Instrumentation kinematics does not affect bacterial reduction, post-operative pain, and flare-ups: A randomized clinical trial.

AIM: This randomized clinical trial aimed to assess the effect of instrumentation kinematics (reciprocation or continuous rotation) on bacterial reduction, post-operative pain, and incidence of flare-ups after root canal treatment of single-rooted mandibular premolars with asymptomatic apical periodontitis. METHODOLOGY: Sixty-six patients were included in this prospective, parallel, randomized clinical trial. Patients were randomly allocated into two groups (N = 33) according to the kinematics of the shaping instrument: WaveOne Gold (WO) used in reciprocation or One Shape (OS) used in continuous rotation. Under complete asepsis, bacterial samples were taken before (S1) and after (S2) a standard cleaning and shaping protocol. Evaluation of bacterial reduction was done by both culture technique and quantitative real-time polymerase chain reaction (qPCR) analysis. Post-operative pain was evaluated using the visual analogue scale (VAS) after 24, 48, and 72 h following treatment, while flare-ups were recorded as a binary outcome (Yes/No). Independent and paired t-tests were used for inter- and intra-group comparisons for bacterial count data, respectively. For post-operative pain score, inter-group comparisons were analyzed using the Mann-Whitney U-test while intra-group comparisons were analyzed using Friedman test followed by pairwise comparisons utilizing the Wilcoxon signed rank test with Bonferroni correction. The significance level was set at p ≤ .05 within all tests. RESULTS: All the allocated participants received the intervention and were analysed. The comparison between culture and qPCR methods showed that qPCR analysis demonstrated significantly higher pre-instrumentation baseline bacterial count (p < .05). The percentage of bacterial reduction, detected by either method, significantly decreased after instrumentation using either rotation or reciprocation kinematics (p < .05). However, the difference between the WOG or OS files was statistically non-significant (p > .05). The intra-group comparisons showed a significant reduction in post-operative pain with time (p < .05) for both groups. However, the inter-group comparison demonstrated that the difference in post-operative pain after the use of either WOG or OS was statistically non-significant (p > .05). The incidence of flare-ups between both groups was also not-significant (p = 1). CONCLUSIONS: Shaping kinematics, either rotation or reciprocation motions, had no impact on bacterial reduction and the incidence of post-operative pain and flare-ups after root canal preparation of single-rooted premolars with asymptomatic apical periodontitis.

The antibacterial effect and the incidence of post-operative pain after the application of nano-based intracanal medications during endodontic retreatment: a randomized controlled clinical trial.

OBJECTIVE: This clinical trial aimed to evaluate the effect of nano-silver and nano-calcium hydroxide intracanal medicaments (ICM) during retreatment regarding their antibacterial effect and their effect on post-operative pain and flare-ups. MATERIALS AND METHODS: Sixty-nine patients scheduled for endodontic retreatment were included in this randomized clinical trial and randomly allocated to 3 equal groups (n = 23) according to the type of ICM used. The first microbial sampling (S1) representing the original microbiota was obtained after the removal of the old canal filling. After chemo-mechanical debridement, another sample (S2) was obtained representing the microbial state before ICM application. Patients were randomly allocated to receive either nano-silver (nano-Ag), nano-calcium hydroxide (nano-CH), or calcium hydroxide (CH) as ICM. Patients rated their pain pre-operatively and then after 6, 12, 24, 48, and 72 h. During the second visit (7 days later), the last microbial sample (S3) was obtained after removal of the ICM. Reduction of total bacterial and total E. faecalis counts and the biofilm-forming capability of the existing microbiota were determined. RESULTS: Results showed reduction in total bacterial count, total E. faecalis count and the biofilm-forming,capability of the existing microbiota after chemo-mechanical debridement (S1-S2) and after the application of ICM (S3-S2). However, the reduction after cleaning and shaping was significantly more pronounced (p < 0.001) compared to the effect of ICM application, with no difference between the 3 ICM (p > 0.05). Post-operative pain was significantly reduced at the 48- and 72-h intervals after the application of nano-Ag and nano-CH only (p < 0.001), with no significant difference between these two ICM (p > 0.05). The incidence of flare-ups in all groups was similar (p > 0.05). CONCLUSIONS: The antibacterial effect of the nano-Ag and nano-CH was equivalent to that of CH, but they contributed to better pain control. CLINICAL RELEVANCE: Nanoparticles may have a positive impact on post-endodontic pain.

Effect of XP-endo Shaper versus conventional rotary files on postoperative pain and bacterial reduction in oval canals with necrotic pulps: a randomized clinical study.

AIM: To assess postoperative pain and bacterial reduction following the use of XP-endo Shaper versus conventional rotary files in preparation of oval canals with necrotic pulps. METHODOLOGY: This superiority, parallel, randomized, double blinded clinical trial was conducted in the clinic of the Endodontic Department, Faculty of Dentistry, Cairo University, Egypt. Sixty single-canalled mandibular premolars with necrotic pulps were randomly assigned into two equal groups. Canals were instrumented using XP-endo Shaper files in the intervention group and iRaCe rotary files in the control group. Bacterial samples were taken before and after canal instrumentation. Incidence and severity of postoperative pain was assessed using a modified VAS after 6, 12, 24 h and daily for 5 days. A culture method was used to assess the number of bacterial colony forming units. Incidence of analgesic intake as well as flare-ups was recorded. Data were analysed using chi-square, Fisher Exact, Mann-Whitney, Independent t-test, and Spearman's correlation for pain and bacterial counts. RESULTS: The XP-endo Shaper compared with the iRaCe group was associated with a significantly lower incidence of postoperative pain at 6, 12, and 24 h (P = 0.039, 0.047, and 0.026, respectively), and severity of postoperative pain at 6 h (mean difference: 1.33, 95% CI: 0.307-2.352, P = 0.02), 12 h (mean difference: 1.1, 95% CI: 0.26-1.936, P = 0.007), 24 h (mean difference: 0.94, 95% CI: 0.178-1.701, P = 0.008) and 48 h (mean difference: 0.97, 95% CI: 0.192-1.747, P = 0.038). There was a significant decrease in bacterial count following canal instrumentation in both groups (P < 0.001) with no significant difference between them (mean difference: 0.83 × 105 , 95% CI: 0.336 × 105 -1.996 × 105 , P = 0.56). A weak correlation existed between postoperative pain severity and bacterial counts (P = 0.54). There was no significant difference in analgesic intake between the two groups (P = 0.085). Flare-ups occurred in 3.3% of teeth in the iRaCe group, while no flare-ups occurred in the XP-endo Shaper group. CONCLUSIONS: XP-endo Shaper was associated with a significantly lower frequency of postoperative pain for up to 24 h, and lower severity of postoperative pain for up to 48 h compared with iRaCe files. Both systems were equally effective in bacterial reduction from oval root canals with necrotic pulps.

Mechanical reduction in intracanal Enterococcus faecalis when using three different single-file systems: an ex vivo comparative study.

AIM: To evaluate the bacterial reduction achieved by WaveOne Gold (Dentsply Sirona Endodontics, Ballaigues, Switzerland), Hyflex EDM (Coltene-Whaledent, Altstätten, Switzerland), and XP-endo Shaper (FKG Dentaire SA, La Chaux-de-Fonds, Switzerland) in canals infected with Enterococcus faecalis. The null hypothesis (H0 ) was that there would be no difference amongst the NiTi systems in reducing the root canal bacterial load. METHODOLOGY: Seventy-four mandibular premolar teeth with straight and round root canals were selected. Sixty-two root canals were contaminated with E. faecalis for 4 weeks and subjected to mechanical preparation with one of three single-file NiTi rotary systems (WaveOne Gold, Hyflex EDM, and XP Endo Shaper). Twelve non-contaminated root canals were used as negative controls. Bacterial samples were collected with sterile paper points (Dentsply Sirona Endodontics) before and after rotary instrumentation to quantify the bacterial load. Five roots from each instrumentation group were evaluated topographically from the coronal, middle and apical thirds by SEM. The bacterial reduction was calculated and analysed statistically by the Kruskal-Wallis and Dunn post hoc tests, all at 5% significance. RESULTS: The samples taken before instrumentation showed approximately 9.64 log CFU bacterial load. Instrumentation with the Hyflex EDM and XP-endo Shaper resulted in significantly greater bacterial reduction than those with WaveOne Gold (P = 0.00). All specimens had bacterial growth. SEM images supported the CFU/mL data. Thick and dense debris was observed in WaveOne Gold samples. Instrumentation resulted in the disruption of the biofilm-like structure, and both areas of clean and open dentinal tubules and areas with thick debris were observed in Hyflex EDM and XP-endo Shaper samples. CONCLUSIONS: Instrumentation in straight and round canals of premolar teeth with the Hyflex EDM and XP-endo Shaper resulted in significantly greater bacterial reduction than WaveOne Gold. No instrumentation system rendered root canals completely free from bacteria.

Passive ultrasonic irrigation in root canal: systematic review and meta-analysis.

OBJECTIVE: To investigate whether there are differences between the root canal disinfection, comparing the passive ultrasonic irrigation technique with the conventional technique. MATERIALS AND METHODS: The following electronic databases were searched: Pubmed; VHL; Web of Sciences and OVID with no publication date restriction. The study's quality evaluation was carried out using the Handbook by Cochrane. The online research identified 5464 studies. From the nine studies selected for a full reading of the text, five were included in the present systematic review. Meta-analysis was performed in three articles, which evaluated the root canal's cleanness through microbiological analysis. RESULTS: Only one article concluded that the ultrasonic passive irrigation showed a better performance compared with the conventional irrigation. None of the articles analyzed presented a low risk of bias in all domains. According to the results of the meta-analysis, there was no statistical difference between the groups (OR = 0.34, IC 95%: 0.10-1.19). CONCLUSIONS: The level of evidence comparing the two techniques is fragile since in all studies some type of bias was observed which may interfere in the results and conclusions.

Selective photoantisepsis.

BACKGROUND AND OBJECTIVE: Selective killing of pathogens by laser is possible due to the difference in absorption of photon energy by pathogens and host tissues. The optical properties of pathogenic microorganisms are used along with the known optical properties of soft tissues in calculations of the laser-induced thermal response of pathogen colonies embedded in a tissue model. The objective is to define the laser parameters that optimize pathogen destruction and depth of the bactericidal effect. MATERIALS AND METHODS: The virtual periodontium is a computational model of the optical and time-dependent thermal properties of infected periodontal tissues. The model simulates the periodontal procedure: Laser Sulcular Debridement.1 Virtual pathogen colonies are placed at different depths in the virtual periodontium to determine the depth for effective bactericidal effects given various laser parameters (wavelength, peak power, pulse duration, scan rate, fluence rate) and differences in pathogen sensitivities. RESULTS: Accumulated background heat from multiple passes increases the depth of the bactericidal effect. In visible and near-IR wavelengths the large difference in absorption between normal soft tissue and Porphyromonas gingivalis (Pg) and Prevotella intermedia (Pi) results in selective destruction. Diode laser (810 nm) efficacy and depth of the bactericidal effect are variable and dependent on hemin availability. Both pulsed-Nd:YAG and the 810 nm diode lasers achieve a 2-3 mm deep damage zone for pigmented Pg and Pi in soft tissue without surface damage (selective photoantisepsis). The model predicts no selectivity for the Er:YAG laser (2,940 nm). Depth of the bactericidal effect is highly dependent on pathogen absorption coefficient. Highly sensitive pathogens may be destroyed as deep as 5-6 mm in soft tissue. Short pulse durations enable confinement of the thermal event to the target. Temporal selectivity is achieved by adjusting pulse duration based on target size. CONCLUSION: The scatter-limited phototherapy model of the infected periodontium is applied to develop a proper dosimetry for selective photoantisepsis. Dosimetry planning is essential to the development of a new treatment modality. Lasers Surg. Med. 48:763-773, 2016. © 2016 Wiley Periodicals, Inc.

The Black Bug Myth: Selective photodestruction of pigmented pathogens.

BACKGROUND AND OBJECTIVE: It is commonly believed that pigmented pathogens are selectively targeted by dental lasers. To test this notion optical diffuse reflection spectroscopy (DRS) was used to obtain absorption spectra for the periodontal pathogens, Porphyromonas gingivalis (Pg) and Prevotella intermedia (Pi). MATERIALS AND METHODS: Spectra from 400 to 1,100 nm wavelengths of Pg colonies cultured with different concentrations of hemin were obtained to test the hypothesis that "visual pigmentation" predicts absorption of near-infrared (IR) dental laser energy. Ablation threshold at 1,064 nm [1] was measured for the pathogenic fungus, Candida albicans (Ca). RESULTS: The hypothesis was demonstrated to be true at 810 nm, it was false at 1,064 nm. Diode laser (810 nm) efficacy and "depth of kill" is dependent on hemin availability from 400 to about 900 nm. Pg and Pi absorption at 1,064 nm (µa = 7.7 ± 2.6 cm(-1) ) is independent of hemin availability but is determined by another unknown chromophore. Ca is non-pigmented but very sensitive to 1,064 nm irradiation. CONCLUSIONS: The amount of visual pigmentation does not necessarily predict sensitivity to dental laser irradiation. Spectra in visible and near-IR wavelengths demonstrate a large difference in absorption between soft tissue and Pg or Pi. This difference represents a host/pathogen differential sensitivity to laser irradiation, the basis for selective photoantisepsis. Lasers Surg. Med. 48:706-714, 2016. © 2016 Wiley Periodicals, Inc.

Does the Reciproc file remove root canal bacteria and endotoxins as effectively as multifile rotary systems?

AIM: To evaluate the effectiveness of Reciproc for the removal of cultivable bacteria and endotoxins from root canals in comparison with multifile rotary systems. METHODOLOGY: The root canals of forty human single-rooted mandibular pre-molars were contaminated with an Escherichia coli suspension for 21 days and randomly assigned to four groups according to the instrumentation system: GI - Reciproc (VDW); GII - Mtwo (VDW); GIII - ProTaper Universal (Dentsply Maillefer); and GIV -FKG Race(™) (FKG Dentaire) (n = 10 per group). Bacterial and endotoxin samples were taken with a sterile/apyrogenic paper point before (s1) and after instrumentation (s2). Culture techniques determined the colony-forming units (CFU) and the Limulus Amebocyte Lysate assay was used for endotoxin quantification. Results were submitted to paired t-test and anova. RESULTS: At s1, bacteria and endotoxins were recovered in 100% of the root canals investigated (40/40). After instrumentation, all systems were associated with a highly significant reduction of the bacterial load and endotoxin levels, respectively: GI - Reciproc (99.34% and 91.69%); GII - Mtwo (99.86% and 83.11%); GIII - ProTaper (99.93% and 78.56%) and GIV - FKG Race(™) (99.99% and 82.52%) (P < 0.001). No statistical difference were found amongst the instrumentation systems regarding bacteria and endotoxin removal (P > 0.01). CONCLUSION: The reciprocating single file, Reciproc, was as effective as the multifile rotary systems for the removal of bacteria and endotoxins from root canals.

Clinical antibacterial effectiveness of the self-adjusting file system.

AIM: To evaluate in vivo the antibacterial effectiveness of the self-adjusting file (SAF) using molecular methods. METHODOLOGY: Root canals from single-rooted teeth with apical periodontitis were instrumented using the SAF system under continuous irrigation with 2.5% NaOCl. DNA extracts from samples taken before and after instrumentation were subjected to quantitative analysis of total bacteria counts and levels of streptococci by quantitative real-time polymerase chain reaction (qPCR). The reverse-capture checkerboard assay was also used to identify 28 bacterial taxa before (S1) and after (S2) SAF instrumentation. SAF was also compared with a conventional hand nickel-titanium instrumentation technique for total bacterial reduction. Data from qPCR were analysed statistically within groups using the Wilcoxon matched pairs test and between groups using the Mann-Whitney U-test and the Fisher's exact test, with significance level set at P < 0.05. RESULTS: Self-adjusting file significantly reduced the total bacterial counts from a mean number of 1.96 × 10(7) cells to 1.34 × 10(4) cells (P < 0.001). Quantitatively, the 99.9% reduction in total bacterial counts associated with the SAF system was significantly superior to the 95.1% reduction obtained by hand instrumentation (P < 0.001). Qualitatively, SAF resulted in significantly more cases with negative PCR results for bacteria (54.5%) than hand instrumentation (4.5%) (P < 0.001). The SAF system succeeded in significantly reducing the streptococcal levels, but four cases still harboured these bacteria in S2. Checkerboard analysis revealed that not only streptococci but also some anaerobic and even as-yet-uncultivated bacteria may resist the effects of chemomechanical procedures. CONCLUSION: The SAF instrumentation system was highly effective in reducing bacterial populations from infected root canals and performed significantly better than hand instrumentation. However, because half of the samples still had detectable bacteria after preparation with SAF, supplementary disinfection is still required to maximize bacterial elimination.

Effects of the Irrigation Needle Design on Root Canal Disinfection and Cleaning.

INTRODUCTION: This ex vivo study evaluated the disinfecting and cleaning effects of root canal preparation using sodium hypochlorite irrigation with 3 different needle designs. METHODS: Mesial roots from extracted mandibular molars with Vertucci class II configuration were anatomically matched based on micro-computed tomography (micro-CT) analyses and distributed into 3 groups (n = 18/group). The canals were contaminated with a mixed bacterial culture for 30 days and then subjected to preparation using 2.5% sodium hypochlorite irrigation with open-ended flat needle (3 mm short of the working length - WL), closed-ended side-vented irrigation needle (1 mm short of the WL), or a closed-ended plastic needle with 2 lateral outlets (TruNatomy) (1 mm short of the WL). Bacteriological samples were taken from the canals before (S1) and after preparation (S2). After another micro-CT scan, the roots were sectioned and samples were also taken from the apical canal segment (S3). Bacterial reduction was assessed by quantitative real-time polymerase chain reaction. The amount of accumulated hard tissue debris was evaluated by micro-CT. RESULTS: A substantial reduction in bacterial counts was observed in all 3 groups when comparing S1 with S2 (99.95%, 98.93%, and 98.90% in the open-ended, closed-ended, and TruNatomy needle groups, respectively) (P < .01). No significant differences were observed between groups for bacterial reduction in the full and apical canal (P > .05). There were no intergroup differences in the amount of accumulated hard tissue debris either (P > .05). The open-ended needle group showed significantly more specimens with quantitative real-time polymerase chain reaction negative results for bacteria in S3 than TruNatomy (P < .05). CONCLUSION: When used up to an appropriate insertion depth, the 3 needle types result in similar antibacterial and cleaning performance, provided variables such as needle size and irrigant type, volume and flow rate are controlled. Exclusive analysis of the apical segment, including the isthmus, revealed that the open-ended needle yielded more cases negative for bacteria.

Bactericidal Effect of Different Photochemical-Based Therapy Options on Implant Surfaces-An In Vitro Study.

Objectives: Photochemical systems are frequently recommended as an adjuvant treatment option in peri-implantitis therapy. The aim of the present study was to evaluate the efficacy of these treatment options, as well as a novel curcumin-based option, in a biofilm model on implants. Methods: Eighty dental implants were inoculated with an artificial biofilm of periodontal pathogens and placed in peri-implant pocket models. The following groups were analyzed: I, photodynamic therapy (PDT); II, PDT dye; III, curcumin/DMSO + laser; IV, curcumin/DMSO only; V, dimethyl sulfoxide (DMSO) only; VI, photothermal therapy (PTT); VII, PTT dye; VIII, control. After treatment, remaining bacterial loads were assessed microbiologically using quantitative real-time polymerase chain reaction analysis. Results: The PDT, PTT, and DMSO treatment methods were associated with statistically significant (p < 0.05) improvements in germ reduction in comparison with the other methods and the untreated control group. The mean percentage reductions were as follows: I (PDT) 93.9%, II (PDT dye) 62.9%, III (curcumin/DMSO + laser) 74.8%, IV (curcumin/DMSO only) 67.9%, V (DMSO) 89.4%, VI (PTT) 86.8%, and VII (PTT dye) 66.3%. Conclusions: The commercially available PDT and PTT adjuvant treatment systems were associated with the largest statistically significant reduction in periopathogenic bacteria on implant surfaces. However, activation with laser light at a suitable wavelength is necessary to achieve the bactericidal effects. The use of curcumin as a photosensitizer for 445 nm laser irradiation did not lead to any improvement in antibacterial efficacy in comparison with rinsing with DMSO solution alone.

Temporary Root Canal Obturation with a Calcium Hydroxide-Based Dressing: A Randomized Controlled Clinical Trial.

Successful bacterial inactivation or elimination is essential for successful outcomes in endodontics. This study investigated the efficacy of a calcium hydroxide paste (Ca(OH)2) as a temporary medical dressing for 1 week after chemomechanical root canal treatment (CMRCT). Microbiological samples from 26 patients were collected after endodontic emergency treatment as follows: (1) removal of the provisional filling material; (2) CMRCT; (3) irrigation with sodium hypochlorite I (3%); (4) medicinal insertion of Ca(OH)2; and (5) irrigation with sodium hypochlorite II (3%). A microbiological examination was carried out after the specimens had been taken from the root canals via saline and sterile paper points. CMRCT resulted in a significant reduction in total bacterial load (TBL) in the root canal (p < 0.05). Additional irrigation (3) resulted in a further significant reduction in TBL (p < 0.05). In contrast, Ca(OH)2 medication did not prevent the bacterial load from returning to the previous level immediately after CMRCT, but did not increase above that level either (p < 0.05). However, the increase in TBL was significant (p < 0.05) in comparison with the disinfection groups (I/II). Administration of Ca(OH)2 for 1 week shows that in combination with an additional disinfection procedure, an increase in TBL must be expected, but not above the level of conditions after CMRCT.

Disinfection and Shaping of Vertucci Class II Root Canals after Preparation with Two Instrument Systems and Supplementary Ultrasonic Activation of Sodium Hypochlorite.

INTRODUCTION: This study compared disinfection and shaping after root canal preparation with either XP-endo Shaper or TruNatomy instrument systems, supplemented by ultrasonic activation of sodium hypochlorite (NaOCl) with either stainless-steel (SS) or nickel-titanium (NiTi) inserts. METHODS: Mesial roots from mandibular molars with Vertucci class II configuration were divided into 2 groups (n = 24) based on anatomically paired micro-computed tomography (micro-CT) analyses. Pre and postpreparation micro-CT scans were obtained to evaluate the shaping performance. The canals were contaminated with a mixed bacterial culture for 30 days and then subjected to preparation with either XP-endo Shaper or TruNatomy instruments using NaOCl irrigation. Supplementary ultrasonic activation of NaOCl was conducted using either an SS (TruNatomy group) or NiTi (XP-endo Shaper group) insert. Bacteriological samples were taken from the canals before preparation (S1), after preparation (S2), and after the supplementary approach (S3). Bacterial reduction was evaluated using a quantitative real-time polymerase chain reaction. RESULTS: Preparation with both instrument systems significantly reduced bacterial counts (P < .01). After preparation, 36% (TruNatomy) and 35% (XP-endo Shaper) were negative for bacteria. These values increased to 59% and 65% after ultrasonic activation with the SS and NiTi inserts, respectively. The quantitative data in S2 showed that XP-endo Shaper promoted a significantly higher bacterial reduction than TruNatomy (P < .05). No significant intragroup differences were observed after ultrasonic activation (P > .05), probably because the SS insert promoted a significantly higher S2-to-S3 reduction than the NiTi insert (P < .01). Micro-CT analysis revealed no significant differences in the unprepared areas between the groups (P > .05). CONCLUSIONS: The XP-endo Shaper caused a significantly higher bacterial reduction than TruNatomy in Vertucci class II canals. Better antibacterial results after ultrasonic activation were observed for the SS ultrasonic inserts than for the NiTi inserts.

Comparative Evaluation of Bacterial Reduction by Laser-Activated Irrigation Technique (LAI) With Conventional Needle Irrigation (CNI) in Single-Rooted Teeth With Pulpal Necrosis: A Single-Blinded Randomized Controlled Trial.

Aim  To compare the bacterial reduction in single-rooted teeth with pulpal necrosis after laser-activated irrigation technique (LAI) and conventional needle irrigation (CNI). Methodology In this clinical trial (CTRI/2021/09/047767), 32 patients with pulpal necrosis were enrolled. Under complete aseptic conditions, access cavity preparation was done and the baseline sample S1 was collected from the root canal using paper points. After chemo-mechanical preparation they were allocated into two groups, following block randomization; Group A - CNI with 27 gauge side-vented needle, Group B - LAI with pulsed Er,Cr:YSGG (erbium, chromium:yttrium-scandium-gallium-garnet) (2780 nm) laser. After irrigant activation, canals were dried and a second sample S2 was taken using paper points. Microbial analysis using quantitative polymerase chain reaction (qPCR) was done to quantify the bacterial reduction among the two groups. Inter-group and intra-group analysis was done using the independent student t-test and Bonferroni test, respectively. The data was represented in terms of quantification cycle (Cq) values, which are inversely proportional to the microbial count.  Results There was no significant difference in S1 between the two groups (mean difference=0.0205; p=0.912). There was a significant difference in S2 between the two groups for the organisms (mean difference=0.8042; p=0.000). The mean percentage of bacterial reduction in CNI was 10.82% and in LAI it was 25.92%.  There was a significant difference in S1 through S2 within the two groups for the organisms (p=0.000). The mean difference of Cq value is high for LAI compared to CNI (1.3494).  The fold change was calculated by taking the ΔCq value and ΔΔCq value after the logarithmic transformation of the Cq value. LAI showed lower levels of DNA at S2 similar to CNI. There is no significant difference in mean fold change between CNI and LAI (p=0.564).  Conclusion This clinical trial concluded that both LAI and CNI were effective in bacterial reduction. There was greater bacterial reduction with LAI (25.92%) than with the CNI (10.82%) in single-rooted teeth with pulpal necrosis using qPCR analysis.

Enhancing the Intracanal Antibacterial Effects of Sodium Hypochlorite with Etidronic Acid or Citric Acid.

INTRODUCTION: This study evaluated the bacterial reduction promoted by root canal preparation using irrigation with sodium hypochlorite (NaOCl) alone, associated with etidronic acid (1-hydroxyethane 1,1-diphosphonic acid [HEDP]) or alternated with citric acid, and after a supplementary agitation step. METHODS: Extracted mandibular premolars were selected and distributed into 3 groups based on anatomically paired micro-computed tomographic analyses. The canals were contaminated with Enterococcus faecalis for 30 days and then subjected to chemomechanical preparation with a reciprocating instrument under irrigation with NaOCl alone, mixed with HEDP (NaOCl/HEDP), or alternated with citric acid (NaOCl/CA). A supplementary agitation step with the XP-endo Finisher was performed in all groups. Intracanal bacteriological samples were taken before (S1) and after preparation (S2) and after the supplementary approach (S3). DNA was extracted from the samples and subjected to quantitative real-time polymerase chain reaction. RESULTS: Intragroup analyses revealed a substantial bacterial reduction from S1 to S2 or S3 in all groups (P < .01). The supplementary agitation resulted in S2-to-S3 bacterial reduction of 6%, 68%, and 80% in the NaOCl, NaOCl/HEDP, and NaOCl/CA groups, respectively. Irrigation with NaOCl alone resulted in 53% and 47% of samples negative for bacteria in S2 and S3, respectively. Corresponding figures for NaOCl/HEDP were 75% and 85%, and 44% and 72% for NaOCl/CA. Intergroup analyses of S2 samples showed that NaOCl/HEDP was significantly more effective than the other 2 in reducing the bacterial levels (P < .05). After the supplementary approach, both NaOCl/HEDP and NaOCl/CA were significantly more effective than NaOCl alone (P < .05), with no significant differences between them (P > .05). CONCLUSIONS: Both the freshly combined NaOCl/HEDP solution and the alternate use of NaOCl and citric acid followed by XP-endo Finisher agitation resulted in significantly higher intracanal bacterial reduction than NaOCl alone.

Impact of Adjunctive Laser Irradiation on the Bacterial Load of Dental Root Canals: A Randomized Controlled Clinical Trial.

Successful root canal treatment depends on the adequate elimination of pathogenic bacteria. This study evaluated the effectiveness of a novel 445-nm semiconductor laser in reducing bacteria after chemomechanical root canal treatment. Microbiological specimens from 57 patients were collected after emergency endodontic treatment, in the following sequence: 1, removal of the temporary filling material; 2, chemomechanical treatment; 3, rinsing with sodium hypochlorite (3%) along with one of three adjuvant protocols (n = 19 in each group). The adjuvant procedures were: (a) sodium hypochlorite rinsing alone (3%); (b) laser irradiation; (c) combined sodium hypochlorite rinsing and laser irradiation. The diode laser was set to 0.59 W in continuous-wave mode (CW) for 4 × 10 s. After the flooding of the root canal with saline, specimens were collected using paper points and analyzed microbiologically. Statistically significant reductions in the bacterial load were observed in all three groups (p < 0.05): 80.5% with sodium hypochlorite rinsing alone and 58.2% with laser therapy. Both results were lower than with the combination of sodium hypochlorite rinsing and 445-nm laser irradiation, at 92.7% (p < 0.05). Additional disinfection of the root canal can thus be achieved with 445-nm laser irradiation after conventional chemical disinfection with sodium hypochlorite solution.

Disinfecting and Shaping Type I C-shaped Root Canals: A Correlative Micro-computed Tomographic and Molecular Microbiology Study.

INTRODUCTION: This ex vivo study compared the disinfection and shaping abilities of 2 preparation protocols in C-shaped canals. METHODS: Mandibular second molars with type I C-shaped canals were pair matched based on micro-computed tomographic (micro-CT) analysis and distributed into 2 groups. The canals were contaminated with a mixed bacterial culture and prepared using 2 protocols, both with 2.5% sodium hypochlorite irrigation: XP-endo Shaper (FKG Dentaire, La Chaux-de-Fonds, Switzerland) supplemented with XP-endo Finisher (FKG Dentaire) (XP-E) and BioRaCe (FKG Dentaire) supplemented with a Hedström file (Dentsply/Sirona, Tulsa, OK) (BR-Hed). Micro-CT scans and intracanal bacteriologic samples were taken before (scan #1 and sample 1) and after preparation (scan #2 and sample 2) and after the supplementary step (scan #3 and sample 3). Canal shaping was evaluated by micro-CT imaging, and disinfection was assessed by quantitative polymerase chain reaction. RESULTS: Micro-CT data from the XP-E (n = 21) and BR-Hed (n = 23) protocols revealed no significant differences between groups regarding shaping parameters (canal volume, surface area, structure model index, and prepared walls) after preparation and after the supplementary step (P > .05). All these parameters significantly increased after each preparation step (P < .05), except for structure model index changes after the XP-endo Finisher (P > .05). Bacteriologic data from the XP-E (n = 21) and BR-Hed (n = 22) groups showed that 14 (66.7%) and 10 (45.5%) S2 samples still had detectable bacteria, respectively. The corresponding figures for supplementary steps with the XP-endo Finisher and Hedström file were 11 (52.4%) and 10 (45.5%), respectively. Bacterial counts in sample 1 significantly decreased in samples 2 and 3 in both groups (P < .01). Intragroup comparison between sample 2 and sample 3 showed a 66% reduction in counts after using the Hedström file and 18% after using the XP-endo Finisher (P > .05 for both groups). The quantitative bacterial reduction was not different between groups (P > .05). CONCLUSIONS: The XP-endo Shaper and BioRaCe systems have similar disinfecting and shaping abilities in C-shaped canals. Supplementary steps with the Hedström file and the XP-endo Finisher were similarly effective in improving shaping, but this was not sufficient to enhance disinfection. About half of the cases, in both groups, still harbored detectable amounts of bacteria.

Quantitative Assessment of the Efficacy of Two Different Single-file Systems in Reducing the Bacterial load in Oval-Shaped Canals: A Clinical Study.

INTRODUCTION: This randomized clinical study compared the in vivo antibacterial efficacy of Reciproc Blue (RB), XP-endo Shaper (XP-S), and XP-endo Shaper associated with XP-endo Finisher (XP-F) systems in infected oval-shaped root canals with primary apical periodontitis. METHODS: In this study, 28 human teeth with a single root and a single canal were randomly assigned to 2 groups according to the instrumentation technique: group 1, RB (n = 14) and group 2, XP-endo (XP-S and XP-F, n = 14). The single-rooted teeth were prepared by reciprocating and rotary nickel-titanium instruments with 5.25% sodium hypochlorite irrigation. Samples were collected from the canal at the baseline (S1), after chemomechanical preparation (S2), and after XP-F instrumentation (S3). The DNA extracts were subjected to quantitative analysis for total bacterial counts by quantitative real-time polymerase chain reaction. The data were analyzed using the analysis of variance test, and the level of significance was set at 5%. RESULTS: All samples tested positive for the presence of bacteria at baseline, and the bacterial counts substantially reduced after treatment procedures (P < .01). The results showed no statistical difference between RB and XP-S instrumentation with respect to the bacterial reduction (P > .05). A marked bacterial reduction was observed after the use of the XP-F instrument (P < .01). CONCLUSIONS: The XP-S and RB systems sharply reduced the bacterial load in oval-shaped root canals with primary apical periodontitis. XP-F used as a supplementary instrument to chemomechanical preparation promoted a significantly higher bacterial reduction.

Impact of Contracted Endodontic Cavities on Root Canal Disinfection and Shaping.

INTRODUCTION: The impact of minimally invasive endodontic procedures on root canal disinfection has not been determined. This ex vivo study compared root canal disinfection and shaping in teeth with contracted or conventional endodontic cavities. METHODS: Mandibular incisors with oval-shaped canals were selected and anatomically matched based on micro-computed tomographic (micro-CT) analysis and distributed into 2 groups. Conservative and conventional access cavities were prepared, and the canals were contaminated with a pure culture of Enterococcus faecalis for 30 days. Root canal preparation in both groups was performed using the XP-endo Shaper instrument (FKG Dentaire, La Chaux-de-Fonds, Switzerland) and 2.5% sodium hypochlorite irrigation. Intracanal bacteriologic samples were taken before and after preparation, and DNA was extracted and subjected to quantitative polymerase chain reaction. Micro-CT scans taken before and after preparation were used for shaping evaluation. Bacteriologic data were analyzed by the Poisson regression model and the chi-square test with Yates correction. Micro-CT data were analyzed by the Wilcoxon, Mann-Whitney, and Student t tests with the significance level set at 5%. RESULTS: All initial samples were positive for E. faecalis. After preparation, the number of bacteria-positive samples was significantly higher in the contracted cavity group (25/29, 86%) than in the conventional cavity group (14/28, 50%) (P < .01). Intergroup quantitative comparison showed that the reduction in bacterial counts was also significantly higher in the group of conventional cavities (P < .01). Micro-CT data revealed no significant difference in the amount of unprepared areas between groups. CONCLUSIONS: Our findings showed that although shaping using an adjustable instrument was similar between groups, disinfection was significantly compromised after root canal preparation of teeth with contracted endodontic cavities.

The Effects of Different Endodontic Access Cavity Design and Using XP-endo Finisher on the Reduction of Enterococcus faecalis in the Root Canal System.

INTRODUCTION: The aim of this study was to evaluate the effect of using the XP-endo Finisher (XPF; FKG Dentaire, La Chaux de Fonds, Switzerland) in teeth that have a traditional access cavity (TEC) and a contracted access cavity (CEC) design on the amount of decrease in the number of Enterococcus faecalis bacteria within the root canal system. METHODS: Eighty mandibular first molar teeth were selected and randomly divided into 2 groups: TEC and CEC (n = 40/group). After access cavity preparation in the 2 groups, 80 mesiobuccal root canals were contaminated with Enterococcus faecalis for 4 weeks. After the first sampling (S1), in order to perform root canal instrumentation, the TEC and CEC groups were further divided into 4 subgroups (10 teeth/group): Reciproc (VDW GmbH, Munich, Germany) and ProTaper Next (Dentsply Maillefer, Ballaigues, Switzerland) with or without XPF. Bacterial sampling from the root canals was performed with sterile paper points before (S1) and after (S2) instrumentation to determine the bacterial load. The bacterial reduction was counted as colony-forming units/mL and analyzed statistically by 3-factor repeated measures analysis of variance. Multiple comparisons of the main factor effect were performed using the Bonferroni correction (α < .05), all at 5% significance. RESULTS: The number of E. faecalis bacteria in all the samples with different cavity designs were significantly reduced after instrumentation. The lowest value of bacterial decrease percentage was observed in the CEC-Reciproc-XPF (82.8%) group. CONCLUSIONS: The bacterial reduction counts of E. faecalis were a similar level in the TEC and CEC cavities, and the use of XPF did not show significant differences between groups.