Antimicrobial and Mechanical Properties of Orthodontic Acrylic Resin Containing Zinc Oxide and Titanium Dioxide Nanoparticles Supported on 4A Zeolite.

Polymethyl methacrylate (PMMA) is widely used to manufacture removable orthodontic appliances. However, since the porous structure, cold-curing acrylic resins are susceptible to bacterial adhesion and colonization. The aim of this study was to investigate the antibacterial and mechanical properties of a cold-curing PMMA resin containing ZnO and TiO2 nanoparticles supported on the 4A zeolite. ZnO and TiO2 nanoparticles supported on the 4A zeolite were synthesized. Nanoparticles were added in three compositions as ZnO/4A, TiO2/4A, and ZnO/TiO2/4A at 2wt% and 4wt% concentrations to cold-curing acrylic resin powder (SR Triplex® Cold Ivoclar Vivadent AG, FL-9494 Schaan/Liechtenstein). X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), energy dispersive X-ray (EDX), transmission electron microscopy (TEM), and dynamic light scattering (DLS) were performed to investigate the nanocomposite characteristics. A direct test method was used to assess the antibacterial properties against Streptococcus mutans, Klebsiella pneumoniae, and Escherichia coli. The surface roughness of acrylic samples was measured with a profilometer. Flexural strength was evaluated by a three-point bending test, and one-way ANOVA and Tukey's post hoc tests were used for statistical evaluation of the data. A p value of less than 0.05 was considered statistically significant. XRD confirmed the accurate crystalline structure of synthesized nanoparticles; FE-SEM images showed nanoparticle dispersion within polymerized acryl. The addition of 2 and 4 wt% of ZnO/4A, TiO2/4A, and ZnO/TiO2/4A caused colony reduction in all types of tested microorganisms more than 99% and 100%, respectively. The mean flexural strengths of acrylic specimens containing 2wt% and 4wt% of synthesized nanoparticles were significantly lower than those of the resin without nanoparticles. Fabricated samples showed favorable antibacterial properties but decreased flexural strength.

Fracture resistance of endodontically treated maxillary incisors restored with single or bundled glass fiber-reinforced composite resin posts.

Background: To compare the fracture resistance of endodontically treated maxillary incisors restored with single versus bundled glass fiber-reinforced composite resin posts (FRC). Material and Methods: Twenty-four maxillary incisors underwent root canal preparation (1.5-mm-diameter post spaces after canal obturation). Teeth were randomly divided into two groups (n = 12). Two different FRC groups were used for the intracanal post treatment. Single FRC (Rebilda Post system, 1.5 mm diameter) and bundled FRC (Rebilda Post GT, 12 fiber bundles, 1.4 mm diameter) were bonded to the prepared canals using dual-cure resin-based luting cement. Specimens were kept in humid at 37°C for one day. The fracture resistance testing was performed using universal testing machine by applying a compressive static load at a 135° angel to the axis of the teeth. The failure type after fracture was examined by visual inspection. Results: The fracture resistance of teeth with single FRC (Rebilda Post) and bundled FRC (Rebilda Post GT) were 787 ± 156 and 850 ± 166 Newton, respectively. There was no statistical significant difference between the two groups. Root fracture was the major failure type in both groups. Conclusions: The fracture resistance of endodontically treated maxillary incisors with bundled FRC (Rebilda Post GT) did not differ from incisors with single FRC (Rebilda Post). Key words:Endodontically-treated teeth, fracture resistance, glass fiber post, intracanal post.

Vital pulp therapy following pulpotomy in immature first permanent molars with deep caries using novel fast-setting calcium silicate cement: A retrospective clinical study.

OBJECTIVES: To compare the success rate of vital pulp therapy following complete pulpotomy in immature first permanent molars, during caries treatment, using novel fast-setting calcium silicate cement (Novel CSC) versus MTA. METHODS: Six- to eight- years old children, who received pulpotomy of first immature permanent molar using one layer novel CSC (Protooth) or two layers slow-setting MTA (MTA Angelus) covered with glass ionomer were recalled for radiographic and clinical evaluation after two years. The effects of cement type, age, gender, jaw, anesthesia type, and restoration type were assessed on the clinical success of pulpotomy and continued root formation (apexogenesis) as the treatment outcome. RESULTS: Out of 366 included teeth in the study, 316 teeth were available for statistical analysis. The mean observation time was 28.2 ±â€¯2.7 months. Novel CSC showed significantly higher clinical success rate (93.1%) compared to MTA (84.5%). Restored teeth with stainless steel crowns after pulpotomy and treatments performed under general anesthesia had a statistically significant effect on treatment outcome in contrast to age, gender, and jaw type. CONCLUSION: The observations of this retrospective study suggested that the success rate of vital pulp therapy following complete pulpotomy using one layer fast-setting novel CSC was significantly higher than slow-setting MTA covered with glass ionomer. Treatment under general anesthesia and restoration using stainless steel crowns influenced the treatment outcome. CLINICAL SIGNIFICANCE: Novel fast-setting calcium silicate cement is a promising new biomaterial for vital pulp therapy in immature permanent molars that allows complete root formation overtime with apexogenesis. Clinicians must also be aware of the importance of immediate definitive restoration and proper sealing and isolation in vital pulp therapy.

Pull-Out Bond Strength of Titanium Post Cemented with Novel Fast-Setting Calcium Silicate Cement.

OBJECTIVE: The aim of this study was to compare the pull-out bond strength of prefabricated titanium posts cemented with novel fast-setting calcium silicate, zinc phosphate, or glass ionomer cements. METHODS: Sixty extracted human maxillary incisors were selected and received root canal treatment. Post space was prepared for titanium ParaPost XP size 5 (diameter=1.25 mm). The posts were cemented using novel calcium silicate cement, zinc phosphate cement, or glass ionomer cement (n=20). Specimens were stored in phosphate-buffered saline for 4 weeks. Subsequently, the posts were subjected to axial tensile force until bond failure. Data were analyzed by one-way ANOVA followed by multiple comparisons. RESULTS: The posts cemented with novel calcium silicate cement (10.5±3.8 MPa) demonstrated significantly higher bond strength than zinc phosphate (8.0±2.6 MPa) and glass ionomer cements (8.0±2.7 MPa) (P<0.05). CONCLUSION: Within the limitation of the study, the pull-out bond strength of titanium post cemented with novel calcium silicate cement in endodontically treated teeth was superior to zinc phosphate and glass ionomer cements.

Marginal and internal fit of crowns based on additive or subtractive manufacturing.

OBJECTIVE: To assess the marginal and internal fit of crowns manufactured by additive and subtractive manufacturing technique. MATERIALS AND METHODS: Twenty extracted teeth prepared for complete coverage crowns were scanned with an intra-oral scanner (Omnicam, DentsplySirona). For the subtractive manufacturing (SM) group, ten crowns were manufactured in a hybrid resin block (Vita Enamic, Vita Zahnfabrik). For the additive manufacturing (AM) group, the crowns were manufactured in a hybrid resin material (NextDent C&B, 3D systems). The design parameters were identical for the two groups. The marginal and internal fit (determined at the axial wall, the cusp tip and occlusally) was assessed before cementation with the replica technique and after cementation under stereomicroscope after sectioning of the crowned teeth. RESULTS: For the SM group, the marginal fit was 91 µm (±28 µm) before cementation and 85 µm (±18 µm) after cementation. In the AM group, the marginal fit was 75 µm (±29 µm) before cementation and 71 µm (±18 µm) after cementation. The differences were not statistically significant. As regards the internal fit, the fit at the axial wall was statistically significantly better in the SM group than in the AM group (p=.009 before cementation and .03 after cementation). Occlusally the fit in the AM group was significantly better than in the SM group after cementation (p<.001). CONCLUSION: Within the limitations of the current study, the marginal fit of additively manufactured crowns is comparable to crowns manufactured with chair-side subtractive technique and within the clinically acceptable range. As regards the internal fit no one technique was consistently superior.

Effect of different surface treatments of presintered or sintered zirconia on bond strength to dentine.

Aim: To compare the effect of different zirconia surface treatments on cement bond strength to dentine. Materials and Methods: Stick-shaped pre-sintered zirconia (N = 128) were prepared and divided into eight groups (n = 16). Three surface treatments (sandblasting, neodymium-doped yttrium aluminum garnet [Nd:YAG] or carbon dioxide laser irradiation) were applied, either before (later to be sintered) or after sintering. The last test group was sintered zirconia coated with feldspathic veneering ceramic. Sintered zirconia without surface treatment was tested as the control group. Zirconia samples were cemented to dentine using Panavia F2 cement. The micro-shear bond strength was measured after 24 h (n = 8) or 10,000 thermocycling (n = 8). Statistical Analysis: Data were analyzed using one-way analysis of variances and Student's t-tests. Results: Zirconia coated with feldspathic ceramic revealed the highest bond strength (P < 0.001). Presintered zirconia treated with Nd: YAG laser showed a significantly improved bond strength compared to the control group before and after thermocycling. The bond strength after thermocycling was significantly reduced in presintered zirconia treated with Nd: YAG or sandblasting. Adhesive failure at the zirconia-cement interface was the dominant failure type. Conclusions: Surface treatment of presintered zirconia by Nd:YAG laser or coating of the sintered specimens with feldspathic veneering ceramic increased the zirconia-cement bond strength.

Bond strength between dentine and a novel fast-setting calcium silicate cement with fluoride.

The aim of this study was to evaluate the dentine bond strength of a novel fast-setting calcium silicate cement (Protooth) versus a calcium hydroxide-based cement (Dycal), a calcium silicate cement (ProRoot MTA), and a glass ionomer cement (Ketac-Molar). Mid-root dentine slices of 1 mm thickness were obtained from human maxillary incisors. After enlarging the lumen of the canal to 1.3 mm, the cavities were randomly filled with test materials. Samples were immersed in physiological-like solution. The push-out bond strength was tested on days 1, 28, and 180 (n = 12). Failure types of bonding were determined using a stereomicroscope. We analysed the data using linear regression. Dycal and day 1 were considered as reference for cement type and assessment time, respectively. Protooth, Ketac-Molar, and ProRoot MTA demonstrated higher push-out bond strength than Dycal. The push-out bond strength in the Protooth group increased on day 28 and 180. The bond strength of Ketac-Molar was significantly reduced on day 28. Dycal showed a significant decrease in bond strength on day 180 compared with that on day 1 and 28. Mixed failure was the dominant failure type. Protooth bonding to dentine was increased with time, in contrast to that of ProRoot MTA, Dycal, and Ketac-Molar, as a function of time.

Direct pulp capping of primary molars using a novel fast-setting calcium silicate cement: a randomized clinical trial with 12-month follow-up.

Objective: Novel fast-setting calcium silicate cement with fluoride (Protooth) has been developed for potential applications in tooth crowns. The aim of this study was to evaluate the success rate of direct pulp capping in primary molars using two-layer mineral trioxide aggregate (MTA) and overlying glass ionomer cement versus one-layer novel calcium silicate cement with 4 to 10 minutes setting time. Materials and methods: Ninety bilaterally symmetrical primary molars in the same jaw in 45 patients aged 5 to 7 years were included. Exposed pulps following caries removal were randomly capped with one-layer novel calcium silicate cement or two-layer MTA and glass ionomer cement. All cavities were filled with amalgam. Clinical and radiographic evaluations were performed after six and twelve months. 41 patients were available for the evaluations at the end of the 12-month follow-up. Results: The overall success rate of direct pulp capping, in a split-mouth design, using MTA covered with glass ionomer cement or one-layer novel calcium silicate cement after 12 months were 90% (37 out of 41 cases) and 85% (35 out of 41 cases), respectively, without statistically significant differences after 6 and 12 months. Conclusion: Within the limitations of this study, clinical and radiographic evaluations suggested one-layer novel calcium silicate cement would be successfully used in direct pulp capping of primary molars as a practical alternative to two-layer MTA and overlying glass ionomer cement.

Children's Pain Perception and Behavioral Feedback during Local Anesthetic Injection with Four Injection Site Preparation Methods.

Introduction:An effective pain control significantly contributes to an optimal dental treatment in pediatric dentistry. This study was conducted to compare children's pain perception and behavioral feedback during local anesthetic injection accompanied with counter-irritation, refrigerant, ice precooling or topical benzocaine. Methods:This study was conducted on 99 children who needed dental treatment in bilateral maxillary primary molars by local anesthesia. Subjects were randomly assigned to three groups, in which the injection site was prepared using counter-irritation in group I, ice precooling in group II, and refrigerant spray precooling in group III. In all three groups, 20% benzocaine gel was used in the injection site of opposite quadrant as a control. The perceived pain and behavioral feedback of children during injection were evaluated using the visual analogue scale (VAS) and sound, eye, and motor (SEM) indexes. Sign and Kruskal-Wallis tests were used to analyze data at a significance level of P < 0.05. Results:The perceived pain was significantly lower when using benzocaine compared to the other three methods (P < 0.05). Behavioral feedback of children when using benzocaine was not significantly different from the counter-irritation method (P=1.00). However, behavioral feedback with counter-irritation was significantly better than precooling (P < 0.05). Counter-irritation was significantly more effective than precooling methods in reduction of pain perception and improvement of behavioral feedback (P < 0.05). Conclusions:The perceived pain was significantly lower when the benzocaine method was used. Behavioral feedback was significantly better with benzocaine and counter-irritation methods compared to precooling procedures.

In vitro cytotoxic evaluation of novel fast-setting calcium silicate cement compositions and dental materials using colorimetric methyl-thiazolyl-tetrazolium assay.

A novel fast-setting calcium silicate cement with fluoride (CSC) has been developed for potential application in tooth crowns. This study compared the cytotoxicity of CSC compositions and a variety of dental materials. We tested CSC compositions (Protooth), MTA, Biodentine, Ketac Molar, Fuji II LC, Vitrebond, DeTrey Zinc, Dycal, and IRM, DMEM (negative control) and 1% NaOCl (positive control). After setting of cements for 24 h, specimens were immersed in DMEM for 24 h to obtain material elutes. The elutes were serially diluted in serum-free DMEM to obtain three dilutions. L929 mouse fibroblast cells (1 × 104 cells per well) were treated for 24 h with elute dilutions (n = 3). Cytotoxicity was determined using methyl-thiazolyl-tetrazolium assay in triplicate. CSC compositions, MTA, and Biodentine showed no significant reduction in cell viability compared to DMEM. There was no significant difference in cell viability, at any of three dilutions, between CSC compositions and either MTA or Biodentine. Cytotoxicity was significantly lower for CSC compositions than for Vitrebond, DeTrey Zinc, Dycal, IRM, and 1% NaOCl, at all three dilutions, and undiluted Fuji II LC elute. In contrast to resin-modified glass ionomers, zinc phosphate cements, Dycal, and IRM, the CSC compositions showed no cytotoxic potential.

Calcium phosphate precipitation in experimental gaps between fluoride-containing fast-setting calcium silicate cement and dentin.

A novel fast-setting calcium silicate cement containing fluoride (novel-CSC) has been developed for applications in tooth crowns. The aim of this study was to assess the ability of the novel-CSC to close the experimental gaps at the dentin-cement interface. The novel-CSC was tested against Vitrebond and GC Fuji II LC. Experimental gaps of 50 or 300 µm width were created between the materials and dentin. Specimens with the 300-µm-wide gap were immersed in phosphate-buffered saline and the closed gap area was measured during 96 h. All specimens with 50 or 300 µm gap width were analyzed by scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (SEM/EDX) to assess the morphology and chemical composition of the precipitates after 96 h immersion in phosphate-buffered saline. High-resolution micro-computed tomography (µCT) was used to evaluate the integrity and continuity of the precipitiates after 96 h and 180 d. In all novel-CSC samples, precipitates closed the gap area completely after 96 h. The SEM/EDX revealed that the globular precipitates closing the gap area were mainly composed of calcium and phosphorus. After 180 d, µCT indicated thicker precipitates compared with initial precipitates only in the novel-CSC group, whereas no precipitates were observed in resin-modified glass ionomers. Novel-CSC promoted continuous precipitation of calcium phosphate, including apatite, and closed the experimental gaps.

A Review on Root Anatomy and Canal Configuration of the Maxillary Second Molars.

INTRODUCTION: The complexity of the root canal system presents a challenge for the practitioner. This systematic review evaluated the papers published in the field of root canal anatomy and configuration of the root canal system in permanent maxillary second molars. METHODS AND MATERIALS: All articles related to the root morphology and root canal anatomy of the permanent maxillary second molars were collected by suitable keywords from PubMed database. The exhaustive search included all publications from 1981 to December 2015. The articles relevant to the study were evaluated and data was extracted. The author/year of publication, country, number of the evaluated teeth, type of study (method of the evaluation), number of roots and the canals, type of canals and the morphology of the apical foramen was noted. RESULTS: The highest studied populations were in Brazil and United States. A total of 116 related papers were found, which had investigated 11945 teeth in total. Across all the studied populations, the three-rooted anatomy was most common, while the four-rooted anatomy had the lowest prevalence. The presence of the second mesiobuccal canal ranged from 11.53 % to 93.7%, where type II (2-1) configuration was the predominant type in Brazil and USA and types II and III (1-2-1) in Chinese populations. In 8.8-44% of cases, fusion was observed. The main reported cases were related to palatal root. The major method of anatomical investigation in case reports was periapical radiography, and the chief method in morphological studies was CBCT. CONCLUSION: The clinicians should be aware of normal morphology and anatomic variations to reduce the treatment failure.

Prevalence of Extra Roots in Permanent Mandibular First Molars in Iranian Population: A CBCT Analysis.

INTRODUCTION: Having knowledge about the anatomy of root canal system is essential for success of endodontic treatment. The present study used cone-beam computed tomography (CBCT), to evaluate the prevalence of third root in mandibular first molars in a selected Iranian population. METHODS AND MATERIALS: A total of 386 CBCT images from subjects referred to oral and maxillofacial radiology department of dental faculty of Tabriz University of Medical Sciences from 2011 to 2013 were selected and evaluated for this study and the cases with well-developed permanent mandibular first molars were included. The 3D images were reconstructed in axial cross sections and evaluated by two endodontists for the presence of the third extra lingual (radix entomolaris) or buccal (radix paramolaris) root. The chi-squared test was used to evaluate the relationship between gender and bilateral incidence of extra roots in mandibular first molars. RESULTS: The distribution of three-rooted mandibular first molars with an additional root was 3%, (3.53% in female and 2.50% in male patients). There was no significant relationship between gender and bilateral occurrence of three-rooted mandibular first molars. CONCLUSION: The occurrence of three-rooted mandibular first molars in Iranian population is not uncommon which should be taken into consideration by the dental practitioners during root canal treatment of these teeth.

Diametral tensile strength of novel fast-setting calcium silicate cement.

Novel fast-setting calcium silicate cement with fluoride (CSC) has been developed for potential applications in tooth crown. The aim of this study was to test the diametral tensile strength (DTS) of different CSC compositions in humid condition on day1, 28, and 180. We tested 'bond CSC' with 3.5% fluoride and no radiocontrast, 'CSC' with 3.5% fluoride and 10% radiocontrast, 'ultrafast CSC' with 3.5% fluoride and 20% radiocontrast, 'high fluoride CSC' with 15% fluoride and 25% radiocontrast, Biodentine, and MTA. We filled the cements after mixing to cylindrical molds. Specimens were stored in >95% humidity. DTS was measured at each time point. CSC compositions had statistically higher DTS compared to MTA and Biodentine on day1. Bond CSC showed higher DTS versus all cements, except CSC, at all time points. DTS of all cements, except Biodentine, significantly increased in humid condition on day28 and day180 compared to day1.

Survival of Composite Resin Restorations of severely Decayed Primary Anterior Teeth retained by Glass Fiber Posts or Reversed-orientated Metal Posts.

AIM: The aim of this study was to compare the survival of composite resin restorations retained by glass fiber posts or reversed-orientated (upside-down) metal posts in severely decayed primary anterior teeth after 6, 12, and 18 months. MATERIALS AND METHODS: A total of forty-four 3- to 5-year-old children with bilateral severely decayed primary maxillary canines were included. Patients were treated under general anesthesia. After pulpectomy, an intracanal post was seated in the primary maxillary canine on each side: either a glass fiber post or a metallic post in reversed orientation and teeth restored with light-cured composite. Survival rate of each technique was evaluated at predetermined follow-ups and data were analyzed with McNemar's test (α = 0.05). RESULTS: The difference in survival of restorations retained by two types of posts was not statistically significant in clinical and radiographical evaluations after 6, 12, and 18 months. The survival rate of reversed-orientated metal and glass fiber posts after 18 months was 81.1 and 67.6% respectively (p = 0.14). CONCLUSION: Reversed-orientated metal post did not show lower clinical survival compared with glass fiber posts in 18-month follow-up. Hence, reversed-orientated metal post can be considered as a potential method to obtain retention for composite restorations in severely decayed primary anterior teeth. How to cite this article: Vafaei A, Ranjkesh B, L0vschall H, Erfanparast L, Jafarabadi MA, Oskouei SG, Isidor F. Survival of Composite Resin Restorations of severely Decayed Primary Anterior Teeth retained by Glass Fiber Posts or Reversed-orientated Metal Posts. Int J Clin Pediatr Dent 2016;9(2):109-113.

Apatite precipitation on a novel fast-setting calcium silicate cement containing fluoride.

Aim: Calcium silicate cements are widely used in endodontics. Novel fast-setting calcium silicate cement with fluoride (Protooth) has been developed for potential applications in teeth crowns including cavity lining and cementation. Objective: To evaluate the surface apatite-forming ability of Protooth compositions as a function of fluoride content and immersion time in phosphate-buffered saline (PBS). Material and methods: Three cement compositions were tested: Protooth (3.5% fluoride and 10% radiocontrast), ultrafast Protooth (3.5% fluoride and 20% radiocontrast), and high fluoride Protooth (15% fluoride and 25% radiocontrast). Powders were cap-mixed with liquid, filled to the molds and immersed in PBS. Scanning electron microscopy, energy dispersive X-ray analysis, and Raman spectroscopy were used to characterize the precipitations morphology and composition after 1, 7, 28, and 56 days. Apatite/belite Raman peak height indicated the apatite thickness. Results: Spherical calcium phosphate precipitations with acicular crystallites were formed after 1-day immersion in PBS and Raman spectra disclosed the phosphate band at 965 cm-1, supporting the apatite formation over Protooth compositions. The apatite deposition continued and more voluminous precipitations were observed after 56 days over the surface of all cements. Raman bands suggested the formation of ß-type carbonated apatite over Protooth compositions. High fluoride Protooth showed the most compact deposition with significantly higher apatite/belite ratio compared to Protooth and ultrafast Protooth after 28 and 56 days. Conclusions: Calcium phosphate precipitations (apatite) were formed over Protooth compositions after immersion in PBS with increasing apatite formation as a function of time. High fluoride Protooth exhibited thicker apatite deposition.

Impact of Self-concept on Preschoolers' Dental Anxiety and Behavior.

Background and aims . Different factors affect children's behavior during dental treatment, including psychological and behavioral characteristics. The aim of this study was to evaluate the correlation of self-concept on child's anxiety and behavior during dental treatment in 4 to 6-year-old children. Materials and methods. A total of 235 preschoolers aged 4 to 6 years were included in this descriptive analytic study. Total self-concept score for each child was assessed according to Primary Self-concept Scale before dental treatment. Child's anxiety and child's behavior were assessed, during the restoration of mandibular primary molar, using clinical anxiety rating scale and Frankl Scale, respectively. Spearman's correlation coefficient was used to evaluate the correlation between the total self-concept score with the results of clinical anxiety rating scale and Frankl Scale. Results. There was a moderate inverse correlation between the self-concept and clinical anxiety rating scale scores (r = -0.545, P < 0.001), and a moderate correlation between the self-concept and child's behavior scores (r = 0.491, P < 0.001). A strong inverse relation was also found between the anxiety and behavior scores (r = -0.91, P < 0.001). Conclusion. Children with higher self-concept had lower anxiety level and better behavioral feedback during dental treatment.

Effect of MTAD as a final rinse on removal of smear layer in ten-minute preparation time.

INTRODUCTION: The aim of this study was to evaluate the effect of MTAD as final rinse on removal of the smear layer subsequent to primary irrigation with 1.3% sodium hypochlorite (NaOCl) during 10-minute instrumentation periods. METHODS: Forty teeth were divided into 2 experimental groups, each containing 15 teeth, and 1 positive control group of 10 teeth. The canals were prepared with hand and rotary instruments. In the MTAD group, the root canals were flushed with 1.3% NaOCl solution during 10-minute instrumentation, and MTAD was used as the final rinse. In other experimental group, 5.25% NaOCl was used during instrumentation, and 17% ethylenediaminetetraacetic acid (EDTA) was used as the final rinse. In the positive control group, sterile distilled water was used for irrigation. The overall instrumentation period for each canal was 10 minutes. The amount of the smear layer and degree of erosion qualified according to the study by Torabinejad et al by using a scanning electron microscope. Data were analyzed by Kruskal-Wallis and Mann-Whitney tests. All statistical analyses were set with a significance level of α = 0.05. RESULTS: In the positive control group, debris and heavy smear layer covered the root canal surface and the tubules. In MTAD group, moderate smear layer covered the root canal surface and the tubules. In EDTA group, there was no smear layer on surface of canals. There were significant differences between groups (α < 0.0001). Mann-Whitney test showed significant difference between experimental groups (α = 0.01). CONCLUSIONS: In 10-minute instrumentation period, the use of 5.25% NaOCl during instrumentation and 17% EDTA as the final rinse is more effective than using 1.3% NaOCl as primary irrigation and MTAD as final rinse on removal of the smear layer.

Comparison of two histopathologic methods for evaluating subcutaneous reaction to mineral trioxide aggregate

Objectives: One of the most important factors for suitable materials for pulp therapy is biocompatibility. Two histopathologic methods of Cox and Federation Dentaire International (FDI) were used to evaluate inflammation. In Cox method, density of inflammatory cells, tissue reactions like fibrosis, vascular responses like congestion and fibrin extravasation have been used to evaluate inflammatory reactions. The aim of this study was to compare the accuracy of pathologists’ interpretations using two different methods. Study design: Three pathologists observed the degree of inflammation in 225 histopathologic sections. These sections showed inflammation in subcutaneous connective tissue of rats adjacent to polyethylene tubes, filled with white or gray mineral trioxide aggregate. Empty tubes served as controls. Samples were harvested after 7-, 15-,30-, 60-, and 90-days. All pathologists examined the sections under a light microscope (Carl Zeiss, Oberkochen,Germany) at ×400 magnifications. Chi-Square test was used to evaluate the difference between inflammation grades when one pathologist used two methods. Cohen’s Kappa value was used to measure agreement of three pathologists to recognize the degrees of inflammations when using one of the methods(..) (AU)

Comparison of two histopathologic methods for evaluating subcutaneous reaction to mineral trioxide aggregate.

OBJECTIVES: One of the most important factors for suitable materials for pulp therapy is biocompatibility. Two histopathologic methods of Cox and Federation Dentaire International (FDI) were used to evaluate inflammation. In Cox method, density of inflammatory cells, tissue reactions like fibrosis, vascular responses like congestion and fibrin extravasation have been used to evaluate inflammatory reactions. The aim of this study was to compare the accuracy of pathologists' interpretations using two different methods. STUDY DESIGN: Three pathologists observed the degree of inflammation in 225 histopathologic sections. These sections showed inflammation in subcutaneous connective tissue of rats adjacent to polyethylene tubes, filled with white or gray mineral trioxide aggregate. Empty tubes served as controls. Samples were harvested after 7-, 15-, 30-, 60-, and 90-days. All pathologists examined the sections under a light microscope (Carl Zeiss, Oberkochen, Germany) at ×400 magnifications. Chi-Square test was used to evaluate the difference between inflammation grades when one pathologist used two methods. Cohen's Kappa value was used to measure agreement of three pathologists to recognize the degrees of inflammations when using one of the methods. RESULTS: There were no significant differences between the two methods when one of the pathologist used these methods to report the degree of inflammation (p=0.054). However, two other pathologists reported significant differences between two methods (p=0.005, p=0.001). In the FDI method, there was an acceptable agreement between first and second, and first and third pathologist in terms of the degree of inflammation, and intermediate agreement existed between the second and third pathologist. With the Cox method, no agreement among the pathologists could be found. CONCLUSION: The results of three pathologists in terms of rating inflammation with the FDI method showed better agreement than with the Cox method. Therefore, FDI method is more reliable than the Cox method to evaluate inflammation.