Root Canal Dentin Microhardness after Contact with Antibiotic Medications: An In Vitro Study

Background: Antibiotic pastes used as intracanal medication in cases of revascularization therapy might cause negative effects on tooth properties, such as a reduction in dentin microhardness. This in vitro study investigated dentin microhardness in three different locations distancing from the canal lumen after 20 days of treatment with a tri-antibiotic paste (ciprofloxacin, metronidazole, and minocycline), and with a double-antibiotic paste (ciprofloxacin and metronidazole), with calcium hydroxide [Ca(OH)2] UltracalTM XS-treated dentin as comparison. Material and Methods: Human mandibular premolars (n = 48) had the root canals cleaned and shaped and were used to produce dentin slices. Dentin slices remained immersed in the medications for 20 days. The Knoop microhardness (KHN) test was performed before (baseline/Day-0) and after treatment (Day-20) with the medications. Indentations were made at 25 µm, 50 µm, and 100 µm distances from the root canal lumen. The KHN was compared intra-group using Wilcoxon's test. Independent groups were compared using Mann-Whitney's and Kruskal-Wallis' tests, at α = 5%. Results: The microhardness in all the tested groups was reduced at Day-20 in comparison with Day-0 (p < 0.001) (intra-group comparison/same distances). The Day-0 values were similar, and the Day-20 values were higher for the Ca(OH)2 group (p < 0.05) (comparison between groups/same distances). Conclusions: Calcium hydroxide for 20 days would be preferred rather than antibiotic pastes to minimize the expected reduction in dentin microhardness during regenerative procedures.

Effect of canal medicaments triple antibiotic paste, Bio-C Temp, and Nano-silver gel activated by visible blue light on canal dentin microhardness and extrusion bond strength of AH plus sealer: A SEM and EDX analysis

AIM

Assessment of contemporary canal medicaments (Triple antibiotic paste (TAP), Bio-C Temp, and Nano silver gel activated by visible blue light on the dentin microhardness (MH) and push-out bond strength (PBS) of AH plus endodontic sealer.

METHOD

Sixty extracted premolars were obtained and decontaminated. Canal cleaning and shaping were performed. The samples were randomly allocated into four groups based on the intracanal medicaments. Group 1= CH paste, Group 2= TAP, Group 3= Bio-C Temp, and Group 4= Nano-silver gel activated by visible blue light. MH assessment was performed using a Vickers Microhardness tester. Forty specimens, ten from each group underwent root canal obturation. PBS and failure mode evaluation were performed. ANOVA and Post Hoc Tukey test were utilized to conduct intra and inter-group comparisons.

RESULTS

The maximum outcome of surface hardness was presented by Group-3 (Bio-C Temp®) specimens. However, minimum scores of MH were displayed by Group 1 (CH) treated teeth. The highest outcomes of EBS were exhibited by the cervical third of Group 3 (Bio-C Temp®) samples. The apical section of Group 4 Teeth with Nano Silver gel activated by visible blue light revealed the lowest scores of bond integrity.

CONCLUSION

Bio-C Temp and TAP proved to be better intracanal medicament than other tested groups in terms of the push-out bond strength of the sealer. TAP displayed lower microhardness as compared to the Bio-C Temp.

Progress of Research on the Application of Triple Antibiotic Paste and Hydrogel Scaffold Materials in Endodontic Revascularization: A Systematic Review

Objective

To evaluate the application of hydrogel scaffold materials and triple antibiotic paste in endodontic regeneration through literature review.

Methods

An electronic search of the literature published on PubMed, Wangfang database, and CNKI database using the search terms “endodontic regeneration,” “pulp blood flow reconstruction,” “recanalization,” “triple antibiotic paste,” and “scaffold material” was conducted. The searched literature was used for analysis. Results and Conclusion. Hydrogels regulate stem cell fates, modulate growth factor release, and encapsulate antibacterial and anti-inflammatory drugs. The triple antibiotic paste is composed of metronidazole, ciprofloxacin, and minocycline, which exhibits promising antibacterial effects and duration at appropriate concentrations, with low cytotoxicity, and effectively promotes the preservation and regeneration of pulp tissues and the formation of dental hard tissues. However, issues such as tooth discoloration and bacterial drug resistance also exist. The present article reviews the progress of research on the application of hydrogel scaffold materials and triple antibiotic paste in endodontic revascularization.

Does the use of fiber posts increase the fracture resistance of simulated immature teeth? A systematic review

This systematic review aimed to assess if the use of fiber posts reinforces weakened immature teeth. A systematic review was conducted of laboratory studies that evaluated the fracture resistance of simulated immature teeth restored with fiber posts compared to teeth restored exclusively with resin. An electronic search was performed using the following databases: PubMed/MEDLINE, Web of Science, Scopus and LILACS, BBO, and grey literature. Two independent researchers screened the titles and abstracts of the retrieved studies for relevance to the research question. Subsequently, the full texts of potentially relevant studies were screened based on the exclusion criteria. Ten out of 1792 unique records were included in this systematic review. Risk of bias was assessed using an adapted tool based on the Cochrane risk of bias tool. The laboratory studies included in this systematic review were performed on both human and bovine teeth. Eight studies concluded that fiber posts reinforce the structure of weakened roots, and two studies reported that fiber posts did not strengthen the radicular structure compared to teeth exclusively restored with resin composite. The highly heterogeneous data made it challenging to synthesize the results into a summary estimate, and thus no meta-analysis was undertaken. A summary effect could not be estimated without a meta-analysis. Although the laboratory literature suggests that fiber posts reinforce the structure of immature teeth, the results should be interpreted with caution, as most of the studies had an unclear or high risk of bias.

A Comparative Evaluation of Microhardness and Chemical Structure of Radicular Dentin with Two Combinations of TAP and MTAP: An In Vitro Study

Background

The success of regenerative endodontics depends on various factors and the most vital being the complete eradication of microorganisms in the dentinal tubules. This could lead to changes that leave the radicular dentin prone to fracture.

Aim

The purpose of the present study is to investigate the effects of triple antibiotic paste (TAP) and modified triple antibiotic paste (MTAP) of different concentrations on the microhardness and chemical structure of radicular dentin.

Materials and methods

Human root cylinders were instrumented and randomized into four treatment groups and an untreated control group. Two treatment groups received 1 g/mL TAP or MTAP, and the other two treatment groups received 1 mg/mL methylcellulose-based TAP or MTAP. Cylinders were stored at 100% relative humidity for 4 weeks. Each root cylinder was subjected to a microhardness test before and after treatment. Different sets of radicular dentin specimens were treated as mentioned previously, and were examined using attenuated total reflection Fourier transform infrared spectroscopy.

Results

Significant reductions in microhardness of treated groups was noticed when compared to untreated control roots at 1,000 and/or 500 µm from the pulp-dentin interface.

Conclusion

The use of 1 mg/mL methylcellulose-based TAP and MTAP may minimize the reduction in microhardness of roots compared with the currently used 1 g/mL concentration of these antibiotics.

How to cite this article

Daneswari M, Reddy NV, Chris PA, et al. A Comparative Evaluation of Microhardness and Chemical Structure of Radicular Dentin with Two Combinations of TAP and MTAP: An In Vitro Study. Int J Clin Pediatr Dent 2022;15(S-2):S151-S157.

Effect of different intracanal medicaments on the fracture resistance of the human root

Background:

The effect of different intracanal medicaments on root fracture resistance has not been thoroughly investigated in the short and long term. To assess the effect of calcium hydroxide (CH), CH combined with Chlorhexidine (CHX), double antibiotic paste (DAP), and simvastatin as intracanal medicaments on the fracture resistance of the human root. One hundred and twenty single-rooted mandibular premolars which were extracted for periodontal reasons were collected for this in vitro study.

Materials and Methods:

This was an in vitro study. All teeth were decoronated. Root canals were prepared by the Pro taper system, and %2.5 NaOCl was used for irrigation. The smear layer was removed using %5.25 NaOCl and 17% ethylenediaminetetraacetic acid each for 3 min. The samples were randomly divided into five groups based on the medicament: (1) CH (2) CH + CHX (3) Simvastatin (4) DAP (5) Control group. All specimens in each group were incubated for 1 week (Subgroup A) and 1 month (Subgroup B). Then, medicaments were removed and filled with gutta-percha and AH26 sealer. All samples were tested for fracture resistance. The data were statistically evaluated with the SPSS software 17. ANOVA and Mann–Whitney U and Wilcoxon tests were used for the analysis of the data. P = 0.05 was considered statistically significant.

Results:

Although CH and CH + CHX increased the fracture resistance in a 1-week period, there was no significant difference between the groups after 1 month.

Conclusion:

Under the limitations of this study, CH and CH + CHX, DAP and simvastatin do not have a negative effect on root fracture resistance when used as intracanal medicaments for <1 month.

Effect of triple antibiotic paste on the bond strength of epoxy and methacrylate resin-based sealers to root canal dentin

Purpose:

This study aimed to evaluate the effect of triple antibiotic paste (TAP) as an endodontic intracanal medicament on the bond strength of epoxy and methacrylate resin-based sealers to root canal dentin.

Materials and Methods:

In this in vitro study, 80 single-rooted human mandibular premolars were prepared using ProTaper rotary system. The specimens were randomly divided into a control group (without intracanal dressing) and an experimental group receiving TAP (n = 40). The intracanal dressing was removed after 3 weeks. Then, samples of each group were randomly divided into four subgroups (n = 10) and obturated with gutta-percha and different resin-based sealers. G1: AH Plus, G2: Syntex, G3: EndoREZ, and G4: MetaSEAL. After 1 week, 16 slices of 1 ± 0.1 mm thickness were obtained from the midroots of teeth in each subgroup, and a push-out test was used to measure the bond strength. Slices were examined using a stereomicroscope at 30 × to determine the mode of failure. The data were analyzed using two-way analysis of variance, one-way analysis of variance, and Tukey post hoc tests (α = 0.05).

Results:

Compared to control group, TAP significantly increased the bond strength of MetaSEAL and EndoREZ (P < 0.05). In the control group, epoxy resin-based sealers showed higher bond strength compared to methacrylate ones (P = 0.00). In TAP group, Syntex and EndoREZ showed significantly the greatest and the lowest bond strengths, respectively, (P < 0.05). The analysis of failure modes revealed a predominance of mixed failures in all groups except for Syntex group in which most failures were cohesive.

Conclusions:

TAP significantly increased the bond strength of methacrylate resin-based sealers.

Microhardness and Fracture Resistance of Radicular Dentin Treated with Different Concentrations of Calcium Hydroxide in Endodontic Regeneration Procedures

Purpose: to reveal the effect of different concentrations of prepared calcium hydroxide pastes (70%, 50%, and 30%) used in regenerative endodontic on microhardness and fracture resistance of radicular dentin. Material and methods: Different concentrations of calcium hydroxide (Ca(OH)2) were prepared with measured pH, then forty eight single rooted teeth were prepared and randomized into three groups according to Ca(OH)2 paste concentrations (12 samples each) and 12 samples were availed as control group. Group I: root canal contained 30% Ca(OH)2 paste. Group II: root canal contained 50% Ca(OH)2 paste. Group III: root canal contained 70% Ca(OH)2 paste. Samples were stored at 37 0C with 100% humidity for four weeks for subsequent microhardness and fracture resistance tests. Results: There was a statistically significant reduction of microhardness  and fracture resistance between test groups and control group (P≤ 0.05), group III showed a  significant reduction  in both microhardness and fracture resistance compared to group I. However, there was no significant difference in pH between different concentration of Ca(OH)2. Conclusion: Increasing concentration of Ca(OH)2 paste can negatively affect microhardness and fracture resistance of radicular dentin in revascularization procedure.

Effect of hydrogel-based antibiotic intracanal medicaments on crown discoloration

Objectives

This study evaluated the effects of low and moderate concentrations of triple antibiotic paste (TAP) and double antibiotic paste (DAP) loaded into a hydrogel system on crown discoloration and explored whether application of an adhesive bonding agent prevented crown discoloration.

Materials and Methods

Intact human molars (n = 160) were horizontally sectioned 1 mm apical to the cementoenamel junction. The crowns were randomized into 8 experimental groups (calcium hydroxide, Ca[OH]₂; 1, 10, and 1,000 mg/mL TAP and DAP; and no medicament. The pulp chambers in half of the samples were coated with an adhesive bonding agent before receiving the intracanal medicament. Color changes (ΔE) were detected by spectrophotometry after 1 day, 1 week, and 4 weeks, and after 5,000 thermal cycles, with ΔE = 3.7 as a perceptible threshold. The 1-sample t-test was used to determine the significance of color changes relative to 3.7. Analysis of variance was used to evaluate the effects of treatment, adhesive, and time on color change, and the level of significance was p < 0.05.

Results

Ca(OH)₂ and 1 and 10 mg/mL DAP did not cause clinically perceivable tooth discoloration. Adhesive agent use significantly decreased tooth discoloration in the 1,000 mg/mL TAP group up to 4 weeks. However, adhesive use did not significantly improve coronal discoloration after thermocycling when 1,000 mg/mL TAP was used.

Conclusions

Ca(OH)₂ and 1 and 10 mg/mL DAP showed no clinical discoloration. Using an adhesive significantly improved coronal discoloration up to 4 weeks with 1,000 mg/mL TAP.

Comparison of Modified Triple Antibiotic Paste in Two Concentrations for Lesion Sterilization and Tissue Repair in Primary Molars: An In Vivo Interventional Randomized Clinical Trial

Introduction

"Lesion sterilization and tissue repair" (LSTR) is a non-instrumentation endodontic treatment modality that has recently gained popularity with promising results in several clinical trials. However, there is a dearth of evidence regarding the concentration of modified triple antibiotic paste (MTAP) to be used for the procedure.

Aim and objective

To compare the clinical and radiographic efficacy of 1 mg/mL and 1 g/mL concentrations of MTAP (ciprofloxacin, metronidazole, and clindamycin) used in LSTR of primary molars.

Materials and methods

Sixty-four infected primary molars in children between 4 years and 10 years of age were randomly allocated to two groups. Lesion sterilization and tissue repair at 1 mg/mL concentration of MTAP (group I) and 1 g/mL concentration of MTAP (group II) was performed. Clinical and radiographic outcomes were evaluated using Coll and Sadrian's criteria at 10 days, 1 month, and 3 months and the results were tabulated.

Statistical analysis

The data obtained were subjected to statistical analysis with IBM. SPSS statistics software 23.0 Version. To test the significance in categorical data, a Chi-square test was used. The probability value of 0.05 was considered significant.

Results

At the end of 3 months review, clinical success rates of group I and group II were 84.4 and 90.6%, respectively, and radiographic evaluation showed group I-78.1% and group II-90.6%.

Conclusion

Both 1 mg/mL and 1 g/mL concentrations of MTAP used in LSTR of primary molars had similar success rates with no statistically significant difference.

Clinical significance

Lesion sterilization and tissue repair when found to be equally effective in less concentration may aid in achieving adequate infection control with the least detrimental effect on the remaining vital pulp and periradicular structures. In addition, this circumvents the systemic administration of potent antibiotics thus combating antibiotic resistance.

How to cite this article

Shankar K, Ramkumar H, Dhakshinamoorthy S, et al. Comparison of Modified Triple Antibiotic Paste in Two Concentrations for Lesion Sterilization and Tissue Repair in Primary Molars: An In Vivo Interventional Randomized Clinical Trial. Int J Clin Pediatr Dent 2021;14(3):388-392.

Evaluation of the Effect of Long-term Use of Three Intracanal Medicaments on the Radicular Dentin Microhardness and Fracture Resistance: An in vitro study

Objectives

The aim of this research was to evaluate the effect of long-term use of three intracanal medicaments on the radicular dentin microhardness and fracture resistance.

Material and methods

A chemomechanical preparation was done using the Protaper rotary instruments up to F3. The teeth were stored in an incubator at 37°C at 100% humidity and were categorized in three groups by random allocation, namely: Triple Antibiotic Paste (TAP), Calcium hydroxide paste (Apexcal) and Ledermix. Following medicament application, the access openings of all teeth were sealed with 4 mm thickness of cavit. The samples were stored for periods of 1 week, 1 month and 3months. Two dentin cylinders measuring 5mm and 3mm were obtained from each sample. The cervical third was used for fracture resistance and the middle third was used for micro hardness evaluation. The microhardness testing was done using a Knoop microhardness tester, and the fracture resistance testing was done using the universal testing machine.

Results

Calcium hydroxide showed maximally negative effect on the physical properties of radicular dentin compared to TAP (p= 0.0100 at one month and Ledermix (p=0.0001 at one month). With an increase in the application time, there was an increased deterioration in the physical properties of radicular dentin.

Conclusion

Long-term placement of calcium hydroxide, Triple Antibiotic Paste, and Ledermix (p= 0.0001at 3 months) significantly affects the microhardness and fracture resistance of radicular dentin.

Efficacy of EDDY, ultrasonic activation, XP-endo Finisher and needle irrigation on the removal of mTAP from artificially created grooves in root canals

This study analysed the effect of needle irrigation (NI), passive ultrasonic irrigation (PUI), EDDY and the use of the XP-endo Finisher (XPF) on the removal of modified triple antibiotic paste (mTAP) from artificially created grooves in root canals. Forty-eight maxillary incisors were prepared up to size 50, with a standard groove on one surface of the root canal wall and filled with mTAP. Re-attached roots were analysed based on the activation techniques applied for 180 s with 5 ml 3% sodium hypochlorite. The results showed that EDDY was more effective at removing mTAP than PUI, XPF and needle irrigation (P < 0.05), whereas XPF and PUI were significantly more effective than needle irrigation. (P < 0.05). No significant difference in mTAP removal was observed between XPF and PUI (P > 0.05). These findings suggest that the removal of mTAP can be more efficiently achieved with EDDY than with XPF, PUI or NI.

Effect of Hydrogel-Based Antibiotic Intracanal Medicaments on Push-Out Bond Strength

OBJECTIVE

 This study aimed to evaluate the effects of typical clinical concentration (1,000 mg/mL), low concentration (1 mg/mL) triple antibiotic pastes (TAP), and double antibiotic pastes (DAP) on the bond strength between various root cements and radicular dentin.

MATERIALS AND METHODS

 Intact single-rooted human teeth (n = 144) were horizontally decoronated and canals instrumented. The roots were treated for 4 weeks with Ca(OH)₂, 1,000 mg/mL of TAP or DAP, and 1 mg/mL of TAP or DAP. Untreated roots served as a control. After treatment, the medicaments were irrigated and each group was divided into three subgroups receiving MTA, Biodentine, or Endosequence putty cement. After 2 weeks, coronal and middle root cylinders were obtained from each root. Push-out bond strength test and failure analysis were performed for all root cylinders.

STATISTICAL ANALYSIS

 Three-way ANOVA, pairwise comparisons and logistic regression were used for statistical analyses. A significance level of 5% was used.

RESULTS

 For MTA applied in the coronal part of the roots, 1 mg/mL DAP and TAP and Ca(OH)₂ demonstrated significantly higher bond strength compared with the typical clinical concentration and the control groups. For Biodentine applied coronally in the roots, 1 mg/mL of DAP resulted in significantly higher bond strength than all other groups. For Endosequence putty cement applied coronally in the roots, 1 mg/mL of DAP offered significantly higher bond strength than all groups except for Ca(OH)₂.

CONCLUSION

 The use of 1 mg/mL DAP resulted in significantly higher push-out bond strength compared with the typical clinical concentration of TAP and DAP regardless of the type of the root cement used.

Comparison of Antibacterial Effects of Photodynamic Therapy, Modified Triple Antibiotic Paste and Calcium Hydroxide on Root Canals Infected With Enterococcus faecalis: An In Vitro Study

Introduction: A pivotal issue to achieve success in the treatment of the root canal is root canal disinfection. One of the most important bacteria that infect the root canal is Enterococcus faecalis. This study seeks to examine the effectiveness of 3 methods for disinfecting the root canal: photodynamic therapy, modified triple antibiotic paste (MTAP), and calcium hydroxide. Methods: Sixty-two single-rooted extracted anterior teeth were collected. After cleaning and disinfecting the teeth, their crowns were cut at the CEJ point. The root canals were shaped to the working length up to file F3 ProTaper (F1, F2, F3). EDTA 17% and sodium hypochlorite 2.5% were used for 5 minutes to wash and remove the smear layer, and then the apical foramen was sealed using composite. After that, the teeth were sterilized in an autoclave at 121°C for 15 minutes. Then 10 samples were taken randomly as the negative control. The remaining samples were immersed and cultivated in a suspension containing E. faecalis for 21 days. Then the samples were divided into 5 groups: 2 positive control groups, 1 group treated with the antibiotic paste with the concentration of 1 mg/mL, 1 group treated with calcium hydroxide, and 1 group treated with photodynamic therapy. Then, to collect the biofilm, the ProTaper file F4 was used. After that, the microbial suspension was provided and counting the colonies was carried out to compare the groups. Results: The findings indicated that the amount of CFU/mg of MTAP samples, including clindamycin, metronidazole, ciprofloxacin in the concentration of 1 mg/mL and photodynamic therapy and calcium hydroxide was lower than that in the control group. Antibiotic paste cleansed the root canal up to 99.9%. Photodynamic therapy reduced the amount of CFU/mg to 98.8%, and calcium hydroxide reduced the amount of CFU/mg to 94.13%. Conclusion: Using photodynamic therapy causes a reduction in the biofilm and inhibits the growth of the E. faecalis bacterium. In addition, in this study, MTAP with a concentration of 1 mg/mL was used, which expunged the bacteria completely. Meanwhile, calcium hydroxide had the weakest effect of all on the E. faecalis bacterium.

Effect of intracanal time of triple antibiotic paste on its removal from simulated immature roots using passive ultrasonic irrigation and XP-endo Finisher

Background. The aim of this study was to evaluate the effectiveness of different irrigation techniques in the removal of triple antibiotic paste (TAP), which was applied for 7, 21 or 90 days, from simulated root canals of immature teeth.

Methods. The root canal spaces of 190 maxillary canine teeth were filled with TAP and randomly divided into a control and 3 experimental groups according to the intracanal medicament period (7, 21 or 90 days). Syringe irrigation (SI), passive ultrasonic irrigation (PUI) and XP-endo Finisher (XP) were used for the removal of TAP (n=20). The amount of remaining medicament was calculated under a stereomicroscope using a 4-grade scoring system. Kruskal-Wallis H and Wilcoxon signedrank tests were used for statistical analyses (P<0.05).

Results. The mean percentage of residual TAP was significantly greater in the SI group compared to PUI and XP at all the time intervals (P<0.05). Paste removal efficacy of PUI was not affected by the intracanal time of TAP (P>0.05), whereas the efficacy of SI and XP was significantly affected (P<0.05). No significant differences were detected between PUI and XP at 7- and 21-day intervals (P>0.05); however, at 90-day interval, PUI removed significantly greater amount of TAP than XP did (P<0.05).

Conclusion. The time of the TAP in the root canal negatively affected the removal efficacy of the SI and XP-Endo Finisher; however, it did not affect the efficacy of the PUI.

Triple antibiotic paste: momentous roles and applications in endodontics: a review

This study investigated the latest findings and notions regarding ‘triple antibiotic paste’ (TAP) and its applications in dentistry, particularly endodontics. TAP is a combination of 3 antibiotics, ciprofloxacin, metronidazole, and minocycline. Despite the problems and pitfalls research pertaining to this paste has unveiled, it has been vastly used in endodontic treatments. The paste's applications vary, from vital pulp therapy to the recently introduced regeneration and revascularisation protocol. Studies have shown that the paste can eliminate the root canal microorganisms and prepare an appropriate matrix for further treatments. This combination is able to remove diverse groups of obligate and facultative gram-positive and gram-negative bacteria, providing an environment for healing. In regeneration protocol cases, this allows the development, disinfection, and possible sterilization of the root canal system, so that new tissue can infiltrate and grow into the radicular area. Moreover, TAP is capable of creating a discipline in which other wanted and needed treatments can be successfully performed. In conclusion, TAP, as an antibacterial intracanal medication, has diverse uses. Nevertheless, despite its positive effects, the paste has shown drawbacks. Further research concerning the combined paste and other intracanal medications to control microbiota is a must.

Retention of BioAggregate and MTA as coronal plugs after intracanal medication for regenerative endodontic procedures: an ex vivo study

Objectives

This study compared the retention of BioAggregate (BA; Innovative BioCeramix) and mineral trioxide aggregate (MTA; Angelus) as coronal plugs after applying different intracanal medications (ICMs) used in regenerative endodontics.

Materials and Methods

One-hundred human maxillary central incisors were used. The canals were enlarged to a diameter of 1.7 mm. Specimens were divided into 5 groups (n = 20) according to the ICM used: calcium hydroxide (CH), 2% chlorhexidine (CHX), triple-antibiotic paste (TAP), double-antibiotic paste (DAP), and no ICM (control; CON). After 3 weeks of application, ICMs were removed and BA or MTA were placed as the plug material (n = 10). The push-out bond strength and the mode of failure were assessed. The data were analyzed using 2-way analysis of variance, the Tukey's test, and the χ² test; p values < 0.05 indicated statistical significance.

Results

The type of ICM and the type of plug material significantly affected bond strength (p < 0.01). Regardless of the type of ICM, BA showed a lower bond strength than MTA (p < 0.05). For MTA, CH showed a higher bond strength than CON, TAP and DAP; CHX showed a higher bond strength than DAP (p < 0.01). For BA, CH showed a higher bond strength than DAP (p < 0.05). The mode of failure was predominantly cohesive for BA (p < 0.05).

Conclusions

MTA may show better retention than BA. The mode of bond failure with BA can be predominantly cohesive. BA retention may be less affected by ICM type than MTA retention.

Direct and indirect antibacterial effects of various concentrations of triple antibiotic pastes loaded in a methylcellulose system

We investigated the direct and indirect (residual) antibacterial effects of various concentrations of triple antibiotic paste (TAP) loaded into a methylcellulose system. Enterococcus faecalis (E. faecalis) was grown on sterilized dentin blocks (n = 60) and treated with clinically used TAP (1,000 mg/mL), low concentrations of methylcellulose-based TAP (100, 10, and 1 mg/mL), placebo paste, or 1.5% NaOCl (n = 10). The pastes were then removed, and biofilm disruption assays were performed. Additional dentin blocks (n = 120) were pretreated with the same experimental groups (n = 20). The pastes were rinsed off, and the samples were immersed independently in phosphate-buffered saline for 2 and 4 weeks (n = 10). E.faecalis was then grown on the dentin blocks, and biofilm disruption assays were performed. Fisher's Exact and Wilcoxon rank sum tests were used for statistical analyses. With regard to direct antibacterial effects, all treatment groups demonstrated complete eradication of biofilms in comparison to placebo paste, while 10 mg/mL of TAP or higher provided substantial residual antibacterial effects. However, dentin treated with 1 mg/mL of TAP or 1.5% NaOCl did not provide substantial residual antibacterial effects. Dentin pretreated with 10 mg/mL of TAP or higher exhibited extended residual antibacterial effects and can thus be used during endodontic regeneration.(J Oral Sci 58, 575-582, 2016).