Effect of two different tooth bleaching techniques on microhardness of giomer

Tooth bleaching is a safe and conservative treatment modality to improve the esthetic appearance of discolored teeth. One of the problems with the use of bleaching agents is their possible effect on surface microhardness of resin-based materials. The present study was carried out to evaluate the effect of in-office and at-home bleaching on surface microhardness of giomer. Seventy-five disk-shaped giomer samples (Beautifil II) were prepared and cured with a light-curing unit. The samples were randomly assigned to three groups (n=25). In group 1 (control), the samples were stored in distilled water for 14 days. The samples in groups 2 and 3 underwent a bleaching procedure with 15% carbamide peroxide (CP) (8 hours daily) and 45% CP (30 minutes daily), respectively, for 14 days. Finally, the microhardness of samples was measured with Vickers hardness tester using a 100-g force for 20 seconds. One-way ANOVA was used to compare the mean microhardness values among the study groups, followed by post hoc Tukey test for two-by-two comparison of the groups. Statistical significance was set at P<0.05. One-way ANOVA showed significant differences in the mean microhardness values among the study groups (P<0.001). Based on the results of Tukey test, microhardness in the bleached groups was significantly less than that in the control group (P<0.0005). In addition, microhardness in the 45% CP group was significantly less than that in the 15% CP group (P<0.0005). Use of both bleaching agents during in-office and at-home bleaching techniques resulted in a decrease in surface microhardness of giomer. The unfavorable effect of in-office bleaching (45% CP) was greater than that of at-home bleaching (15% CP)

Synthesis and characterization of two novel antibacterial dendritic methacrylate-based dental monomers

This study explores the synthesis and characterization of two novel antibacterial dendritic methacrylate-based dental monomers. For this purpose, two dendritic esters have been synthesized via condensation reaction and then reacted with methacryloyl chloride to afford methacrylate-end caped dendritic esters. These compounds are subsequently converted to quaternary ammonium fluoride monomers (QAFMs) with decyl substituted side chain to produce two novel antibacterial dendreticdental monomers. The chemical structures of synthesized samples have been characterized using Fourier transform infrared (FTIR) and proton nuclear magnetic resonance (1H NMR) spectroscopies.The obtained monomers can be used to replace 2,2-bis[4-(2-hydroxy-3-methacryloyloxypropyl)-phenyl]propane (Bis-GMA) as the base monomer of universal resin-based dental composites in the presence of a diluting monomer (e.g.,triethyleneglycoldimethacrylate; TEGDMA), mainly due to their superior characteristics such as multifunctionalities as well as antibacterial activities

Synthesis and characterization of two novel antibacterial dendritic methacrylate-based dental monomers

504-513This study explores the synthesis and characterization of two novel antibacterial dendritic methacrylate-based dental monomers. For this purpose, two dendritic esters have been synthesized via condensation reaction and then reacted with methacryloyl chloride to afford methacrylate-end caped dendritic esters. These compounds are subsequently converted to quaternary ammonium fluoride monomers (QAFMs) with decyl substituted side chain to produce two novel antibacterial dendreticdental monomers. The chemical structures of synthesized samples have been characterized using Fourier transform infrared (FTIR) and proton nuclear magnetic resonance (1H NMR) spectroscopies.The obtained monomers can be used to replace 2,2-bis[4-(2-hydroxy-3-methacryloyloxypropyl)-phenyl]propane (Bis-GMA) as the base monomer of universal resin-based dental composites in the presence of a diluting monomer (e.g.,triethyleneglycoldimethacrylate; TEGDMA), mainly due to their superior characteristics such as multifunctionalities as well as antibacterial activities

Effect of hemostatic agent on marginal gaps of class V giomer restorations

Contamination of dentin with hemostatic agents might exert a deleterious effect on adhesive procedures on dentin. The present study was undertaken to investigate the effect of aluminum chloride hemostatic agent on marginal gaps in Cl V giomer restorations. Fifty sound bovine permanent incisors were selected for the purpose of this in vitro study and Cl V cavities were prepared on their buccal surfaces; the gingival margins of the cavities were placed in dentin. The tooth samples were randomly assigned to two groups (n=25). The samples in groups 1 and 2 underwent a restorative procedure without and with the application of aluminum chloride hemostatic agent in the cavity, respectively, before application of the adhesive. BeautiBond one-step self-etch adhesive and Beautifil II giomer restorative material were used for the restoration of the cavities in both groups. The samples were thermocycled and sectioned, followed by measuring the gap sizes at gingival margins in µm under a stereomicroscope. The marginal gaps were compared with Mann-Whitney U test. Statistical significance was set at P<0.05. The results showed significant differences in the mean marginal gaps between the two groups under study (P<0.001); the mean marginal gaps were higher in group 2 (with hemostatic agent) compared to those in group 1 (without hemostatic agent) (P<0.0005). Contamination with aluminum chloride hemostatic agent in giomer restorations gave rise to higher gingival margin gaps

Effect of disinfecting the cavity with chlorhexidine on the marginal gaps of Cl V giomer restorations

Considering the effect of cavity disinfecting agents on the bonding and sealing ability of restorations bonded to dentin, the aim of this study was to evaluate the effect of chlorhexidine (CHX) disinfecting agent on the marginal gaps of Cl V giomer restorations. Cl V cavities were prepared on the buccal surfaces of 60 sound bovine permanent incisors in this in vitro study, with the occlusal and gingival margins in enamel and dentin, respectively. The teeth were randomly divided into two groups (n=30). The teeth in groups 1 and 2 were restored without and with the use of the disinfecting agent in the cavity, respectively, before applying the adhesive. BeautiBond one-step self-etch adhesive and Beautifil II giomer were used to restore the cavities in both groups. After thermocycling and sectioning of the samples, the sizes of marginal gaps at gingival margins were measured in µm under a stereomicroscope. Mann-Whitney U test was used to compare marginal gaps at P<0.05 level of significance. The means of marginal gaps were significantly different between the two study groups (U=180, P<0.001), with higher means of marginal gaps in group 2 (with CHX disinfection) compared to group 1 (without CHX disinfection) (P<0.0005). Application of CHX for the disinfection of cavities in giomer restorations resulted in an increase in gingival margin gaps

Effect of Different Luting Cements on Fracture Resistance in Endodontically Treated Teeth

INTRODUCTION: The aim of the present study was to evaluate the effect of three types of luting cements used for post cementation on the fracture resistance of endodontically treated maxillary premolars, restored with resin composite. MATERIALS AND METHODS: One hundred intact single-rooted human maxillary premolars were randomly divided into 5 groups of 20 each. In groups 2-5, post spaces were prepared after root canal treatment and clinical crown reduction up to 1.5 mm above the CEJ. Teeth were divided in groups as follows: Group 1: intact teeth, Group 2: active prefabricated metallic posts (PMP), Group 3: PMP cemented with zinc phosphate luting cement, Group 4: PMP cemented with glass ionomer luting cement and Group 5: PMP cemented with resin luting cement. In groups 2-5 the teeth were restored with resin composite. Following thermocycling, the palatal cusp of each specimen was loaded to compression at an angle of 150˚ to its longitudinal axis at a strain rate of 2 mm/min until fracture occurred. Data were analyzed using one-way ANOVA and a post hoc Tukey test. Chi-square test was used for comparison of failure mode. RESULTS: There were significant differences in fracture resistance between the test groups (P&lt;0.001). The differences between group 2 with groups 1, 4 and 5 were statistically significant (P&lt;0.05); whereas there were no significant differences in fracture resistance between the two other groups (P&gt;0.05). Furthermore, there were no significant differences in the mode of failure between the 5 groups (P&gt;0.05).  CONCLUSION: Zinc phosphate, glass ionomer and resin luting cements showed similar behaviors and achieved fracture resistance comparable to intact teeth. However, the use of active post (without cement) adversely affected the fracture resistance of root canal treated teeth

Effect of calcium hydroxide dressing on microleakage of composite restorations in endodontically treated teeth subsequent to bleaching

Objective: This study evaluates the effect of calcium hydroxide dressing on microleakage of composite restorations following non-vital bleaching. Methods: A total of 45 sound extracted human maxillary central incisors underwent endodontic treatment. The teeth were randomly divided into three groups (n=15). In group 1, access cavities were restored with composite. In group 2, the teeth underwent a bleaching procedure for one week before being restored with composite. In group 3, following a bleaching procedure, calcium hydroxide paste was placed in the pulp chamber for one week. The teeth were then restored with composite. The specimens were subjected to a dye leakage test. The data was analyzed using Kruskal-Wallis and Mann-Whitney U tests. Results: There were significant differences between the groups (P<0.0005). No statistically significant differences were found between groups 2 and 3, while the differences between other groups were significant. Conclusions: The bleaching agent increased microleakage of composite restorations in non-vital bleaching, whereas microleakage was not found to be increased by calcium hydroxid

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 aluminum chloride hemostatic agent on microleakage of class V composite resin restorations bonded with all-in-one adhesive

Objectives: Since hemostatic agents can induce changes on enamel and dentin surfaces and influence composite resin adhesion, the aim of the present study was to evaluate the effect of the aluminum chloride hemostatic agent on the gingival margin microleakage of class V (Cl V) composite resin restorations bonded with all-in-one adhesive. Study design: Cl V cavities were prepared on the buccal surfaces of 60 sound bovine permanent incisors. Gingival margins of the cavities were placed 1.5 mm apical to the cemento-enamel junction (CEJ). The teeth were randomly divided into two groups of 30. In group 1, the cavities were restored without the application of a hemostatic agent; in group 2, the cavities were restored after the application of the hemostatic agent. In both groups all-in-one adhe sive and Z250 composite resin were used to restore the cavities with the incremental technique. After finishing and polishing, the samples underwent a thermocycling procedure, followed by immersion in 2% basic fuschin solution for 24 hours. The samples were sectioned and gingival microleakage was evaluated under a stereomicroscope. The non-parametric Mann-Whitney U test was used to compare microleakage between the two groups. Statistical significance was defined at P<0.05. Results: A statistically significant difference was observed in microleakage between the two groups (P<0.001). Conclusions: Contamination of Cl V composite resin restorations bonded with all-in-one adhesive with aluminum chloride hemostatic agent significantly increases restoration gingival margin microleakage

Effect of three prophylaxis methods on surface roughness of giomer

Objectives: Plaque and stains are removed by prophylaxis methods from tooth surfaces. Since prophylaxis methods can have a detrimental effect on the surface finish of restorations, the aim of this in vitro study was to investigate the effect of three prophylaxis methods, including pumice with rubber cup, pumice with brush, and air-powder polishing device (APD) on the surface roughness of giomer. Study design: Sixty four cylindrical giomer (Beautifil II, Shofu) samples with a diameter of 6 mm and a height of 2 mm were used. Subsequent to a 3-month period of storage in distilled water at 37ºC, the samples were randomly divided into four groups of 16. In group 1 (control), no prophylaxis procedure was carried out. In groups 2 to 4 the samples were exposed to pumice with rubber cup, pumice with brush, and APD prophylaxis methods, respectively. The surface roughness of the samples was measured using a profilometer and the effect of different prophylaxis methods on surface topography was characterized by atomic force microscopy (AFM). All data were analyzed by one-way ANOVA and Duncan?s post hoc test at a significance level of P < 0.05. Results: There were statistically significant differences in surface roughness among the groups (P < 0.0005). Furthermore, in pairwise comparisons there were statistically significant differences between all the groups (P < 0.05). The roughest surfaces, in descending order, were observed with the use of APD, pumice with brush, and pumice with rubber cup. Conclusions: The use of different prophylaxis methods resulted in an increased surface roughness of giomer compared with the control group. APD prophylaxis exerted the most detrimental effects on the surface of giomer