Effect of smear layer removal agents on the microhardness and roughness of radicular 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.

Comparative Evaluation of the Effect of EDTA, Chitosan, Etidronic Acid, and Silver Citrate on the Mineral Content of Root Canal Dentin Using Energy Dispersive X-ray Spectroscopy: An In-Vitro Study

OBJECTIVE

Sodium hypochlorite is a common irrigant in endodontics, used to eliminate microorganisms and dissolve pulpal tissue. However, adjunctive chelating agents, while aiding in smear layer removal, can reduce dentinal wall microhardness, affecting dentin permeability, solubility, and the sealing ability of root canal sealers. This study aims to evaluate the impact of newer chelating agents-Silver Citrate, Chitosan, HEBP, and EDTA-on the mineral composition of root canal dentin using energy-dispersive X-ray Spectroscopy (EDXS).

METHODS

The root canals of 120 freshly extracted human mandibular premolars with single straight canals and intact, mature apices were prepared following standard endodontic procedures using Rotary Pro Taper nickel-titanium files. Final irrigation was conducted with 5 mL of the respective chelating solution. Changes in the mineral composition of the root canal dentin were analyzed using EDXS. Descriptive statistics were presented as means and standard deviations. The impact of chelating solutions on the mineral content of root canal dentin at the cervical, middle, and apical thirds was compared between groups using One-Way ANOVA followed by a post hoc Bonferroni test.

RESULTS

The highest mean concentrations of minerals such as Mg, Ca, and P at both the coronal and apical levels (p<0.05), along with the Ca/P ratio in the coronal third, were observed with distilled water, followed by HEBP, Chitosan, EDTA, and Silver Citrate, which showed the lowest values. In the middle third, the concentrations of Ca and P, as well as the Ca/P ratio in the apical and middle thirds, followed the sequence: Distilled Water>EDTA>HEBP>Chitosan>Silver Citrate. The difference in the levels of all minerals was statistically significant (p<0.05) at the coronal, middle and apical third levels.

CONCLUSION

Among the tested solutions, 9% HEBP caused the least alteration in the mineral content of root canal dentin when compared to 0.2% Chitosan, 17% EDTA, and Silver Citrate. This suggests that HEBP may be a preferable choice in endodontic procedures where minimal alteration of dentin mineral content is desired. (EEJ-2024-08-124).

The effect of different conditioning agents on dentin roughness and collagen structure

OBJECTIVES

To assess the impact of various organic and inorganic acids on the roughness, demineralization, and collagen secondary structures of human dentin and to compare these effects with those of traditional agents, specifically phosphoric acid (PA) and ethylenediaminetetraacetic acid (EDTA).

METHODS

Coronal dentin discs (n = 10) were examined by optical profilometry (roughness) and ATR-FTIR before and after conditioning with 32 % PA, 3 % nitric acid (NA), 20 % citric acid (CA), 20 % phytic acid (IP6) or 17 % EDTA. Spectra data were processed to quantify dentin demineralization (DM%) and percentage area of amide I curve-fitted components of β-turns, 310-helix, α-helix, random coils, β-sheets, and collagen maturation index. Statistical analysis was performed by one-way ANOVA or Kruskal-Wallis for DM% and roughness parameters, and paired t-test/Wilcoxon test for amide I components at significance level set at α = 0.05.

RESULTS

All treatments resulted in increased roughness parameters, with the most significant changes occurring primarily with PA, while EDTA exhibited the least changes. DM% was NA>PA>IP6>CA>EDTA in a descending order. Regarding amide I components, NA demonstrated a significant reduction in β-turns, 310-helices, and α-helices and it increased β-sheets and random coils. PA resulted in reduction in β-turns and α-helices while it increased β-sheets. CA and EDTA did not cause significant changes. The collagen maturation index significantly increased only after IP6 treatment.

CONCLUSIONS

The effect on dentin roughness parameters, demineralization, and collagen secondary structures varied based on the type of dentin surface treatment.

CLINICAL SIGNIFICANCE

Understanding the impact of acids on the intrinsic properties of dentin is clinically essential for gaining insights into how these effects influence adhesion to dentin, the long-term stability of resin-based restorations, and the success of remineralization therapies.

Oracle of phytic acid in dental panacea - Insight into properties, therapeutic effect, regeneration, materials interaction and oral physiology

Phytic acid (inositol hexaphosphate/IP6) is a versatile chemical that is abundant in nature and is required for a variety of biological processes. It is harnessed in a wide range of fields, including drug discovery, daily supplies, chemical industries, medicine, and dentistry. IP6 is becoming increasingly popular in dentistry, with promising results. Several properties, such as cariostatic ability, beneficial impact on enamel disintegration, and anti-plaque, anti-tartar, and dental adhesive-forming properties, have been investigated thus far. Due to many constraints in the literature, there was a point in time when IP6 received less attention, which impacted knowledge in this field. Nevertheless, the positive outcomes of the flourishing of IP6 have recently been reconsidered from a number of papers that have improved our understanding of its modes of action in the aforementioned applications. The role of phytic acid in refining the properties and manoeuvring of dental resources is being investigated in novel endeavors in treating diseases of pulp and tissues supporting tooth structure, but to show its novel therapeutic potential, more precisely calibrated clinical trials are needed. This review examines and discusses the various uses proposed in the literature, as well as the applications of IP6 in dentistry.

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.

Optimizing Dental Bond Strength: Insights from Comprehensive Literature Review and Future Implications for Clinical Practice

This review examines the modifying factors affecting bond strength in various bonding scenarios, particularly their relevance to the longevity of dental restorations. Understanding these factors is crucial for improving clinical outcomes in dentistry. Data were gathered from the PubMed database, ResearchGate, and Google Scholar resources, covering studies from 1992 to 2022. The findings suggest that for dentin-resin bonds, minimizing smear layers and utilizing MMP inhibitors to prevent hybrid layer degradation are essential. In the case of resin-resin bonds, reversing blood contamination is possible, but preventing saliva contamination is more challenging, underscoring its critical importance during clinical procedures. Additionally, while pretreatment on ceramics has minimal impact on bond strength, the influence of specific colorings should be carefully considered in treatment planning. This comprehensive review highlights that although established practices recognize significant bond strength factors, ongoing research provides valuable insights to enhance the clinical experience for patients. Once confirmed through rigorous experimentation, these emerging findings should be swiftly integrated into dental practice to improve patient outcomes.

Evaluation of the effects of different chelation agents on root dentin roughness

Successful root canal treatment requires effective irrigation of the entire root canal system. While chelating agents support irrigation, they can also alter physicochemical properties of the root dentin structure. The aim of this study is to evaluate the effect of different chelation agents on root dentin roughness. Twenty-five extracted maxillary incisors were used in this study. Samples were separated longitudinally and divided into five groups: distilled water, NaOCl, ethylenediaminetetraacetic acid (EDTA), phytic acid and citric acid (CA). Atomic force microscope and energy dispersive X-ray spectroscopy analyses were used for analysing. One-way analysis of variance and Turkey tests were used in the statistical analysis of the study. EDTA, CA and phytic acid solutions increased the roughness and phytic acid and CA solutions decreased the Ca/P ratio in dentin tissue. No statistical difference was observed in the other groups. The decrease of Ca/P ratio should be taken under consideration during irrigation. The increase in surface roughness may provide clinical benefit by supporting the adhesion of the root canal filling materials to the dentin surface.

Application of Inositol Hexaphosphate and Inositol in Dental Medicine: An Overview

Phosphorylated inositol hexaphosphate (IP6) is a naturally occurring carbohydrate, and its parent compound, myoinositol (Ins), is abundantly present in plants, particularly in certain high-fiber diets, but also in mammalian cells, where they regulate essential cellular functions. IP6 has profound modulation effects on macrophages, which warrants further research on the therapeutic benefits of IP6 for inflammatory diseases. Here, we review IP6 as a promising compound that has the potential to be used in various areas of dentistry, including endodontics, restorative dentistry, implantology, and oral hygiene products, due to its unique structure and characteristic properties. Available as a dietary supplement, IP6 + Ins has been shown to enhance the anti-inflammatory effect associated with preventing and suppressing the progression of chronic dental inflammatory diseases. IP6 in dentistry is now substantial, and this narrative review presents and discusses the different applications proposed in the literature and gives insights into future use of IP6 in the fields of orthodontics, periodontics, implants, and pediatric dentistry.

Characterization of pulp calcifications and changes in their composition after treatments with citric acid and ethylenediaminetetraacetic acid solutions

The ectopic calcifications of non-mineralized tissues can occur in several forms throughout life, such as pulpal calcification. The presence of pulp stones is a challenge in endodontic treatment because they partially or fully obliterate the pulp chamber hindering access to root canals and their subsequent shaping. This study aimed to determine their crystallographic properties and evaluate the capacity of citric acid (CA) and ethylenediaminetetraacetic acid (EDTA) to promote the demineralization of pulp calcifications. The samples were obtained from patients with indications of endodontic treatment, and the radiographic examination was suggestive of pulp stone in at least one permanent tooth. The samples were isolated and analyzed by scanning electron microscopy/energy-dispersive x-ray spectroscopy (SEM/EDX). The Fourier Transform by high resolution-transmission electron microscopy, Raman microscopy, and X-ray diffraction (XRD) were used to identify the mineral phase and crystallographic characteristics. To evaluate the effect of CA and EDTA on the crystallinity of calcifications, they were submerged into these two individual solutions and the changes were assessed in situ by Raman spectroscopy. The SEM images obtained from calcifications demonstrated irregular morphologies. EDX of sample surfaces shows a high presence of oxygen, carbon, calcium, and phosphorous, however, other elements such as sodium, magnesium, nitrogen, chlorine, potassium, sulfur, and zinc were identified in less quantity. According to Raman, XRD, and high-resolution transmission electron microscopy, the predominant mineral phase identified in the pulpal calcification was a poor crystallinity apatite. According to in situ analyses, the effect of CA and EDTA was observed on the signals of PO₄ ^3- and CH₂ groups corresponding to inorganic and organic components. The changes with CA were evident at 7 min while the effect of EDTA was observed until 15 min of treatment. All results indicate that pulp stones have a heterogeneous composition principally composed of apatite with low crystallinity. The solubility of these pathological minerals is adequate using solutions such as EDTA or CA; however, the effectivity depends on the mineralization grade of calcifications, time, and concentration of exposition to this chemical.

Primer application technique and remaining dentin thickness affected microtensile bond strength of contemporary dentin adhesives under simulated pulp pressure

OBJECTIVES

To evaluate the effect of application techniques, type of adhesives and remaining dentin thicknesses on microtensile bond strength (µTBS) of 3 adhesive systems.

MATERIALS AND METHODS

112 flat occlusal dentinal surfaces of third molar were randomly allocated into 16 groups based on 2 remaining dentin thicknesses (RDT), 2 application techniques, and 3 adhesive systems (Optibond FL, OFL; Clearfil SE Bond, CSE; and Single Bond Universal, SB); SB was applied in either etch-and-rinse (ER) or self-etch (SE) mode. Simulated pulpal pressure was performed during restorative procedure and water storage. The stick-shaped specimens from each tooth underwent µTBS testing. The data were evaluated using a paired t test and ANOVA followed by a post hoc test. The fractured specimens were evaluated for mode of failure using a stereomicroscope.

RESULTS

The mean µTBS values were significantly affected by RDT, application technique, and types of adhesives. Neither RDT nor application technique affected µTBS of SB in ER mode, whereas application technique affected both conventional and universal self-etch adhesives. RDT also influenced µTBS of OFL.

CONCLUSIONS

RDT and application technique differently affected the µTBS of dentin bonding which was product-related. Etch-and-rinse systems had higher bond strength to superficial than to deep dentin, whereas self-etch systems were more sensitive to both RDT and application technique.

CLINICAL RELEVANCE

The universal adhesive is less sensitive to intrinsic wetness and can be used according to manufacturer's instructions.

To compare the efficacy of various organic solvents on retrievability of Biodentine and their effect on microhardness of Biodentine and radicular dentin: An in vitro study

Background

Rotary and ultrasonic instruments are not appreciable in the complete removal of Biodentine from root canals. Therefore, organic solvents can be used as an adjunct for its retrieval.

Aim

The aim of this study was to compare the efficacy of 10% citric acid, 2% acetic acid, and 20% tartaric acid on the microhardness of Biodentine and radicular dentin.

Materials and Methods

Forty single-rooted extracted teeth were decoronated at the cementoenamel junction and root canals were prepared with peeso reamers. Two-millimeter sections were obtained and restored with Biodentine. All samples were subjected to Vicker's microhardness test to record the microhardness of Biodentine and radicular dentin. Samples were randomly divided into four experimental groups and treated with (n = 20) - distilled water, 10% citric acid, 2% acetic acid, and 20% tartaric acid groups for 10 min, after which specimens were again subjected to the same microhardness test.

Statistical Analysis

The data were subjected to Kruskal-Wallis ANOVA test, followed by Wilcoxon signed-rank test with a level of significance set at P ≤ 0.05.

Results

10% citric acid followed by 2% acetic acid exhibited the lowest mean microhardness values after immersing in respective solutions, whereas 20% tartaric acid exhibited the highest mean microhardness values on Biodentine and radicular dentin.

Conclusion

10% citric acid can be used for retrieving Biodentine from root canals for a limited time without adversely affecting the physical and chemical composition of radicular dentin.

Effect of phytic acid on dentinal collagen solubilization and its binding and debinding potentials to dentin

OBJECTIVES

To study phytic acid (IP6) effect on collagen solubilization by assessing hydroxyproline (HYP) release, evaluate its binding to demineralized (DD) and mineralized dentin (MD) and determine the effect of different media on debinding of IP6.

METHODS

Demineralized dentin beams were incubated in 1%, 2% or 3% IP6 and HYP release was evaluated at 1 or 3 weeks and compared to those obtained in untreated control or phosphoric acid (PA)-treated beams. DD or MD powder was treated with 1%, 2% or 3% IP6 and the decrease in IP6 amount was quantitated by ultraviolet-visible spectroscopy. IP6-treated samples were re-suspended in distilled water, ethanol, urea or sodium chloride and the amount of IP6 displaced was determined.

RESULTS

At 1 week, the control group and IP6 showed lower HYP release when compared to PA (P < 0.05). There was no difference among PA, IP6 and control at 3 weeks (P = 0.22). IP6 binding was concentration dependent. 1% IP6 had higher binding potential with MD compared to DD while 2% IP6 showed the opposite result (P<0.05). 3% IP6 had similar binding values between DD and MD (P = 0.53). The highest debinding in MD occurred with urea for 2%, 3% and 1% IP6 in descending manner. Within each concentration of IP6 in DD, the highest debinding effect was reported with ethanol.

CONCLUSIONS

IP6 bound to DD and MD in a concentration-dependent manner. IP6 was debound from DD mostly by the action of ethanol, while in MD, urea caused the most displacement. Collagen solubilization of IP6-treated DD was comparable to untreated DD.

CLINICAL SIGNIFICANCE

These findings add to the potential use of IP6 as an alternative to PA for dentin etching which possibly results in long-term stability of resin-dentin adhesion.

The Effect of a Novel Silver-Citrate Root Canal Irrigation Solution (BioAkt), Ethylenediamine Tetraacetic Acid (EDTA), and Citric Acid on the Microhardness of Root Canal Dentin: A Comparative In Vitro Study

Background and objective The use of a chelating agent as an adjunct to disinfectant irrigation is very necessary to remove the smear layer formed during root canal treatment. However, the decalcifying solutions have a negative impact on dentin microhardness, which might affect the result of endodontic therapy. The aim of this study is to evaluate the effect of 17% ethylenediamine tetraacetic acid (EDTA), a novel silver-citrate root canal irrigation solution (BioAkt), 10% citric acid, and 40% citric acid on the microhardness of root canal dentin. Materials and methods Forty-five single-root teeth were distributed equally into five groups A, B, C, D, and E treated with distilled water as a control, 17% EDTA, BioAkt, 10% citric acid, and 40% citric acid, respectively. The dentin microhardness was measured before and after the experiment, and the collected data were analyzed using paired sample T-test, One-way ANOVA test, and least significant difference (LSD) test (multiple comparisons), (P < 0.05). Result The results showed that the averages of dentin microhardness values before the experiment were 62.83 kg/mm², 65.34 kg/mm², 64.79 kg/mm², 62.95 kg/mm², and 56.47 kg/mm² for groups A, B, C, D, and E, respectively, while the averages after the experiment were 62.60 kg/mm², 54.92 kg/mm², 54.50 kg/mm², 51.31 kg/mm², and 49.37kg/mm² accordingly. Statistical analysis revealed that 17% EDTA, BioAkt, 10% citric acid, and 40% citric acid decreased the dentin microhardness significantly comparing with the negative control group, without statistical differences among them. Conclusion The chelating agents 17% EDTA, BioAkt, 10% citric acid, and 40% citric acid declined the microhardness of root canal dentin similarly, which might have possible effects on endodontic treatment and the properties of root canal filling materials as well.

Natural Extracts as Biological Smear Layer Removing Agents: A Literature Review

OBJECTIVES

The aim of this article is to identify whether natural irrigants are better than synthetic conventional irrigants for smear layer removal and to analyze their influence on mechanical and chemical radicular dentin properties.

MATERIALS AND METHODS

The last electronic search was performed on June 2020 through five databases, limited to articles either published or accepted for publication in the English language using the following keywords: "Natural extracts" or "Fruit and plant extracts" and "Smear layer removal."

RESULTS

According to the inclusion criteria, 36 articles were included. Most studies revealed that apple or apple cider vinegars, grape seed extract, citrus aurantifolia, 5-10% glycolic acid, and 0.5-1% phytic acid effectively removed the smear layer better or similar to synthetic conventional agents.

CONCLUSION

Natural irrigants are effective smear layer removing agents with the least deteriorated effect on mechanical and chemical radicular dentin properties compared with synthetic agents.