A Cone-Beam Computed Tomography-Based Evaluation of Root Dilaceration in Permanent Premolars: A Retrospective Study.

Statement of the Problem: As a developmental disorder characterized by an abnormal bend and angle in the longitudinal axis of the tooth root, dilaceration can cause complications in routine dental procedures such as endodontics, orthodontics, and surgical treatments. Purpose: The purpose of this study was to investigate the prevalence of dilaceration in maxillary and mandibular premolar teeth in a population of Shiraz city based on cone-beam computed tomography (CBCT). Materials and Method: This is a retrospective cross-sectional study on 927 premolar teeth and 132 CBCT radiographs of patients obtained from four private radiology clinics in Shiraz (Iran). In this study, the presence, location, direction, and severity of dilaceration in premolar roots as well as its relationship with gender were investigated. Chi-square and Fisher tests were used to analyze the data. Results: The results showed that 17% of the studied 927 teeth had dilaceration. The prevalence of dilaceration was significantly higher in women than in men (20.3% vs. 13.6%, p= 0.005). The dilaceration rates were significantly higher in the mandibular first and second premolar teeth (31.6% and 26%, p= 0.002) than in the other teeth. In addition, the highest prevalence was in the distal direction with mild severity in the apical third of the root (p< 0.001). Conclusion: According to the results of this study, the prevalence of dilaceration was relatively high in mandibular premolar teeth especially in women.

Combination of metformin and double antibiotic paste for the regeneration of non-vital immature teeth: a preliminary randomized clinical study.

BACKGROUND: The present study aimed to investigate whether incorporating metformin in double antibiotic paste (DAP) can promote the regeneration process of non-vital immature teeth. METHODS: Out of 32 pediatric patients undergoing regenerative endodontic procedures (REPs), 6 cases with a follow-up period of less than 12 months or lack of documentation were excluded then the remaining 26 were analyzed. 15 cases received DAP, and 11 cases received a DAP + metformin as the intra-canal medicament, kept for an average of 23 days. During 18 months of follow-up, clinical and radiographic examinations were performed to evaluate the treatment outcomes based on the resolution of apical periodontitis, root development, and the occurrence of intracanal calcification. The chi-square test was used for the statistical analysis (P < 0.05). RESULTS: All patients demonstrated resolution of apical periodontitis; however, complete apical closure was only seen in 50% of the patients. The rate of apical closure and root length was significantly higher in the DAP + metformin group (P = 0.047), although the two groups were not significantly different in terms of root width (P = 0.184). Canal obliteration was seen in 15% of cases, all of which were in the DAP group. CONCLUSIONS: According to the present findings, metformin could promote root development in the regeneration process when incorporated in DAP. TRIAL REGISTRATION: This clinical trial was registered on the Iranian Registry of Clinical Trials (IRCT20200120046197N1) on 26.2.2021.

Evaluation of Root Dilaceration in Permanent Anterior and Canine Teeth in the Southern Subpopulation of Iran Using Cone-Beam Computed Tomography.

Statement of the Problem: Developmental anomalies such as dilacerations can affect the eruption pattern of permanent anterior teeth. They are characterized by a curvature in the crown and roots of the teeth relative to their normal axis. This anomaly can cause some complexities in routine dental treatments such as root canal treatment, orthodontics, and surgery. Purpose: The purpose of this study was to assess the prevalence of dilaceration in maxillary and mandibular anterior and canine teeth in Shiraz, Iran using cone-beam computed tomography (CBCT). Materials and Method: In this retrospective study, a total of 1537 encompassed 400 CBCT images collected from 4 private radiology clinics in Shiraz were assessed. Each tooth was radiographically examined in order to diagnose root dilacerations considering their location (apical, middle, coronal), position in the jaw (maxillary or mandibular), direction (mesial, distal buccal and palatal/lingual), and severity of dilaceration (mild, moderate, and severe). The obtained data were analyzed by Chi-square statistical test and Fisher's exact test. Results: In this study, out of 1537 studied teeth, 5.98% had dilaceration. The maxillary and mandibular canine teeth (9.8% and 9.7%, respectively) were significantly the most common teeth involved in this anomaly (p< 0.001). The distal direction with mild severity in the apical third of the root was also the most common result obtained from this study (p<0.001). In addition, there was no statistically significant relationship between gender and type of jaw regarding the prevalence of dilaceration in the studied dental groups (p=0.670 and p=0.231, respectively). Conclusion: In the current research, it was demonstrated through CBCT records that the prevalence of dilaceration in maxillary and mandibular anterior and canine teeth is relatively uncommon. The most prevalent dilaceration was found to be distal direction with mild severity in the apical third of the root.

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

BACKGROUND: Given 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. METHODS: In 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). RESULTS: Im-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. CONCLUSIONS: The irrigants containing Im-AgNPs and ZnONPs significantly enhanced the root dentin microhardness. However, the use of AgNPs resulted in decreased microhardness.

The effect of aging on the fracture resistance of different types of screw-cement-retained implant-supported zirconia-based restorations.

Structural durability of screw-cement-retained implant-supported zirconia-based restorations is an important factor in choosing the best type of restoration for clinical use. This study aimed to evaluate the effects of thermocycling on the fracture resistance of different types of screw-cement-retained implant-supported zirconia-based restoration. Two experimental groups (monolithic zirconia and porcelain-veneered zirconia) and a control group of porcelain-fused-to-metal restorations were fabricated via CAD-CAM (n = 14 per group). Half of the specimens of each group (n = 7) were subjected to 10000 thermal cycles. The compressive force was applied and the force leading to fracture was measured by using a Universal Testing Machine. The fractured modes were classified under a scanning electron microscope. The data were analyzed through two-way ANOVA, one-way ANOVA, and independent samples t-test (α = 0.05). Among the non-thermocycled subgroups, the monolithic zirconia specimens were significantly more fracture-resistant than the porcelain-veneered zirconia and porcelain-fused-to-metal groups (P<0.05); but it was not the same with aging (P>0.05). Thermocycling decreased the fracture resistance of all groups; however, the difference was not statistically significant (P<0.05). The monolithic zirconia presented higher fracture resistance than the bilayered restorations for screw-cement retained implant-supported restorations. Thermocycling decreased the fracture resistance of all types of restorations insignificantly which can be clinically important.

Evaluation of Root Dilaceration by Cone Beam Computed Tomography in Iranian South Subpopulation: Permanent Molars.

Statement of the Problem: Root dilaceration is a developmental anomaly, which was first described in the 19th century as an abrupt change in the axial inclination between the crown and root of a tooth. Such an anomaly would potentially alter the dental therapeutic procedures and often demands special care. Hence, it is of great importance to diagnose dilaceration before starting any treatment procedure on the tooth. Purpose: The aim of the current study was to evaluate the prevalence of dilaceration in the first and second maxillary and mandibular molar teeth in Shiraz, Iran, using cone-beam computed tomography (CBCT) radiography. Materials and Method: In this retrospective study, 472 teeth from 141 CBCT images were studied. Each tooth was assessed by CBCT to diagnose dilaceration, its severity, direction, and anomaly location. Results: In this study, among 472 studied teeth, 136 teeth (28.8%) were diagnosed with root dilaceration. The most frequently affected tooth was the maxillary second molar tooth (45%). The results showed a statistically significant relationship between the gender of the patients and the prevalence of dilaceration. Most dilacerations were observed in distal direction, with a mild intensity, and located in the apical third of the roots. Conclusion: In this study, CBCT was presented as an advanced method for diagnosing dilaceration in maxillary second molar teeth and especially in the mesial root, which can be influenced by gender and it can play an important role in designing the treatment plans.

Effect of Calcium Hydroxide and Nano Calcium Hydroxide on Push-out Bond Strength of Epoxy Resin Sealer to Root Canal Dentin.

Introduction: The goal of this paper was to determine the impact of calcium hydroxide (CH) and nano-calcium hydroxide (NCH) on the push-out bond strength of an epoxy resin-based sealer. Materials and Methods: A total of 48 mandibular premolars were decoronated in vitro and instrumented by a ProTaper rotary system up to F4. The specimens then were randomly allocated into 3 groups (n=16). The two intervention groups were treated with either CH or NCH and one control group which did not receive any intracanal medicament. After one week of medicament placement, the specimens were irrigated by 10 mL 17% EDTA, followed by 10 mL 2.5% NaOCl and an ultimate flushing by 5 mL sterile saline. The samples were obturated using AH-Plus Jet sealer and gutta-percha by lateral condensation technique. Push-out test was done by a universal test machine to evaluate the bond strength among the sealer and the root canal dentin. Repeated measurement analysis followed by Tukey's HSD and Bonferroni post-hoc tests were used for data analysis. Results: The control group showed a higher push-out bond strength in comparison to the specimens in the CH and NCH groups (P<0.05). In spite of the greater push-out bond strength of the samples treated with NCH in comparison to those in CH group, no statistically notable difference was found among them (P>0.05). Additionally, irrespective of the kind of medicament, the bonding at the apical level of the root canal was stronger compared to the coronal third (P<0.001). Conclusion: According to the present in vitro study, application of CH and NCH resulted in a significant reduction of the bond strength between the epoxy resin-based sealer and dentinal walls. Although, application of these medicaments resulted in reduction of bonding of epoxy resin-based sealers root canal dentin significantly.

A Comparison of the Apical Extrusion of Debris during the Preparation of Root Canal with Medin, RaCe, and ProTaper Rotary Systems.

STATEMENT OF THE PROBLEM: The extrusion of intracanal debris is one of the challenging problems related to almost all root canal preparation systems, which may cause flare-ups and impairment in the healing process. PURPOSE: This study was conducted to evaluate the amount of apically-extruded debris during root canal preparation using Medin (MEDIN Co., Czech Republic) rotary system compared with two common rotary systems, including ProTaper (Dentsply Maillefer., Switzerland) and RaCe (FKG Dentaire, Switzerland). MATERIALS AND METHOD: In this in vitro study, Sixty mandibular premolars with single canal were randomly assigned to three groups (n=20). The root canals were prepared with Medin, ProTaper, and RaCe rotary instruments based on their manufacturers' instructions. The debris were collected into pre-weighted Eppendorf tubes. The weight of the extruded debris was calculated by subtracting the pretreatment weight of the vials. Data were analyzed using the Kruskal-Wallis test at a 5% significance level. RESULTS: Medin instrument caused significantly less debris extrusion in comparison with ProTaper and RaCe (p< 0.05). The differences between the ProTaper and RaCe rotary systems were not statistically significant (p= 0.752). CONCLUSION: Within the limitations of this in vitro study, Medin rotary system produced less apical extrusion than ProTaper and RaCe.

Comparative in vitro Assessment of Tooth Color Change under the Influence of Nano Fast Cement and MTA.

STATEMENT OF THE PROBLEM: Tooth color changes followed by treatment with bioceramic materials are always a matter of concern. PURPOSE: The aim of the present in vitro study was to compare tooth discoloration that occurs in human teeth filled with ProRoot WMTA (DENTSPLY Tulsa Dental Specialties, Tulsa, OK) and those filled with Nano Fast Cement (NFC) over the course of 3 months. MATERIALS AND METHOD: In this experimental study, Thirty human intact premolars were obtained. The roots of all teeth were removed by a horizontal cut about 2 mm below the cementoenamel junction. The pulp tissues were removed using a barbed broach (Mani, Tokyo, Japan).The teeth were randomly divided to 3 groups (n= 10) including the control (no material), ProRoot WMTA and NFC. The experimental materials were condensed into the crowns and the teeth ends were sealed with light-cure glass ionomer cement (GC Corporation, Tokyo, Japan). The color was assessed at TBL (baseline; after preparation of the cavities but before placement of the materials), TPO (immediately after placement of the filling material and provisional restoration), T4 (after 4weeks of storage), and T12 (after 12weeks) of storage. RESULTS: The discoloration was evident in all teeth, immediately (TPO) after applying MTA and NFC. The highest ΔΕ was noted in WMTA at 12 weeks, followed by NFC; however, there was no significant difference between the discolorations induced by these two materials. CONCLUSION: Similar levels of clinically observable tooth discoloration were detected by using either WMTA or NFC.

Assessment of sodium thiosulfate neutralizing effect on micro-hardness of dentin treated with sodium hypochlorite.

BACKGROUND: This study aims to evaluate the ability of sodium thiosulfate (STS) to neutralize the adverse effect of sodium hypochlorite (NaOCl) on dentin micro-hardness. METHODS: Fifty single-rooted teeth were longitudinally sectioned. The samples divided into a control and four sample groups (n = 20). All the samples were immersed in different solutions as follows, Control: Normal saline for 15 min, G1and G2: 2.5% NaOCl for 15 min, G3: 2.5% NaOCl for 15 min, followed by 5% STS for 10 min, G4: Normal saline for 15 min followed by 5% STS for 10 min. All groups except G1 incubated for one week before the test. The micro-hardness of samples was measured. Data were analyzed using the Kruskal-Wallis test for pairwise comparisons. A p value < 0.05 was considered significant. RESULTS: All groups showed a significant decrease in the micro-hardness value compared with the control group. NaOCl for one week (G2) reduced the micro-hardness of dentine compared with samples, tested immediately after immersion in NaOCl (G1) (p < 0.05). NaOCl alone (G2) or treated with STS (G3) resulted in a significant decrease in micro-hardness compared with the STS group (G4) (p < 0.05). CONCLUSIONS: STS as a neutralizing agent could not prevent the dentin micro-hardness downturn caused by NaOCl.

Morphological Evaluation of Maxillary Premolar Canals in Iranian Population: A Cone-Beam Computed Tomography Study.

STATEMENT OF THE PROBLEM: A thorough knowledge of the morphological and anatomical variations of root canal system can help identify all root canals, adequate instrumentation, and consequently leads to a successful endodontic treatment. The knowledge of root morphology can influence the outcome of root canal therapy. PURPOSE: The aim of this study was to investigate the morphology of maxillary premolar canals in Iranian population by analyzing cone-beam computed tomography (CBCT) scans. MATERIALS AND METHOD: This cross-sectional retrospective study consisted of CBCT of 280 patients over 16 years of age. The position, number of roots, and root morphology of maxillary premolars were inspected. The root canal configurations of maxillary premolar teeth were also analyzed according to the Vertucci classification. The statistical analyses wee performed using chi-square test. Significance level was set at p < 0.05. RESULTS: In the present study, of 462 maxillary first premolars, 8 (1.73%) teeth had three roots, 222 (48.05%) teeth had two roots, and 232 (50.22%) were single-rooted. In the second maxillary premolar group, of 400 premolars, 2 (0.5%) teeth had three roots, 34 (8.5%) teeth were two-rooted, and 364 (91%) were single-rooted. The most root canal configurations were type IV (71.64%) and type I (63%) in maxillary first and second premolars, respectively. Among females, single rooted premolars were the most prevalent (56.83%), and among males, two-rooted premolars were the most prevalent (57.61%). CONCLUSION: This study provided information about the root canals of maxillary premolar teeth for Iranian subpopulation leading to more optimal diagnosis and treatment planning for the endodontists. According to the findings, the complexity of root canal system and the number of roots were less common in females compared to males.

Histological Evaluation of Periapical Tissues after Root Canal Treatment with or without Coronal Seal in Dogs for Six Months.

Introduction: Preventing recontamination of the obturated root canal is important for successful root canal treatment (RCT). The main purpose of this study was assessing the histological health of periradicular tissue in obturated root canals with or without coronal seal between two and six months. Methods and Materials: Sixty roots from five dogs with vital pulps were randomly assigned to one of the following five groups (n=12): Group 1, RCT and six months oral exposure; Group 2, RCT and immediate amalgam restoration; Group 3, RCT and amalgam restoration after two months exposure to the oral cavity; Group 4, RCT and amalgam restoration after four months exposure to the oral cavity; Group 5, RCT with two months exposure to oral cavity. The teeth were prepared and filled with gutta-percha and sealer using lateral condensation technique. Two intact root canals of each animal were regarded as the negative control group (n=10), and the two root canals exposed to the oral cavity constituted the positive one (n=10). After six months the animals were euthanized. The upper and lower jaws were removed and submitted for histological processing. Longitudinal sections were obtained from each root. After staining the sections, periradicular regions were examined histologically under light microscope. The Kruskal-Wallis and Mann-Whitney tests was used to analyze the data (P<0.05). Results: The results showed a significant difference between all groups (P<0.05). The negative control group was free of any inflammation. Two-by-two comparison revealed that the positive control group, Group 1 and Group 4 displayed the most intense inflammation. Groups 2, 3 and 5 showed similar results without developing any significant inflammation. Conclusion: Based upon the findings of this animal study, it can be recommended that the obturated root canals which are exposed to oral cavity for around four months or more should be retreated before crown restoration.

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.

Tooth Discoloration Induced by Imidazolium Based Silver Nanoparticles as an Intracanal Irrigant.

STATEMENT OF THE PROBLEM: The endodontically treated teeth usually suffer from the discoloration induced by endodontic materials, which can adversely affect the esthetical outcome of a treatment. PURPOSE: This study aimed to compare the discoloration caused by the silver nanoparticles coated with imidazolium as an irrigant, sodium hypochlorite (NaOCl), and chlorhexidine gluconate (CHX). MATERIALS AND METHOD: The root tips of 65 single-rooted human teeth were resected and root canal systems were chemomechanically prepared from the apical aspect. The specimens were randomly divided into three experimental (n=15) and two control groups (n=10). In the experimental groups, the substance was placed in the root canal for 30 minutes, and then washed with normal saline. Saline or blood alone was used in the control groups. The discoloration was assessed spectrophotometrically right after substance placement (T1), 1 week (T2), and 1 (T3) and 3 months (T4) after and color change values were calculated. Statistical analysis was performed using multi-sample repeated measures analysis of variance, Tukey's HSD, and Sidak tests. RESULTS: In T1, there was no significant difference in color change between silver nano particle, blood and CHX (p> 0.05); but these three groups had significantly more ∆E value than NaOCl and Normal Saline (p< 0.05). NaOCl and normal saline had no significant difference in T1 (p> 0.05). In T2, T3 and T4 results were the same and showed blood and silver nano particle had significantly higher color change in comparison with NaOCl, CHX and normal saline (p< 0.05). There was no significant difference between NaOCl, CHX, and normal saline in tooth discoloration (p> 0.05). There was no significant difference between silver nano particle and blood in ability of tooth discoloration (p> 0.05). CONCLUSION: Within the limitation of this study, silver nano particle material could not be suggested as an intra-canal irrigant regarding its unfavourable tooth discoloration.

The effects of Various Endodontic Irrigants on the Push-out Bond Strength of Calcium-Enriched Mixture Cement and Mineral Trioxide Aggregate.

INTRODUCTION: The aim of this in vitro study was to evaluate the effect of various irrigants on the push-out bond strength of calcium-enriched mixture (CEM) cement and mineral trioxide aggregate (MTA). METHODS AND MATERIALS: A total of 140 dentin disks with a thickness of 1.5±0.2 mm and lumen size of 1.3 mm, were randomly divided into 12 groups (n=10) and 4 control groups (n=5). The lumen of disks in groups 1, 2, 3, 7, 8, 9 were filled with CEM and groups 4, 5, 6, 10, 11, 12 were filled with MTA. Control groups were filled with CEM and MTA. Specimens were incubated at 37°C for one day in groups 1 to 6 and seven days in groups 7 to 12. After incubation the samples were divided into three subgroups (n=10) that were either immersed for 30 min in 5.5% sodium hypochlorite (NaOCl), 2% chlorhexidine (CHX) or saline solution. The push-out bond strength values were measured by using a universal testing machine. The nature of the failures were determined by light microscope. Data was analyzed using the three-way ANOVA to evaluate the effect of material type, different irrigants and time intervals. Post hoc Tukey's test was used for two-by-two comparison of the groups. RESULTS: CEM cement significantly showed a higher push-out bond strength in comparison with MTA (P=0.001). The elapse of time significantly increased the bond strength (P=0.001). There was no significant difference between the irrigants used in this study (P=0.441). Bond failure was predominantly of mixed type in MTA and of cohesive type in CEM samples. CONCLUSION: Based on this study, endodontic irrigants did not influence the push-out bond strength of MTA and CEM cement.

Time-dependent antibacterial effects of Aloe vera and Zataria multiflora plant essential oils compared to calcium hydroxide in teeth infected with Enterococcus faecalis.

AIM: In the present in vitro study, we investigated the time-related antimicrobial efficacy of Aloe vera and Zataria multiflora (Z. multiflora) plant essential oils compared to calcium hydroxide ([Ca[OH]2 ) to eliminate Enterococcus faecalis (E. faecalis) from root canals. METHODS: A new strain of E. faecalis (Enterococcus spp. AGH04) was isolated from a previously root-filled tooth with persistent apical periodontitis. The 16S rRNA sequence was analyzed and deposited in GeneBank under accession number KF465681. A total of 108 extracted human single-rooted teeth were contaminated with this bacterial strain and treated with Aloe vera essential oil, Z. multiflora essential oil, and Ca(OH)2 for 1, 7, and 14 days. Gas chromatography-mass spectrometry (GC-MS) was used to determine the chemical composition of the oils. The percentage reduction from initial c.f.u./mL counts were calculated and analyzed. RESULTS: Carvacrol, thymol, and linalool were the main constituents of both essential oils. The c.f.u./mL count reductions significantly increased for all three medicaments when the contact time was extended. A statistically-significant difference was observed between the medicaments after 1 and 7 days, but there was no significant difference after 14 days. CONCLUSIONS: Both medicinal herbs showed equal antimicrobial efficiency against E. faecalis, comparable to Ca(OH)2 for the prolonged contact time of 14 days.

Comparison of the Hemostatic Activity of Quercus persica Jaub. & Spach. (Oak) With Ferric Sulfate in Bony Crypts.

Effective tissue hemostasis in periapical surgical site is important in the procedures. Plants with large amount of tannins may act as a local hemostatic agent. We aimed to compare the hemostatic effect of the extract of Quercus persica with one of the common hemostatic material used in periapical surgery. Six standardized bone holes were prepared in the calvaria of 5 Burgundy rabbits. Two hemostatic medicaments were tested for their hemostatic effect and were compared with control defects: Group 1, cotton pellet soaked in 15.5% ferric sulfate solution; Group 2, cotton pellet soaked in pure ethanolic extract of Q. persica. Bleeding score between the groups was compared. The ferric sulfate group exhibited significantly less bleeding than the other 2 groups. Q. persica was found to cause more hemostasis than the control group at 4 and 5 minutes but there were no significant differences between normal saline and Q. persica extract in bleeding control.

Solubility of Two Root-End Filling Materials over Different Time Periods in Synthetic Tissue Fluid: a Comparative Study.

STATEMENT OF THE PROBLEM: Insolubility is an important criterion for an ideal root-end filling material to both prevent any microleakage between the root canal and the periradicular space and provide sealing ability. PURPOSE: Many recent studies have shown that mineral trioxide aggregate (MTA) and calcium-enriched mixture (CEM) have acceptable sealing ability. The purpose of this in vitro study was to evaluate the solubility of these root-end filling materials. MATERIALS AND METHOD: Forty stainless steel ring moulds with an internal diameter of 10±1 mm and a height of 2±0.1 mm were selected. Samples of MTA and CEM were mixed according to the manufacturer's instructions and inserted into the moulds. The specimens were divided into 4 experimental groups and kept in synthetic tissue fluid (STF) for 2 different time periods (7 and 28 days). The control group contained 8 empty rings. The moulds' weights were recorded before and after immersion in STF. The changes in the weight of the samples were measured and compared using a two- way ANOVA test at a significance level of 5%. Specimens were evaluated with scanning electron microscopy (SEM) at a magnification of 500×. RESULTS: There was no significant difference in weight changes between MTA and CEM samples (p> 0.05). CONCLUSION: MTA and CEM have similar solubility in STF in different time periods.

Effect of different mixing and placement methods on the compressive strength of calcium-enriched mixture.

INTRODUCTION: The aim of this experimental laboratory study was to evaluate the effect of different mixing and placement techniques on compressive strength (CS) of calcium-enriched mixture (CEM) cement. METHODS AND MATERIALS: CEM powder was mixed with its liquid either by hand mixing or amalgamator mixing. The mixture was loaded to cylindrical acrylic molds with 6.0±0.1 mm height and 4.0±1 mm diameter. Half of the specimens in each group were selected randomly and ultrasonic energy was applied to them for 30 sec. All samples were incubated for 7 days at 37(°)C. The CS test was performed by means of a universal testing machine. The data were analyzed by the two-way analysis of variance (ANOVA) and Tukey's post hoc tests. The level of significance was set at 0.05. RESULTS: The maximum CS was seen in the amalgamator-mixed samples that did not receive ultrasonic agitation. The CS value of amalgamator-mixed samples was significantly higher than manually-mixed ones (P=0.003). Ultrasonic vibration did not change the CS of specimens. CONCLUSION: According to the results, mixing with amalgamator increases the CS of CEM cement, while ultrasonic vibration had no positive effect.

Effect of Different pH Values on the Compressive Strength of Calcium-Enriched Mixture Cement.

INTRODUCTION: The aim of this study was to evaluate the compressive strength of calcium-enriched mixture (CEM) cement in contact with acidic, neutral and alkaline pH values. METHODS AND MATERIALS: The cement was mixed according to the manufacturer's instructions, it was then condensed into fourteen split molds with five 4×6 mm holes. The specimens were randomly divided into 7 groups (n=10) and were then exposed to environments with pH values of 4.4, 5.4, 6.4, 7.4, 8.4, 9.4 and 10.4 in an incubator at 37(°) C for 4 days. After removing the samples from the molds, cement pellets were compressed in a universal testing machine. The exact forces required for breaking of the samples were recorded. The data were analyzed with the Kruskal-Wallis and Dunn tests for individual and pairwise comparisons, respectively. The level of significance was set at 0.05. RESULTS: The greatest (48.59±10.36) and the lowest (9.67±3.16) mean compressive strength values were observed after exposure to pH value of 9.4 and 7.4, respectively. Alkaline environment significantly increased the compressive strength of CEM cement compared to the control group. There was no significant difference between the pH values of 9.4 and 10.4 but significant differences were found between pH values of 9.4, 8.4 and 7.4. The acidic environment showed better results than the neutral environment, although the difference was not significant for the pH value of 6.4. Alkaline pH also showed significantly better results than acidic and neutral pH. CONCLUSION: The compressive strength of CEM cement improved in the presence of acidic and alkaline environments but alkaline environment showed the best results.