Comparison of Endodontic Medicaments on Bond Strength of Fiber Post to Root Dentin Using Resin Cement.

STATEMENT OF THE PROBLEM Endodontic irrigants and medicaments may affect the bond strength of intracanal posts to root dentin. PURPOSE The aim of this study was to compare the effect of calcium hydroxide (Ca(OH)2) and 2% chlorhexidine gel (CHX) on bond strength of fiber post cemented with resin cement to root dentin. MATERIALS AND METHOD This in vitro experimental study was conducted on 36 mandibular premolars. Canals were prepared using the step back technique. After root canal irrigation, the teeth were divided into three groups of 12. Ca(OH)2 paste and CHX gel were used as intracanal medicaments in the first and second groups respectively. No intracanal medicament was used in the third group (control group). Access cavities were then sealed and the teeth were incubated for one week. The root canals were then filled using gutta percha and AH26 sealer and the teeth were incubated for 72 hours. Tooth crowns were then cut at the level of the cementoenamel junction and intracanal posts were placed. The teeth were mounted in auto-polymerizing acrylic resin, and incubated for one week .They were then sectioned into 1.5mm thick slices from their coronal surface using a fully automated cutting machine, and subjected to push-out test until failure. The load at debonding was recorded and data were analyzed using one-way ANOVA, post-hoc test and t-test. The coronal margin of the root was at the level of the surface of acrylic resin in the mold. RESULTS The mean bond strength was 4.45 MPa in the Ca(OH)2, 2.45 MPa in the CHX and 2.48 MPa in the control group. The difference in this regard was statistically significant among groups (p= 0.04). The Ca(OH)2 group had significant differences with the CHX and control groups (p= 0.03 and p= 0.02, respectively). The difference between the CHX and control groups was not significant (p= 0.974). CONCLUSION Based on the results, Ca(OH)2 increased the bond strength of fiber post to root dentin but 2% CHX had no effect on bond strength

Comparison of coronal microleakage of resin modified glass ionomer and composite resin as intra-orifice barriers in internal bleaching

Introduction: Internal bleaching is a treatment option for wightening endodontically treated discolored teeth. Cervical resorption is one of the side effects of this method. The aim of this study was to compare the sealing ability of resin composite and light-cured resin modified glass ionomer (RMGI) as intra-orifice barriers in internal bleaching. Materials &Methods: In this study, 34 single-canal anterior teeth were used. All samples were endodontically prepared and divided into two experimental groups (n=12) and two control groups (n=5). In the experimental groups, Gutta-percha was removed up to 3 mm below the cemento enamel junction (CEJ). RMGI and composite resin was placed over gutta-percha in the experimental groups up to the level of CEJ. After 24-hours incubation period, the bleaching agent (a mixture of sodium perborate and 30% hydrogen peroxide) was placed in the access cavities. The bleaching agents were replaced every 3 days over 9 days. Then, the access cavity was filled with 2% methylene blue for 48 hours. All samples were longitudinally sectioned and the dye penetration range was evaluated using stereomicroscope. Data was statistically analyzed by using T-student test and variance analysis. Results: The microleakage in RMGI group was 0.945mm and in composite resin group was 0.641mm. Statistically, no significant difference was observed in microleakage between the experimental groups (p=0.121). Conclusion: Both materials can be applied as the intra-orifice barriers for internal bleaching

Evaluating the effect of dentin surface pretreatment on the static contact angle of a drop of a bonding agent: an in vitro study

Introduction: The aim of this study was to investigate the effect of dentinal pretreatment on the static contact angle of a bonding agent as a measure of dentin surface wettability. Materials &Methods: Twenty mid-coronal dentin surfaces were prepared and randomly allocated to four groups (n=5) according to the priming solutions. All segments were etched with 35% phosphoric acid gel for 15 s, rinsed for 30 s and dried. Each group was rehydrated with 10 µL of distilled water, 0.2 % chlorhexidine, 70% ethanol and 5.25% Sodium Hypochlorite respectively and the excess solution was removed after 60 sec using an absorbent paper. Using a micro syringe, a droplet of the Adper Single Bond 2 was placed on each prepared surface. Then the profile and the static contact angle of the droplet were analyzed with a video-based optical contact angle measuring system. The statistical analysis was performed using One-way ANOVA and Dunnett’s t tests (p<0.05). Results: There was a statistically significant difference between the water and sodium hypochlorite groups which indicates the negative effect sodium hypochlorite may have on dentinal surface energy. (p=0.013). The differences between the water and ethanol groups (p=0.168) and between the water and chlorhexidine groups (p=0.665) were not significant. Conclusion: The use of 5.25% sodium hypochlorite as a priming solution in bonding procedure is not recommended. There is no improvement in dentinal surface wettability by using 70% ethanol or 0.2% chlorhexidine instead of water and the recommendation for use of any of the two should be based on other long-term or short-term effects they may have on the bonding procedure

Assessment of micro-leakage for light-cure glass ionomer and pro-root mineral trioxide aggregate as coronal barriers in intracoronal bleaching of endodontically treated teeth

Introduction: Cervical root resorption is one of the most important complications of intra coronal bleaching. A way of preventing this type of resorption is using a coronal barrier under the bleaching materials. The aim of this study was to compare the sealing ability of glass ionomer cement and Pro Root Mineral Trioxide Aggregate (MTA) as a coronal barrier in intra coronal bleaching. Materials &Methods: In this study, 40 single-root maxillary anterior teeth were endodontically prepared and divided into two experimental groups (n= 15) and two positive and negative control groups (n=5). In the experimental groups, gutta percha was removed up to 3 mm below the cemento enamel junction (CEJ).RMGI and MTA were placed over gutta percha up to the level of CEJ. After a 24-hour incubation period, the bleaching agent (a mixture of sodium perborate and 30% hydrogen peroxide) was placed in the access cavities. The bleaching agents were replaced every 3 days over 9 days. Then, the access cavity was filled with 2% methylene blue for 48 hours. All samples were longitudinally sectioned and the dye penetration range was evaluated using a stereomicroscope. Data were statistically analyzed using Kruskal-Wallis and Mann–Whitney tests (α=0.05). Results: Leakage mean indicated that there was a significant difference between these two groups and leakage was less in ProRoot than glass ionomer. Conclusion: It seems that the MTA can provide a better coronal seal during the bleaching

The effect of chronic periodontitis on serum levels of tumor necrosis factor-alpha in Alzheimer disease

Background: Despite the outbreak in dental science, oral and dental complications in Alzheimer are of the unsolved problems. It is assumed that tumor necrosis factor-α, which is a key factor in Alzheimer, has a relation with periodontal complications in patients with Alzheimer disease. The present study evaluated the effect of chronic periodontitis on serum levels of tumor necrosis factor-α in Alzheimer disease. Materials and Methods: This case-control study was performed on 80 patients with Alzheimer disease seeking medical care at Nour Hospital, Isfahan, Iran. Eighty patients with Alzheimer disease between 40 and 70 years old attended this study. Forty had chronic periodontitis (case group), and 40 patients had healthy periodontium (control group). Blood sample was taken, and serum levels of tumor necrosis factor-α were measured by means of an ELISA Reader device. Independent T-Test was used to analyze data, and P < 0.05 was considered significant. Results: The mean of tumor necrosis factor-α was 749.1 ng/μL in case group and 286.8 ng/μL in control group. Independent t-test showed that the mean of tumor necrosis factor-α in patients with Alzheimer and periodontitis was approximately three folds higher than the patients only with Alzheimer, and this difference was statistically significant (P < 0.001). Conclusion: According to the results of this study, it seems that there is a difference between serum levels of tumor necrosis factor-α in patient with Alzheimer and chronic periodontitis and patients with Alzheimer disease and healthy periodontium. Tumor necrosis factor-α level in serum may act as a diagnostic marker of periodontal disease in patients with Alzheimer diseas

Effects ofOral Liquid Medicaments in Children on Shear Bond Strengthof Resin Composite in Primary Teeth

Due to the prevalence of the use of oral liquid medications in children with chronic diseases (asthma, heart problems, seizures and kidney problems) and also in children with transient diseases (influenza, colds, tonsillitis, ear infections, sinusitis and seasonal allergy) and due to the fact that several studies have shown that children’s' common medications affect topography and enamel structure, and composite bonding is dependent on enamel structure, the aim of this study was to investigate the effect of oral liquid medications used in children on composite bond strength to primary canine dental enamel.Materials & Methods:In this experimental-laboratory study, 90 teeth were divided into 9 groups, 8 drug groups and 1 control group (artificial saliva). Each group of 10 teeth was immersed 3 times a day for 1 minute in 10 ml of the desired drug. After 7 days and after 14 days, 5 teeth from each group were bonded with composite and their shear bond strengths were measured. Data were analyzed by one-way ANOVA, paired T-test and Pearson correlation coefficient tests. (α = 0.05).Results:In all groups, in comparison with the control group, the mean bond strength was not significantly different in the first and second weeks (p value > 0.05). Also, there was no significant difference between the mean composite shear bond strengths in each ofthe nine groups in the first and second weeks (p value > 0.05). Pearson correlation coefficient showed that there was no significant relationship between PH value with shear bond strength of composite in first weeks (p value = 0.53) and second (p value =0.83).Conclusion:Based on this study, short-term use (up to 14 days) of medications did not significantly change the shear bond strength of the composite to ename

Emdogain effect on gingival fibroblast adhesion in bioabsorbable and non-resorbable barrier membranes: An in vitro study

Background: Tissue engineering represents very exciting advances in regenerative medicine; however, periodontal literature only contains few reports. Emdogain (EMD) consists of functional molecules that have shown many advantages in regenerative treatments. This study investigated EMD effect on gingival fibroblast adhesion to different membranes. Materials and Methods: Two dense polytetrafluoroethylene membranes (GBR-200, TXT-200), Alloderm and a collagenous membrane (RTM Collagen) were used in this experimental study. Each membrane was cut into four pieces and placed at the bottom of a well in a 48-well plate. 10 μg/mL of EMD was added to two wells of each group.Two wells were left EMD free. Gingival fibroblasts were seeded to all the wells. Cell adhesion was evaluated by means of a Field Emission Scanning Electron Microscope after 24 hours incubation. Data was analyzed by independent t-test, one-way and two-way ANOVA and post hoc LSD test. P < 0.05 in independent t-test analysis and P < 0.001 in one-way ANOVA, two-way ANOVA and post hoc LSD analysis was considered statistically significant. Results: Alloderm had the highest cell adhesion capacity in EMD+ group and the difference was statistically significant (P < 0.001). In EMD- group, cell adhesion to TXT-200 and Alloderm was significantly higher than GBR-200 and collagenous membrane (P < 0.001). Conclusion: This study showed that EMD may decrease the cell adhesion efficacy of GBR-200, TXT-200 and collagenous membrane but it can promote this efficacy in Alloderm. It also showed the composition of biomaterials, their surface textures and internal structures can play an important role in their cell adhesion efficacy

The Effect of Three Irrigants on the Coronal Leakage of the Root Canals System Irrigants

INTRODUCTION: The production of smear layer during canal instrumentation is thought to increase coronal microleakage even after canal obturation. Previous studies have shown that the type of irrigant does not necessarily affect the seal of the obturation. Our study aimed to evaluate the effect of three irrigation solutions (MTAD, citric acid and EDTA/NaOCl) on the coronal microleakage of root canals. MATERIALS AND METHODS: Fifty five intact single rooted teeth were instrumented and randomly divided into three experimental groups (15 teeth each) and two control groups (5 teeth each). Final irrigation was carried out with MTAD in group I, citric acid in group II, and EDTA/NaOCl in group III. EDTA/NaOCl was used for the negative control group and saline irrigation was carried out in the positive control group. After lateral compaction with gutta-percha, the access cavities of the experimental specimens were restored with temporary restorative material. Temporary cement was not used in the positive control group. In the negative control group, access cavities and foramen apices were sealed with glass ionomer. Microleakage of samples was measured using the dye penetration technique. Data were analyzed with ANOVA and Tukey test to determine statistical differences between groups. RESULTS: MTAD, citric acid and EDTA/NaOCl all had less microleakage compared to normal saline. However, no difference was detected between the experimental groups. CONCLUSION: In this study, all three groups demonstrated effective seal with gutta-percha obturation. This is likely to be due to various factors including their ability to remove smear layer

Degree of Conversion of Metacrylate- and Silorane-based Dental Composites at Various Depths and Using Different Matrix Bands

Introduction:To improve the quality of tooth-colored restorations, various equipment and materials are being used. In this study, we sought to determine the degree of conversion of metacrylate- and silorane-based composites using transparent blue matrix strip at different depths. Materials and Methods: In this experimental-laboratory study, 48 specimens of methacrylate- and silylane-based composites were prepared in pre-made molds in thicknesses of 1, 2 and 3 mm. half of the specimens were cured with transparent polyester strips and the other half with blue strips, and then they were hardened by using a light-curing unit. The degree of conversion was determined by FT-IR. The degree of polymerization was assessed by comparing the IR absorption spectra between monomer and polymer specimens. The data were analyzed by performing Mann-Whitney and Kruskal-Wallis tests in SPSS. Results: The highest degree of conversion pertained to P90 composite with using transparent strip in 1 mm thickness (45.5±1.29), while the lowest degree belonged to Z350 composite with using transparent strip in 3 mm thickness (14.7±1.70). In comparison of the four groups, the silorane-based group with blue strip (41%) had the highest conversion degree, followed by the same composite (silorane) with transparent strip (39.6%). Conversion degrees in these types of materials were much greater than those in metacrylate-based types (21%). Conclusion: In deep restorations with limited access to a light source, the use of silorane-based composites and blue polyester strips enhances the degree of conversion

Effects of ethanol concentrations of acrylate-based dental adhesives on microtensile composite-dentin bond strength and hybrid layer structure of a 10 wt% polyhedral oligomeric silsesquioxane (POSS)-incorporated bonding agent

Background: The aim of this study was to assess for the first time the effects of different amounts of ethanol solvent on the microtensile bond strength of composite bonded to dentin using a polyhedral oligomeric silsesquioxane (POSS)-incorporated adhesive. Materials and Methods: This experimental study was performed on 120 specimens divided into six groups (in accordance with the ISO TR11405 standard requiring at least 15 specimens per group). Occlusal dentin of thirty human molar teeth was exposed by removing its enamel. Five teeth were assigned to each of six groups and were converted to 20 microtensile rods (with square cross-sections of 1 mm × 1 mm) per group. The “Prime and Bond NT” (as a common commercial adhesive) was used as the control group. Experimental acrylate-based bonding agents containing 10 wt% POSS were produced with five concentrations of ethanol as solvent (0, 20, 31, 39, and 46 wt%). After application of adhesives on dentin surface, composite cylinders (height = 6 mm) were bonded to dentin surface. The microtensile bond strength of composite to dentin was measured. The fractured surfaces of specimens were evaluated under a scanning electron microscope to assess the morphology of hybrid layer. Data were analyzed using one-sample t-test, one-way analysis of variance (ANOVA), and Tukey tests (α = 0.05). Results: the mean bond strength in the groups: “control, ethanol-free, and 20%, 31%, 39%, and 46% ethanol” was, respectively, 46.5 ± 5.6, 29.4 ± 5.7, 33.6 ± 4.1, 59.0 ± 5.5, 41.9 ± 6.2, and 18.7 ± 4.6 MPa. Overall difference was significant (ANOVA, P < 0.0001). Pairwise differences were all significant (Tukey P < 0.05) except those of “ethanol 0% versus 20%” and “20% versus 31%.” All groups except “0% and 46% ethanol” had bond strengths above 30 MPa (t-test P < 0.05). Conclusion: Incorporation of 31% ethanol as solvent into a 10 wt% POSS-incorporated experimental dental adhesive might increase the bond strength of composite to dentin and improve the quality and morphology of the hybrid layer. However, higher concentrations of the solvent might not improve the bond strength or quality of the hybrid layer