Recent Advances in Bioactive Carbon Nanotubes Based on Polymer Composites for Biosensor Applications.

Recent breakthroughs in the field of carbon nanotubes (CNTs) have opened up unprecedented opportunities for the development of specialized bioactive CNT-polymers for a variety of biosensor applications. The incorporation of bioactive materials, including DNA, aptamers and antibodies, into CNTs to produce composites of bioactive CNTs has attracted considerable attention. In addition, polymers are essential for the development of biosensors as they provide biocompatible conditions and are the ideal matrix for the immobilization of proteins. The numerous applications of bioactive compounds combined with the excellent chemical and physical properties of CNTs have led to the development of bioactive CNT-polymer composites. This article provides a comprehensive overview of CNT-polymer composites and new approaches to encapsulate bioactive compounds and polymers in CNTs. Finally, biosensor applications of bioactive CNT-polymer for the detection of glucose, H2O2 and cholesterol were investigated. The surface of CNT-polymer facilitates the immobilization of bioactive molecules such as DNA, enzymes or antibodies, which in turn enables the construction of state-of-the-art, future-oriented biosensors.

Time-Dependent Antibacterial Effects of Citrullus Colocynthis Seed Extract Compared to Calcium Hydroxide in Teeth Infected with Enterococcus Faecalis.

Statement of the Problem: Endodontic efforts are focused on eliminating intracanal pathogens. Applying intracanal medicament for infected teeth is beneficial for achieving better antibacterial effects in endodontic treatments. Different intracanal medicaments should be assessed and compared for this purpose. Purpose: The aim of this study was to assess the antibacterial efficacy of Citrullus colocynthis seed extract comparing to Ca(OH)2 on teeth contaminated with Enterococcus faecalis. Materials and Method: In this in vitro study, a novel strain of Enterococcus faecalis (Enterococcus spp. ATCC 19433) yielded from the root canal treated tooth with persistent apical periodontitis. The canals of 78 human single-rooted extracted teeth were contaminated with mentioned strain and treated with Citrullus colocynthis essential oil and Ca(OH)2 for 1, 7, and 14 days. To determine the chemical composition of the oils, gas chromatography-mass spectrometry (GC-MS) was applied. The percentage reduction from baseline c.f.u./mL values was estimated. Results: Oleic acid, benzoic acid, and gallic acid were the major contents of Citrullus colocynthis essential oil. The c.f.u./mL count decreased considerably as contact duration rose for both medicaments. After 7 days, a statistically significant difference was identified between the medicaments. Citrullus colocynthis showed higher antimicrobial efficacy. However, after 14 days, no substantial difference was found. Conclusion: Citrullus colocynthis essential oil, displayed great antimicrobial efficacy against Enterococcus faecalis higher than Ca(OH)2 over the first week contact period.

Sealing Ability of Nano-fast Cement vs. Mineral Trioxide Aggregate as Retrograde Apical Plugs: An In-vitro Microleakage Study.

Introduction: Apical surgery aims to eradicate the apical part of the root and the lesion to enhance the healing. The sealing ability of retrograde filling material is an essential factor affecting the success rate of the surgery. Mineral trioxide aggregate (MTA) is the gold standard of retrograde filling materials, with approved sealing capability and biocompatibility. Newly introduced root repair material with an approved antibacterial effect similar to MTA is Nano-fast cement (NFC) which should be investigated for its sealing ability. This study aimed to evaluate the sealing ability of NFC vs. MTA. Materials and Methods: Root apices of 48 single-rooted teeth were resected at 90 degrees and were prepared at 3 mm depth. The teeth were randomly divided into 2 experimental groups (n=21), negative control group (n=3), and positive control group (n= 3). MTA and NFC plugs were condensed as retrograde filling material. The samples were evaluated by a modified fluid filtration device for 1 hour. The measurement was conducted at 24 h, 1, and 3 months. Data were analyzed by Friedman Test and Kruskal-Wallis test. Results: According to the results, NFC at 3-months interval showed the least microleakage, and MTA had the highest at the baseline. However, the results between the two groups were not statistically significant in all intervals. NFC reached the ideal sealing ability within 1 month, which was reached for MTA after 3 months. Conclusions: The results of this in vitro study showed that the microleakage value of NFC is comparable to MTA. In light of current findings, NFC shows characteristics of a suitable calcium silicate-based cement. Further clinical researches are needed to introduce the NFC as retrograde apical plug or for other endodontic applications.

Innovative Metal-Organic Frameworks for Targeted Oral Cancer Therapy: A Review.

Metal-organic frameworks (MOFs) have proven to be very effective carriers for drug delivery in various biological applications. In recent years, the development of hybrid nanostructures has made significant progress, including developing an innovative MOF-loaded nanocomposite with a highly porous structure and low toxicity that can be used to fabricate core-shell nanocomposites by combining complementary materials. This review study discusses using MOF materials in cancer treatment, imaging, and antibacterial effects, focusing on oral cancer cells. For patients with oral cancer, we offer a regular program for accurately designing and producing various anticancer and antibacterial agents to achieve maximum effectiveness and the lowest side effects. Also, we want to ensure that the anticancer agent works optimally and has as few side effects as possible before it is tested in vitro and in vivo. It is also essential that new anticancer drugs for cancer treatment are tested for efficacy and safety before they go into further research.

The antimicrobial efficacy of nanographene oxide and double antibiotic paste per se and in combination: part II.

BACKGROUND: Finding strategies to overcome the rising trends of antimicrobial resistance against currently available antimicrobial agents has become increasingly relevant. Graphene oxide has recently emerged as a promising material due to its outstanding physicochemical and biological properties. This study aimed to validate previous data on the antibacterial activity of nanographene oxide (nGO), double antibiotic paste (DAP), and their combination (nGO-DAP). METHODS: The antibacterial evaluation was performed against a wide range of microbial pathogens. Synthesis of nGO was achieved using a modified Hummers' method, and loading it with ciprofloxacin and metronidazole resulted in nGO-DAP. The microdilution method was utilized to assess the antimicrobial efficacy of nGO, DAP, and nGO-DAP against two gram-positive bacteria (S. aureus and E. faecalis), two gram-negative bacteria (E. coli, and S. typhi), and an opportunistic pathogenic yeast (C. albicans). Statistical analysis was conducted using one-sample t-test and one-way ANOVA (α = 0.05). RESULTS: All three antimicrobial agents significantly increased the killing percent of microbial pathogens compared to the control group (P < 0.05). Furthermore, the synthesized nGO-DAP exhibited higher antimicrobial activity than nGO and DAP per se. CONCLUSION: The novel synthesized nGO-DAP can be used as an effective antimicrobial nanomaterial for use in dental, biomedical, and pharmaceutical fields against a range of microbial pathogens, including gram-negative and gram-positive bacteria, as well as yeasts.

The antimicrobial efficacy of graphene oxide, double antibiotic paste, and their combination against Enterococcus faecalis in the root canal treatment.

BACKGROUND: Inter-appointment medication of the root canals with appropriate intracanal medicaments has been advocated to improve root canal disinfection. Graphene oxide (GO) has shown promising antimicrobial activity against a wide range of microorganisms, besides the capability of carrying antibiotics. The current study aimed to compare the antibacterial activity of double antibiotic paste (DAP) and GO per se and in combination (GO-DAP) against Enterococcus faecalis (E. faecalis). METHODS: A total of 108 extracted human mandibular premolars were contaminated with three-week-old E. faecalis and subjected to a primary microbial assessment. The samples were categorized into 15 groups concerning the intracanal medicament (DAP, GO, GO-DAP, and control) and contact time (1, 7, and 14 days). Then, the root canals were medicated, incubated, and resubjected to a secondary antimicrobial evaluation. The colony-forming units (CFU) were counted to calculate the antimicrobial efficacy. The data were analyzed via the Kruskal-Wallis test (α = 0.05). RESULTS: GO-DAP was the only medicament that completely eradicated E. faecalis in 1 day. The percentage reduction of CFU/ml in the GO-DAP and DAP groups was higher than that in the GO group at all allocated contact times. Furthermore, a significant decrease of the CFU/ml was seen in the GO and DAP groups after 7 and 14 days of being medicated (P < 0.05). CONCLUSION: Since GO-DAP improved root canal disinfection, this novel material can be introduced as a promising intracanal medicament against E. faecalis even in the short run.

Synergistically Enhancing the Therapeutic Effect on Cancer, via Asymmetric Bioinspired Materials.

The undesirable side effects of conventional chemotherapy are one of the major problems associated with cancer treatment. Recently, with the development of novel nanomaterials, tumor-targeted therapies have been invented in order to achieve more specific cancer treatment with reduced unfavorable side effects of chemotherapic agents on human cells. However, the clinical application of nanomedicines has some shortages, such as the reduced ability to cross biological barriers and undesirable side effects in normal cells. In this order, bioinspired materials are developed to minimize the related side effects due to their excellent biocompatibility and higher accumulation therapies. As bioinspired and biomimetic materials are mainly composed of a nanometric functional agent and a biologic component, they can possess both the physicochemical properties of nanomaterials and the advantages of biologic agents, such as prolonged circulation time, enhanced biocompatibility, immune modulation, and specific targeting for cancerous cells. Among the nanomaterials, asymmetric nanomaterials have gained attention as they provide a larger surface area with more active functional sites compared to symmetric nanomaterials. Additionally, the asymmetric nanomaterials are able to function as two or more distinct components due to their asymmetric structure. The mentioned properties result in unique physiochemical properties of asymmetric nanomaterials, which makes them desirable materials for anti-cancer drug delivery systems or cancer bio-imaging systems. In this review, we discuss the use of bioinspired and biomimetic materials in the treatment of cancer, with a special focus on asymmetric nanoparticle anti-cancer agents.

Cytotoxic Effect of Nano Fast Cement and ProRoot Mineral Trioxide Aggregate on L-929 Fibroblast Cells: an in vitro Study.

Statement of the Problem: Endodontic materials that are placed in direct contact with living tissues should be biocompatible. The cytotoxicity of Nano Fast Cement (NFC) compared to ProRoot Mineral Trioxide Aggregate (ProRoot MTA) must be evaluated. Purpose: This In vitro study aimed to assess the cytotoxic effects of NFC in comparison to ProRoot MTA on L-929 mouse fibroblast cells. Materials and Method: In this animal study, L-929 mouse fibroblast cells were grown in Dulbecco's Modified Eagle's medium (DMEM) supplemented with 10% fetal bovine serum (FBS) in an atmosphere of 5% co2/95% air at 37 C̊. A total of 104 cells from the fourth collection were plated in each well of a 96-well micro-titer plate. Materials were mixed according to the manufacturer's instruction and placed into the related plastic molds with 5 mm diameter and 3 mm height. After 24 hours and a complete setting, the extracts of the tested materials were produced at six different concentrations and placed in the related wells. Cells in DMEM served as the negative control group. DMEM alone was used as the positive control group. Methyl-thiazoltetrazolium (MTT) colorimetric assay was conducted after 24, 48, and 72 hours. The absorbance values were measured by ELISA plate reader at 540 nm wavelength. Three-way analysis of variance, post-hoc Tukey, LSD, and independent t-test were used for the statistical analyses using SPSS software, version 16.0. Results: There was no statically significant difference between MTA and NFC in cell viability values at different concentrations and different time intervals (p= 0.649). Viability values were significantly decreased after 72 hours, but there was no significant difference between the first and second MTT assays (p= 0.987). Cytotoxicity significantly increased at concentrations higher than 6.25 µÉ¡/ml. Conclusion: Cytotoxicity depends on time, concentration, and cement composition. There was no statistically significant difference between NFC and MTA concerning their cytotoxic effects on L-929 mouse fibroblast cells.

Maintaining a Hopeless Traumatized Maxillary Central Incisor as a Transient Treatment Option: A Case Report with a 3-Years Follow-Up.

An open apices tooth is among the rare types of traumatic dental injuries is horizontal root fracture. Many factors may affect the treatment and prognosis of root fractures, like the time between trauma and treatment, degree of dislocation and mobility, stage of tooth development, fracture site, and patient's age. This case presents a horizontal root fracture of a maxillary central incisor in an 8-year-old boy. The tooth was considered for extraction due to excessive mobility and deep probing depth, but the patient's parents refused to extract the tooth. After one year, during the follow-up examination, we noticed an unprecedented healing process had been initiated. Due to the weak crown-to-root ratio, the traumatized tooth was splinted to the surrounding teeth to reduce the wrecking forces and promote healing. In a three-year follow-up, the cone-beam computed tomography examination showed that the coronal and apical fragments continued to develop separately. Also, it was observed that the mobility and probing depth were reduced significantly.

Surgical Treatment of a Dens Invagination Type (І) in a Maxillary Lateral Incisor with 6-Year Follow-Up.

Dens invagination is a developmental anomaly that requires specific treatment approaches. The invagination is enamel-lined in the crown of the tooth truly negligible, and usually there is no extension on the level of the external amelocemental junction. A well ending surgical root canal treatment of an invaginated tooth with a retrograde filling is presented in this case report. Periapical radiographic examination, after 3 months and 6 years of follow-up, showed periapical healing with osseous formation .

The Effects of Various Restorative Techniques on the Fracture Resistance of Pulpotomized Permanent Premolars.

AIM: This study aimed to evaluate the effects of various restorative techniques on the fracture resistance of pulpotomized premolars with mesioocclusodistal (MOD) cavities treated with mineral trioxide aggregate (MTA) or calcium enriched mixture (CEM) cement. MATERIALS AND METHODS: One hundred and eight sound extracted maxillary premolars were randomly assigned to nine experimental groups (n = 12). The teeth in group 1 did not receive any preparation. Class II MOD cavities were prepared in the other experimental groups. In groups 2, 4, 6, and 8, tooth-colored MTA was used for pulpotomy. In groups 3, 5, 7, and 9, CEM cement was used for pulpotomy. Groups 2 and 3 were left unrestored. Groups 4 and 5 were restored with amalgam. Groups 6 and 7 were restored with a conventional composite resin, and groups 8 and 9 were restored with bulk-fill giomers. Fracture resistance was measured, the fracture pattern of each specimen was assessed, and the results were statistically analyzed. RESULTS: The fracture resistance of group 1 was significantly higher than those of the other groups (p < 0.05). The fracture resistance of group 2 (MTA + amalgam) was statistically lower than those of all experimental groups (p values < 0.05) except groups 3, 4, and 5 (p values > 0.05). No statistically significant differences were found between the groups restored with amalgam, conventional composite resin, and bulk-fill giomer (groups 4, 5, 6, 7, 8, and 9) (p values < 0.05). The highest rate of mode 1 fracture (restorable fracture) was observed in group 1 followed by groups 8 and 9. CONCLUSION: No significant differences were found among the fracture resistances of the restored teeth using various restorative techniques. Bulk-fill giomers followed by conventional composite resin were better able to prevent unfavorable fractures compared to amalgam. Therefore, they seem to be more reliable for the restoration of pulpotomized teeth with MOD cavities.

Effect of restorative technique on the fracture strength and fracture mode of premolars after mineral trioxide aggregate pulpotomy.

This study aimed to compare the effects of different combinations of adhesive bases and restorative materials on the fracture strength and mode of maxillary premolars with mesio-occlusodistal (MOD) cavities after mineral trioxide aggregate (MTA) pulpotomy. Ninety-six extracted human maxillary premolars were divided into 8 groups (n = 12). Group 1 (negative control) consisted of intact teeth. In the other teeth, MOD and endodontic access cavities were prepared, and a layer of MTA was placed. Group 2 was left unrestored as the positive control. Group 3 was restored with a glass ionomer cement (GIC) base and amalgam. The remaining groups were restored with a microhybrid composite after application of different bases: 4, resin-modified GIC (RMGIC); 5, zirconia-reinforced GIC (ZRGIC); 6, self-adhesive flowable composite (SAFC); 7, self-adhesive resin cement (SARC); and 8, short fiber-reinforced composite (SFRC). After fracture strength testing via continuous compressive axial loading, the fracture mode was classified as restorable or unrestorable. Data were analyzed using 1-way analysis of variance and post hoc Tamhane tests (P < 0.05). The fracture strength of the negative control group was significantly higher than that of all other groups (P < 0.001). The fracture strengths of groups 2 and 3 were not significantly different (P > 0.05) from each other but were significantly lower (P = 0.002) than those of all composite-restored groups. Group 8 showed a significantly greater fracture strength than group 4 (P < 0.001). Unlike GIC/amalgam, all of the base/composite restoration groups partly restored the strength of pulpotomized premolars. Although their fracture strengths were statistically similar, the fracture modes were more favorable in groups with SAFC or SARC bases than in groups with RMGIC or ZRGIC bases. The SFRC/composite specimens revealed advantages in both fracture strength and fracture mode compared to RMGIC/composite specimens.

Influence of dentin presealing on the fracture strength of endodontically treated maxillary premolars.

This in vitro study aimed to evaluate the influence of endodontic irrigation solutions and resin sealing of the dentin surfaces of the cavity before irrigation on the fracture strength (FS) of maxillary premolars. Seventy-two human maxillary premolars were randomly assigned to 6 groups (n = 12). Group 1 consisted of intact teeth that served as negative controls. In groups 2 to 6, root canal treatment was performed after mesio-occlusal preparation. In group 6, the dentin surfaces of the mesio-occlusal cavity were sealed with a self-adhesive flowable composite resin before instrumentation and irrigation of the canal. The volume and contact time of the irrigation solutions used during endodontic treatment of groups 2, 4, 5, and 6 were standardized as follows: 2 mL of 5.25% sodium hypochlorite (NaOCl) for 1 minute after each file, 5 mL of 17% ethylenediaminetetraacetic acid (EDTA) for 3 minutes after instrumentation was completed, and 5 mL of 5.25% NaOCl for 1 minute as the final irrigation. In group 3, the irrigation solution was normal saline solution only. After root canal obturation, in group 2, the cavities were left unrestored as a positive control. In groups 3 (saline-rinsed), 4 (conventionally restored), and 6 (presealed), the restorations were carried out with an etch-and-rinse adhesive and composite resin immediately after root canal obturations. In group 5 (delay-restored), the restorations were carried out with an etch-and-rinse adhesive and composite resin after a 1-week delay. After thermomechanical cycling, the teeth were subjected to FS testing under continuous compressive force. Data were analyzed with 1-way analysis of variance and Tukey tests. The unrestored group, which demonstrated the lowest FS, did not differ significantly from the conventionally restored group; the FS of both groups was significantly lower than that in the other groups (P ≤ 0.001). The presealed group exhibited the highest FS (P ≤ 0.02). The FS values of the saline and delay-restored groups were statistically comparable. In the present study, NaOCl/EDTA irrigation had an adverse effect on the FS. Presealing of the dentin surfaces of the cavity with self-adhesive flowable composite resin significantly increased the FS of aged composite resin-restored premolars.

Evaluation of the Antibacterial and Antifungal Effects of ProRoot MTA and Nano-fast Cement: An In Vitro Study.

AIM: One of the most vital characteristics of an ideal root filling material is the capability to inhibit the growth of the microorganisms. Mineral trioxide aggregate (MTA) is one of the most used root repair materials, with approved antibacterial effect. A newly introduced root repair material is nano-fast cement (NFC) which should be investigated. The antibacterial and antifungal activities of NFC were evaluated in the present study. MATERIALS AND METHODS: Enterococcus faecalis (PTCC 1394), Escherichia coli (ATTC 15224), and Candida albicans (PTCC 5027) were employed for the antimicrobial assessment. The following were the steps used to conduct the agar diffusion test (ADT): six agar plates were used. 0.5 McFarland concentration of each strain was cultured on two plates by a sterile cotton-tipped swab. Three holes with 5mm diameter were created on each plate. Freshly mixed cement was placed in the holes of the related plate. After two hours, the plates were incubated at 37°C for 24 hours. Then, the diameter of the growth inhibition zones were measured, and the mean values were used for the analysis. Direct contact test (DCT) was done by using the following steps: Freshly mixed materials were placed in the 96-well microtiter plate. 10 µL of each bacterial suspension was added to the tested cement. After one-hour incubation at 37°C, 245 µL of BHI broth was added to each well, and the plate was vortexed for 2 minutes. About 15 µL of this bacterial suspension was added to a new well which contained 215 µL of fresh medium. The kinetics of the bacterial outgrowth were measured by the microplate spectrophotometer hourly for 12 hours. RESULTS: No significant differences were observed between the diameters of the growth inhibition zones of MTA and NFC groups in ADT. In DCT, the MTA inhibits E. coli more effectively than NFC (p value < 0.001). Both cements had the same inhibitory effect on E. faecalis and C. albicans. CONCLUSION: The MTA and NFC are almost equally effective against the tested microorganisms. CLINICAL SIGNIFICANCE: The antibacterial characteristic of any dental material is an important matter. As well, the antibacterial efficacy of the NFC should be evaluated.

The Effect of Silver, Zinc Oxide, and Titanium Dioxide Nanoparticles Used as Final Irrigation Solutions on the Fracture Resistance of Root-Filled Teeth.

AIM: This study was conducted to evaluate the effect of three nanoparticle solutions used as final root canal irrigants on the fracture resistance of endodontically treated roots. MATERIALS AND METHODS: Sixty intact single-rooted premolar teeth were used after removing the crowns below the cementum-enamel junction to standardize the length of the remaining roots to 13 mm. After instrumenting the roots using ProTaper Universal rotary instruments up to size F4, the roots were randomly divided into six groups (n=10) according to the final irrigating solutions: Group 1: normal saline; Group 2: 2% chlorhexidine (CHX); Group 3: 17% EDTA+2.5% NaOCl; Group 4: 17% EDTA+0.1% silver nanoparticle (SNP) solution; Group 5: 17% EDTA+0.1% titanium dioxide nanoparticle (TNP) solution; Group 6: 17% EDTA+0.1% zinc oxide nanoparticle (ZNP) solution. After filling the root canals with gutta-percha and AH Plus sealer, the fracture resistance (FR) values were measured. The data were subjected to the one-way analysis of variance and the Tamhane post hoc test (p=0.05). RESULTS: EDTA + NaOCl had the lowest FR value, followed by normal saline and CHX (p values < 0.05). No significant difference was found between the FR of roots irrigated with CHX and normal saline (p > 0.05). The application of nanoparticles (SNP, TNP, and ZNP) was associated with a significantly greater FR than that of other irrigation solutions (p values < 0.05). CONCLUSION: The final irrigation of root canals with nanoparticles enhanced the fracture resistance of the endodontically treated roots. The lowest FR value was observed for NaOCl.

Antimicrobial Efficacy of Intracanal Medicaments against E. Faecalis Bacteria in Infected Primary Molars by Using Real-Time PCR: A Randomized Clinical Trial.

AIM: This study aimed to compare the antimicrobial efficacy of calcium hydroxide (CH) and triple antibiotic paste (TAP) against E. faecalis bacteria in infected primary molars. METHODS AND MATERIALS: Thirty-nine 4-6-year-old children with an infected primary molar were randomly divided into three equal groups (n = 13) to receive either CH or TAP and an untreated control group. Following access cavity preparation, the first microbiological samples (S1) were collected by using absorbent paper points. The canals were prepared and rinsed. Then, CH or TAP was applied in the root canals. Seven days later, the second microbiological samples (S2) were collected. DNA extraction was performed to count E. faecalis bacteria by using real-time PCR for S1 and S2 samples. Data were analyzed through one-way ANOVA and Tukey's test (α = 0.05). RESULTS: E. faecalis bacteria counts decreased significantly in CH and TAP groups compared with the control group (P ≤ 0.001). However, no statistically significant difference existed between these two groups (P=0.698). CONCLUSION: Both TAP and CH have significant antimicrobial effects as intracanal medicament between the treatment sessions in infected primary teeth.

Prevalence of Self-Medication with Antibiotics amongst Clients Referred to Outpatient University Dental Clinics in Iranian Population: A Questionnaire-Based Study.

Self-medication with antibiotics may increase the risk of inappropriate use and development of antibiotic-resistant bacteria. The aim of this study was to determine the prevalence of self-medication with antibiotics amongst dental outpatients in Iranian population. Methods and Materials: One thousand and two hundred of dentistry patients, who were referred to dental school clinics in ten major provinces of Iran, participated in this study. A valid self-administered questionnaire regarding self-medication with antibiotics in case of dental pain was used to collect data. Data were analysed using descriptive statistics and Logistic regression analysis. Results: In our study population, the prevalence of self-medication was 42.6%. Amongst the Iranian cities, the highest prevalence of self-medication with antibiotics belonged to the city of Bandar Abbas (64%) and the lowest was seen in the city of Kerman (27.3%). Men were more likely to take antibiotics. Amoxicillin was the mostly used antibiotic. Severe pain, previous self-medications and high costs of dental visits were the most common reasons for self-medication with antibiotics in the investigated population. In addition, the present study showed that marriage, acceptable financial status and high level of education could decrease self-medication with antibiotics. Conclusions: In the current investigation, an alarming fact was that self-medication for dental problems seemed very common amongst the studied population. One of its most important consequences was bacterial resistance. Therefore, there should be plans to promote and prioritize public health awareness and encourage general public's motivation to reduce the practice of self-medication.

The Simultaneous Effect of Apical Resection Angle and Depth of Retrograde Cavity on Apical Microleakage via Fluid Filtration Method.

Introduction: The goal of apical surgery is to eliminate the root apex, apical lesions and promote tissue repair. In apical surgery, the root is resected at an angle of 45, 60 or 90 degree. In many cases, it is not possible to resect the root at 90-degree bevel and prepare a root-end cavity with 4-mm depth. The aim of this study was to evaluate the simultaneous effect of apical resection angle and depth of the retrograde filling with mineral trioxide aggregate (MTA) on apical microleakage. Methods and Materials: Root ends were resected at 45 degree, 60 degree and 90 degree bevels in 110 extracted human single root permanent teeth. For each apical surgery, root-end cavities were filled with MTA to depths of 2 mm, 3 mm and 4 mm. Root end-filled teeth were mounted in fluid filtration device. The evaluation was conducted after 24-h, 1 week, 1 month, 2 months and 3 months. Each group included 10 samples. Also 20 roots were used as positive and negative control samples, in the negatives the entire root surface was coated with 2 layers of nail varnish and positives were unfilled root-end preparation. Statistical analysis consisted of the Kruskal-Wallis test and Pairwise comparison. Results: There were no significant differences in apical microleakage after 24 h and 1 week in the experimental groups. In the 3rd month, samples with 90° bevel and 4-mm-thick MTA showed significant statistical differences with all samples with 45° and 60° bevels and depths of 2- and 3-mm-thick MTA (P<0.05). Conclusions: This in vitro study showed that when the resection angle is 90°, retrograde depth does not affect microleakage, but resection angles other than 90°, require 4 mm-retrograde depth to be sealed.

Effect of a New Imidazolium-based Silver Nanoparticle Irrigant on the Bond Strength of Epoxy Resin Sealer to Root Canal Dentine.

Introduction: The aim of this study was to evaluate the effect of a new imidazolium-based silver nanoparticle (ImSNP) root canal irrigant on the bond strength of AH-Plus sealer to root canal dentine. Methods and Materials: Forty single-rooted extracted human teeth were used in this study. The crowns were resected and according to the irrigation solutions used during root canal preparation, the roots were divided into 5 groups (n=8): Group 1: normal saline (control group), Group 2: 2.5% Sodium Hypochlorite (NaOCl), Group 3: 2.5% NaOCl+17% ethylene diamin tetracetic acid (EDTA), Group 4: silver nanoparticles (AgNPs), Group 5: AgNPs +17% EDTA. After root canal instrumentation, the canals were filled with AH-Plus. Then, after 7 days, 2 or 3 dentine disks were obtained from the mid-root of each sample. Bond strength was measured by the push-out test. Additionally, failure patterns were classified as adhesive, cohesive and mixed. Data were statistically analyzed by one-way ANOVA and Tamhane post hoc tests. The level of significance was set at 0.05. Results: There was no statistically significant differences between groups (P>0.05). Groups 4 (AgNPs), 3 (2.5% NaOCl+17% EDTA) and 2 (2.5% NaOCl) showed statistically higher bond strength compared to group 1 (control group) (P<0.05). Also, Group 4 showed a significant difference with group 5 (AgNPs+17% EDTA) (P=0.017). The failure patterns were mainly cohesive. Conclusion: This in vitro study showed that, when used without EDTA, AgNPs improved the bond strength of AH-Plus to radicular dentine.

In Vitro Evaluation of Dynamic Viscosity, Surface Tension and Dentin Wettability of Silver Nanoparticles as an Irrigation Solution.

Introduction: The aim of this study was to evaluate dynamic viscosity, surface tension and dentin wettability of a newly introduced imidazolium-based silver nanoparticle solution (Im AgNP) in comparison with three common root canal irrigants. Methods and Materials: The irrigants were Im AgNPs at 5.7×10-8 mol/L-1, 5.25% Sodium hypochlorite (NaOCl), 2% Chlorhexidine (CHX) and 17% Ethylenediaminetetraacetic acid (EDTA) and distilled water (control group). Dynamic viscosity was measured using rotational digital viscometer at 25, 37, 45 and 60°C. Surface tension was evaluated using dynamic contact angle analyzer at room temperature (25°C). Wettability was assessed by contact angle measurement for five groups of 10 dentin samples after each group was treated in each irrigant for 10 min. One-way ANOVA, and post hoc Tukey's test were used for statistical analysis. Significance was set at P<0.05. Results: Dynamic viscosity of all irrigants decreased as the temperature increased. 17% EDTA was the most viscous solution in all examined temperatures (P<0.05). Viscosity of Im AgNP solution at 25, 37 and 45°C was significantly lower than that of 17% EDTA and 5.25% NaOCl (P<0.05). Im AgNPs exhibited a higher surface tension than other irrigants except distilled water. The wettability of dentin increased when it was in contact with 2% CHX and 5.25% NaOCl while Im AgNPs decreased the wettability of dentin surfaces (P<0.05). Conclusion: Im AgNP irrigant has the potential to reach apical portions of root canals due to its lower viscosity compared to the other tested irrigants. However, it may not bring better penetration inside dentinal tubules because of its higher surface tension. Furthermore, Im AgNPs can influence physiochemical properties of dentin by decreasing its surface wettability.