Root Canal Dentin Research Articles

Antibacterial effectiveness of different final irrigation activation techniques.

Background and objective: To evaluate and compare the antibacterial effectiveness of ultrasonic, diode laser, XP endo finisher and finisher gentle file brush against Enterococcus faecalis in root canal dentin. Methods: Fifty-five single-rooted extracted mandibular premolars were decoronated to have a length of 12 mm, instrumented biomechanically with protaper Next up to size X3. After sterilization, five roots were selected as negative controls and the remaining teeth were inoculated with E. faecalis and incubated for 48 hr and at 37 ºC. The roots were then randomly divided into five groups (n=10), GI: Control group, GII: 5.25% NaOCl irrigation was activated by the ultrasonic system , GIII: By 980-nm diode laser , GIV: By Xp-endo finisher and GV : Activated by Finisher gentle file-brush. The antimicrobial efficacy was tested by collecting transfer fluid saline from the canals and counting the colony forming units (CFUs) of viable E. faecalis on agar plates. The statistical calculations were performed in JMP pro 14.3.0. using Analysis of Variance (ANOVA) followed by a Tukey test to define the differences between the tested groups. Result: The mean bacterial CFU were 10.6 X 10^7 for Finisher gentle file brush, 35.6×10^7 for Diode laser, 39.6×10^7 for ultrasonic and 42.3×10^7 for XP Endo Finisher. Finisher gentle file brush showed a significant reduction in the colony count compared to the other groups. Conclusion: None of the irrigation activation techniques removed the bacteria completely from the canal. The four tested irrigation activation techniques were shown to be effective in the disinfection of the E. faecalis-contaminated root canals. Finisher gentle file brush was the most effective against E. faecalis, while XP endo finisher was the least effective against E. faecalis. treatment against E. faecalis in the root canal. Keywords: Utrasonic, Diode laser, XP endo finisher, irrigation activation techniques

Effects of immersion in 4-methacryloyloxyethyl trimellitate anhydride/methyl methacrylate-tri-n-butyl borane resin-activated liquid on microtensile bond strength of root canal dentin

Background/purpose4-methacryloyloxyethyl trimellitate anhydride/methyl methacrylate-tri-n-butyl borane (4-META/MMA-TBB) resin is used for indirect restorations. We aimed to evaluate effects of immersion in 4-META/MMA-TBB-activated liquid on the bond strength of root canal dentin. Materials and methodsWe used freshly extracted single-rooted human teeth. After decoronation, each root was vertically sectioned into halves; their dentin walls were polished and flattened. The control group underwent dentin treatment with Green Activator. The immersion group was treated with Green Activator and Teeth Primer and immersed in 4-META/MMA-TBB-activated liquid. After bonding the resin blocks with Super-Bond, microtensile bond strength (μTBS) tests were performed (n = 6), and fracture surfaces were analyzed. Before surface treatment, dentin was immersed in a sodium fluorescein solution for 3 h, and resin blocks were bonded with Super-Bond with rhodamine B as in the bond strength test. The bonded cross section was observed using confocal laser scanning microscopy (CLSM). ResultsμTBS was significantly higher in the immersion group than in the control group (61.5 [51.3–66.7] vs. 33.0 [20.4–57.8] MPa; P < 0.05). Fracture mode analysis showed that, compared with the control group, the immersion group had a significantly lower rate of adhesive failure at the dentin interface and a significantly higher rate of cohesive failure in Super-Bond (P < 0.01). CLSM showed a water droplet-like accumulation of fluorescein dye above the hybrid layer in the control group, not in the immersion group. ConclusionImmersion in a 4-META/MMA-TBB-activated liquid inhibited water exudation from the root canal dentin and improved the bond strength.

Effect of EDTA Activation on Blood Clot Structure in Regenerative Endodontics: A Scanning Electron Microscopy Study

IntroductionEDTA plays a crucial role in regenerative endodontic therapy (RET) because of its significant biological effects. However, EDTA is also recognized as the preferred anticoagulant for hematologic tests. Thus, this study aimed to assess the influence of different EDTA activation techniques on the morphology of blood clots after conditioning the root canal dentin. MethodsForty extracted human teeth were prepared to simulate immature teeth and divided into the following 5 groups: (1) saline solution (negative control), (2) EDTA 17% + saline solution (CNI), (3) CNI + ultrasonic activation, (4) CNI + Easy clean activation, and (5) CNI + XP-endo Finisher activation. After irrigation, the roots were cleaved, and the root canals were filled with human blood to clot formation. The morphology and density of erythrocytes, platelets, and the fibrin network were observed using a scanning electron microscope. The fibrin network density was classified using a 4-point scale. Data were analyzed using the Friedman test and the Kruskal-Wallis test with Bonferroni adjustment (α = 5%). ResultsAll groups exhibited consistent blood clot morphology characterized by a high density of erythrocytes, platelets, and white blood cells throughout the entire length of the root canal. The negative control group showed statistically significant high scores of fibrin density compared with the CNI group in all root thirds (P < .05). However, there was no statistical difference in the scores for the fibrin network density between the groups irrigated with EDTA with and without activation (P > .05). ConclusionsEDTA may impair the fibrin network formation compared with the saline group. However, EDTA activation did not significantly change the effects on the blood clot in contact with the conditioned intraradicular dentin.

Minimally invasive management of vital teeth requiring root canal therapy

The present study aimed to investigate the possible use of a non-instrumentation technique including blue light irradiation for root canal cleaning. Extracted human single rooted teeth were selected. Nine different groups included distilled water, NaOCl, intra-canal heated NaOCl, and NaOCl + EDTA irrigation after either instrumentation or non-instrumentation, and a laser application group following non-instrumentation technique. The chemical assessment of the root canal dentine was evaluated using energy dispersive spectroscopy (EDS) and Fourier transform infrared (FT-IR) spectroscopy. Surface microstructural analyses were performed by using scanning electron microscopy (SEM). The antimicrobial efficacy of different preparation techniques was evaluated using microbial tests. Light application didn’t change the calcium/phosphorus, carbonate/phosphate and amide I/phosphate ratios of the root canal dentin. The root canal dentin preserved its original chemistry and microstructure after light application. The instrumentation decreased the carbonate/phosphate and amide I/phosphate ratios of the root canal dentin regardless of the irrigation solution or technique (p < 0.05). The application of light could not provide antibacterial efficacy to match the NaOCl irrigation. The NaOCl irrigation both in the non-instrumentation and instrumentation groups significantly reduced the number of bacteria (p < 0.05). The use of minimally invasive root canal preparation techniques where the root canal is not instrumented and is disinfected by light followed by obturation with a hydraulic cement sealer reduced the microbial load and preserved the dentin thus may be an attractive treatment option for management of vital teeth needing root canal therapy.

Mechanical properties of simulated dentin caries treated with metal cations and L-ascorbic acid 2-phosphate.

This pH cycling study aimed to investigate the effects of L-Ascorbic acid 2-phosphate (AA2P) salts of Mg, Zn, Mn, Sr, and Ba on the surface microhardness, compressive strength, diametral tensile strength (DTS), and solubility of root canal dentin. 186 cylindrical dentin specimens from 93 teeth were fortified with optimal concentrations of AA2P salts of Mg (0.18mM), Zn (5.3µM), Mn (2.2 × 10-8M), Sr (1.8µM), and Ba (1.9µM). Saline was used as the control group. These dentin specimens underwent a 3-day cycling process simulating dentin caries formation through repeated sequences of demineralization and remineralization. Surface microhardness at 100 and 500µm depths (n = 10/subgroup), scanning electron microscopy (n = 3/group), compressive strength (n = 10/group), DTS (n = 6/group), and solubility (n = 5/group) tests were performed to analyze the dentin specimens. Data were analyzed using Kolmogorov-Smirnov, one-way ANOVA, and Post Hoc Tukey tests (p < 0.05). The control group had significantly lower microhardness at both depths (p < 0.001), reduced DTS (p = 0.001), decreased compressive strength (p < 0.001), and higher weight loss (p < 0.001) than all other groups. The Sr group had the highest compressive strength and microhardness among all the groups. The microhardness was significantly higher for the 500µm depth than the 100µm depth (p < 0.001), but the difference in microhardness between depths across groups was not significant (p = 0.211). All fortifying solutions provided some protection against artificial caries lesions. Therefore, these elements might have penetrated and reinforced the demineralized dentin against acid dissolution.

Evaluation of the Effects of Different Types of Resin Cement Systems on the Push-Out Bond Strength of the Fiber Post to Intracanal Dentin in Anterior Primary Teeth.

This study aimed to evaluate the effects of using three different resin cements on push-out bond strength (PBS) of fiber posts to root canal dentin of primary teeth. Fifty primary canines were randomly divided into five experimental groups according to the type of the luting agent used for fiber post cementation after endodontic treatment and post space preparation as the following: Group 1: glass ionomer cement (GIC), Group 2: flowable resin composite, Group 3: etch and rinse (E&R) resin cement, Group 4: self-etch (SE) resin cement, Group 5: self-adhesive (SA) resin cement. The PBS values of the cemented fiber posts to root canals were measured. The data were statistically analyzed using a one-way analysis of variance, followed by Tukey's post hoc test. The highest mean PBS value was observed in Group 4 (SE resin cement), followed by Group 3 (E&R resin cement), and the lowest PBS value belonged to Group 1 (GIC), followed by Group 5 (p-values < 0.05). The mean PBS of Group 3 (E&R resin cement) was significantly higher than those of Groups 1 (GIC), 2 (flowable resin composite), and 5 (SA resin cement) (p-values < 0.05). However, no significant difference was found between the mean PBS of GIC and SA resin cement (p-value >0/05). Using SE resin cement for fiber post cementation in primary anterior teeth showed the best results, followed by E&R resin cement. The lowest PBS was observed for GIC, followed by SA resin cement.

Efficacy of calcium hydroxide-loaded poly(lactic-co-glycolic acid) biodegradable nanoparticles as an intracanal medicament against endodontopathogenic microorganisms in a multi-species biofilm model.

This study aimed to evaluate the antimicrobial activity of calcium hydroxide-loaded poly(lactic-co-glycolic acid) nanoparticles (CH-loaded PLGA NPs) on multi-species biofilms. Human root blocks were prepared (n = 40), and multi-species suspensions of Candida albicans, Enterococcus faecalis and Streptococcus gordonii were incubated within the root canals for 21 days. Canals (n = 10/group) were then medicated with saline solution (negative control), chlorhexidine (positive control), calcium hydroxide and CH-loaded PLGA NPs for 7 days. Samples taken from the 0.1 mm root canal dentin were collected, and cell growth was detected by culture on BHI agar. The viable cell count of the Ca(OH)2, chlorhexidine gel and CH-loaded PLGA NPs group was significantly lower than the normal saline group (p < 0.001). CH-loaded PLGA NPs demonstrated a significant lower viable cell than Ca(OH)2 (p < 0.001); it has potential as a medicament for endodontic therapy.

Endodontic Dentistry: Analysis of Dentinal Stress and Strain Development during Shaping of Curved Root Canals.

Endodontic shaping causes stress and strain in the root canal dentin. Dentin microcracks have the potential to be later followed by root fractures occurring under the occlusal load. The aim of our research was to theoretically determine the values of such dentinal states of stress and strain during the endodontic shaping of curved root canals using finite element analysis (FEA). To highlight the stress concentrations in dentin, two geometric models were created considering the volume of the curved dental root and the contact between the endodontic file and the root canal walls. The application of forces with different values was simulated both on a uniform curved root canal and on a root canal with an apical third curvature of 25° as they would be applied during the preparation of a root canal. In the case of the first model, which was acted upon with a force of 5 N, the deformations of the root canal appeared along the entire working length, reaching the highest values in the apical third of the root, although there were no geometric changes in the shape of the root canal. Regarding the second root model, with an apical third curvature of 25°, although the applied force was 2 N, the deformations were accompanied by geometric changes in the shape of the root, especially in the upper part of the apical third. At a higher force of 7 N exerted on the endodontic file, the geometric shape changed, and the deformation reached extreme critical values. The resulting tensile stresses appearing in the experimental structure varied similarly to the deformations. Significant stress and strain can develop, especially in the apical third of curved root canals during their shaping, and the risk of cracks is higher for endodontically treated teeth presenting severe curvatures in the apical third of the root.

Evaluating the Thickness of the Root Canal Dentin Wall in Primary First Molars Using Cone-beam Computed Tomography

Evaluating the Thickness of the Root Canal Dentin Wall in Primary First Molars Using Cone-beam Computed Tomography

Impact of Heating Exposure on the Micro-Push-Out Bond Strength of Bioceramic Sealers

Introduction. The aim of this study was to evaluate the effect of heating of bioceramic and epoxy resin-based sealers on their micro-push-out bond strength (BS) to root canal dentin. Methods. After criterial selection, 30 human teeth were decoronated and 1-mm thick slices (n = 60) were obtained perpendicularly along tooth axis, from cervical and middle root thirds, with a diamond disc attached to a cutting machine. In each slice, three 1.0-mm diameter orifices were made. After rinsing with 17% EDTA and 2.5% NaOCl, each orifice was filled with Bio-C Sealer or BioRoot RCS or AH Plus, according to the manufacturers’ instructions. After filling, half of the slices (n = 30) were heated at 100°C for 1 min, and the other half were kept at room temperature. After 7 days-controlled storage, micro-push-out test was performed in a Universal Testing Machine. Failures were analyzed using a stereomicroscope. Statistical analysis was performed with One-Way ANOVA and post hoc Tukey (α = 5%) tests. Results. AH Plus demonstrated higher BS values after heating ( p = 0.001 ) when compared to nonheated. The other sealers did not show a statistically significant difference ( p &gt; 0.05 ). When heated, the average BS values for AH Plus were higher than for BioRoot RCS and Bio-C Sealer ( p &lt; 0.001 ). Cohesive failure mode was the most frequent, followed by adhesive and mixed ones. Conclusion. Heating provided a higher push-out BS to root dentin for AH Plus and did not influence BioRoot RCS or Bio-C sealer.

Scanning Electron Microscopy Analysis of the Intratubular Radicular Dentin Penetration of Calcium Hydroxide, Triple Antibiotic Paste, and Nitrofurantoin.

The aim of this study is to assess and analyze the intratubular penetration of the intracanal medications nitrofurantoin (Nit), triple antibiotic paste (TAP), and calcium hydroxide (CH). Sixty freshly extracted single-rooted teeth were acquired and decoronated to a standard length of 15 mm. To prepare specimens up to size F3, rotary ProTaper instrumentation was employed. The prepared teeth were divided into three groups, each of which received one of the tested intracanal medicaments: Group I (calcium hydroxide), Group II (triple antibiotic paste), and Group III (nitrofurantoin). Using a size #30 Lentulo spiral, a freshly prepared therapeutic paste was placed into the canals, and the intracanal medicaments were allowed to set in the incubator at 100% humidity. The samples were subsequently sliced perpendicularly to their long axis using a precision saw and assessed under a scanning electron microscope to assess the depth of penetration of intracanal medicaments at the coronal, middle, and apical portions of the root canal dentin. The data were analyzed using one-way ANOVA and Tukey's post hoc test. The statistical analysis revealed a significant difference between the experimental groups in the quantity and depth of sealer penetration (p < 0.05). In particular, as compared to the Nit group, both the CH and TAP groups had significantly smaller penetration areas (p < 0.05). In conclusion, this ongoing investigation indicates that nitrofurantoin penetrated dentinal tubules better than calcium hydroxide or triple antibiotic paste.

Effect of Endo-Z bur or Bladesonic ultrasonic tip on the adaptation of filling material. A micro-CT study.

This study aimed to evaluate the effect of apicoectomy performed with a bur or an ultrasonic tip on the adaptation of the filling material to root canal dentin. Twenty human mandibular incisors were selected and prepared with a ProDesign Logic system up to diameter 40/.05. The root canals were filled with Bio-C Sealer (Angelus, PR, Brazil) using the single cone technique and were stored at 37ºC and 95% relative humidity for 7 days. After this period, the apicoectomy of the 3 millimeters of the root apex was performed using Endo-Z bur (Dentsply Sirona) or Bladesonic ultrasonic tip (Helse Ultrasonic, Santa Rosa de Viterbo, Brazil) (n=10). The specimens were scanned by micro-computed tomography (micro-CT; SkyScan 1176) with a voxel size of 8.74 µm after obturation and after apicoectomy. The percentage of voids at the interface between the filling material and the root canal wall was evaluated in the apical 4 mm of the root after apicoectomy, besides the time cutting to both devices. The data obtained were submitted to paired and unpaired t-tests (α = 0.05). Endo-Z and Bladesonic increased the percentage of voids between the filling material and the dentin after apicectomy (p<0.05), and they were similar (p>0.05). Endo-Z has a shorter time to perform apicoectomy compared to Bladesonic (p<0.05). Apicectomies with Endo-Z or Bladesonic could harm the material/dentin interface, while the Endo-Z bur was faster than the Bladesonic ultrasonic tip.

Antibacterial ability of green okra fruit (Abelmoschus esculentus) extract at concentrations of 12.5-100% against Staphylococcus aureus

Introduction: The common bacteria found in infected root canals are Gram-positive bacteria such as Staphylococcus aureus (20%). S. aureus infection can spread to the periapical tissues causing periapical lesions. Pulp necrosis requires root canal treatment. One of the irrigants used in root canal treatment is 17% ethylenediaminetetraacetic acid (17% EDTA). This material can soften the root canal dentine making it easier to prepare because it can dissolve the inorganic material of smear layer. The disadvantage of 17% EDTA is low antibacterial power, so an alternative irrigation material is needed. Irrigants should ideally be antibacterial. The green okra fruit extract contains antibacterial properties such as alkaloids, flavonoids, saponins, tannins, and terpenoids. This study aims to determine the antibacterial ability of green okra fruit extract concentrations of 12.5%, 25%, 50%, and 100% against S. aureus. Methods: This type of research was an in-vitro laboratory experiment with a posttest-only control group design. The antibacterial test used the disc diffusion method consisted of 6 groups, i.e, green okra fruit extract concentrations of 12.5%, 25%, 50%, 100%, 17% EDTA (positive control), and aquadest (negative control). Antibacterial ability indicated by the clear zone around the disc paper Results: The average diameter of the inhibition zone was green okra fruit extract concentrations of 12.5% (12.14 mm), 25% (14.89 mm), 50% (18.53 mm), 100% (21.1 mm ), 17% EDTA (22.08 mm), and aquadest (0 mm). The results were analyzed with the Mann-Whitney test and showed a significant difference between all research groups (α &lt;0.05). Conclusion: The antibacterial ability of green okra fruit extract (Abelmoschus esculentus) increased from concentrations of 12.5%, 25%, 50%, and 100%, but still lower than the antibacterial ability of 17% EDTA against Staphylococcus aureus.

The effect of nanobased irrigants on the root canal dentin microhardness: an ex-vivo study

BackgroundGiven the favorable antimicrobial properties of zinc oxide (ZnONPs), standard silver (AgNPs), and imidazolium-based silver (Im-AgNPs) nanoparticles, this study aimed to evaluate their influence on the microhardness of root canal dentin.MethodsIn this experimental study, 40 mandibular premolars were decoronated at the cementoenamel junction and longitudinally sectioned into halves to create 80 specimens. They were randomly allocated to 5 groups (n = 16) and irrigated with ZnONPs, AgNPs, Im-AgNPs, NaOCl, or normal saline (as the negative control) for 15 min. The Vickers Hardness Number (VHN) was measured on each root canal third before and after being soaked in irrigants. Statistical analysis was performed using paired t-test, one-way ANOVA, and post hoc Tukey’s test (α = 0.05).ResultsIm-AgNPs and ZnONPs irrigants improved the microhardness of root dentin, whereas, AgNPs and NaOCl decreased it. ZnONPs yielded the highest VHN at the coronal third (P˂0.001), while the Im-AgNPs provided the highest VHN at the middle and apical thirds (P˂0.001). The AgNPs group showed the lowest VHN at the apical third.ConclusionsThe irrigants containing Im-AgNPs and ZnONPs significantly enhanced the root dentin microhardness. However, the use of AgNPs resulted in decreased microhardness.

Effect of gallic acid as a final irrigant on push-out bond strength of an epoxy resin sealer to root canal dentin

Effect of gallic acid as a final irrigant on push-out bond strength of an epoxy resin sealer to root canal dentin

Morphological Analyses of Effects of Endodontic Irrigant Solutions Using a Root Canal Model and an Immersion Model.

This study aimed to compare an experimental model simulating clinical root canal irrigation (root canal model) with a conventional experimental model immersing dentin sample to irrigants (immersion model) to evaluate removal of the smear layer and decalcification of the root canal dentin using sodium hypochlorite (NaOCl) and two different concentrations of ethylenediaminetetraacetic acid (EDTA) solution. Forty-five single-rooted extracted human teeth were prepared using a Ni-Ti rotary file. EDTA, NaOCl, and citric acid were used in the root canal models and the immersion models. After the irrigation protocol, root canal surfaces were observed under scanning electron microscopy. Residual smear and decalcification of the root canal dentin were evaluated objectively by measuring the percentage of the area occupied by visible dentin tubules, the number of visible dentin tubules, and the mean area of a visible single dentin tubule. Root canal and immersion models with the same irrigation protocol showed significantly different results for smear residues and decalcification of root canal dentin. In the root canal model, neither different EDTA concentrations nor the order of EDTA and NaOCl applications significantly impacted smear residues or decalcification of root canal dentin. Furthermore, no erosion of the root canal dentin surface was observed in any experimental groups in the root canal model using EDTA and NaOCl compared to intact dentin. Experimental design affected results for residual smear layer and decalcification of root canal dentin. The order of EDTA and NaOCl use and the concentration of EDTA did not affect results. EDTA and NaOCl irrigation did not cause erosion in the root canal model in this study.

Effects of Diabetes on Elemental Levels and Nanostructure of Root Canal Dentin

IntroductionThis study evaluated the effects of diabetes mellitus (DM) on the nanostructure of root canal dentin using high-resolution transmission electron microscopy (HRTEM) and inductively coupled plasma mass spectrometry (ICP-MS). MethodsTwenty extracted human premolars from diabetic and nondiabetic patients (n = 10 in each group) were decoronated and sectioned horizontally into 40 2-mm-thick dentin discs, with each disc designated for a specific test. ICP-MS was used to determine the different elemental levels of copper, lithium, zinc, selenium, strontium, manganese, and magnesium in diabetic and nondiabetic specimens. HRTEM was used to analyze the shape and quantity of the apatite crystals in diabetic and nondiabetic dentin at the nanostructural level. Statistical analysis was performed using Kolmogorov-Smirnov and Student t test (P < .05). ResultsICP-MS revealed significant differences in trace element concentrations between the diabetic and nondiabetic specimens (P < .05), with lower levels of magnesium, zinc, strontium, lithium, manganese, and selenium (P < .05), and higher levels of copper in diabetic specimens (P < .05). HRTEM revealed that diabetic dentin exhibited a less compact structure with smaller crystallites and significantly more crystals in the 2500 nm2 area (P < .05). ConclusionDiabetic dentin exhibited smaller crystallites and altered elemental levels more than nondiabetic dentin, which could explain the higher root canal treatment failure rate in diabetic patients.

Morphological changes in root dentin after irradiation with diode laser 980 nm in two directions: an in-vitro study

Background/aim Laser technology is an essential aid tool for endodontic treatment procedures. The most common type of laser used in the endodontic field was diode laser 980 nm. The present work aimed to assess the morphological variations and chemical changes in root canal dentin treated with diode laser 980 nm in two directions parallel and perpendicular by scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS). Materials and methods Thirty extracted human single-rooted lower premolars teeth with mature apex were chosen from Dental Department of Research Institute of Ophthalmology, Egypt. Their crowns were resected at the cement-enamel junction (CEJ), and their roots were mechanically prepared. The roots were categorized into two groups (each = 15): according to the direction of laser application. In group A the laser was directed parallel to the root canal, while in the group B it was directed perpendicular to the root canal. All groups were analyzed by SEM and EDS examination. Statistical analysis was done by Kolmogorov-Smirnov and Shapiro-Wilk tests and comparison between two groups was performed by independent t-analysis, while in qualitative data Chi-square test was used. Results The results of group A where the laser was directed parallel to the root canal exhibited score 1 (86.7%) in the coronal section, score 3 (80%) in the middle section, and score 4 (80%) in the apical section. The results of group B where the laser was directed perpendicular to the root canal represented score 1 (86.7%) in the coronal section, score 1 (73.3%) in the middle section, and score 3 (73.3%) in the apical section. Conclusion Diode laser 980 nm in a perpendicular direction to root canal dentin surface produced more morphological changes than when used in a parallel direction, however regarding the chemical changes, there were no chemical changes detected between the two directions.

Comparative assessment of antibacterial effect of two types of laser and their effect on morphology and mineral content of dentin

Background/aim Scientists have proven that the main cause of endodontic diseases and failures is the existence of micro-organisms in the root canals and inside the dentinal tubules. So the aim of the study was to compare the antibacterial effect of Erbium, chromium-doped yttrium, scandium, gallium, and garnet (Er,Cr:YSGG) laser and diode laser 980 nm alone and in combination with 5.25% sodium hypochlorite (NaOCl) irrigant against Enterococcus faecalis biofilm and also compare their effect on the morphology and mineral content of root canal dentin by scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDX) analysis. Materials and methods The specimens used in our study were fifty four extracted human single-rooted teeth. They were collected from the Dental Department of the Research Institute of Ophthalmology, Egypt. Mechanical preparation was done to all teeth after their crowns were removed. They were autoclaved, and after that, they were inoculated with Enterococcus faecalis for 30 days. Roots were divided into six groups (each=9) according to type of treatment. Group A: 5.25% NaOCl, group B: Er,Cr:YSGG laser, group C: 5.25% NaOCl and Er,Cr:YSGG laser, group D: diode laser 980 nm, group E: 5.25% NaOCl and diode laser 980 nm, in addition to control group: saline. Their antibacterial effect was assessed before and after treatment. Changes in the morphology and mineral content of root canal dentin were assessed by SEM and EDX. Statistical analysis was done. Results Group C had significantly the highest percentage of Enterococcus faecalis reduction (98.95%), followed by group E (98.04%), then group D (95.27%), then group A (94.65%), then group B (92.99%), while the control group had significantly the lowest percentage of Enterococcus faecalis reduction (0.22%). Regarding SEM results, group B and group D exhibited score 1 (88.9%), control group and group C score 3 (77.8%), group A score 4 (88.9%), and group E score 5 (88.9%). Regarding EDX results, group B was significantly the lowest in Ca/P ratio, while there was an insignificant difference between other groups. Conclusions Er,Cr:YSGG laser, and diode laser, when used without 5.25% NaOCl irrigant, produced less morphological changes to dentinal tubules, but when combined with 52.5% NaOCl irrigant, produced more antibacterial effect against Enterococcus faecalis. Lasers alone or combined with 5.25% NaOCl irrigant produced changes in the mineral content of root canal dentin.

A comparative evaluation of the effect of various chelating agents on the microhardness of root canal dentin: An in vitro study

ABSTRACT Aim: The aim of this study was to evaluate and compare the effect of 17% liquid ethylenediaminetetraacetate (EDTA), 10% citric acid, and 9% 1-hydroxy ethylidene-1,1-bisphosphonate (HEBP) on the microhardness of root canal dentin. Materials and Methods: Eighteen mandibular premolars which were freshly extracted were selected and randomly assigned to one of the three groups (n = 6). After decoronating, the teeth at the cementoenamel junction, specimens were prepared up to F3 (ProTaper Universal). After each instrument, irrigation was done with 3% sodium hypochlorite. Specimens were sectioned longitudinally to expose dentin surface and mounted on acrylic resin blocks. One half served as the test group and the other served as its control. The dentin was covered with test solutions throughout its length for 5 min. Group 1: 17% liquid EDTA, Group 2: 10% citric acid, and Group 3: 9% HEBP. Measurement of microhardness was done using Vickers indenter at 1000 μm, 1200 μm, 1400 μm from orifice of root canal and 100 μm from pulp-dentin junction, a load of 50 g for 15 s dwell time was applied. A mean of the three readings was used to calculate microhardness. Statistical analysis was performed using one-way ANOVA and post-hoc Tukey test at P ≤ 0.05. Results: The mean microhardness of EDTA reduced from 52.28 VHN to 39.00 VHN, and that of citric acid reduced from 52.50 VHN to 47.30 VHN, whereas, HEBP showed least reduction, from 52.46 VHN to 50.52 VHN. Conclusion: A reduction in microhardness was evident on using all three chelating agents. However, HEBP caused the least reduction in microhardness and can be a potential chelating agent for use in endodontics.