In vitro evaluation of the antimicrobial activity of calcium hydroxide combined with chlorhexidine gel used as intracanal medicament

The aim of this study was to investigate the antimicrobial activity of calcium hydroxide (Ca(OH)2) combined with 2% chlorhexidine gluconate (CHX) gel against endodontic pathogens and to compare the results with the ones achieved by Ca(OH)2 mixed with sterile water and by CHX gel alone. Two methods were used: the agar diffusion test and the direct contact test. Ca(OH)2 + 2% CHX gel produced inhibitory zones ranging from 2.84 to 6.5 mm, and required from 30 seconds to 6 hours to eliminate all tested microorganisms. However, 2% CHX gel showed the largest microbial growth zones from 4.33 to 21.67 mm, and required 1 minute or less to inhibit all tested microorganisms. A paste of Ca(OH)2 plus sterile water inhibited only the microorganisms with which it was in direct contact and required from 30 seconds to 24 hours to kill all tested microorganisms. In conclusion, 2% CHX gel + Ca(OH)2 showed better antimicrobial activity than Ca(OH)2 manipulated with sterile water.     

In vitro antimicrobial activity of calcium hydroxide pastes and their vehicles against selected microorganisms

The aim of this study was to investigate in vitro the antimicrobial activity of calcium hydroxide in combination with several vehicles against some microorganisms commonly isolated from root canals. Antimicrobial activity was determined by the agar diffusion method. Stainless-steel cylinders were placed on each inoculated agar medium. The test medicaments and their controls were placed inside the cylinders. The zones of growth inhibition were measured and recorded after incubation for each plate and the results were analyzed statistically (ANOVA). The in vitro antimicrobial effects of the medications were ranked from strongest to weakest as follows: Ca(OH)2 + CMCP + glycerine, Ca(OH)2 + CMCP, Ca(OH)2 + glycerine, Ca(OH)2 + anesthetic, Ca(OH)2 + saline, Ca(OH)2 + H2O, Ca(OH)2 + polyethyleneglycol. The pastes with oily vehicles showed significantly larger mean zones of inhibition compared to those with aqueous or viscous vehicles. It was concluded that diffusion and antimicrobial activity of calcium hydroxide were affected by the type of vehicle used.     

Microbial susceptibility to calcium hydroxide pastes and their vehicles

The aim of this study was to investigate the susceptibility of some microorganisms commonly isolated from root canals to calcium hydroxide in combination with several vehicles by the agar diffusion method. Stainless-steel cylinders were placed on each inoculated agar medium. The test medications and their controls were placed inside the cylinders. The zones of growth inhibition were measured and recorded after the incubation period for each plate, and the results were analyzed statistically. Enterococcus faecalis was most resistant, whereas the anaerobic Porphyromonas endodontalis was more susceptible to all medications, followed by P. gingivalis and Prevotella intermedial intermedia. Ca(OH)2 + CMCP + glycerin showed significantly larger mean zones of inhibition when compared with the other medications. We conclude that anaerobic Gram-negative bacteria are more susceptible to calcium hydroxide pastes than facultative Gram-positive microorganisms.     

Antioxidant and pro-oxidant properties of chlorhexidine and its interaction with calcium hydroxide solutions

AIM: To evaluate the antioxidant and pro-oxidant properties of chlorhexidine (CHX). METHODOLOGY: The scavenging and generation of reactive oxygen species (ROS) by CHX in the presence or absence of saturated Ca(OH)(2) solutions was evaluated. The reaction emitted chemiluminescence in the presence of lucigenin thus was determined by a luminometer to evaluate the levels of ROS production. Changes in DNA conformation were analysed by agarose gel electrophoresis. Paired Student's t-test was used to compare the difference between groups. RESULTS: Chlorhexidine (0.00002-0.02%) effectively scavenged 56-88% of the superoxide radicals generated by the xanthine/xanthine oxidase reaction. Through analysis of PUC18 DNA conformation changes, CHX was shown to be a mild scavenger of hydroxyl radicals generated by H(2)O(2) plus FeCl(2). However, CHX (>0.083%) decreased the mobility of PUC18 plasmid DNA with potential production of DNA-DNA cross-link and severe DNA breaks (presence of DNA smear) at further higher concentrations. Furthermore, CHX induced ROS production including H(2)O(2) and superoxide radicals in 0.1N NaOH (pH = 12.76) or Ca(OH)(2) (pH = 12.5) solutions. CONCLUSION: Chlorhexidine exhibited both antioxidant and pro-oxidant properties under different conditions. These events are possibly involved in the killing of root canal and periodontal microorganisms when CHX and Ca(OH)(2) were used in combination or separately. Potential genotoxicity and tissue damage when extruded into the periradicular tissue and at higher concentrations should be considered during periodontal and endodontic practice.     

Efficacy of chlorhexidine- and calcium hydroxide-containing medicaments against Enterococcus faecalis in vitro

OBJECTIVE: We sought to assess the efficacy of chlorhexidine (CHX) and calcium hydroxide, Ca(OH)(2), against Enterococcus faecalis in vitro. STUDY DESIGN: The effect of CHX (0.2% and 2% in gel or solution) and Ca(OH)(2) (alone or with 0.2% CHX gel) was evaluated by using the agar diffusion test and an in vitro human root inoculation method, to measure zone of inhibition or bacterial growth with optical density analysis, respectively. For optical density analysis, samples from infected root canals were collected after 7 days of medication and were cultured for 24 hours in brain-heart infusion to detect viable bacteria. RESULTS: In the agar diffusion test, CHX was effective against E faecalis in a concentration-dependent fashion, but Ca(OH)(2) alone had no effect. In the root canal inoculation test, CHX was significantly more effective against E faecalis than Ca(OH)(2) was (P < .05), but there were no significant differences between the modes of medication or concentrations of CHX. CONCLUSIONS: CHX is effective against E faecalis in vitro. Further in vivo studies are needed to confirm the value of CHX in clinical treatment.     

In vitro antimicrobial activity of phytotherapic Uncaria tomentosa against endodontic pathogens

The aim of this study was to evaluate the antimicrobial activity of Uncaria tomentosa (Willd.) DC (cat's claw) against Enterococcus faecalis, Staphylococcus aureus, and Candida albicans. Suspensions with 10(8) cells/ml of each microorganism were plated in triplicate on Mueller-Hinton agar. Wells in the agar were made and filled with 2% chlorhexidine (CHX) gel, 2% cat's claw (CC) gel, 2% CHX+CC, and 1% hydroxyethylcellulose (NAT) gel. Inhibition halos were measured after 24 h at 37°C and differences were analyzed using one-way ANOVA. The mean diameter of the microbial growth inhibition zones of 2% CHX+CC against the tested microbial strains ranged from 21.7 to 33.5 mm. This was the most effective substance against E. faecalis and C. albicans, followed by CHX and CC. Against S. aureus, CHX+CC, CHX, and CC showed similar antimicrobial activity (P > 0.05). The results indicate that all the investigated compounds had antimicrobial activity against microorganisms frequently found in infected root-filled teeth.     

Bacterial quantification in teeth with apical periodontitis related to instrumentation and different intracanal medications: a randomized clinical trial

The antibacterial efficacy of intracanal medication with calcium hydroxide [Ca(OH)2], 2% chlorhexidine gel (CHX), and a combination of both [Ca(OH)2/CHX] was assessed in teeth with chronic apical periodontitis. Thirty-three canals were instrumented, randomly divided into three groups, and medicated with either Ca(OH)2, CHX, or Ca(OH)2/CHX. Bacteriological samples obtained from the operative field and the root canals before (S1) and after instrumentation (S2) in the first treatment session, and after medication (S3) in the second session 1 week later, were assessed for bacterial growth, observed by turbidity and in agar plates, and viable colony-forming unit (CFU) counts. Bacterial growth and CFU counts decreased significantly from S1 to S2 (Mann-Whitney, p<0.05). Differences in growth and counts between S2 to S3 were not statistically significant for all three intracanal medication groups. It was concluded that the antibacterial efficacy of Ca(OH)2, CHX, and Ca(OH)2/CHX was comparable.     

Release and diffusion of hydroxyl ion from calcium hydroxide-based medicaments

The release and diffusion of hydroxyl ions (OH(-)) of calcium hydroxide (Ca(OH)(2))-based intracanal medications may be affected by the association with other substances. The aim of this study was to evaluate the diffusion of OH- ions through root dentin by the medications: G1, Ca(OH)(2)/saline; G2, Calen; G3, Calen/camphorated p-monochlorophenol (CMCP); and G4, Calen/0.4% chlorhexidine (CHX). Root canals from bovine teeth were prepared in a standardized manner. A cavity until dentin was prepared in the middle third of the root surface of each specimen. The external surface of the root was made impermeable using a layer of adhesive, except the prepared cavity. The root canals were filled with different medications, and teeth were individually stored in flasks containing 10 ml distilled water at 37°C. The water pH was measured at 1, 3, 7, 14, 21, 30, and 60 days. Data obtained were subjected to anova and Tukey's tests. Increase in pH was observed at 3 days for Calen/CHX and from 7 to 14 days for the other mixtures. Calen paste promoted pH increase up to 21 days. Calen/CMCP had the highest pH up to 21 days, and all groups had similar results at 30 days. At 60 days, the greatest pH values were observed for Calen/CMCP and Calen alone. All different formulations of Ca(OH)(2)-based medications tested release hydroxyl ion that can diffuse through the dentin.     

Substantive antimicrobial activity in chlorhexidine-treated human root dentin

OBJECTIVE: The aim of this in vitro study was to assess the substantive antimicrobial activity of different medicaments in human root dentin. STUDY DESIGN: Canals of 98 roots were enlarged to standard size and medicated for 7 days with the following: (1) 2% chlorhexidine (CHX) gel, (2) 0.2% CHX gel, (3) 2% CHX solution, (4) Ca(OH)(2), (5) Ca(OH)(2)+ 0.2% CHX gel, (6) 2% CHX solution + a 25% CHX-containing controlled-release device, (7) saline, and (8) gel vehicle. After medication, canals were inoculated with Enterococcus faecalis for 21 days. Dentin samples were collected with Gates-Glidden burs into brain heart infusion broth, and bacterial growth was assessed with spectrophotometric analysis of optical density after 72 hours of incubation. RESULTS: Mean optical densities were significantly lower for groups with 2% CHX (1, 3, and 6) when compared with those of the controls (P < .05, analysis of variance with the Tukey test). Other groups did not differ significantly from the controls. CONCLUSIONS: Canal dressing for 1 week with 2% CHX may provide residual antimicrobial activity against E faecalis.     

Bacterial leakage in roots filled with different medicaments and sealed with Cavit

The aim of this study was to evaluate the time required by four different root canal medications coupled with the temporary filling material Cavit (ESPE, Seefeld, Germany) to prevent penetration of bacteria into the root canal. There were 145 roots prepared in a standardized manner. Four groups with 15 samples each were dressed with calcium hydroxide (Ca(OH)(2)), a 5% chlorhexidine gel (CHX), a chloromono-campherphenolic compound (ChKM), and Ledermix (LM), respectively, and sealed with Cavit. Four control groups contained identical medications but the roots were left unsealed. The 25 remaining roots served as additional controls. A standard setup for bacterial leakage studies was chosen with Staphylococcus epidermidis as test strain. Cavit application resulted in a significantly better seal compared with the unsealed groups. In the Cavit-sealed groups, all groups differed significantly from one another except for the CHX and the ChKM groups. The Ca(OH)(2) medicated roots provided the longest protection (median of 36 days), followed by the Ledermix-group (27 days) and the CHX (18 days) or ChKM groups (19 days). It may be concluded that Cavit-sealed and medicated root canals do not provide adequate protection against bacterial leakage for more than 1 month.     

Adhesion of glass-ionomer cement sealers to bovine dentin conditioned with intracanal medications

This in vitro study assessed the adherence of glass-ionomer cement (GIC) root canal sealers to dentin conditioned by three endodontic intracanal medications. Three GIC sealers were used: (i) Ketac-Endo; (ii) KT-308, an experimental GIC sealer; and (iii) ZUT, a combination of KT-308 and a silver-containing zeolite (0.2% by weight). Superficial dentin of 120 bovine incisor crowns was used as a substrate. The dentin was irrigated with 2.6% NaOCI for 30 s and then blotted dry. One of the following conditioning media (n = 30) was maintained in contact with the dentin for 7 days: (i) Ca(OH)2 paste; (ii) chlorhexidine gluconate (CHX) liquid 0.12%; (iii) formocresol (FML) liquid; (iv) distilled water (dH2O) used as control. The GIC sealers were applied to the conditioned dentin, bench set for 90 min, stored in 100% humidity at 37 degrees C for 48 h, then tested to failure for shear bond strength (MPa) in an Instron machine. In the ZUT specimens, the shear bond strength did not differ significantly among those conditioned with Ca(OH)2, CHX, FML, and dH2O. For KT-308, the mean scores were significantly lower (p < 0.05) after conditioning with CHX than with dH2O. For Ketac-Endo, the mean scores were significantly lower after conditioning with Ca(OH)2 and FML than with dH2O (p < 0.05). Furthermore Ketac-Endo demonstrated significantly lower (p < 0.05) shear bond strength than KT-308 or ZUT to the dentin conditioned with Ca(OH)2 or FML. The results suggest that intracanal medications differentially influence the adhesion of various GIC sealers to root canal dentin.     

Control of microorganisms in vitro by endodontic irrigants

The aim of this study was to determine the minimum inhibitory concentration (MIC) and antimicrobial effectiveness by the direct exposure test of 4 endodontic irrigants [1% sodium hypochlorite (NaOCl), 2% chlorhexidine (CHX), 1% calcium hydroxide (Ca(OH)2; prepared with 1 g of Ca(OH)2 and 100 mL of sterile distilled water), a solution of Ca(OH)2 + detergent (HCT20)] for S. aureus, E. faecalis, P. aeruginosa, B. subtilis, C. albicans and a mixed culture. Microbial growth was analyzed by two methods: turbidity of the culture medium that was confirmed by Gram stain and subculture in a specific nutrient broth. In the dilution test, NaOCl solution showed MIC equal to 0.1% for S. aureus, E. faecalis, P. aeruginosa and C. albicans and equal to 1% for B. subtilis and the mixed culture. CHX (2%) presented MIC equal to 0.000002% for S. aureus, 0.02% for E. faecalis, B. subtilis, C. albicans and the mixed culture and 0.002% for P. aeruginosa. Ca(OH)2 solution (1%) showed MIC greater than 1% for all the microorganisms except P. aeruginosa for which it was equal to 1%. Calcium hydroxide solution + detergent showed MIC equal to 4.5 mL for S. aureus, P. aeruginosa, B. subtilis, C. albicans and the mixed culture and greater than 4.5 mL for E. faecalis. In the direct exposure test, NaOCl had better antimicrobial effectiveness for all microorganisms at all times. CHX (2%) was effective for S. aureus, E. faecalis and C. albicans at all times, and ineffective for P. aeruginosa, B. subtilis and the mixed culture. The other solutions showed the worst results.     

Comparative analysis of endodontic pathogens using checkerboard hybridization in relation to culture

Background/Aim:  The purpose of this study was to detect bacterial species and to quantify the total number of bacteria from samples of infected root canals before (S1) and after chemo-mechanical preparation using 2% chlorhexidine (CHX) gel as auxiliary chemical substance (S2) and after 7 days of intracanal dressing (S3) to compare microbial changes.
Method:  Twenty-four teeth were selected for this study. Chemo-mechanical preparation was performed using 2% CHX gel, then three different intracanal medicaments [M1: Ca(OH)₂ paste; M2: 2% CHX gel; and M3: Ca(OH)₂ paste plus 2% CHX gel] were used for 7 days. Checkerboard DNA–DNA hybridization was performed to detect 40 bacterial species. Aerobic and anaerobic culture techniques were used to determine the bacterial community by counting the colony-forming units (CFU).
Results:  The species most frequently identified by checkerboard in S1 were: Fusobacterium nucleatum ssp . polymorphum , Treponema socranskii ssp. socranskii , Parvimonas micra and Enterococcus faecalis. In S2 and S3 a total of eight different species were identified; and only one of them was gram-positive ( E. faecalis ). Microorganisms were not identified after use of M2 for 7 days. The quantification obtained on agar plates ranged from 4 × 10⁵ to 2.6 × 10⁶ CFU/ml in S1, mean CFU was reduced by 99.96% in S2, and there was no statistical difference between the CFU in S2 and S3.
Conclusion:  The antibacterial effect of the mechanical preparation supplemented by the use of an antibacterial auxiliary substance greatly reduced the microorganisms in the main root canal.     

Antimicrobial substantivity of bovine root dentin exposed to different chlorhexidine delivery vehicles

Root canal dentin acquires antimicrobial substantivity after exposure to chlorhexidine gluconate (CHX) for 1 wk. Therefore development of a vehicle for delivery of CHX as an intracanal medication is desirable. This in vitro study assessed the efficacy of two CHX delivery vehicles, a controlled-release device and a gel, to affect antimicrobial substantivity of bovine root dentin. Sixty bovine incisor root specimens were prepared with standardized length (10 mm) and canal diameter (3.3 mm), and coated externally with nail polish. Specimens were divided into four equal groups and their canals medicated for 7 days with either: (i) an experimental controlled-release device containing 25% CHX that was immersed in sterile saline; (ii) 2% CHX gel; or (iii) Ca(OH)2 paste. Sterile saline was used as the positive control. After medication, the canals of the specimens were inoculated with Enterococcus faecalis for 21 days. Root canal dentin samples ranging in depth from 0.1 to 0.45 mm were then obtained using sterile round burs of ascending diameter. Each dentin sample was placed in a separate test tube containing Brain Heart Infusion broth and incubated for 24 h. The optical density (OD) of the broth was then measured spectrophotometrically at 540 nm. The positive control showed significantly higher mean OD values (one-way ANOVA and Tukey's Studentized Range Test; p < 0.001) than the three test groups. The CHX controlled-release device group showed significantly lower OD values than the Ca(OH)2 group; however only at dentin depths up to 0.2 mm. In contrast, the CHX gel group consistently showed significantly lower OD values than both the CHX controlled-release device and Ca(OH)2 groups. These results suggest that bovine root canals medicated with 2% CHX gel for 7 days acquire antimicrobial properties for at least 21 days.     

Effects of mouth rinses with chlorhexidine and zinc ions combined with fluoride on the viability and glycolytic activity of dental plaque

Inhibition of plaque acidogenicity by a mouthrinse with chlorhexidine (CHX) or zinc ions has been ascribed to a prolonged bacteriostasis due to substantive properties of the agents. The present aim was to study the effects of mouthrinses with CHX and Zn ions combined with fluoride on the viability and glycolytic activity of dental plaque in order to assess the bacteriostatic versus possible bactericidal effects. Following 2 d of plaque accumulation, 4 groups of 10 students rinsed with either 12 mM NaF (F), 0.55 mM CHX diacetate + F (F-CHX), 10 mM Zn acetate+F (F-Zn), or with the three agents in combination (F-CHX-Zn). Plaque samples were collected before and 90 min after mouthrinsing. Thereafter, the in vivo plaque pH response to sucrose was monitored in each student using touch microelectrodes. F-CHX and F-CHX-Zn reduced the in vivo pH fall significantly as compared with F. whereas F-Zn exerted a non-significant inhibition. Pooled pre- and post-rinse plaque samples were used to measure the pH fall during fermentation of [¹⁴C]-glucose, and the glycolytic profiles were analyzed by HPLC. Bacterial viability was assessed by counting the colony-forming units (CPU). All mouthrinses except F reduced glucose consumption and acid formation and thus the pH fall. F-CHX reduced the CFU equal to the reduction of glucose consumption, indicating that inhibition of plaque acidogenicity was due to a bactericidal rather than a bacteriostatic effect. F and F-Zn did not reduce the CFU, thus F-Zn decreased glucose metabolism without affecting plaque viability. F-CHX-Zn reduced both the CFU and glucose metabolism of surviving plaque microorganisms.     

Calcium hydroxide mixed with camphoric p-monochlorophenol or chlorhexidine in delayed tooth replantation

This study evaluated the repair process after delayed replantation of rat teeth, using calcium hydroxide (Ca(OH)2) mixed with camphorated p-monochlorophenol (CMCP), chlorhexidine 2% (CHX), or saline as temporary root canal dressing to prevent and/or control inflammatory radicular resorption. Thirty Wistar rats (Rattus norvegicus albinos) had their right upper incisor extracted, which was bench-dried for 60 minutes. The dental papilla, the enamel organ, the dental pulp, and the periodontal ligament were removed. The teeth were immersed in 2% acidulated-phosphate sodium fluoride solution for 10 minutes. The root canals were dried with absorbent paper cones and divided into 3 groups of 10 animals according to root canal dressing used: group 1: Ca(OH)2 + saline, group 2: Ca(OH)2 + CMCP, and group 3: Ca(OH)2 + CHX 2%. Before replanting, the teeth sockets were irrigated with saline. Histological analysis revealed the presence of inflammatory resorption, replacement resorption, and ankylosis in all 3 groups. Statistical analysis showed a significant difference between group 3 and the other groups. The use of Ca(OH)2 mixed with CMCP or CHX did not show an advantage over the use of Ca(OH)2 mixed with saline in preventing and/or controlling inflammatory resorption in delayed replantation of rat teeth.     

Detection and eradication of microorganisms in root-filled teeth associated with periradicular lesions: an in vivo study

This study determined the presence of microorganisms by culture and polymerase chain reaction in asymptomatic root-filled teeth with periradicular lesions. Furthermore, a disinfecting regimen using sodium hypochlorite (NaOCl), ethylenediaminetetraacetic acid (EDTA), chlorhexidine digluconate (CHX) irrigation, and calcium hydroxide (Ca(OH)(2)) dressing was assessed. After removal of the root-filling material, specimens of 20 cases undergoing retreatment were sampled. Moreover, the canals were sampled after each step of the disinfecting regimen. Prevalence of microorganisms was 60% by culture and 65% by polymerase chain reaction. In four of those samples (31%), DNA of Enterococcus faecalis was found. After further root canal preparation and irrigation using NaOCl and EDTA, microorganisms could be detected in none of the teeth. Thus, CHX and Ca(OH)(2) could not show further disinfection. In contrast, microorganisms were found in two teeth after the interappointment dressing. It may be concluded that proper root canal preparation and irrigation using NaOCl and EDTA are sufficient for decontamination of the root canal system during endodontic retreatment.     

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.     

Removal efficacy of various calcium hydroxide/chlorhexidine medicaments from the root canal

Aim To compare the efficiency of removing calcium hydroxide [Ca(OH)₂]/chlorhexidine (CHX) (gel), Ca(OH)₂/CHX (solution) and Ca(OH)₂/saline pastes with the use of instrumentation and irrigation with sodium hypochlorite and ethylene diamine tetraacetic acid (EDTA) solutions. Moreover the role of the patency file in the cleanliness of the apical third of the root canal was evaluated. Methodology Sixty‐four human single‐rooted teeth with straight canals were used. Root canal preparation was performed with a stepback technique using Hedström (H) files. Teeth were randomly assigned to three groups and subsequently filled with one of the pastes: Ca(OH)₂/CHX (gel), Ca(OH)₂/CHX (solution) and Ca(OH)₂/saline paste. The medicaments were removed 10 days later using instrumentation and irrigation with 1% sodium hypochlorite and 17% EDTA, with or without obtaining patency of the apical foramen with a size 10 H‐file. The crowns were removed at the cemento‐enamel junction and the roots were grooved longitudinally and split into halves. Images of all halves were acquired with the use of a flatbed scanner. A scoring system of 1 to 4 was used to assess the amount of residue on the cervical, middle and apical third of the canal. Data were subjected to statistical analysis using Kruskal–Wallis and Mann–Whitney tests, with Bonferroni correction, at 95% confidence level (P < 0.05). Results Remnants of medicament were found in all experimental teeth regardless of the experimental material used and the use of the patency file. When examining the root canal as a whole, Ca(OH)₂/CHX (gel) paste was associated with significantly larger amount of residue, whereas the Ca(OH)₂/CHX (solution) paste was associated with less amount (P < 0.05) than the other two medicaments with or without the use of a patency file. Conclusions None of the techniques used in this study removed the inter‐appointment root canal medicaments effectively; the use of the patency file facilitated removal of more of the medicament in the apical third of those straight canals.     

Physical and chemical properties of chlorhexidine and calcium hydroxide-containing medications

This study was performed to evaluate the physicochemical properties (pH, contact angle, working time, radio-opacity, and viscosity) of chlorhexidine (CHX) and calcium hydroxide-containing medications in gel form in different concentrations. The pH value was assessed with a pH meter. The contact angle was measured with a goniometer. The radio-opacity and working time measurements were taken in accordance with the standards of the International Organization for Standardization. The viscosity was evaluated using a Brookfield RVDV viscometer. The results showed that CHX did not affect the pH, radio-opacity, and working time of the calcium hydroxide-containing medications (p < 0.05). However, adding CHX lowered the contact angle and increased the viscosity of calcium hydroxide significantly. This research showed that CHX in different concentrations and in combination with calcium hydroxide has satisfactory physicochemical properties to be used as an intracanal medication.