Efficacy of lasers as an adjunct to chemo-mechanical disinfection of infected root canals: a systematic review

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1 doi: /iej Efficacy of lasers as an adjunct to chemo-mechanical disinfection of infected root canals: a systematic review H. Fransson 1 *, K. M. Larsson 2 & E. Wolf 1 1 Department of Endodontics, Faculty of Odontology, Malmö University, Malmö; and 2 Department of Pedodontics, Faculty of Odontology, Malmö University, Malmö, Sweden Abstract Fransson H, Larsson KM, Wolf E. Efficacy of lasers as an adjunct to chemo-mechanical disinfection of infected root canals: a systematic review. International Endodontic Journal, 46, , The aim was to evaluate the efficacy of various types of lasers used as an adjunct to chemo-mechanical disinfection of infected root canals with the outcome measures normal periapical condition or reduction of microbial load. PubMed, CENTRAL and ISI Web of Knowledge literature searches with specific indexing terms and a subsequent hand search were made with stated limits and criteria. Relevant publications were retrieved, followed by interpretation. The quality of each included publication was assessed as high, moderate or low. The initial search process yielded 234 publications. All abstracts of these publications were read, and the reference lists of relevant publications were hand-searched. Ten articles were read in full text and interpreted according to a data extraction form. Five were included in the systematic review and were assessed. A meta-analysis was impossible to perform because the included studies were heterogeneous with regard to study design, treatment and outcome measures. Positive effects were reported; however, no concluding evidence grade could be made because each included study was judged to have low quality, primarily due to lack of a power analysis, blinding and reproducibility. The evidence grade for whether lasers can be recommended as an adjunct to chemomechanical disinfection of infected root canals was insufficient. This does not necessarily imply that laser should not be used as an adjunct to root canal treatment but instead underscores the need for future high-quality studies. Keywords: chemo-mechanical, disinfection, endodontics, infection, lasers, systematic review. Received 1 February 2011; accepted 24 August 2012 Introduction In the great majority of teeth requiring root canal treatment, the goal is either prevention or elimination of a microbial infection in the root canal system (Haapasalo et al. 2005). Traditionally, the cleaning and shaping of root canals has been achieved with Correspondence: Helena Fransson, Department of Endodontics, Faculty of Odontology, Malmö University, SE Malmö, Sweden (Tel.: ; Fax: ; Helena.Fransson@mah.se). chemo-mechanical methods, which aim at removing infected pulp tissue and dentine as well as shaping the canals to prepare for the obturation. Even when chemo-mechanical treatment is meticulously performed in infected root canals, healing does not always occur. Antimicrobial irrigants are reported to reduce bacterial load (Johal et al. 2007), although studies with clinical outcome measures such as a decrease in the frequency of apical periodontitis are lacking. One disadvantage with irrigants, however, might be their inability to penetrate the deeper parts of the dentinal tubuli where microorganisms may 296 International Endodontic Journal, 46, , International Endodontic Journal

2 Fransson et al. Efficacy of laser disinfection reside (Berutti et al. 1997). Failures manifested as persisting or newly developing apical periodontitis could be due to residual microorganisms; it has been shown that a residual root canal infection present at the time of root filling adversely affects the outcome (Sjögren et al. 1997). As stated by Ng et al. (2011), it would be beneficial to develop adjunctive antibacterial therapeutic strategies to chemo-mechanical methods to target residual microorganisms and thus enhance the healing rates of teeth with infected root canals. Various laser techniques have been considered as alternative methods for root canal disinfection (Gordon et al. 2007) and are suggested to more effectively affect bacteria located deep in the dentine than traditional chemo-mechanical methods (Klinke et al. 1997). Laser techniques are also reported to substantially reduce bacterial load when used as an adjunct to conventional treatment (Garcez et al. 2007). The bactericidal effects when lasers are used in conjunction with root canal treatments depend on the type of laser used, but the exact killing effects are not fully understood. Nd:YAG lasers are thought to eradicate bacteria mainly by thermal effects, whereas the suggested bactericidal mechanism of action for Er:YAG lasers is linked to the strong water absorption of the laser output. Lasing parameters such as pulse length, fluence and irradiance are also suggested to be involved in the anti-bacterial effect (Meire et al. 2011). Lasers are also used in techniques that employ photoactivated substances or photosensitizers; however, the mode of action is completely different from the ones described above. This technique, photodynamic therapy, was developed as a cancer therapy but has been used to target bacteria and viruses. It requires three basic elements: a photosensitizer, a light source and tissue oxygen. A light source with a suitable wavelength, for instance a diode laser, excites the photosensitizer to produce highly cytotoxic singlet oxygen, which causes the chemical destruction of a limited area of tissue or bacteria that either have selectively taken up the photosensitizer or have been locally exposed to light (Dougherty et al. 1998). Obviously, these laser applications each have their own drawbacks and thus varying risks when used. Regardless of mode of action, commercially available laser systems are considered to improve clinical performance of root canal disinfection when used as an adjunct to conventional chemo-mechanical disinfection. The aim of this systematic review was to evaluate the clinical efficacy of lasers as an adjunct to chemo-mechanical disinfection with the outcome measures normal periapical condition or reduction of microbial load in infected root canals. Materials and methods Goodman s (1993) systematic approach for assessing healthcare practices was used to search the literature and interpret and assess evidence. The systematic review was conducted using the PRISMA checklist (Moher et al. 2009). Problem specification As an adjunct to chemo-mechanical disinfection of infected root canals, do lasers: Improve prognosis, that is, improve the frequency of normal periapical conditions in teeth with infected root canals? or Reduce the microbial load? The problem was specified as a PICO question (Sackett et al. 1997): P (Patient or Problem) Infected human root canals I (Intervention) Use of lasers as an adjunct to conventional chemomechanical disinfection: (i) with heat or power generation as the mode of action or (ii) in conjunction with photoactivated substances or photosensitizers C (Comparison) Orthograde, conventional chemo-mechanical disinfection, including the use of manual or rotary instruments and a disinfecting solution O (Outcome) Radiologically confirmed normal periapical conditions or a reduction in the number or ratio of viable microorganisms in the root canal and/or adjacent dentine The two defined outcomes mean that the patient groups may differ. With periapical tissue status as the outcome measure, two groups were necessary for comparison: one group that received conventional chemo-mechanical disinfection alone and one group that received conventional chemo-mechanical disinfection with laser treatment as an adjunct. With reduction of bacterial load as the outcome measure, it was possible to have one group of patients and to compare the bacterial samples taken after conventional chemo-mechanical disinfection and after adjunct treatment with laser International Endodontic Journal International Endodontic Journal, 46, ,

3 Efficacy of laser disinfection Fransson et al. Systematic literature search Three databases were searched for relevant articles: PubMed, the Cochrane Controlled Trials Register (CENTRAL) and the ISI Web of Knowledge. Endodontics, lasers and laser therapy were the Medical Subject Headings (MeSH) terms chosen for the PubMed ( assessed on 27 October 2011) search. Table 1 describes the PubMed search, the MeSH terms used and the limits defining the search. To supplement the PubMed search, the terms endodontics, root canal treatment, root canal therapy and laser were used to search CENTRAL and the ISI Web of Knowledge. The three authors independently read the retrieved abstracts to select relevant publications. Original scientific studies had to be in vivo studies with study groups comprising more than five teeth. Reviews had to meet these selection criteria: The title or abstract contained the words laser and endodontics. The article was indexed as a review in PubMed. Review articles were used as sources of additional publications, that is, only their reference lists were used for further analysis. Abstracts considered relevant by at least one author led to the retrieval of the full text. No discussion of consensus preceded selection at this stage. Interpretation and assessment of publications Original scientific studies that fulfilled the selection criteria were read in full text and evaluated using a data extraction form (Appendix 1). The form was piloted on several articles, modified and then agreed Table 1 Medical subject headings (MeSH) indexing terms and numbers of retrieved publications in the PubMed database search Searches MeSH indexing terms No. of publications #1 Endodontics 7899 #2 Lasers #3 Laser Therapy #4 Dental Pulp Capping 374 #5 Lasers OR Laser Therapy #6 Endodontics AND #5 247 #7 #6 NOT #4 234 Limits: The search was performed on 27 May The PubMed search was limited to publications that were (i) written in English, (ii) had an abstract, (iii) included only humans and (iv) had an Entrez date between 1 January 1966 and 1 May amongst the authors through consensus. Using a modification of Guyatt et al. s criteria (1993, 1994), the three authors independently assessed the quality of the studies that fulfilled the inclusion criteria. Table 2 lists the criteria for high, moderate and low quality. Findings were discussed until consensus was reached. Neither process was blinded. The concluding level of evidence (scientific evidence) was rated as strong, moderately strong, limited or insufficient depending on the quality of the assessed publications. Hand-searching The next step was to hand-search (i) the reference lists of the original scientific articles that had been included after data extraction and (ii) the reference lists of the reviews that met the selection criteria. Preliminary selection criteria for studies in reference lists were that the title must contain: One of these terms: laser, photoactivated disinfection, photosensitization, photodynamic therapy. Names of microorganism species or any of these word stems or phrases: bacter*, endodont*, antibacter*, antimicrob*, microbiolog*, infect*, disinfect*, root canal*, clean*, steriliz*, periapical lesion*, apical periodontitis, periapical radioluscenc*, root canal therap*. Original scientific studies that met the selection criteria were retrieved and read in full text, followed by data extraction and assessment of level of evidence as above (Fig. 1). Results Systematic literature search The PubMed search yielded 234 publications that were indexed according to the selected MeSH terms. After the abstracts were read, 14 studies were found that satisfied the inclusion criteria: seven original scientific studies and seven reviews. The seven original studies were read in full text and subjected to data extraction. Three of the seven studies met all criteria for inclusion in the review. A hand search of the reference lists of the three included studies and the seven reviews yielded three additional original scientific studies. These three new studies were then read in full text and subjected to data extraction. Of these three, two met the criteria for inclusion in the review. Thus, five studies met all inclusion criteria and were interpreted and assessed for quality. Searches of CENTRAL and the ISI Web of Knowledge yielded no new publications (Fig. 1). 298 International Endodontic Journal, 46, , International Endodontic Journal

4 Fransson et al. Efficacy of laser disinfection Table 2 Levels of evidence High level of evidence The study was judged to have a high level of evidence if it fulfilled these criteria: The sample size was sufficiently large to detect a treatment effect calculated by a power analysis There was a clear research question/hypothesis/aim to address The research question/hypothesis/aim was answered by the authors The study was a true prospective experiment in which investigators randomly assigned the sample of patients and teeth to one or more intervention groups and a control group The study personnel were blinded regarding the intervention The sample was sufficiently described One tooth/patient or adjustment in the analysis of the results for more teeth was carried out Criteria for healing/successful treatment were stated The experimental procedures were described in sufficient detail to permit replication There was a proper account of the subjects/teeth/canals that entered the trial and attributed to its conclusion The results were well documented and presented in terms of relevant data Moderate level of evidence A study was judged to have a moderate level of evidence if any of the above criteria was not met. On the other hand, the study was judged not to have deficits that are described for studies with a low level of evidence Low level of evidence The study was judged to have a low level of evidence if it fulfilled any of these criteria: The sample size was not sufficiently large to detect a treatment effect There was no power analysis There was no clear research question/hypothesis/aim to address There was a clear research question/hypothesis/aim to address, but it was not answered by the authors The data were collected retrospectively There was no control group The treatment and control groups were not equal regarding preoperative status at the start of the trial There was no clear statement of a randomization procedure to receive treatment The sample was not described in sufficient detail to permit replication Withdrawals were large and not accounted for The results were not well documented The methods were not suitable to enable the research question to be answered These criteria are a modification of Guyatt et al. (1993, 1994). Figure 1 Flow diagram of the literature search, data extraction and reasons for excluding retrieved full-text articles. Modified after Moher et al. (2009) International Endodontic Journal International Endodontic Journal, 46, ,

5 Efficacy of laser disinfection Fransson et al. Interpretation and assessment of publications Four of the five included studies reported a positive effect when laser treatment was used as an adjunct to conventional chemo-mechanical treatment of infected root canals; in these studies, the outcome measure was a reduction in number of viable bacteria (Dostálová et al. 2002, Bonsor et al. 2006, Garcez et al. 2008, 2010). Despite this, no concluding level of evidence for such an effect can be established as all assessed studies were judged to be of low quality. The main reason for the assessment of low quality was that no study reported a rationale for sample size: none presented a power analysis. None of the assessed studies reported blinding, during either the operative procedure or outcome analysis. One study (Koba et al. 1999) was classified as a randomized controlled trial (RCT), which may be considered a prerequisite when appraising treatment effects; this study, however, was assessed to have other methodological faults. As described later, heterogeneity in performance was extensive. Table 3 summarizes data from the five included studies. Disinfection procedures Conventional chemo-mechanical disinfection differed amongst the studies and was not described in sufficient detail to make the procedures reproducible. Operation fields were disinfected with various solutions before treatment, and in one study, no report of rubber dam use was made (Dostálová et al. 2002). Tests to assess aseptic conditions were not performed. Sodium hypochlorite (NaOCl) was used in varying concentrations ( %), either alone or in combination with other irrigating solutions. None of the assessed studies stated whether the NaOCl solution used was buffered. In three of the included studies, the infected root canals were treated with various kinds of photosensitizing agents in combination with laser (Bonsor et al. 2006, Garcez et al. 2008, 2010). Three studies (Koba et al. 1999, Dostálová et al. 2002, Bonsor et al. 2006) did not describe the lasing procedure in sufficient detail to be replicated. Outcome measures The outcome measure in one of the five studies was radiological confirmation of postoperative periapical healing (Koba et al. 1999). Radiographic follow-ups were made at 3 and 6 months. Findings were rated as good, poor or unchanged. The criteria for evaluating periapical healing were not stated. In the other studies, a reduction in number or ratio of viable microorganisms constituted the outcome measure (Dostálová et al. 2002, Bonsor et al. 2006, Garcez et al. 2008, 2010). Neither study using reduction of cultivable bacteria as the outcome measure described the sampling or the cultivation procedures in sufficient detail to be replicated (Dostálová et al. 2002, Bonsor et al. 2006, Garcez et al. 2008, 2010). Discussion Broad MeSH terms were used in the PubMed search to reduce the chance of overlooking a study. This yielded a wide search field with 234 matches. To reduce the risk of overlooking studies not indexed in PubMed, CENTRAL or the ISI Web of Knowledge, hand searches of reference lists of the included articles as well as of the reviews were performed. Thus, biases related to the selection of sources were avoided. The risk of an existing publication bias was judged to be slight because unpublished studies tend to be studies that found small effects or whose findings were nonsignificant (Schlosser 2007). Choosing studies in which laser treatment was used as an adjunct to traditional chemo-mechanical debridement limited matches in the literature search because many studies evaluate the effect of the laser alone in reducing microbial load. Nevertheless, laser used as an adjunct to traditional debridement was considered to be relevant from a clinical point of view and was the starting point of this review. The radiological confirmation of normal periapical conditions as the outcome measure was considered clinically relevant because it correlates with the absence of root canal infection in teeth associated with apical periodontitis. A reduction in number or ratio of viable microorganisms is considered a surrogate outcome measure. However, in vivo studies with this outcome were included, because few studies with normal periapical conditions as an outcome were expected to be found. The reasons for excluding in vitro studies with measurements of bacterial load are due to the low external validity of such studies. The results from in vitro studies conducted in strict, controlled environments cannot be directly extrapolated to the more complex true clinical situation. Non-RCT studies were included because a well-designed and implemented nonrandomized study may still contribute valuable experience that can improve future studies (Goodman 1993). A systematic search of the literature followed by data extraction, and quality assessment is an accepted 300 International Endodontic Journal, 46, , International Endodontic Journal

6 Fransson et al. Efficacy of laser disinfection Table 3 Data from included publications concerning study design, description of subjects, aim, outcome measure, reported result, diagnosis, aseptic conditions, conventional chemo-mechanical treatment, laser, preparation before sampling, sampling, cultivation and subjects accounted for. Koba et al. (1999) Dostálová et al. (2002) Bonsor et al. (2006) Garcez et al. (2008) Garcez et al. (2010) Study design Randomized controlled trial Experimental study of other design Description of subjects/teeth 44 teeth from 38 patients (24 incisors, 10 premolars, 10 molars) Study aim To evaluate the postoperative symptoms and healing after root canal treatment with the use of pulsed Nd:YAG laser Outcome measure A reduction of periapical lesions viewed radiologically, evaluated at 3 and 6 months Reported result No significant differences between the groups regarding periapical healing seen radiologically Diagnosis of periapical bone and pulp before treatment Conventional chemomechanical treatment Apical periodontitis pulps did not respond to electric stimulation 5% NaOCl and 3% H 2 O 2,no amounts stated. K-files, stepback, apically enlarged one size beyond the file that produced clean and sound dentine shavings to 1 mm short of the canal length, apex locator (Root ZX, Morita, Tokyo, Japan) 44 teeth (premolars and molars) Experimental study of other design Teeth with 32 canals from 14 patients No clear aim stated To determine the microbiological effect of photoactivated disinfection (PAD) as an adjunct to normal root canal disinfection A reduction in number/ ratio of viable microorganisms 100% sterilization with laser compared to conventional treatment; effective in 60% of the sample A reduction in number/ratio of viable microorganisms 3 of the 4 canals that remained infected after conventional treatment were cultured negative after laser treatment Not stated Symptoms of irreversible pulpitis or apical periodontitis 5.25% NaOCl (Clordent, C.S.C. Czech Republic), amount per canal unclear. K-type files (Maillefer, Swiss), stepback, #10 55, to 30 minimum average >20 ml 2.25% NaOCl (commercial thin bleach, Tesco UK, diluted with water 50 : 50)/canal and >20 ml 20% citric acid solution (Western Infirmary Glasgow, UK)/ canal GT Rotaries (Dentsply Maillefer), crown down, Profiles.04 (Dentsply Maillefer) for apical 2 mm, last file size not stated Experimental study of other design 20 teeth from 20 patients (incisors and canines, 1 canal/tooth) To test the combination of conventional endodontic therapy followed by antimicrobial photodynamic therapy (PDT) in a clinical trial in patients requiring endodontic treatment A reduction in number/ ratio of viable microorganisms Combination with PDT significantly enhanced the reduction Apical periodontitis Necrotic pulp 10 ml 2.5% NaOCl/canal and 10 ml 3% H 2 O 2 / canal, 5 ml 17% EDTA. Gates-Glidden drills (Maillefer Instruments SA, Ballaigues, Switzerland), #1, #2, #3, coronal part, #40 file, apical part Experimental study of other design 30 teeth from 21 patients (anterior teeth) To investigate the effect of combination of photodynamic therapy with endodontic treatment in patients with infected root canals that previously had been roof filled and treated with antibiotics A reduction in number/ratio of viable microorganisms The use of PDT added to conventional treatment leads to further major reduction of microbial load Apical periodontitis, previously root filled 2.5% NaOCl and 3% H 2 O 2, 10 ml each, alternated between instrumentation. After instrumentation 5 ml 17% ethylenediaminetetraacetic acid, 5 ml phosphate buffered saline (PBS) K-files (Maillefer Instruments SA), manual crown down, file #45 average apical preparation diameter to 1 mm short of the working length 2012 International Endodontic Journal International Endodontic Journal, 46, ,

7 Efficacy of laser disinfection Fransson et al. Table 3 Continued Koba et al. (1999) Dostálová et al. (2002) Bonsor et al. (2006) Garcez et al. (2008) Garcez et al. (2010) Laser (type, lasing time, effect, wave length, any photosensitizer) Nd:YAG, d-lase 300 pulsed (American Dental Laser, Birmingham, MI, USA) 1s,1W Er:YAG Inconsistent data Sampling Not relevant By irrigation with 0.2 ml sterile RTF transport medium inserted into 3 ml brain heart infusion Cultivation (Micro organisms searched for and identified, medium, temperature, atmosphere, time, etc.) All subjects accounted for Not relevant 21 various microorganisms, specific named species and others, 3 ml brain heart infusion, 37 C, 24 h, stated identification of microorganisms according to description above Diode laser 120 s, 100 mw Tolonium chloride With a file, one size larger than the last one used for treatment, transferred to sterile bottle Common facultative anaerobes, blood Agar plate (Oxoid Columbia Blood Agar base + 5% sterile horse blood), 37 C, atmosphere <1% O2, streaking technique stated standardized, evaluated total bacterial load, no identification of specific species Diode laser (MMOptics, São Carlos, SP, Brazil) 240 s, 40 mw, 660 nm A no commercial PAD Paper point, left in the canal for 1 min, transferred to Moller s VMGA III, anaerobic, transport medium Common aerobes, facultative anaerobes, microaerophilics, serial dilution, according to referred technique, brain-heart infusion agar, 37 C, microaerophilic chamber, 5% O 2, 72 h, evaluated total bacterial load, no identification of specific species Diode laser (MMOptics, São Carlos, SP, Brazil) 240 s, 40 mw Polyethyleneimine and chlorine in PBS Three sterile paper points, transferred to sterile bottle (VMGA III) At least nine different species were identified and subjected to antibiogram analysis Yes Cannot be concluded Cannot be concluded Yes Cannot be concluded 302 International Endodontic Journal, 46, , International Endodontic Journal

8 Fransson et al. Efficacy of laser disinfection component of evidence-based medicine and dentistry. The five studies in this systematic review were assessed to have low quality. This means that no concluding evidence grade could be given and, consequently, that no recommendations can be made, either for or against the use of adjunctive lasers. Substantial methodological heterogeneity occurred amongst the five studies, which made meta-analyses and comparisons impossible. Thus, no conclusions can be drawn concerning the efficacy of lasers as an adjunct to chemo-mechanical disinfection of infected root canals, regardless of mode of action. It is possible that there is indeed a difference in effect between high- and low-power lasers as well as when laser parameters vary. However, no studies with the clinical outcome measures chosen for this systematic review showed such a difference. The control of infection during root canal treatment is crucial to treatment outcome, which motivates thorough evaluation of how this occurred in the included studies. Infection sources can only be controlled with the use and sterilization of a rubber dam (Möller 1966). Dostálová et al. (2002) did not use a rubber dam, so the origin of the cultivated microorganisms cannot be determined. The most commonly used disinfectant solution, NaOCl, has an antibacterial effect between ph 4 and 7 (Haapasalo et al. 2005). This means that not only solution concentration but also whether the NaOCl solution is buffered is important to report; none of the studies reported the latter. It is also valuable to record the distance between the actual working length and the apical foramen, in order to evaluate infection treatment accuracy. Only one of the included studies (Koba et al. 1999) takes this aspect into account. Obtaining a representative sample of microorganisms can be difficult (Mercade et al. 2009); thus, any reported positive effect of the laser treatment may be smaller than is actually possible because the most remote parts of the root canals, where the laser is said to have its effect, might not be sampled. Use of an inactivating agent to minimize the risk of disinfectants influencing the outcome is important (Mercade et al. 2009). It is questionable whether the included studies accounted for this aspect. Assessments of cultivation outcome are uncertain because it may be difficult to determine whether the cultured bacteria originate from the root canal or from a possible contamination during sampling. This is especially worrisome if only total bacterial load is assessed. In this systematic review, all five included studies were assessed as having low quality, which means that no conclusions can be drawn regarding the efficacy of laser as an adjunct to conventional chemomechanical treatment of infected root canals. To improve study quality, future studies ought to (i) describe a clinically relevant outcome measure, such as normal periapical condition evaluated after a sufficient period of time and (ii) be designed as RCTs with a sample size (determined by a pre-study power analysis) that is large enough to detect a difference in treatment effect. To study an intervention outcome in the clinical context, multi-centre studies using normal periapical conditions as the outcome measure are preferable. It is important to report methods and procedures in detail so that it would be possible to select data from studies with a similar design in order to perform a quantitative systematic review or metaanalysis, which constitutes a powerful method for synthesizing and summarizing data (Sutherland 2001). Conclusions All included publications were assessed to have low quality. This insufficient evidence does not necessarily imply that there is no positive effect of laser treatment as an adjunct to chemo-mechanical treatment of infected root canals or that laser treatment should not be used. But it does imply a need for high-quality studies because current knowledge of the efficacy of laser as an adjunct to chemo-mechanical disinfection of infected root canals is limited. References Berutti E, Marini R, Angeretti A (1997) Penetration ability of different irrigants into dentinal tubules. 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9 Efficacy of laser disinfection Fransson et al. necrotic pulps and periapical lesion. Journal of Endodontics 34, Garcez AS, Núñez SC, Hamblin MR, Suzuki H, Ribeiro MS (2010) Photodynamic Therapy associated with conventional endodontic treatment in patients with antibioticresistant microflora: a preliminary report. Journal of Endodontics 36, Goodman C (1993) Literature searching and evidence interpretation for assessing health care practice. Stockholm: SBU, The Swedish Council on Technology Assessment in Health Care. Gordon W, Atabakhsh VA, Meza F et al. (2007) The antimicrobial efficacy of the erbium, chromium:yttrium-scandium-gallium-garnet laser with radial emitting tips on root canal dentin walls infected with Enterococcus faecalis. Journal of the American Dental Association 138, Gutknecht N, Friedhelm K, Hassan A, Lampert F (1996) Long-term clinical evaluation of endodontically treated teeth by Nd-YAG lasers. Journal of Clinical Laser Medicine and Surgery 14, Guyatt G, Sacket D, Cook D (1993) Users guides to the medical literature II. How to use an article about therapy and prevention. A. Are the results of the study valid? Evidence- Based Medicine Working Group. JAMA: The Journal of the American Medical Association 270, Guyatt G, Sacket D, Cook D (1994) Users guides to the medical literature II. How to use an article about therapy and prevention. B. What were the results and will they help me in caring for my patients? Evidence-Based Medicine Working Group. JAMA: The Journal of the American Medical Association 271, Haapasalo M, Endal U, Zandi H, Coil J (2005) Eradication of endodontic infection by instrumentation and irrigation solutions. Endodontic Topics 10, Jha D, Guerrero A, Ngo T, Helfer A, Hasselgren G (2006) Inability of laser and rotary instrumentation to eliminate root canal infection. Journal of the American Dental Association 137, Johal S, Baumgartner J, Marshall J (2007) Comparison of the antimicrobial efficacy of 1.3% NaOCl/BioPure MTAD to 5.25% NaOCl/15% EDTA for root canal irrigation. Journal of Endodontics 33, Kesler G, Koren R, Kesler A, Hay N, Gal R (1998) Histological changes induced by CO2 laser microprobe specially designed for root canal sterilization: in vivo study. Journal of Clinical Laser Medicine and Surgery 16, Klinke T, Klimm W, Gutknecht N (1997) Antibacterial effects of Nd-YAG laser irradiation within root canal dentine. Journal of Clinical Laser Medicine and Surgery 15, Koba K, Kimura Y, Matsumoto K (1999) Post-operative symptoms and healing after endodontic treatment of infected teeth using pulsed Nd:YAG laser. Endodontics & Dental Traumatology 15, Meire MA, Coenye T, Nelis HJ, De Moor RJ (2011) In vitro inactivation of endodontic pathogens with Nd:YAG and Er:YAG lasers. Lasers in Medical Science 27, Mercade M, Duran-Sindreu F, Kuttler S, Roig M, Durany N (2009) Antimicrobial efficacy of 4.2% sodium hypochlorite adjusted to ph 12, 7.5 and 6.5 in infected human root canals. Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontics 107, Moher D, Liberati A, Tetzlaff J, Altman DG, The PRISMA Group (2009) Preferred Reporting Items for Systematic Reviews and Meta Analysis. The PRISMA Statement. PLoS Medicine 6, e Möller Å (1966) Microbial examination of root canals and periapical tissues of human teeth. Methodological studies (PhD Thesis). Göteborg, Lund, Sweden. University of Göteborg, University of Lund. Moritz A, Doertbudak O, Gutknecht N, Goharkhay K, Schoop U, Sperr W (1997) Nd:YAG laser irradiation of infected root canals in combination with microbiological examinations. Journal of the American Dental Association 128, Ng R, Singh F, Papamanou DA et al. (2011) Endodontic photodynamic therapy ex vivo. Journal of Endodontics 37, Sackett DL, Richardson WS, Rosenberg W, Haynes RB (1997) Evidence-based medicine: How to practice and teach EBM. New York: Churchill Livingston. Schlosser R (2007) Appraising the quality of systematic reviews. Focus Technical brief no 17. Sjögren U, Figdor D, Persson S, Sundqvist G (1997) Influence of infection at the time of root filling on the outcome of endodontic treatment of teeth with apical periodontitis. International Endodontic Journal 30, Sutherland S (2001) Evidence-based dentistry: Part IV. Research design and Levels of Evidence. Journal of the Canadian Dental Association 67, Weichman J, Johnson F, Nitta L (1972) Laser use in endodontics. Oral Surgery, Oral Medicine and Oral Pathology 34, International Endodontic Journal, 46, , International Endodontic Journal

10 Fransson et al. Efficacy of laser disinfection Appendix 1 Publication number: First author: Interpretation made by: Date: 1. Was the research question/hypothesis/aim of the study clearly stated? Yes Cannot be decided No The aim of the study: 2. Study design RCT CCT Case control Series of consecutive cases Other 3. Description of subjects In vivo (if in vivo, go to A) In vitro (if in vitro, go to B) Age: Mean: Range: No. of patients: No. of teeth: Permanent teeth Primary teeth Can t tell Type of teeth: Can t tell Animal Human Can t tell Diagnosis, teeth: Pulpa sana Pulpitis Necrotic pulp Other Can t tell No. of root canals: Can t tell A. In vivo Diagnosis, periapically: Normal periapical conditions Apical periodontitis Can t tell If the canals were naturally infected, go directly to no. 5, Chemo-mechanical treatment B. In vitro Naturally infected canals (Go to no. 5) Artificially inoculated canals 4. Inoculation Was any chemo-mechanical debridement performed prior to inoculation? If Yes, how? Was any disinfection/sterilization procedure performed after the debridement and prior to inoculation? If Yes, how? Microorganism/microorganisms inoculated, inoculation time and temperature: Control of microbial growth? If Yes, how was it controlled? 5. Chemo-mechanical treatment Was a rubber dam used? Was the operation field washed with any disinfectants? If Yes, what disinfectants were used? State the concentrations. Were any tests made to control aseptic conditions? Was the chemo-mechanical treatment blinded? (If it is not clear that the procedure was blinded, the alternative No is the option to choose.) What disinfectants or rinsing solutions were used? State concentrations and volumes if described in the study. If NaOCl was used, was it buffered? (If it is not clear whether a buffered solution was used, the alternative Can t tell is the option to choose) Was the disinfecting procedure described in a way that makes it reproducible? Yes No 2012 International Endodontic Journal International Endodontic Journal, 46, ,

11 Efficacy of laser disinfection Fransson et al. What was the size of the final root canal instrument used? What was the distance from the apical end of the prepared root canal to the apex of the tooth? mm Can t tell Was the mechanical debridement procedure described in a Yes No way that makes it reproducible? Was any kind of intracanal dressing used before the canals were examined for viable microorganisms/radiologically examination of the periapical bone? If yes, what intracanal dressing was used? For how long? Describe when the sampling for cultivation was performed: If the canals were obturated, what materials were used? Describe materials and methods: Was the quality of the obturation of the canals evaluated? If Yes, what qualities were evaluated? Were any teeth subsequently excluded? If Yes, how many? 6. Laser treatment Laser type: Wave length: Effect/Power: Brand name: Photosensitizing agent, if used: For how long were the canals treated with laser? How many groups were treated with laser? How many samples per group were treated with laser? Was the procedure blinded? Was the procedure described in a way that makes it reproducible? Yes No 7. Outcome measure A reduction in number of viable microorganisms (go to A) (A) How many samples were taken for each tooth? How was the sampling performed? Describe the cultivation technique: A reduction in a periapical lesion viewed radiologically (go to B) Other How many cultivations were carried out per sample? Transport medium: Was the cultivation medium/technique selective for any kind of microorganisms? If Yes, what microorganisms? Time elapsed between root canal treatment and cultivation of microorganisms Cultivation immediately after debridement Cultivation not immediate If cultivation was not immediate, the elapsed time was: Types of microorganisms identified after cultivation: Was the interpretation of the cultivation results (e.g. counting CFU) blinded? Was the cultivation process described in a way that makes it reproducible? (B) Elapsed time between the treatment of the canal and the radiograph: Was any standardized method used to evaluate the healing/nonhealing of apical periodontitis? Can t tell when the cultivation was performed in relation to debridement Yes No Was the interpretation of the radiographs blinded? 306 International Endodontic Journal, 46, , International Endodontic Journal

12 Fransson et al. Efficacy of laser disinfection 8. Control material Was there a control group? How many control groups were included? Can t tell Number of teeth in each control group: Description of the treatment of the control groups: Was/were the control group/groups identical with the test group? 9. Were all patients or teeth that entered the trial properly accounted for? Yes No Can t tell If not, what were the reasons? 10. Relevance to the project: Yes No, because Non-English literature Animal experiment Laser treatment was not used as an adjunct No disinfectant was used after the canal was artificially inoculated No mechanical debridement was used after the canal was artificially inoculated Review Other, namely: 11. What were the results regarding the reduction of viable microorganisms/periapical lesion viewed radiographically? Did laser treatment have positive effects, as described above, according to the authors? Results according to the interpreter: 12. Adverse effects Were any adverse effects reported? Yes No If Yes, which effects? 2012 International Endodontic Journal International Endodontic Journal, 46, ,