International Endodontic Journal 31, 53-6.
Wilson M (1994) Bactericidal effect of laser light and its potential use in the treatment of plaque-related diseases. International Dental Journal 44, 181-9.
Wilson M, Dobson J, Harvey W (1992) Sensitization of oral bacteria to killing by low-power laser radiation. Current Microbiology 25, 77-81.
Wilson M, Dobson J, Sarkar S (1993) Sensitisation of periodontopathogenic bacteria to killing by light from a low-power laser. Oral Microbiology and Immunology 8, 182-7.
Zakariasen KL, Dederich DN, Tulip J, Decoste S, Jensen SE, Pickard MA (1986) Bactericidal action of carbon dioxide laser radiation in experimental dental root canals. Canadian Journal of Microbiology 32, 942-6.