Antimicrobial substantivity of chlorhexidine-treated bovine root dentin

Previous studies have demonstrated antimicrobial substantivity in root canal dentin up to 7 days after treatment with chlorhexidine. This in vitro study assessed the antimicrobial substantivity of chlorhexidine-treated bovine root dentin over a period of 21 days. Sixty standardized bovine root sections were randomly divided into three equal groups, and their canals immersed in one of the following solutions: (i) sterile saline; (ii) 2.5% NaOCl; or (iii) 0.2% chlorhexidine (CHX). Half the specimens in each group were treated with the solution for 5 min and the other half for 7 days. After solutions were removed, the specimens were incubated at 37 degrees C in Brain Heart Infusion broth containing Enterococcus faecalis (ATCC 29212). A fresh inoculum was added to the broth every other day over a 21-day period. The canals were then enlarged with sterile burs, and the dentin shavings collected and cultured for the presence of cultivable bacteria in the dentinal tubules. Specimens treated with CHX for 7 days demonstrated significantly less dentin colonization by E. faecalis than the other specimens. CHX has potential as an intracanal medicament, if it can be applied for a period of at least 7 days.     

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.     

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.     

In vitro antimicrobial activity of various medication preparations on E. faecalis in root canal dentin

The purpose of this study was to evaluate the antimicrobial activity of several medication preparations in root canal dentin infected with Enterococcus faecalis. Roots of extracted bovine incisors were prepared to standardized cylindrical test specimens, 5 mm in height. The smear layer was removed and the samples were autoclaved and then incubated at 37 degrees C/5% CO2 for 24 h in brain-heart infusion (BHI) broth containing 7.0 x 10(4) colony forming units per ml of E. faecalis. The samples were washed in phosphate buffered saline and mounted to individual culture wells with sticky wax. Test medications were applied to fill the canal lumina; medication groups were: (a) sterile H2O (positive control); (b) a 10% mixture of 1.0 g Ca(OH)2 USP in 10 ml sterile H2O; (c) 10% Ca(OH)2 in 0.12% chlorhexidine gluconate (Peridex); (d) Peridex; and (e) uninoculated BHI (negative control). The samples were incubated at 37 degrees C/5% CO2 for 24 h. Dentin samples for quantitative microbiology were then obtained with consecutive sterile burs (ISO 029, 035, 042). All three experimental groups demonstrated significantly greater antimicrobial activity than the positive control (p < 0.001). Group 2 demonstrated significantly greater antimicrobial activity than Group 3 or Group 4 at all dentin depths (p < 0.05). These results suggest that 10% Ca(OH)2 may be more effective than Peridex or 10% Ca(OH)2 in Peridex for the elimination of E. faecalis from dentin tubules.     

Residual antibacterial activity of chlorhexidine and MTAD in human root dentin in vitro

The purpose of this in vitro study was to compare the antimicrobial substantivity of BioPure MTAD, 2% chlorhexidine (CHX) and 2.6% sodium hypochlorite (NaOCl) in human root dentin. One hundred and ten dentin tubes prepared from human maxillary incisors were infected in vitro for 14 days with Enterococcus faecalis. The specimens were divided into five groups as follows: CHX; BioPure MTAD; NaOCl; infected dentin tubes (positive control); and sterile dentin tubes (negative control). Dentin chips were collected with round burs into Brain Heart Infusion (BHI) broth. After culturing, the number of colony-forming units (CFU) was counted. In all experimental groups, CFU was minimum after treatment (day 0), and the results obtained were significantly different from each other at any time period (P < 0.05). After treatment, the NaOCI group and BioPure MTAD group showed the lowest and highest number of CFU, respectively. In each group, the number of CFUs increased significantly by time-lapse (P < 0.05). In conclusion, the substantivity of BioPure MTAD was significantly greater than CHX and NaOCl.     

Antimicrobial efficacy of chlorhexidine and two calcium hydroxide formulations against Enterococcus faecalis

The purpose of this study was to investigate the efficacy of chlorhexidine (CHX) and calcium hydroxide (Ca(OH2) against Enterococcus faecalis in vitro. Extracted single-rooted human teeth were instrumented up to size 40. After removal of the smear layer, an inoculum of E. faecalis was inserted into the root canals. After incubation, the inoculum was removed and the root canals were filled with one of three different disinfectants: Ca(OH2 paste, CHX 2%, and a mixture of CHX and Ca(OH2 paste (n = 10 in each group). Control teeth were filled with water of standardized hardness (n = 10). The teeth were then incubated for 3 days. After incubation, each root canal was instrumented, and the removed dentin was examined microbiologically. CHX was significantly more effective against E. faecalis than was Ca(OH2 paste or a mixture of CHX with Ca(OH2 paste (p < 0.05). There was no increase in the efficiency of Ca(OH2 paste when CHX was added (p > 0.05). The results suggest that CHX is effective in the elimination of E. faecalis from dentinal tubules under the conditions of this study.     

An in-vitro investigation of the antibacterial effect of nisin in root canals and canal wall radicular dentine

AIM: To determine whether nisin, a bacteriocin, would be effective at killing Enterococcus faecalis and Streptococcus gordonii cells in solution and within the root canal system. METHODOLOGY: Bacterial isolates of E. faecalis and S. gordonii were grown from glycerol stocks in closed tubes containing BHY broth at 37 degrees C. The minimum bactericidal concentration (MBC) of nisin for both bacterial species was determined by a microdilution method. Extracted human teeth were decoronated to produce roots of equal length with a single canal and divided into six groups of 10 roots. The canals were prepared to a master apical size 30 file using 0.04 taper Ni-Ti rotary instruments. Bacterial samples of each species were inoculated into three groups of prepared roots and incubated in closed tubes at 37 degrees C for 21 days. The root canals in each group were then medicated with water (control), calcium hydroxide powder mixed with sterile water [Ca(OH)2], or nisin and incubated for a further 7 days. Rotary Ni-Ti files were used to take radicular dentine samples from the walls of each canal which were then incubated in BHY broth for 24 h. Optical density (OD600) readings were taken as a measure of bacterial growth. RESULTS: The MBC of nisin for E. faecalis and S. gordonii was 70 and 20 mg mL(-1) respectively. Calcium hydroxide and nisin medication eradicated infection within the root canal while cells remained viable in the control group. Mean optical density (OD600) readings from canal wall dentine shavings infected with E. faecalis were 1.32 +/- 0.98, 0.73 +/- 0.27 and 0.69 +/- 0.38 for the control, Ca(OH)2 and nisin samples respectively. Corresponding mean readings for S. gordonii were 1.19 +/- 0.18, 0.73 +/- 0.15 and 0.60 +/- 0.29. The Ca(OH)2 and nisin group readings were significantly (P < 0.01) lower than the control for each species as tested by Student's t-test and Mann-Whitney U statistical analysis. Values for Ca(OH)2 and nisin were not significantly (P > 0.01) different. CONCLUSION: Nisin was effective at eradicating E. faecalis and S. gordonii cells in pure culture and was comparable with Ca(OH)2 in the elimination of these species from within the root canal system.     

Antimicrobial activity of several calcium hydroxide preparations in root canal dentin.

The purpose of this study was to evaluate the antimicrobial activity of several calcium hydroxide (Ca(OH)2) preparations in root canal dentin infected with Enterococcus faecalis. Roots of extracted bovine incisors were prepared to standardized cylindrical test specimens of 5 mm in height; the smear layer was removed, and the specimens were incubated for 24 h at 37 degrees C in bacteriological culture medium that contained 7.0 x 10(4) colony forming units per milliliter of E. faecalis. The specimens were mounted in individual 4-mm diameter culture wells, and the test material was applied to fill the canal lumen. There were five treatment groups: group 1, a thick mixture of Ca(OH)2 USP (1.0 g/ml H2O); group 2, a thin mixture of Ca(OH)2 USP (0.1 g/ml H2O); group 3, Pulpdent TempCanal paste; group 4, sterile H2O (positive control); and group 5, 25 dentin specimens in sterile, uninoculated brain-heart infusion broth that were included as negative controls. Quantitative microbiological analysis of dentin at various depths was completed after 24 h. All groups showed a significant (p < 0.001) decrease in numbers of E. faecalis in all depths of dentin compared with the control. Groups 2 and 3 demonstrated significantly greater antimicrobial activity (73%-86% reduction) at all depths of dentin tested compared with group 1 (13%-26%) (p < 0.05). These results suggest that Ca(OH)2 can decrease the numbers of E. faecalis at all depths of dentinal tubules within 24 h and that thin preparations of Ca(OH)2 may be more effective in the elimination of E. faecalis from dentinal tubules than thick preparations.     

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.     

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.     

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.     

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.     

根管预备后的牙本质壁对兔骨髓间充质干细胞生长的影响

目的:采用不同的处理方法改变根管内壁的微环境,观察根管内壁微环境的改变对骨髓间充质干细胞生物学行为的影响。方法:收集患根尖周炎的离体牙,感染根管采用3种方法进行预备:A组机械预备后封三联抗生素,B组机械预备后封氢氧化钙,C组单纯化学预备后封氢氧化钙。将预备后的根管内壁分别与兔骨髓间充质干细胞复合进行体外培养,扫描电镜观察,检测细胞碱性磷酸酶活性。结果:3组均有细胞粘附于根管内壁生长;碱性磷酸酶活性染色,3组的阳性率分别为A组为2.39%、B组为32.59%、C组为31.10%。结论:骨髓间充质干细胞可以在根管经过机械预备或单纯化学预备后的牙本质壁上贴壁生长,氢氧化钙可促进细胞碱性磷酸酶的活性。     

Chlorhexidine substantivity in root canal dentin

OBJECTIVE: The purpose of this investigation was to evaluate the substantivity of chlorhexidine (CHX) within a root canal system and to assess how long the CHX remains antimicrobially effective. STUDY DESIGN: Bovine roots were sectioned and standardized to 8 mm. Sections, which served as controls, were treated with 1% sodium hypochlorite and 1 mol/L EDTA, then obturated with gutta percha and AH26 sealer. Experimental sections were treated similarly except they were placed in 2% CHX for 10 minutes prior to obturation. Control specimens were divided into 4 control groups and stored in saline for 1 day, 3 weeks, 6 weeks, and 12 weeks. Experimental specimens were divided into 4 groups and stored in saline for 1 day, 3 weeks, 6 weeks, and 12 weeks. After their respective storage periods, all specimens were halved and canal wall dentin was ground out with Peeso reamers. Dentin specimens were agitated in 700 microl of saline for 5 hours to release CHX. After centrifugation the supernatants were analyzed with UV spectrophotometry at 253 nm. To determine whether the CHX from dentin samples remained antimicrobial, the extracts from experimental and control groups were mixed with cultures of Enterococcus faecalis. RESULTS: After 1 day of storage, the dentin extract contained approximately 0.0048% CHX. After 3, 6 and 12 weeks, dentin extracts contained approximately 0.0023%, 0.0016%, and 0.0010% CHX respectively. Extracts from the storage groups were found to be highly antimicrobial corresponding to the CHX concentration. CONCLUSION: The results of this study indicate that CHX is retained in root canal dentin in antimicrobially effective amounts for up to 12 weeks.     

Effectiveness of 2% chlorhexidine gel and calcium hydroxide against Enterococcus faecalis in bovine root dentine in vitro

AIM: To evaluate the effectiveness of 2% chlorhexidine gluconate gel and calcium hydroxide (Ca(OH)2) as intracanal medicaments against Enterococcus faecalis. METHODOLOGY: One hundred and eighty dentine tubes prepared from intact freshly extracted bovine maxillary central incisors were infected in vitro for 7 days with E. faecalis. The specimens were divided into four groups, according to the intracanal medicament used, as follows: Group 1: 2% chlorhexidine gluconate gel; Group 2: calcium hydroxide in a viscous vehicle (polyethyleneglycol 400); Group 3: 2% chlorhexidine gluconate gel + calcium hydroxide and Group 4: Brain Heart Infusion (BHI) broth (control group). The medicaments were placed into the canal lumen and left there for experimental times of 1, 2, 7, 15 and 30 days. After each period, irrigation with sterile saline to remove the medicament was performed and the canals were dried with sterile paper points. Dentine chips were removed from the canals with sequential sterile round burs at low speed. The samples obtained with each bur were immediately collected in separate test tubes containing BHI broth. The tubes were incubated at 37 degrees C and daily observed for microbial growth, visualized by the medium turbidity. RESULTS: Chlorhexidine gel alone completely inhibited the growth of E. faecalis after 1, 2, 7 and 15 days. Calcium hydroxide allowed microbial growth at all experimental times. The combination of chlorhexidine and Ca(OH)2 was effective after 1 and 2 days demonstrating 100% antibacterial action; however, its antibacterial activity reduced between 7 and 15 days. CONCLUSION: Under the conditions of this study, it can be concluded that 2% chlorhexidine gel alone was more effective against E. faecalis than calcium hydroxide (P < 0.05). However, its antibacterial activity depended on how long it remained inside the root canal.     

Evaluation of the antibacterial substantivity of several intra-canal agents

The aim of this in vitro study was to compare the antimicrobial substantivity of 2% chlorhexidine gluconate (CHX), 100 mg ml(-1) doxycycline and 2.6% sodium hypochlorite (NaOCl) in bovine root dentine. Eighty dentine tubes prepared from bovine incisors were infected in vitro for 14 days with Enterococcus faecalis. The specimens were divided into five groups as follows: doxycycline HCl; CHX; NaOCl; infected dentine tubes (positive control); and sterile dentine tubes (negative control). Dentine chips were collected with round burs into tryptic soy broth. After culturing, the number of colony-forming units (CFU) was counted. In all experimental groups, the number of CFU was minimum in the first cultures, and the results obtained were significantly different from each other at any time period (P < 0.05). In the first culture, the NaOCl group and doxycycline HCl group showed the lowest and highest number of CFU, respectively. In each group, the number of CFU increased significantly by time-lapse (P < 0.05). In conclusion, the substantivity of CHX was significantly greater than NaOCl and doxycycline.     

Determination of the bactericidal activity of different calcium hydroxide presentations on a dentin model.

Calcium hydroxide placed as a temporary dressing in the root canal helps sterilize infected canals. Hycal and Roeko calcium hydroxide points are two delayed-action medications containing Ca(OH)2 recommended for root canal treatment. The purpose of this study was to test their bactericidal activity in comparison with that of C-PMCP on Streptococcus sanguins strain NCTC 7823. Artificially infected 4-mm high blocks of dentin obtained from bovine incisors were used as an experimental model (n = 192). After three days of treatment with the two antiseptics, intracanal dentin powder was collected by serial drillings and used to inoculate a culture broth. The turbidity of this broth after 24 hours showed if the bacteria were eliminated or not and was used as criterion of antiseptic efficacy. No bacterial growth was observed in the samples treated with C-PMCP. Hycal had a considerable bactericidal activity with 94% of negative cultures whereas first-generation Roeko points had no activity on the strain of S. sanguis tested.     

Effect of calcium hydroxide intracanal dressing on the bond strength of a resin-based endodontic sealer

The aim of this in vitro study was to evaluate the bond strength of Epiphany resin-based sealer to dentin walls after placement of calcium hydroxide [Ca(OH)2] dressings. Fifteen extracted single-rooted human teeth were instrumented using 2.5% NaOCl + EDTA as irrigants. The teeth were randomly assigned to 3 groups (n=5), according to the intracanal dressing: G1= Ca(OH)2 + saline; G2= Ca(OH)2 + 2% chlorhexidine gluconate (CHX) gel; and G3= saline (control). After 10 days of storage in 100% humidity at 37 degrees C, the dressings were removed and the root canals were filled with Epiphany sealer. After additional 48 h of storage, the specimens were sectioned transversally into 2-mm-thick discs. Push-out tests were performed (1 mm/min, Instron 4411) and the maximum loads at failure were recorded in MPa. One-way ANOVA and Newman-Keuls tests showed a statistically significant decrease in bond strength when a Ca(OH)2 dressing was used before root canal filling with Epiphany (G1= 10.18 +/- 1.99 and G2= 9.98 +/- 2.97) compared to the control group (13.82 +/- 3.9) (p< 0.05). It may be concluded that the use of Ca(OH)2 as an intracanal dressing material affected the adhesion of Epiphany to the root canal walls, but even though the values were within the acceptable range found in the literature.     

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.