The effect of intracanal medication variations on microhardness of simulated immature root dentin

Effects of phytic acid and etidronic acid using continuous and sequential chelation on the removal of smear layer, dentin microhardness, and push-out bond strength of calcium silicate-based cement

BACKGROUND

This study assessed the effects of sequential and continuous chelation using phytic acid and etidronic acid on smear layer removal, microhardness, and push-out bond strength (PBS) at radicular dentin.

METHODS

One hundred twenty single-rooted teeth were selected. Thirty teeth were split longitudinally, and initial microhardness was measured. The roots were then divided into six groups. In sequential chelation, 2.5% sodium hypochlorite (NaOCl) was used for 20 min, followed by 17% ethylenediaminetetraacetic acid (EDTA), 9% etidronic acid (HEDP), or 2.5% phytic acid (PA) for 2 min, while no chelator was applied in the control group. In continuous chelation, etidronic acid (DR HEDP) or phytic acid (DR PA) was mixed with NaOCl and applied for 20 min. Final microhardness values were measured, and the change was calculated as a percentage. Mid-root sections were obtained from the 60 teeth for the PBS test and divided into six groups. Irrigants were applied as in the microhardness test. Sections obturated with calcium silicate cement. PBS values were measured, and the types of failures were analyzed. Thirty teeth were analyzed using scanning electron microscopy (SEM). In sequential chelation, 2.5% NaOCl irrigation was performed during instrumentation, followed by 17% EDTA, 9% HEDP, or 2.5% PA for 2 min, while no chelator was applied in the control group. In continuous chelation, DR HEDP or DR PA was mixed with NaOCl and used during instrumentation. Images were taken, and smear layer scores were recorded. The PBS data were analyzed using one-way ANOVA, and the alterations in microhardness and remaining smear layer were analyzed using a two-way ANOVA test. The pairwise comparisons were analyzed using Tukey's HSD post hoc test. The failure patterns and smear scores were compared using Pearson's chi-squared test (α = 0.05).

RESULTS

Results showed that DR HEDP (4.02 ± 0.68%) caused the least reduction in microhardness. DR HEDP (10.26 ± 1.74 MPa) exhibited the highest bond strength, followed by PA (7.97 ± 0.92 MPa) and DR PA (7.74 ± 1.16 MPa). Failure patterns did not differ significantly. Lower percentages of the remaining smear layer area were observed in the DR PA (26.7 ± 18%), PA (24.2 ± 9.8%), and DR HEDP (37.1 ± 16.5%) groups compared to the others.

CONCLUSIONS

The use of etidronic acid with the continuous chelation technique and phytic acid with the sequential chelation technique may be an alternative method to sequential EDTA irrigation.

Effect of allicin-incorporated graphene oxide hydrogel on dentin microhardness

OBJECTIVE

The success of root canal treatment and regenerative endodontics relies on thorough disinfection and dentin integrity preservation to ensure long-term tooth survival. This study evaluates the pH stability, material characteristics, microhardness and antimicrobial effects of an allicin-incorporated GO-AgNP hydrogel compared to conventional intracanal medicaments.

METHODS

An allicin-incorporated GO-AgNP hydrogel was synthesized using allicin extract, GO-AgNPs, and sodium alginate. Characterization was performed via FTIR, SEM, and EDX. pH stability of AllGOAgNP, CaOH, CHX, and TAP was assessed at 5 min, 24 h, and 7 days using a digital pH meter. A total of 120 extracted human premolars were randomly assigned to four groups: (1) Control, (2) CaOH, (3) TAP, and (4) AllGOAgNP. Medicaments were applied and incubated at 37 °C with 100% humidity for 1 week, 1 month, and 3 months. Dentin microhardness was evaluated using a Vickers microhardness tester before and after treatment across the coronal, middle, and apical thirds. Additionally, antimicrobial efficacy against E. faecalis and C. albicans was assessed using the disc diffusion method, with inhibition zones measured for each medicament. Statistical analysis was performed using one-way ANOVA and Tukey's post-hoc test (p < 0.05).

RESULTS

FTIR analysis confirmed the successful incorporation of allicin, GO, AgNPs, and sodium alginate. SEM images showed a uniform nanoparticle distribution in the hydrogel, and EDX confirmed the presence of key elements, including silver and sulfur. The Allicin-GO-AgNP hydrogel maintained a near-neutral pH (mean 7.083), while CaOH (mean 12.297) and TAP (mean 12.683) exhibited highly alkaline pH levels. ANOVA results demonstrated significant differences in microhardness across groups and regions (p < 0.05). The Allicin-GO-AgNP hydrogel exhibited significantly higher microhardness than CaOH and TAP across all regions (p < 0.001), with no significant difference from the control in the coronal and middle thirds (p > 0.05). SEM-EDX analysis of treated dentin confirmed minimal structural alterations in the Allicin-GO-AgNP hydrogel group compared to the control. In antimicrobial testing, the hydrogel demonstrated moderate efficacy with inhibition zones of 20 mm against E. faecalis and 13 mm against C. albicans, outperforming calcium hydroxide after 24 h.

CONCLUSION

The Allicin-GO-AgNP hydrogel demonstrated superior dentin preservation compared to conventional intracanal medicaments. Its near-neutral pH, structural stability, and microhardness retention make it a promising alternative for endodontic applications, particularly in regenerative endodontics. Future studies should focus on its long-term biocompatibility and antimicrobial effectiveness in clinical settings.

CLINICAL SIGNIFICANCE

The Allicin-GO-AgNP hydrogel preserves dentin integrity better than conventional medicaments, reducing the risk of structural weakening. Its near-neutral pH minimizes collagen degradation, making it a promising option for regenerative endodontics. This novel hydrogel offers a biocompatible alternative with potential long-term clinical benefits.

Comparative Evaluation of the Effects of Calcium Hydroxide Intracanal Medicament and Antibiotic Paste on Dentin Microhardness: A Systematic Review

An infectious environment is reported to hinder the process of pulp tissue regeneration by damaging the cells responsible for tissue formation, including stem cells in the periapical tissues. Therefore, a sterile environment is critical for pulp tissue regeneration, which can be achieved by copious irrigation and intracanal medicament (ICM) placement. This systematic review compares the effect of calcium hydroxide (Ca(OH)2) and various antibiotic pastes, such as triple antibiotic paste (TAP), modified triple antibiotic paste (MTAP), and double antibiotic paste (DAP), on dentin microhardness when used as ICMs. MeSH terms and specific keywords were used to search Scopus, EBSCOhost, Cochrane Library, and PubMed. In vitro studies that compared the impact of Ca(OH)2 and antibiotic pastes, such as TAP, MTAP, and DAP, on dentin microhardness were included. Data from the included articles were extracted, and their quality was assessed using the revised Quality Assessment Tool for In Vitro Studies (QUIN) tool. Seven articles were included for the qualitative synthesis, and data were extracted from each. Within the scope of this systematic review, Ca(OH)2, an alternative ICM recommended by the American Association of Endodontics Glossary of Endodontic Terms for REPs, showed a lesser reduction in microhardness than TAP. DAP and MTAP caused a reduction in dentin microhardness compared to that of Ca(OH)2.

Antibiofilm effect of Nano chitosan and calcium hydroxide intracanal medications and their effects on the microhardness and chemical structure of radicular dentine

BACKGROUND

Disinfection of the root canal system is a challenge to all clinicians, calcium hydroxide Ca(OH)2, one of the most popular intracanal medications used for this purpose, has some unwanted effects on dentine. This study aimed to investigate the antibiofilm effect of Nanochitosan (CSNPs) and Calcium hydroxide Ca(OH)2 intra canal medications and their effect on the microhardness and chemical structure of radicular dentine.

METHODOLOGY

A total of 52 extracted human mandibular premolars were used. Eighteen premolars were instrumented, sterilized, and inoculated with Enterococcus faecalis (E. faecalis) then divided randomly into 2 groups based on the intracanal medication used: group (A) 2% CSNPs gel and group (B) Ca(OH)2 paste. Antibiofilm effect was evaluated using bacterial counts. For the effect on microhardness, 56 specimens were subjected to Vicker's microhardness test before and after 1 week, and 4 weeks of medication application. Twelve cervical radicular dentine specimens (6 samples per group) were examined using Fourier transform infrared spectroscopy and scanning electron microscope.

RESULTS

Both groups showed a significant reduction in the bacterial count at (p = 0.008) with no significant difference between them (P = 0.605). Ca(OH)2 showed the highest reduction in the microhardness compared to CSNPs groups after 1 week (P = 0.0495) and after 4 weeks (P = 0.0495). FTIR spectrum results revealed that the control group (no treatment) showed the highest significant Phosphate: amide ratio compared to both CSNPs and Ca(OH)2 at p = 0.006. SEM images revealed absence of discernible smear layer in CSNPs treated samples after 4 weeks and all the dentinal tubules were open.

CONCLUSIONS

Nanochitosan gel could be considered as a viable option as an intra canal medication.

Impact of calcium hydroxide and 2-hydroxyisocaproic acid on the microhardness of root dentine: an in vitro study

To evaluate and compare the effect of calcium hydroxide [Ca(OH)2] and 2-hydroxyisocaproic acid (HICA) on the microhardness of root dentine. Fifty-one matured maxillary central incisors with straight root and type I canal configuration were decoronated to a standardized length of 16 mm. The root canals were cleaned and shaped using rotary instruments up to size F5. The tooth samples were then randomly assigned into three groups (n = 17) based on the intracanal medicament placed. Group A: control group with no intracanal medicament, Group B: root canals placed with Ca(OH)2, and Group C: root canals placed with HICA. After 1 week, the intracanal medicaments placed within the root canals were removed and the canals were dried. Subsequently, the specimens were split longitudinally into two halves and subjected to the Vickers microhardness test with indentations made at the coronal, middle, and apical-third root regions. The data were analyzed using one-way ANOVA and Tukey's post hoc tests. The control group showed significantly highest microhardness value (P < 0.001), followed by HICA and finally, Ca(OH)2 at the coronal, middle, and apical-third root regions, respectively. Nonetheless, there were no statistically significant differences in microhardness values across different root regions within each group. HICA was found to have a significantly lesser reduction in root dentine microhardness which could be a potential alternative to Ca(OH)2. Nevertheless, future studies are warranted to verify the present outcomes in the clinical setting.

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.

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.

Comparison of the efficacy of three different supplementary cleaning protocols in root-filled teeth with a bioceramic sealer after retreatment-a micro-computed tomographic study

OBJECTIVE

The present study evaluated the efficacy of three different supplementary cleaning protocols on the removal of bioceramic-based root canal filling materials from oval-shaped canals.

MATERIALS AND METHODS

A total of 36 human mandibular premolars were instrumented and obturated with gutta-percha and iRoot SP using the single-cone technique. Retreatment was performed with ProTaper Universal retreatment files. The samples were randomly divided into the following supplementary cleaning protocols: conventional syringe irrigation (CSI), passive ultrasonic irrigation (PUI), and XP-endo Finisher R (XPR). The samples underwent micro-CT scanning to quantify the amount of residual filling materials after retreatment and after performing the cleaning protocols. The volume of filling material removal was analyzed by one-way analysis of variance and post hoc Bonferroni and Games-Howell tests (P < 0.05).

RESULTS

There were significant differences in the amount of root canal filling material removal in every comparison group (P < 0.05). The XPR removed significantly more residual filling materials (P < 0.01) followed by PUI and CSI (P < 0.05). Similar efficacy was found in the total root canal and all root thirds.

CONCLUSIONS

The additional use of XP-endo Finisher R and passive ultrasonic irrigation effectively removed the bioceramic-obturated root filling materials from the oval-shaped canals. However, none of the techniques completely removed the filling materials.

CLINICAL RELEVANCE

The XP-endo Finisher R and passive ultrasonic irrigation exhibited greater efficacy compared with syringe irrigation in the reduction of residual filling materials after retreatment in root-filled teeth with a bioceramic sealer.