Macrophage Cell Activation with Acute Apical Abscess Contents Determined by Interleukin-1 Beta and Tumor Necrosis Factor Alpha Production

Introduction

This clinical study has investigated the antigenic activity of bacterial contents from exudates of acute apical abscesses (AAAs) and their paired root canal contents regarding the stimulation capacity by levels of interleukin (IL)-1 beta and tumor necrosis factor alpha (TNF-α) throughout the root canal treatment against macrophage cells.

Methods

Paired samples of infected root canals and exudates of AAAs were collected from 10 subjects. Endodontic contents were sampled before (root canal sample [RCS] 1) and after chemomechanical preparation (RCS2) and after 30 days of intracanal medication with calcium hydroxide + chlorhexidine gel (Ca[OH]₂ + CHX gel) (RCS3). Polymerase chain reaction (16S rDNA) was used for detection of the target bacteria, whereas limulus amebocyte lysate was used to measure endotoxin levels. Raw 264.7 macrophages were stimulated with AAA exudates from endodontic contents sampled in different moments of root canal treatment. Enzyme-linked immunosorbent assays were used to measure the levels of TNF-α and IL-1 beta.

Results

Parvimonas micra, Porphyromonas endodontalis, Dialister pneumosintes, and Prevotella nigrescens were the most frequently detected species. Higher levels of endotoxins were found in samples from periapical exudates at RCS1 (P < .005). In fact, samples collected from periapical exudates showed a higher stimulation capacity at RCS1 (P < .05). A positive correlation was found between endotoxins from exudates with IL-1 beta (r = 0.97) and TNF-α (r = 0.88) production (P < .01). The significant reduction of endotoxins and bacterial species achieved by chemomechanical procedures (RCS2) resulted in a lower capacity of root canal contents to stimulate the cells compared with that at RCS1 (P < .05). The use of Ca(OH)₂ + CHX gel as an intracanal medication (RCS3) improved the removal of endotoxins and bacteria from infected root canals (P < .05) whose contents induced a lower stimulation capacity against macrophages cells at RCS1, RCS2, and RCS3 (P < .05).

Conclusions

AAA exudates showed higher levels of endotoxins and showed a greater capacity of macrophage stimulation than the paired root canal samples. Moreover, the use of intracanal medication improved the removal of bacteria and endotoxins from infected root canals, which may have resulted in the reduction of the inflammatory potential of the root canal content.     

Monitoring the effectiveness of root canal procedures on endotoxin levels found in teeth with chronic apical periodontitis

Objective:

The aim of this study was to monitor the effectiveness of root canal procedures by using different irrigants and intracanal medication on endotoxin levels found in root canals of teeth with chronic apical periodontitis.

Material and Methods:

Thirty root canals of teeth with pulpal necrosis associated with periapical lesions were selected and randomly divided into groups according to the irrigants used: GI - 2.5% NaOCl, GII - 2% chlorhexidine (CHX) gel, and GIII - saline solution (SS) (all, n=10). Samples were collected with sterile/apyrogenic paper points before (S1) and after root canal instrumentation (S2), after use of 17% ethylenediaminetetraacetic acid (EDTA) (S3), and after 30 days of intracanal medication (Ca(OH)₂+SS) (S4). A turbidimetric kinetic Limulus Amebocyte Lysate assay was used for endotoxin measurement.

Results:

Endotoxins were detected in 100% of the root canals investigated (30/30), with a median value of 18.70 EU/mL. After S2, significant median percentage reduction was observed in all groups, irrespective of the irrigant tested: 2.5% NaOCl (99.65%) (GI), 2% CHX (94.27%) (GII), and SS (96.79%) (GIII) (all p<0.05). Root canal rinse with 17% EDTA (S3) for a 3-minute period failed to decrease endotoxin levels in GI and a slight decrease was observed in GII (59%) and GIII (61.1%) (all p>0.05). Intracanal medication for 30 days was able to significantly reduce residual endotoxins: 2.5% NaOCl (90%) (GI), 2% CHX (88.8%) (GII), and SS (85.7%) (GIII, p<0.05). No differences were found in the endotoxin reduction when comparing s2 and s4 treatment groups.

Conclusion:

Our findings demonstrated the effectiveness of the mechanical action of the instruments along with the flow and backflow of irrigant enduring root canal instrumentation for the endotoxin removal from root canals of teeth with chronic apical periodontitis. Moreover, the use of intracanal medication for 30 days contributed for an improvement of endotoxin reduction.     

In vitro evaluation of the action of irrigating solutions associated with intracanal medications on Escherichia coli and its endotoxin in root canals

Objective

The purpose of this study was to evaluate the efficacy of auxiliary chemical substances and intracanal medications on Escherichia coli and its endotoxin in root canals.

Material and Methods

Teeth were contaminated with a suspension of E. coli for 14 days and divided into 3 groups according to the auxiliary chemical substance used: G1) 2.5% sodium hypochlorite (NaOCl); G2) 2% chlorhexidine gel (CLX); G3) pyrogen-free solution. After, these groups were subdivided according to the intracanal medication (ICM): A) Calcium hydroxide paste (Calen®), B) polymyxin B, and C) Calcium hydroxide paste+2% CLX gel. For the control group (G4), pyrogen-free saline solution was used without application of intracanal medication. Samples of the root canal content were collected immediately after biomechanical preparation (BMP), at 7 days after BMP, after 14 days of intracanal medication activity, and 7 days after removal of intracanal medication. The following aspects were evaluated for all collections: a) antimicrobial activity; b) quantification of endotoxin by the Limulus Amebocyte Lysate test (LAL). Results were analyzed by the Kruskal-Wallis and Dunn’s tests at 5% significance level.

Results

The 2.5% NaOCl and CLX were able to eliminate E. coli from root canal lumen and reduced the amount of endotoxin compared to saline.

Conclusions

It was concluded that 2.5% NaOCl and CLX were effective in eliminating E. coli. Only the studied intracanal medications were to reduce the amount of endotoxin present in the root canals, regardless of the irrigant used.     

A titration model for evaluating calcium hydroxide removal techniques

Objective

Calcium hydroxide (Ca(OH)₂) has been used in endodontics as an intracanal medicament due to its antimicrobial effects and its ability to inactivate bacterial endotoxin. The inability to totally remove this intracanal medicament from the root canal system, however, may interfere with the setting of eugenol-based sealers or inhibit bonding of resin to dentin, thus presenting clinical challenges with endodontic treatment. This study used a chemical titration method to measure residual Ca(OH)₂ left after different endodontic irrigation methods.

Material and Methods

Eighty-six human canine roots were prepared for obturation. Thirty teeth were filled with known but different amounts of Ca(OH)₂ for 7 days, which were dissolved out and titrated to quantitate the residual Ca(OH)₂ recovered from each root to produce a standard curve. Forty-eight of the remaining teeth were filled with equal amounts of Ca(OH)₂ followed by gross Ca(OH)₂ removal using hand files and randomized treatment of either: 1) Syringe irrigation; 2) Syringe irrigation with use of an apical file; 3) Syringe irrigation with added 30 s of passive ultrasonic irrigation (PUI), or 4) Syringe irrigation with apical file and PUI (n=12/group). Residual Ca(OH)₂ was dissolved with glycerin and titrated to measure residual Ca(OH)₂ left in the root.

Results

No method completely removed all residual Ca(OH)₂. The addition of 30 s PUI with or without apical file use removed Ca(OH)₂ significantly better than irrigation alone.

Conclusions

This technique allowed quantification of residual Ca(OH)₂. The use of PUI (with or without apical file) resulted in significantly lower Ca(OH)₂ residue compared to irrigation alone.     

A novel approach to evaluate the effect of medicaments used in endodontic regeneration on root canal surface indentation

Objectives

The aim of this study was to investigate the capability of a novel reference point indentation apparatus to test the indentation properties of root canal surface dentine treated with three intracanal medicaments used in endodontic regeneration.

Materials and methods

Immature human premolars were selected (n?=?22). Four specimens were obtained from each root and randomly assigned to three treatment groups and a control group. Each specimen was exposed to one of the three treatment pastes (triple antibiotic (TAP), double antibiotic (DAP), or calcium hydroxide (Ca(OH)₂)) or neutral deionized water (control) for 1 or 4 weeks. After each time interval, the indentation properties of the root canal dentine surfaces were measured using a BioDent reference point indenter. Two-way ANOVA and Fisher's protected least significant differences were used for statistical analyses.

Results

Significant differences in indentation parameters and estimated hardness between all groups at both time points were found. TAP-treated dentine had the highest significant indentation parameters, followed by DAP-treated dentine, untreated control dentine, and Ca(OH)₂-treated dentine, respectively. Furthermore, TAP-treated dentine had the lowest significant estimated hardness, followed by DAP-treated dentine, untreated control dentine, and Ca(OH)₂-treated dentine, respectively.

Conclusion

BioDent reference point indenter was able to detect significant differences in indentation properties of root canal dentine treated with various medicaments.

Clinical relevance

The use of a reference point indenter is a promising approach to characterize the indentation properties of root canal surfaces without any surface modification. This might provide an in vitro mechanical measurement that is more representative of the actual clinical situation.     

Effectiveness of castor oil extract on Escherichia coli and its endotoxins in root canals

This in vitro study sought to evaluate the effectiveness of castor oil extract used as an irrigating solution on Escherichia coli and its endotoxins in root canals. Sixty single-rooted teeth were prepared (using castor oil extract as irrigating solution) and divided into five groups (n = 12): Group 1 samples were treated with calcium hydroxide (Ca(OH)2), Group 2 samples were treated with polymyxin B, Group 3 samples were treated with Ca(OH)2 and 2% chlorhexidine gel (CHX), and Group 4 samples were treated with castor oil extract. A control group used physiological saline solution as an irrigant. Canal content samples were collected at four different times: immediately after instrumentation, seven days after instrumentation, after 14 days of intracanal medication, and seven days after removal of intracanal medication. A plating method was used to assess antimicrobial activity and the quantification of endotoxins was evaluated by the chromogenic Limulus lysate assay. Data were submitted to ANOVA and a Dunn test (a = 5%). Irrigation with castor oil extract decreased E. coli counts but had no effect on the level of endotoxins. Samples taken seven days after removal of medication revealed a significant reduction in endotoxin levels in Groups 3 and 4. Compared to the saline solution irrigation, castor oil extract decreased microorganism counts in root canals immediately after canal preparation. None of the medications used completely eliminated endotoxins in the root canal.     

ELIMINATION OF INTRACANAL INFECTION IN DOGS' TEETH WITH INDUCED PERIAPICAL LESIONS AFTER ROTARY INSTRUMENTATION: INFLUENCE OF DIFFERENT CALCIUM HYDROXIDE PASTES

The aim of this study was to evaluate the antiseptic efficacy of rotary instrumentation associated with calcium hydroxide-based pastes prepared with different vehicles and antiseptics. Chronic periapical lesions were experimentally induced in 72 premolar root canals of four dogs. Under controlled asepsis, after initial microbiological sampling (A1), the root canals were instrumented using the ProFile system in conjunction with 5.25% sodium hypochlorite and the intracanal medication was placed. Four experimental groups were formed according to the pastes used: group 1- Calen (n=18), group 2- Calen+CPMC (n=20), group 3- Ca(OH)₂ p.a.+ anaesthetic solution (n=16) and group 4- Ca(OH)₂ p.a.+ 2% chlorhexidine digluconate (n=18). After 21 days, the pastes were removed; the canals were emptied and 96 hours later a second microbiological sample was obtained (A2). The incidence of positive microbiological cultures and the number of cfus in stages A1 and A2 were compared statistically by the Wilcoxon test while the influence of the different treatments in intracanal infection was evaluated by Kruskal-Wallis test at 5% significance level (p<0.05). Large numbers of strict and facultative anaerobes, and viridans group streptococci were found in 100% of root canals of A1 samples. Among A2 samples, all treatments showed significant reduction of cfus and positive cultures (p<0.05), but only groups 3 and 4 showed 100% of root canals free of microorganisms. Rotary instrumentation plus NaOCl 5.25% associated with intracanal medication produced a drastic reduction or elimination of intracanal microbiota, whose performance was not influenced by the nature of the vehicle or the antiseptic added to the Ca(OH)₂ p.a.     

氢氧化钙用于根管消毒作用的临床研究

目的观察氢氧化钙对感染根管的临床疗效和细菌学改变。方法采用随机分组对照实验,以樟脑对氯酚为对照,分别记录两组封药前后的临床和实验室指标,并进行统计学分析。结果氢氧化钙组显效率为83.33%,一次封药即可进行根管充填。樟脑对氯酚组显效率为56.67%,两组差异有统计学意义(P<0.05)。细菌培养结果显示两组在厌氧菌、链球菌和乳杆菌阳性率的差异有统计学意义(P<0.05)。结论氢氧化钙是一种高效、广谱的抗菌药物,能很好地改善临床症状。     

Quantification of Endotoxins in Infected Root Canals and Acute Apical Abscess Exudates: Monitoring the Effectiveness of Root Canal Procedures in the Reduction of Endotoxins

Introduction

This clinical study was conducted to measure the endotoxin levels in infected root canals (RCs) and exudates related to acute apical abscesses (AAAs). In addition, the effectiveness of RC procedures in reducing the endotoxin levels in RCs was monitored.

Methods

Paired samples of infected RCs and exudates from AAAs were collected from 10 subjects by using paper points. RCs samples were collected before (RCS1) and after chemomechanical preparation (CMP) (RCS2), after 17% EDTA (RCS3), and after 30 days of intracanal medication (Ca[OH]₂ + chlorhexidine) (RCS4). A turbidimetric kinetic limulus amebocyte lysate assay was used for the measurement of endotoxins.

Results

Endotoxins were detected in 100% of the baseline samples of AAAs and RCs (RCS1) with median values of 175 EU/mL and 41.5 EU/mL, respectively (P < .05). After CMP (RCS2), endotoxins were reduced to a median value of 0.54 EU/mL (P < .05). Subsequent irrigation with EDTA (RCS3) failed to present a significant effectiveness in reducing the endotoxin levels (median= 0.37 EU/mL) (P = .07). However, intracanal medication for 30 days (RCS4) reduced endotoxins to median values of 0.03 EU/mL (P < .01).

Conclusions

The present study revealed a strong association between the high levels of endotoxins found in AAAs and RCs collected from the same tooth. Moreover, the effectiveness of CMP in reducing the endotoxin levels from RCs in acute endodontic infection was improved by the use of RC medication.     

Effects of Intracanal Antimicrobials on Viability and Differentiation of Stem Cells From the Apical Papilla: An In Vitro Study

BackgroundRecent studies have indicated that intracanal antimicrobials used to disinfect the root canal in regenerative endodontic therapies (RETs) may be cytotoxic to stem cells from the apical papilla (SCAP), leading to inconsistent treatment outcomes. However, the effects of intracanal antimicrobial agents on the odontogenic differentiation capacity of SCAP at sub-lethal concentrations have not been investigated. The aim of this study was to determine the effects of intracanal antimicrobials on SCAP viability and odontogenic differentiation capacity using a clinically relevant concentration range (0.1–0.8 mg/mL).MethodsImmature human third molars were collected from 71 patients and the apical papillae were harvested to form single-cell suspensions. The cytotoxic effects of intracanal antimicrobials including double antibiotic paste (DAP), triple or modified-triple antibiotic paste (TAP or MTAP), and calcium hydroxide (Ca(OH)₂) on STRO-1⁺ SCAP were assessed using AlamarBlue and Live/Dead assays after exposing cells to treatment groups for 7 days at 0.1 to 0.8 mg/mL. The odontogenic differentiation potential of STRO-1⁺ SCAP was evaluated by immunocytochemistry staining of dentin matrix protein-1 and dentin sialophosphoprotein expression.ResultsAll concentrations of TAP significantly reduced STRO-1⁺ SCAP viability and odontogenic differentiation (P < .001), whereas no DAP concentrations were significantly cytotoxic. Ca(OH)₂ and MTAP concentrations below 0.4 mg/mL and 0.2 mg/mL, respectively, did not significantly reduce viability. The DAP, MTAP, and Ca(OH)₂ did not significantly impact the odontogenic differentiation capacity of STRO-1⁺ SCAP.ConclusionThe varying effects of intracanal antimicrobials on STRO-1⁺ SCAP in vitro suggest amendments to the current root canal disinfection protocol may improve the success of RETs.     

Comparison of final irrigation techniques in removal of calcium hydroxide

The aim of this study was to compare new irrigation systems with a conventional irrigation technique for the removal of inter‐appointment calcium hydroxide [Ca(OH)₂]. Forty‐seven extracted human single‐rooted teeth were instrumented, and Ca(OH)₂ paste was placed into root canals by using a lentulo spiral at the apical third. Teeth were randomly divided into three groups according to different irrigation protocols using a 30‐gauge slot‐tipped needle, EndoVac system and ProUltra® PiezoFlow? ultrasonic irrigation system. Scanning electron microscopic images of the selected root canal surfaces (cervical, middle and apical third) were evaluated using a 5‐grade scale. The influence of the irrigation system was evaluated using a two‐way analysis of variance test and Tukey's test. The EndoVac and PiezoFlow groups demonstrated the lowest scale values (cleanest canals); however, there was no statistical difference between these two groups. The conventional irrigation group exhibited significantly higher scores (P < 0.05). The conventional needle irrigation was not sufficient to remove Ca(OH)₂ from the root canal system. Irrigation with EndoVac and PiezoFlow? ultrasonic irrigation systems improved the removal of the intracanal medicament resulting in cleaner root canal walls.     

Does Calcium Hydroxide Reduce Endotoxins in Infected Root Canals? Systematic Review and Meta-analysis

IntroductionThe purpose of this study was to evaluate the potential of endotoxin reduction by comparing the number of lipopolysaccharides (LPSs) before and after the use of calcium hydroxide (Ca[OH]₂) as intracanal medication (ICM).MethodsSearches were performed up to June 2020. Clinical and experimental studies comparing the amount of LPSs before and after the use of Ca(OH)₂ as ICM in infected root canals were included. Risks of bias assessment and data extraction were performed. Meta-analysis was conducted by subgrouping according to Ca(OH)₂, the presence of an antimicrobial substance (AS), irrigant solution during chemomechanical preparation (CMP), and the incidence of LPS reduction. The certainty of evidence was determined by the Grading of Recommendations Assessment, Development and Evaluation approach.ResultsNine studies were included in the qualitative synthesis and 7 in the meta-analysis. Three articles had low risk of bias (RB), 1 had moderate RB, 2 had high RB, and 3 “some concerns.” Overall, Ca(OH)₂, with or without AS, reduced mean LPSs before CMP (standardized mean difference [SMD] = −1.087 [confidence interval {CI}, −1.453 to −0.721], P < .001, I² = 58.7%) and after CMP (SMD = −0.919 [CI, −1.156 to −0.682], P < .001, I² = 24.7%). Considering the irrigant solutions, the overall results showed a reduction before (SMD = −1.053 [CI, −1.311 to −0.795], P < .001, I² = 58.7%) and after CMP (SMD = −0.938 [CI, −1.147 to −0.729], P < .001, I² = 24,6%). Analyses presented very low certainty of evidence. The incidence of LPS reduction was 98.9% and 61.7% for Ca(OH)₂ with and without AS, respectively.ConclusionsCa(OH)₂ reduces endotoxin levels when used as ICM but is unable to eliminate LPSs completely independent of the irrigating solution used with very low certainty of evidence.     

INFLUENCE OF CALCIUM HYDROXIDE POINTS ON THE QUALITY OF INTRACANAL DRESSING FILLING

Purpose

The aim of this study was to evaluate, in vitro, the quality of calcium hydroxide [Ca(OH)₂] paste filling (Ultracal, Ultradent) associated or not with Ca(OH)₂-containing gutta-percha points (Calcium Hydroxide Plus Points™, Roeko) in curved root canals.

Material and Methods

One hundred and twenty roots of extracted human teeth, randomly divided into three curvature ranges (mild - 0 to 14°; moderate - 15° to 29°; severe - >30°) were used. After chemomechanical preparation, the roots were assigned to 4 groups (n=30), according to the technique of intracanal dressing placement: group 1 - Ca(OH)₂ paste was applied with a lentulo spiral; group 2 - Ca(OH)₂ paste was applied with a lentulo spiral and a Ca(OH)₂ point was inserted into the canal; group 3 - Ca(OH)₂ paste was applied with a Navitip™ tip (supplied with Ultracal system); group 4 - Ca(OH)₂ paste was applied with a Navitip™ tip and a Ca(OH)₂ point was inserted into the canal. The roots were cleared and the quality of apical third filling was assessed by a calibrated experienced examiner. The specimens were examined under stereomicroscopy and scored 1 to 4 (i.e., from inadequate to complete root canal filling). The results were analyzed statistically by ANOVA and Duncan''s post hoc test at 5% significance level.

Results

There were no statistically significant differences (p>0.05) among the curvature degrees in groups 1, 3 and 4. Severely curved roots in group 2 presented bordering significance (p=0.05). The groups that associated the use of Ca(OH)₂ paste and points (2 and 4) showed better apical filling than the other groups, but this difference was statistically significant (p<0.001) only for roots with severe curvature.

Conclusion

According to the results of this study, the curvature degree did not influence the quality of filling. The techniques that used Ca(OH)₂-containing gutta-percha points yielded better filling of the apical third in roots with severe curvature.     

Relationship between calcium hydroxide pH levels in the root canals and periodontal healing after replantation of avulsed teeth

Calcium hydroxide [Ca(OH)₂], when used as a root canal dressing, has been shown to promote periapical healing, induce formation of an apical hard tissue barrier (apexification), and arrest infection‐related root resorption. The main mechanism of action is thought to be the high alkalinity of Ca(OH)₂ ensuring a bactericidal or bacteriostatic effect upon microorganisms in the root canal and dentinal tubules. Several anatomical factors related to the root canal, such as the coronal access cavity, the apical foramen, the dentinal tubules, and existing resorption cavities on the root surface, all allow leakage of hydroxide ions from the root canal. The purpose of the present clinical study was to analyze pH changes in 63 permanent anterior teeth in which Ca(OH)₂ (Calasept^®) was used as an initial canal dressing after replantation and subsequent pulp necrosis had developed. The pH changes in the pulp canal were studied with relation to observation period, stage of root formation, healing of any periapical radiolucency, infection‐related root resorption, formation of an apical hard tissue barrier, and finally the radiographic appearance of Ca(OH)₂ in the canal (i.e. present or not). The study showed that several factors determined the pH level: the observation period (i.e. observation periods exceeding 6 months showed a significant drop in pH level below a pH of 10), an initial active inflammatory root resorption (tendency to be related to a drop in pH), and a subsequent progression of infection‐related resorption (the same tendency to be related to a drop in pH to below 10). The size of the apical foramen and the length of the pulp had no relation to pH change. The radiographic disappearance of Ca(OH)₂ in the root canal (loss of radiopacity of the canal dressing) was found to be significantly associated with a drop in pH (P=0.001). It was concluded that radiographic monitoring of the Ca(OH)₂ presence in the root canal is essential for endodontic treatment planning (i.e. when to replace Ca(OH)₂ or perform a permanent root filling). Furthermore, continuous activity of inflammatory root resorption may indicate a drop in pH and should result in replacement of new Ca(OH)₂. It should be noted that these findings apply to a Ca(OH)₂ product (Calasept^®) with no added radiopaque material.     

A Retrospective Evaluation of Radiographic Outcomes in Immature Teeth With Necrotic Root Canal Systems Treated With Regenerative Endodontic Procedures

IntroductionSeveral case reports on endodontic regeneration involving immature permanent teeth have recently been published. These case series have used varying treatments to achieve endodontic regeneration including triple antibiotic paste, Ca(OH)₂, and formocresol. However, no study has analyzed the overall results.MethodsIn this retrospective study, we collected radiographs from 54 published and unpublished endodontic regenerative cases and 40 control cases (20 apexification and 20 nonsurgical root canal treatments) and used a geometrical imaging program, NIH ImageJ with TurboReg plug-in, to minimize potential differences in angulations between the preoperative and recall images and to calculate continued development of root length and dentin wall thickness.ResultsThe comparison to the 2 control groups provided a validation test for this method. Forty-eight of the 54 regenerative cases (89%) had radiographs of sufficiently similar orientation to permit analysis. The results showed regenerative endodontic treatment with triple antibiotic paste (P < .001) and Ca(OH)₂ (P < .001) produced significantly greater increases in root length than either the MTA apexification or NSRCT control groups. The triple antibiotic paste produced significantly greater differences in root wall thickness than either the Ca(OH)₂ or formocresol groups (P < .05 for both). The position of Ca(OH)₂ also influenced the outcome. When Ca(OH)₂ was radiographically restricted to the coronal half of the root canal system, it produced better results than when it was placed beyond the coronal half.ConclusionsCa(OH)₂ and triple antibiotic paste when used as an intracanal medicament in immature necrotic teeth can help promote further development of the pulp-dentin complex.     

Efficacy of a combined nanoparticulate/calcium hydroxide root canal medication on elimination of Enterococcus faecalis

The purpose of this study was to evaluate the efficacy of Ca(OH)₂ with or without a silver nanoparticle suspension to eliminate Enterococcus faecalis from root canals. A total of 66 extracted human single‐rooted teeth contaminated with E. faecalis were treated with 10% Ca(OH)₂ alone, Ca(OH)₂ with nanosilver or sterile water (as a negative control). Samples were obtained with paper points and Gates‐Glidden burs at 1 and 7 days after root canal preparation and the number of colony‐forming units (CFU) was determined. The number of CFUs observed after dressing with Ca(OH)₂ + nanosilver was significantly less than the number observed with Ca(OH)₂ alone after 1 or 7 days (P < 0.001, P < 0.001). No differences in antimicrobial properties were observed between the two time points in the Ca(OH)₂ + nanosilver group (P > 0.05). Higher antimicrobial efficacy was observed in the Ca(OH)₂ group after 7 days than 1 day (P < 0.001). This study highlighted the potential advantage of using a mixture of Ca(OH)₂ and nanosilver for intracanal medicament.     

Clinical investigation of the effect of calcium hydroxide intracanal dressing on bacterial lipopolysaccharide reduction from infected root canals

The purpose of this clinical study was to determine the effect of 7 day intracanal dressing with calcium hydroxide on the amount of bacterial lipopolysaccharide (LPS; endotoxin) in human teeth with necrotic and infected pulp and apical periodontitis. Twenty‐five single‐rooted teeth with necrotic pulps and apical periodontitis were selected. Samples were collected before (S1), after root canal preparation (S2) and after 7 day intracanal dressing with calcium hydroxide (S3). The limulus amoebocyte lysate assay was used to quantify LPS. LPS was present in 100% of the root canals before (S1), after preparation (S2) and after 7 day intracanal dressing (S3). A significant reduction, equal to 29.54%, was found after root canal preparation (P < 0.05). A significant difference (equal to 25.26% reduction) was also detected between S2 and S3 (P < 0.05). Total endotoxin reduction (S3 compared with S1) was found to be 47.34%. Endotoxin concentration of the infected root canals was reduced after root canal preparation and also after 7 days of dressing of canals with calcium hydroxide; however, relatively high values of endotoxin remained in the root canals.     

In vitro evaluation of the effectiveness of irrigants and intracanal medicaments on microorganisms within root canals

AIM: To evaluate in vitro the effectiveness of sodium hypochlorite (NaOCl), chlorhexidine (CHX) and five intracanal medicaments on microorganisms within root canals. METHODOLOGY: Ninety-six human single-rooted extracted teeth were used. After removing the crowns, canal preparation was completed and the external root surfaces were coated with epoxy resin. Following sterilization, the teeth were contaminated with Candida albicans and Enterococcus faecalis, and were incubated at 37 +/- 1 degrees C for 7 days. The teeth were divided according to the irrigant solution or intracanal medicament: group 1, sterile physiologic solution (SPS) and calcium hydroxide (Ca(OH)2) paste; group 2, SPS and camphorated paramonochlorophenol (CPMC); group 3, SPS and tricresol formalin; group 4, SPS and CaOH2 + CPMC paste; group 5, SPS and PMC furacin; group 6, 2.5% NaOCl without intracanal medication; group 7, 2.0% CHX without intracanal medication and group 8, SPS without intracanal medication (control group). Microbiological samples were collected with sterile paper points, and bacterial growth was determined. The data were submitted to the analysis of variance (anova, P = 0.05). RESULTS: For C. albicans, groups 3 and 8 were statistically less effective than groups 1, 2, 4 and 5 (Kruskal-Wallis (K-W) = 65.241; gl = 7; P = 0.001). For E. faecalis, groups 6 and 8 were statistically less effective than groups 1-4 and 7 (K-W = 61.048; gl = 7; P = 0.001). CONCLUSIONS: Ca(OH)2 + CPMC paste was the most effective intracanal medicament for the elimination of the two microorganisms; 2.0% CHX solution was more effective than 2.5% NaOCl against E. faecalis.     

Effect of Calcium Hydroxide Dressing on the Dentinal Tubule Penetration of 2 Different Root Canal Sealers: A Confocal Laser Scanning Microscopic Study

Introduction

The purpose of this study was to evaluate the effect of calcium hydroxide (Ca[OH]₂) dressing on the dentinal tubule penetration of epoxy resin–based sealer (AH 26; Dentsply Maillefer, Ballaigues, Switzerland) and tricalcium silicate–based sealer (BioRoot RCS; Septodont, Saint Maurdes Fosses, France).