Effect of self-etching primer/adhesive and conventional bonding on the shear bond strength in metallic and ceramic brackets

Introduction: Bracket debonding from the tooth surface is a common problem in fixed orthodontics. The aims of the present study were to assess the bond strength and failure sites in two ways of bonding technique, with metallic and ceramic brackets. Materials and Methods: One hundred premolars were assigned to 4 groups of 25each: Group A, metallic brack-Methods: 255 GGroup brackets/ conventional procedure; B, metallic brackets/Transbond XT; C, ceramic brackets/conventional procedure; and D, ceramic brackets/Transbond XT. Transbond XT composite paste was used for bracket bonding and cured by conventional light-cure device. Specimens were subjected to thermocycling. One week after bonding shearing force was applied to the bracket-tooth interface. Bonding failure site optically examined using a stereomicroscope under 10 × magnifications and scoring was done using the adhesive remnant index (ARI). Data were subjected to analysis of One-way variance, Tukey post hoc, Chi-square and Spearman's tests. Results: Mean bond strength (in MPa) were: group A=9.2, group B=8.55, group C=6.2 and group D=55.7. Bond strength differences between groups A and B, and between C and D were not significant, (p<0.0005). Insignificant difference found in ARI in all groups. Conclusion: The bond strengths of metallic brackets were significantly higher than ceramic ones and the self-etching primer produce fewer bonds than the conventional method (clinically acceptable). A positive correlation found between changes in shearing bond strength and ARI. © Medicina Oral S. L

Effect of Different Adhesive Systems on Microleakage at the Amalgam/Composite Interface

Introduction: Ditching and marginal defects of amalgam restorations can cause microleakage, recurrent carries, pulp hypersensitivity and finally loss of the tooth. The complete replacement of large restoration is time consuming, difficult and may potentially damage the pulp. Therefore in cases were there is no sings of recurrent caries, composite repair can be chosen as an alternative. The purpose of this study was to compare the effect of different bonding agent application on microleakage between flowable composite & amalgam. Methods and Materials: Standard calss V amalgam preparations were prepared on 60 carries free premolars and the cavities were filled using amalgam. After 24 hours, a 1 mm cavity on the occlusal margin of the class V restorations was prepared and specimens were divided randomly into four treatment groups: First group was filled with flowable composite and Single bond. Second group was filled with flowable composite and SE bond. Third group was filled with flowable composite and Prompt-L-pop. Fourth group Was filled with flowable composite without denting bonding agent. Specimens were thermocycled and sealed with fingernail polish except the composite-amlagam interface, then immersed in basic fuchsine for 24 hours. Specimens were sectioned and microleakage was assessed. The data were analyzed using Kruskal-Wallis test and Mann-Whitney U test. Results: The results indicated that dentin bonding agent is effective in decreasing the degree of microleakage in amalgam-flowable composite interface and also the clearfil SE bond was more effective than Prompt-L-pop. But there was no significant statistical difference in microleakage between SE bond and Single bond. Conclusion: The application of dentin bonding agents in repair of amalgam retoration using flowable composite decreases microleakage but more researches should be performed

Fracture strength of mesiobuccal roots following canal preparation via hand and rotary instrumentation: An in vitro study

INTRODUCTION: The aim of this in vitro study was to compare the effect of hand and rotary instruments on fracture strength of tooth roots.MATERIALS & METHODS: Thirty two teeth were randomly divided into two experimental groups of 15 each and one negative control group with two samples. In group 1, step-back technique with conventional stainless steel K-files was used, and in group 2, instrumentation was performed using rotary Ni-Ti Hero642. Samples in control group did not received cleaning or shaping after access cavity preparation. After obturating each canal, tip of the spreader was locked within canal. The required force for root fracture was measured using Instron testing machine. Recorded data was statistically analyzed using t-test.RESULTS: The mean and standard deviation force required for vertical root fracture were 50.33±19.1 and 63.1±25.46 N for hand and rotary groups respectively. However, no significant difference was found between experimental groups.CONCLUSION: The results indicate that the manual technique did not lower fracture strength of obturated roots in comparison with the rotary preparation technique

Effect of triple antibiotic paste and calcium hydroxide as intracanal medicaments on bond strength of composite to dentin

Objective: Considering the use of triple antibiotic paste (TAP) for root canal treatment of open apex teeth, this study aimed to assess the effect of TAP and calcium hydroxide (CH) on bond strength of composite to dentin. Methods: This in-vitro study was conducted on 32 extracted human premolar teeth. After disinfection with 2% thymol solution, the enamel on the buccal surface of specimens was removed to expose a smooth dentin surface parallel to the long axis of the teeth with approximately 19mm2 surface areas. Specimens were divided into three groups of 11, 10 and 11 specimens. In group one, TAP, in group two CH and in group three, saline solution were applied to dentin surfaces for 14 days. After removal of medicaments, composite cylinders were bonded to the dentin surfaces using a bonding agent. Shear bond strength was measured in an Instron machine at a crosshead speed of 1mm/min. Data were analyzed using one-way ANOVA. Results: The highest mean bond strength belonged to the control group (14.4760 MPa) and the lowest belonged to the TAP group (11.5808 MPa). The mean bond strength in CH group was less than that of the control and higher than that of the TAP group (11.7834 MPa). However, the difference among the three groups was not statistically significant (p=0.327). Conclusion: Use of medicaments such as CH and TAP has no effect on bond strength of composite to dentin

Effect of triple antibiotic paste and calcium hydroxide as intracanal medicaments on bond strength of composite to dentin

Objective: Considering the use of triple antibiotic paste (TAP) for root canal treatment of open apex teeth, this study aimed to assess the effect of TAP and calcium hydroxide (CH) on bond strength of composite to dentin.Methods: This in-vitro study was conducted on 32 extracted human premolar teeth. After disinfection with 2% thymol solution, the enamel on the buccal surface of specimens was removed  to expose a smooth dentin surface parallel to the long axis of the teeth with approximately 19mm2 surface areas. Specimens were divided into three groups of 11, 10 and 11 specimens. In group one, TAP, in group two CH and in group three, saline solution were applied to dentin surfaces for 14 days. After removal of medicaments, composite cylinders were bonded to the dentin surfaces using a bonding agent. Shear bond strength was measured in an Instron machine at a crosshead speed of 1mm/min. Data were analyzed using one-way ANOVA.Results: The highest mean bond strength belonged to the control group (14.4760 MPa) and the lowest belonged to the TAP group (11.5808 MPa). The mean bond strength in CH group was less than that of the control and higher than that of the TAP group (11.7834 MPa). However, the difference among the three groups was not statistically significant (p=0.327).Conclusion: Use of medicaments such as CH and TAP has no effect on bond strength of composite to dentin

Effect of Triple Antibiotic Paste on Bond Strength of Composite to Dentin: An In Vitro Study

Background and Aim: Considering the increasing use of antibiotics in root canal therapy and the possible effects of intracanal medicaments on the bond strength of composite restorations, the aim of this study was to evaluate the effect of triple antibiotic paste (TAP) on shear bond strength of three types of composite resins to dentin. Materials and Methods: In this in-vitro, experimental study, the enamel of 60 extracted premolars was ground parallel to the longitudinal axis of the teeth in order to produce flat dentin surfaces (5 mm2 minimum surface area). The samples were divided into six groups. In the control group, dentin surfaces were stored in saline solution and in the experimental groups dentin surfaces were exposed to TAP for 10 days. After washing and drying, Single Bond was applied for dentin bond to Z100 and Z350 composites. Adhesive resin was used for bond to P90 composite. Composites were applied on the dentin surfaces in six groups and cured in four directions. The shear bond strength was measured by Instron machine. The data were analyzed by t-test, one-way ANOVA and Tukey’s test. Results: The highest mean shear bond strength was found in Z350 composite group following the use of TAP (38.75 MPa) and the lowest mean strength was found in Z100 composite group following the use of TAP (14.64 MPa). The mean shear bond strength of P90 and Z100 composites (in contrast to Z350 composite) was higher in the saline compared to the TAP groups (p=0.1). The differences between saline and antibiotic groups were not significant (p=0.959) but the difference in this regard among the three types of composites was significant. Conclusion: The results of this study showed that use of TAP has no effect on the shear bond strength of composite to dentin but the type of composite significantly affects the shear bond strength

Effect of food simulating liquids on the flexural strength of a methacrylate and silorane-based composite

<div><p>Objective</p><p>The purpose of this study was to assess the effect of food-simulating liquids on the flexural strength of a methacrylate-based and a silorane-based resin composite.</p><p>Materials and methods</p><p>In this in vitro study, sixty specimens of Filtek P90 and Filtek Z350 composite were prepared in a customized mold (2 × 2 × 25 mm). The specimens of each composite were divided into five subgroups as follows: one as a control group and the other four groups included distilled water, heptane, 2% citric acid, and 50% aqueous ethanol. The specimens were stored in the solutions for one week at 37°C, and the control group was stored at room temperature for the same period of time. Then, flexural strength values were measured. The statistical analysis was performed by One-Way ANOVA, Paired T test and post hoc LSD at a significance level of 0.05.</p><p>Results</p><p>In the control group, the mean flexural strength of Filtek P90 and Filtek Z350 were 155.1 MPa and 147.3 MPa, respectively, and there was no significant difference (P-value>0.05). The mean flexural strength of Filtek P90 and Filtek Z350 significantly decreased in ethanol (P-value <0.05). Immersion in 0.02 N citric acid and heptane had no significant effect on the flexural strength of Filtek P90 and Filtek Z350. The maximum flexural strength of Filtek P90 was in the heptane group (192.6 MPa) and minimum flexural strength was in ethanol group (92.7 MPa) the maximum flexural strength of Filtek Z350 was in the heptane group (163.2 MPa) and minimum flexural strength was in the ethanol group (104.7 MPa).</p><p>Conclusion</p><p>The flexural strength of tested resin composites significantly affected by ethanol solution. The flexural strength of resin composites was not affected by other food simulating liquids.</p></div

Mean flexural strength value for the tested materials.

<p>Mean flexural strength value for the tested materials.</p

Means (standard deviations) of flexural strength value [Mpa] for the materials tested.

<p>Means (standard deviations) of flexural strength value [Mpa] for the materials tested.</p

Composition of the materials tested.

<p>Composition of the materials tested.</p