Molecular Identification of Candida albicans in Endodontic Retreatment Cases by SYBR Green I Real-time Polymerase Chain Reaction and its Association with Endodontic Symptoms.

Statement of the Problem: Recent microbiological studies have expressed ever-increasing concerns about Candida albicans as a causal factor in the failure of endodontic treatments. Real-time quantitative polymerase chain reaction (qPCR), including the SYBR Green I system, is a technique in which a fluorescent dye is incorporated into the double-stranded DNA that is produced during DNA polymerase activity. Purpose: This study aimed to determine the relative prevalence of Candida albicans in root canals of retreatment cases and its association with endodontic symptoms. Materials and Method: In the present cross-sectional/analytical study fifty subjects were selected. Clinical features and radiographic status of the teeth were also evaluated. After access cavity preparation, the retrieved material and dentinal chips removed from the root canal were transferred into 1.5-mL microtubes, followed by storage at -20ºC until used for DNA extraction. A DNeasy Tissue Kit was used to extract DNA using the DNeasy protocol for animal tissues. Master Plus SYBR Green I (Jena Bioscience, Germany) was used in a Rotor-gene Real-time PCR System for real-time PCR. The relationship between the presence of Candida albicans and the clinical and radiographic features were analyzed using McNemar's test. Results: There was a significant relationship between the radiographic findings in endodontically treated teeth and the presence of Candida albicans. However, there was no significant relationship between the presence of Candida albicans and any of the clinical symptoms. Conclusion: In spite of the limitations of this study, we concluded that Candida albicans was associated with root canal infections in endodontic retreatment cases, but there was no relationship between root canal infections and the clinical symptoms.

Concentrated Growth Factors Combined with Lipopolysaccharide Stimulate the In Vitro Regenerative and Osteogenic Activities of Human Dental Pulp Stem Cells by Balancing Inflammation.

Aim: We investigated the long-term effects of exposure to concentrated growth factors (CGFs) on the regenerative properties of dental pulp stem cells (DPSCs) in the presence and absence of lipopolysaccharide (LPS) as a proinflammatory agent. Methods: DPSCs were cultured with CGF at different concentrations of LPS (0.1, 1, and 10 µg/ml) for 21 days. Then, using MTT and scratch assays, the cell viability and migration were examined. Osteogenic stimulation was evaluated by alkaline phosphatase (ALP) staining and Sirius Red staining, which determined the ALP activity and collagen levels, respectively. The expression levels of osteogenic markers were quantified using the qRT-PCR method. One-way analysis of variance (ANOVA) and Tukey's HSD test were used to analyze differences between groups. Results: Long-term treatment of DPSCs with CGFs reduced LPS-induced cell death. Moreover, CGF and LPS (1 µg/ml), either in combination or alone, improved the DPSC migratory ability and caused a significant increase in osteogenic stimulation through the upregulation of collagen levels and ALP activity. Additionally, CGFs significantly upregulated RUNX2, DSPP, OCN, and OPN mRNA levels (as osteogenic markers), while LPS (1 µg/ml) only significantly increased OCN overexpression. Conclusion: Our findings are evidence that CGF could be a promising agent to induce dentin-pulp complex healing in long-term chronic inflammation.

The Effect of Submucosal Injection of Corticosteroids on Pain Perception and Quality of Life after Root Canal Treatment of Teeth with Irreversible Pulpitis: A Randomized Clinical Trial.

INTRODUCTION: The aim of the present investigation was to study the effect of local infiltration of corticosteroids on postoperative pain and quality of life (QOL) in teeth with irreversible pulpitis after 1-visit endodontic treatment. METHODS: In this double-blind randomized clinical trial, 242 healthy patients with irreversible pulpitis undergoing 1-visit endodontic treatment were included. Forty-five patients were lost during the follow-up, and the remaining 197 patients were followed for 7 days (67 patients in the placebo group, 66 in the long-acting betamethasone group, and 64 in the dexamethasone group). The patients marked their level of pain and QOL before treatment and at 6-, 12-, 24-, 48-, and 72-hour and 7-day postoperative intervals using a questionnaire. Freidman and Kruskal-Wallis tests were used for statistical analysis. P ≤ .05 was considered significant. RESULTS: The pain was more severe in the placebo group compared with the other groups at all time intervals. A significant increase was observed in pain severity after 12 hours in all 3 groups. In general, the pain was less severe in the dexamethasone group compared with the betamethasone group at 6-, 12-, and 24-hour intervals. The pain severity was similar in both groups at 48 hours, and it was less severe in the long-acting betamethasone group compared with the dexamethasone group after 72 hours and 7 days. There were no significant differences in the betamethasone and dexamethasone groups in pain intensity between males and females. Moreover, overall pain perception was higher in the mandible than in the maxilla. There was an inverse and significant relationship between pain severity and QOL. CONCLUSIONS: Infiltration of long-acting betamethasone and dexamethasone resulted in decreased postoperative pain experience. Dexamethasone was more effective in alleviating pain within the first 24-hour period after treatment. Infiltration of long-acting betamethasone and dexamethasone exhibited the same efficacy in 48 hours. The efficacy of long-acting betamethasone in pain relief lasted for 7 days. The QOL in the 2 groups receiving corticosteroids was higher than that in the placebo group.

The Effects of Different Agitation Techniques of Canal Irrigant on Tubular Penetration of a Bioceramic Sealer.

Introduction: This study aimed to compare the effects of different agitation techniques of sodium hypochlorite (NaOCL) as the final irrigation with XP-Finisher file, passive ultrasonic irrigation (PUI), Er:YAG laser and irrigation with conventional syringes, on penetration of Sure Seal Root bioceramic sealer into dentinal tubules. Methods and Materials: Forty freshly extracted single-rooted human teeth were included in the present in vitro study. All the teeth were prepared up to #40 (4%) with Bio Race rotary file system, using crown-down technique. After chemomechanical preparation, the teeth were randomly assigned to 4 groups based on the agitation protocol: conventional needle irrigation (CNI) with a 30-G needle in a syringe, PUI, Er:YAG laser and XP-Finisher file, Subsequent to the agitation procedure, the root canals were obturated with tapered bioceramic-covered gutta-percha point and, bioceramic sealer, using the single-cone technique. The maximum penetration of the sealer into the dentinal tubules was determined in the coronal, middle and apical thirds using the scanning electron microscope (SEM) technique. After confirmation of the normal distribution of data with Shapiro-Wilk test, Data were analyzed using the one-way ANOVA and Tukey tests. Results: The mean penetration depth of the bioceramic sealer into the dentinal tubules in the PUI group was greater than that of other groups; however, the difference between the two PUI and Er:YAG laser groups in the apical third was not significant (P=0.078). Er:YAG laser, PUI and XP-Finisher file agitation techniques resulted in significantly greater penetration of the bioceramic sealer into the dentinal tubules compared to the CNI (P<0.001). The XP-Finisher file technique in the apical (P=0.752) and middle thirds (P=0.339) and the Er:YAG laser technique in the apical thirds (P=0.086) were not significantly different from the conventional irrigation technique. Conclusion: The PUI technique resulted in significantly deeper penetration of the Bioceramic sealer into the dentinal tubules compared to the three other techniques.

Success Rate of 3 Injection Methods with Articaine for Mandibular First Molars with Symptomatic Irreversible Pulpitis: A CONSORT Randomized Double-blind Clinical Trial.

INTRODUCTION: Previous studies have reported that it is difficult to obtain proper anesthesia in mandibular molars with symptomatic irreversible pulpitis, and supplemental injections are usually unavoidable. The aim of the present study was to determine the anesthetic efficacy of articaine in mandibular first molars with symptomatic irreversible pulpitis with 3 injection methods: an inferior alveolar nerve block (IANB), an IANB with an intraligamentary injection, and an IANB with buccal infiltration before initiating the endodontic treatment. METHODS: Ninety-six patients (54 women and 42 men) with a diagnosis of symptomatic irreversible pulpitis in mandibular first molars were selected and randomly assigned into 3 groups (n = 32) according to the injection method as follows: group 1, a conventional IANB injection; group 2, an IANB injection, and after profound lip numbness after the IANB (after 15 minutes), buccal infiltration was administered; and group 3, an IANB injection, and after profound lip numbness after the IANB (after 15 minutes), an intraligamentary injection was performed, and after 20 minutes from the IANB, the endodontic treatment was initiated. The anesthetic solution was articaine 4% with 1:100,000 epinephrine. Success was defined as no or mild pain on the basis of the visual analog scale recording upon access cavity preparation or initial instrumentation. Data were statistically analyzed using the chi-square and Mann-Whitney U tests, and P < .05 was set as significant. RESULTS: The success rate for IANBs with an intraligamentary injection was 75%, and for IANBs with a buccal injection, it was 65.6%. For IANBs alone, the success rate was 28.1%. CONCLUSIONS: Considering the limitations of the present study, in can be concluded that the success rate of IANBs increased with intraligamentary injections and buccal infiltrations with articaine that were performed before initiating treatment. Also, none of the injection methods showed complete success in anesthesia in all patients.

Effect of the Bone Graft on the Surface Microhardness of Endodontic Biomaterials.

INTRODUCTION: During periapical surgery, using of bone products in large endodontic lesions, is a treatment option that could affect the properties of the retro-filling endodontic material. The aim of present study was to evaluate the effect of Osteon II bone powder on the surface microhardness of calcium-enriched mixture (CEM) and mineral trioxide aggregate (MTA). METHODS AND MATERIALS: Each material was mixed and carried into 40 sterile custom-made plastic cylinders. Half of the samples in each group were exposed to Osteon II. All cylinders were submerged in simulated tissue fluid and incubated at 37°C and 100% relative humidity for 7 days. Surface microhardness values of each study group was attained using Vickers microhardness test. The data were analyzed statistically using two-way ANOVA and independent t-test at a significance level of 0.05. RESULTS: The highest and lowest microhardness values were recorded in the MTA/without Osteon and MTA/with Osteon groups, respectively. Irrespective of the presence or absence of bone powder, the overall microhardness of CEM cement and MTA was not significantly different. In the MTA group, the presence of the powder resulted in a significant decrease (P<0.05) of the microhardness; however, its effect on CEM cement was not significant (P>0.05). CONCLUSION: Under the limitations of the present in vitro study, the presence of Osteon bone powder had no negative effect on the microhardness of CEM cement, contrary to its effect on MTA.

Effect of different mixing methods on the bacterial microleakage of white Portland cement and white Mineral Trioxide Aggregate.

Background. of this study was to investigate the effect of different mixing methods (ultrasonic, amalgamator, and conventional) on the bacterial microleakage of white Portland cement (WPC) and white MTA (Tooth-colored Formula, Dentsply, Tulsa Dental, Tulsa, OK). Methods. A hundred human single-rooted permanent teeth were decoronated to obtain 14 mm of root length in all the samples. The root canals were cleaned, shaped and obturated. Three millimeters of each root apex were cut off and randomly divided into 6 groups of 15 each (3 groups for WMTA and 3 groups for WPC, each with 3 different mixing methods) and 2 positive and negative control groups (each containing 5 samples). Brain-heart infusion agar (BHI) suspension containing the bacterial species Enterococcus faecalis (ATCC 29212) was used for leakage assessment. Statistical analysis was carried out using descriptive statistics and Kaplan Mayer survival analysis with censored data and log rank test using SPSS 18. Statistical significance was set at P<0.05. Results. The survival means in PC for conventional method, amalgamator, and ultrasonic were 80.2±13.64, 78.5±13.46 and 84.667±11.42 days, with 49.13±12.96, 66±13.32 and 69.07±11.5 days for MTA, respectively. The log rank test showed no significant differences between the three methods in each material (P>0.05). Conclusion. Bacterial microleakage in the studied samples was not significantly different in terms of the type of the mixing method.

The Effect of Different Mixing Methods on the pH and Solubility of Mineral Trioxide Aggregate and Calcium-Enriched Mixture.

INTRODUCTION: The aim of this study was to evaluate the effect of different mixing techniques on the pH and solubility of mineral trioxide aggregate (MTA) and calcium-enriched mixture (CEM). METHODS AND MATERIALS: Five samples were prepared from each biomaterial with different mixing techniques including hand-, amalgamator- or ultrasonic-mixing and were then placed in pre-weighted plastic tubes to determine their pH values. Each tube was then incubated in 10 mL deionized distilled water for 1 h at 37(º)C. An electrode was placed in the fluid in each flask at 24(º)C and the pH was recorded. In the next stage, six samples from each mixing technique/material were separately placed in glass bottles containing 50 mL of distilled water at 37(º)C for 1 h and were let dry for 1 h at 37(º)C. The samples' weights were measured and recorded twice. The procedure was repeated at 1-, 7- and 21-day intervals. Data were analyzed with the repeated measures ANOVA (for solubility) and two-way ANOVA (for pH) and then the post-hoc Tukey's test was done. RESULTS: The pH of the materials was not significantly affected by mixing methods. (P=0.8 for CEM and P=0.1 for MTA). The solubility of all test groups was within the acceptable range (=3%). However, the solubility of CEM at 1- and 21-day intervals was significantly different (P=0.03 for 1 day and P=0.001 for 21 days). Different mixing techniques had significant effects on the solubility of MTA at the three time points (P=0.004, 0.003 and 0.002 for 1-, 7- and 21-day intervals, respectively). CONCLUSION: The pH of biomaterials was not influenced by the mixing technique and their solubility was within the acceptable range.

The effect of different mixing methods on the flow rate and compressive strength of mineral trioxide aggregate and calcium-enriched mixture.

INTRODUCTION: Flow rate (FR) and compressive strength (CS) are important properties of endodontic biomaterials that may be affected by various mixing methods. The aim of this experimental study was to evaluate the effect of different mixing methods on these properties of mineral trioxide aggregate (MTA) and calcium-enriched mixture (CEM) cement. MATERIALS AND METHODS: Hand, amalgamator and ultrasonic techniques were used to mix both biomaterials. Then 0.5 mL of each mixture was placed on a glass slab to measure FR. The second glass slab (100 g) was placed on the samples and 180 sec after the initiation of mixing a 100-g force was applied on it for 10 min. After 10 min, the load was removed, and the minimum and maximum diameters of the sample disks were measured. To measure the CS, 6 sample of each group were placed in steel molds and were then stored in distilled water for 21 h and 21 days. Afterwards, the CS test was performed. Data were analyzed with multi-variant ANOVA and post hoc Tukey tests. The level of significance was set at 0.05. RESULTS: There were significant differences in FR of MTA and CEM cement with different mixing techniques (P<0.05). In the MTA group, none of the mixing techniques exhibited a significant effect on CS (P>0.05); however, in CEM group the CS at 21-h and 21-day intervals was higher with the hand technique (P<0.05). CONCLUSION: Mixing methods affected the flowability of both biomaterials and compressive strength of CEM cement.

Placement in an acidic environment increase the solubility of white mineral trioxide aggregate.

AIMS: The aim of the present study was to evaluate solubility of white mineral trioxide aggregate (WMTA) in an acidic environment. MATERIALS AND METHODS: Twenty-four metal rings were prepared, filled with WMTA and randomly divided into two groups. The samples in groups 1 and 2 were set in synthetic tissue fluid with pH values of 7.4 and 4.4, respectively and then were transferred to beakers containing synthetic tissue fluid with pH values of 7.7 and 4.4. Solubility of WMTA samples were calculated at the 9 experimental intervals. Data was analyzed with two-factor ANOVA and Bonferroni test (P < 0.03). RESULTS: The total solubility of WMTA in groups 1 and 2 were -9.1796 ± 1.9158% and -1.1192 ± 2.6236%, (P = 0.028) with weight changes of 9.1574 ± 2.1432% and 7.3276 ± 1.5823%, respectively (P = 0.002). Statistical analysis revealed significant differences between the two groups. CONCLUSIONS: It was concluded that solubility of WMTA increases in acidic environments and additional therapeutic precautions should be taken to decrease inflammation in endodontic treatment.

Effect of premedication with ibuprofen and dexamethasone on success rate of inferior alveolar nerve block for teeth with asymptomatic irreversible pulpitis: a randomized clinical trial.

INTRODUCTION: The aim of this study was to compare 2 kinds of anti-inflammatory medicines (ie, dexamethasone and ibuprofen) with a placebo according to their effects on the success rates of an inferior alveolar nerve block (IANB) for the endodontic treatment of mandibular molars with irreversible pulpitis. METHODS: A total of 165 patients were divided into 3 groups of 55 patients each and were given a capsule of the same color and size (ie, a placebo of lactose powder, 400 mg ibuprofen, or 0.5 mg dexamethasone). One hour after the oral administration of the capsules, all the patients received a standard IANB. In patients with a successful IANB, the teeth were examined with a cold pulp test. Patients were asked to assess their pain using the visual analog scale. Then, endodontic access cavity preparation was initiated. In case of pain during the treatment, the patients were asked to rate the pain on the visual analog scale. Success was defined as no or mild pain during treatment. The chi-square test and analysis of variance were used to compare qualitative and quantitative data among the groups. RESULTS: No significant differences were found regarding the sex of the patients in the 3 groups (P > .05). The dexamethasone group showed significantly higher success rates compared with the placebo group (P = .001). There were no significant differences between the ibuprofen and placebo groups (P = .055) or the dexamethasone and ibuprofen groups (P = .34). CONCLUSIONS: Premedication with dexamethasone increased the success rate of an IANB in mandibular molars with asymptomatic irreversible pulpitis.

Microleakage comparison of four dental materials as intra-orifice barriers in endodontically treated teeth.

INTRODUCTION: The aim of this in vitro study was to compare polymicrobial microleakage of calcium enriched mixture (CEM) cement, mineral trioxide aggregate (MTA), amalgam, and composite resin as intra-orifice sealing materials. MATERIALS AND METHODS: Seventy single-rooted mandibular premolars were instrumented and obturated by cold lateral compaction technique. The teeth were randomly divided into four experimental groups according to used material: CEM, MTA, amalgam and composite resin (n=15) and two control groups (n=5). In experimental groups, 2 mm of coronal gutta-percha was removed and replaced with the study material. All the teeth were mounted in a two-chamber apparatus and the coronal portion was exposed to human saliva. The day the turbidity occurred was recorded for each sample. Data were analyzed using one-way ANOVA. RESULTS: The negative control group showed no leakage while the average microleakage time in the positive control group was 3.5 days. The average bacterial leakage times for amalgam, composite resin, MTA, and CEM groups were 27.42±3.6, 29.35±3.15, 52.57±2.87, and 50.42±2.73 days, respectively. There was no significant difference between CEM and MTA groups (P=0.27) and also between amalgam and composite resin groups (P=0.36). However, in term of average leakage time, MTA and CEM groups exhibited significant differences with amalgam and composite resin groups (P<0.001). CONCLUSION: According to the results of the present in vitro study, in terms of coronal sealing in endodontically treated teeth, CEM and MTA are more effective than amalgam and composite resin.

Effects of various mixing techniques on push-out bond strengths of white mineral trioxide aggregate.

INTRODUCTION: The aim of this study was to evaluate the effect of 3 different mixing methods on push-out bond strength of white tooth-colored mineral trioxide aggregate (MTA). METHODS: Sixty 2-mm-thick root sections were prepared from 60 single-rooted human teeth and filled with MTA. The samples were randomly divided into 3 groups (n = 20) of MTA mixed by ultrasonic, trituration, or conventional methods and then allowed to set for 72 hours in a synthetic tissue fluid environment. Push-out bond strength values of the specimens were measured by a universal testing machine and examined under a stereomicroscope at × 4 to determine the nature of the bond failure. RESULTS: The means of push-out bond strength values of white MTA in the ultrasonic, conventional, and trituration groups were 105.67 ± 12.79, 118.95 ± 12.76, and 99.60 ± 14.27 MPa, respectively. The differences between the 3 groups were not statistically significant. CONCLUSIONS: On the basis of the results of this study, it can be concluded that different mixing methods have no significant effect on push-out bond strength of white MTA.

Effect of alkaline ph on sealing ability of white mineral trioxide aggregate

Objectives: The aim of this study was to evaluate microleakage of white mineral trioxide aggregate (WMTA) after its exposure to a range of alkaline environments during hydration.Study Design: Seventy single-rooted teeth were divided into 4 experimental and 2 control groups. All the teeth were instrumented, and their apices were resected. Root-end cavities were filled with WMTA in the experimental groups. In the control groups, root-end cavities were not filled. Root-end fillings were exposed to alkaline environments with pH values of 7.4, 8.4, 9.4, or 10.4 for 3 days. Microleakage was evaluated by bovine serum albumin.Evaluations were carried out at 24-hour intervals for 80 days. Data were analyzed by one-way analysis of variance and a post hoc Tukey test at the 0.05 level of confidence.Results: The number of days (mean ± standard deviation) needed for color change at pH values of 7.4, 8.4, 9.4, and10.4 were 78.53 ± 5.68, 80.00 ± 0.00, 68.93 ± 19.00, and 34.46 ± 12.73, respectively. The time needed for leakageto occur was significantly shorter in samples stored at a pH value of 10.4 (P<0.001).Conclusions: Within the limits of this study, it can be concluded that pH values greater than 9.4 may jeopardizethe sealing ability of WMTA during hydration (AU)

Effect of alkaline ph on sealing ability of white mineral trioxide aggregate.

OBJECTIVES: The aim of this study was to evaluate microleakage of white mineral trioxide aggregate (WMTA) after its exposure to a range of alkaline environments during hydration. STUDY DESIGN: Seventy single-rooted teeth were divided into 4 experimental and 2 control groups. All the teeth were instrumented, and their apices were resected. Root-end cavities were filled with WMTA in the experimental groups. In the control groups, root-end cavities were not filled. Root-end fillings were exposed to alkaline environments with pH values of 7.4, 8.4, 9.4, or 10.4 for 3 days. Microleakage was evaluated by bovine serum albumin. Evaluations were carried out at 24-hour intervals for 80 days. Data were analyzed by one-way analysis of variance and a post hoc Tukey test at the 0.05 level of confidence. RESULTS: The number of days (mean ± standard deviation) needed for color change at pH values of 7.4, 8.4, 9.4, and 10.4 were 78.53 ± 5.68, 80.00 ± 0.00, 68.93 ± 19.00, and 34.46 ± 12.73, respectively. The time needed for leakage to occur was significantly shorter in samples stored at a pH value of 10.4 (P<0.001). CONCLUSIONS: Within the limits of this study, it can be concluded that pH values greater than 9.4 may jeopardize the sealing ability of WMTA during hydration.

Effect of Er, Cr: YSGG laser irradiation on Enterococcus faecalis in infected root canals.

OBJECTIVE: The purpose of this study was to investigate the eradication of Enterococcus faecalis by high-power settings of Er, Cr:YSGG laser irradiation in root canals of extracted teeth. BACKGROUND DATA: The bacteria entering the root canal system invade dentinal tubules, resulting in persistent infections in root canals due to limited penetration of irrigation solutions into the dentinal tubules. The antibacterial effects of different lasers have been investigated in previous studies. MATERIALS AND METHODS: Sixty newly extracted maxillary central incisors were enlarged chemomechanically and sterilized after removal of the smear layer. Root canals were inoculated with E. faecalis, and bacteria were incubated in root canals for 48 h. Samples were randomly divided into four groups, each containing 15 teeth. One group was considered as control with no intervention. Two groups were irradiated with 2- and 3-W output powers of Er, Cr:YSGG laser for 16 s. In the last group, the canals were irrigated with 1% sodium hypochlorite for 20 min. RESULTS: In the laser groups at 2- and 3-W powers, the number of bacteria was reduced 2.4% and 1.53%, respectively, compared with the controls. No significant differences were found between the two laser groups (p > 0.05). The canals irrigated with 1% NaOCl solution demonstrated no bacterial growth. CONCLUSIONS: According to the results of the present study, 2- and 3-W powers of Er, Cr:YSGG laser have antibacterial effects on E. faecalis in root canals of infected teeth; however, the effect is less remarkable than that of NaOCl solution.

Effect of mineral trioxide aggregates and Portland cements on inflammatory cells.

INTRODUCTION: Recently, some studies have compared mineral trioxide aggregate (MTA) with Portland cements, concluding that the principal ingredients of Portland cements are similar to those of MTA. The purpose of the present study was to evaluate the effect of gray MTA, white MTA, and gray and white Portland cements on inflammatory cells in rats. METHODS: Fresh mixtures mixed with distilled water were placed in polyethylene tubes, which were implanted in the dorsal subcutaneous connective tissue of 60 Sprague-Dawley rats along with empty tubes as controls. Tissue specimens were collected after the rats were sacrificed after 7, 15, 30, 60, and 90 days. The specimens were fixed, stained, processed, and histologically evaluated under a light microscope. Inflammatory reactions were classified as grade 0: without inflammatory cells, grade I: sporadic infiltration of inflammatory cells, grade II: moderate infiltration (<25 cells), grade III: dense and severe infiltration (25-125 cells), and grade IV: very dense and severe infiltration (>125 cells). Data were analyzed with the nonparametric (two factor) analysis of variance and Kruskal-Wallis H-test. RESULTS: All the groups showed grade III inflammation after 7 and 15 days; there was a decrease in the inflammatory process after 30, 60, and 90 days. After 90 days, gray MTA, white MTA, and control groups had grade 0 inflammatory process, but gray Portland cement and white Portland cement groups showed grade 0 to grade I inflammatory processes. CONCLUSION: MTAs were more biocompatible; however, more studies are required.

Connective Tissue Reaction to White and Gray MTA Mixed With Distilled Water or Chlorhexidine in Rats.

INTRODUCTION: The purpose of this study was to compare the histocompatibility of white (WMTA) and gray (GMTA) mineral trioxide aggregate mixed with 0.12% chlorhexidine (CHX) and distilled water (DW) in subcutaneous connective tissues of rats. MATERIALS AND METHODS: The freshly mixed WMTA and GMTA with CHX or DW were inserted in polyethylene tubes and implanted into dorsal subcutaneous connective tissue of 50 Wistar Albino rats; tissue biopsies were collected and were then examined histologically 7, 15, 30, 60 and 90 days after the implantation procedure. The histology results were scored from 1-4; score 4 was considered as the worst finding. Data were analyzed using one-way ANOVA tests. RESULTS: All experimented materials were tolerated well by the connective tissues after 90-day evaluation, except for the WMTA/CHX group that had significantly more mean inflammatory scores (P<0.001). There was a statistically significant difference in the mean inflammation grades between experimental groups in each interval (P<0.001). After 90 days, GMTA/CHX group had the lowest inflammatory score. CONCLUSION: Although adding CHX to WMTA produces significantly higher inflammatory response, it seems a suitable substitute for DW in combination with GMTA. Further research is necessary to recommend this mixture for clinical use.

Comparison of apical microleakage using Ni-Ti with stainless steel finger spreaders.

INTRODUCTION: The purpose of this in vitro study was to compare apical microleakage after obturation with Nickel-Titanium (NiTi) compared to Stainless Steel (SS) finger spreaders. MATERIALS AND METHODS: Eighty straight single-rooted human teeth were instrumented using step-back technique. The specimens were randomly divided into four groups. The two experimental groups (n=30) and the negative control group (n=10) were obturated by lateral condensation technique with Ariadent gutta-percha and AH26 sealer. The roots in the positive control group (n=10) were instrumented but not obturated. In one group, SS and in another group NiTi spreaders were used. Microleakage evaluation was conducted using dye penetration method t-test was used for statistical analysis. RESULTS: The results showed statistically significant differences between NiTi and SS groups (P=0.022), with the greatest dye penetration in SS group and the least in NiTi group. CONCLUSION: According to the results of the present study using NiTi spreader decrease apical microleakage in endodontically treated teeth. [Iranian Endodontic Journal 2009;4(4):149-51].

Root canal morphology of human mandibular first permanent molars in an Iranian population.

BACKGROUND AND AIMS: The knowledge of variations in root canal morphology is critical for a successful endodontic treatment. The purpose of this study was to investigate variations in the root canal system of human mandibular first permanent molars in an Iranian population. MATERIALS AND METHODS: In this study, 209 mandibular first molar teeth were decalcified, dye-injected, and cleared in order to determine the number and configuration of the root canals. RESULTS: The results demonstrated that 65.56% of the mandibular first molars under study had three, 31.57% had four and 2.87% had two canals. CONCLUSION: According to the results of this study and considering variations in the root canal systems of the mandibular first molars, it seems that great care should be taken in the root canal treatment of these teeth.