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Background and Aims: Teaching practical skills is one of the most significant aspects of teaching medical students. The present study aims to compare the two methods of displaying the educational video and demonstration at the patient's bedside in teaching the correct technique of internal bleaching of endodontic teeth. Materials and Methods: Thirty dental students who were taking Theoretical Endo2 Course were equally divided into two groups according to their score of Theoretical Endol Course and the GPA of the previous years. After the theoretical training about internal bleaching of non-vital teeth, they received practical training in the form of demonstration at patient's bedside or by educational video. After that, students completed a survey questionnaire about the effectiveness of the educational method and an attitude and general satisfaction questionnaire. Also student's theoretical endo2 score for "internal bleaching" section were evaluated. The data were evaluated, analyzed, and compared using a T-test in different groups. P<0.05 was considered significant. Results: There was no significant difference between mean ages of the participants in two groups. Also there was no significant difference between their score in final exam. (P=0.541) No significant difference was observed between the attitudes of the students of the two groups of clinical educational videos and demonstration at the bedside (P=0.497). Also, no significant difference was observed between the two educational methods regarding the effectiveness indicators from the student's point of view (P>0.05). Conclusion: Due to the lack of significant difference between the method of training with a demonstration at the patient's bedside and video, it seems that the method of video can be considered as a method along with conventional method but not as a substitute for them. [ABSTRACT FROM AUTHOR]

Background and Aim: This research examines the effect of two antioxidants, pomegranate peel extract, and green tea, on the shear bond strength of microhybrid composite on bleached enamel using sixth-generation bonding. Materials and Methods: 44 premolar teeth were used in this study. The samples were divided into 4 groups, Group A: composite restoration without previous bleaching treatment. Group B: Restoration of teeth immediately after bleaching treatment. Group C: Bleaching treatment, then using 5% green tea extract as an antioxidant on the tooth surface, followed by tooth restoration. Group D: Bleaching treatment, then using 5% pomegranate peel extract as an antioxidant on the tooth surface, followed by tooth restoration. For the restoration, the 6th generation Bond SE (Kuraray Dental, Japan) and micro-hybrid composite (3M ESPE, USA) Filtek Z250 were used. To measure the strength of the shear band, the Zwick universal testing machine (Berlin, Germany) was used, and at the end, the types of failure were examined using a stereomicroscope. Calculations were done using PASS II and SPSS 25 software, OneWay ANOVA, Tukey, and homogeneity of variance tests. Results: No significant difference was observed between groups A, C, and D (P>0.99), but between these groups and group B, the amount of shear band strength was significantly different (P<0.001). Conclusion: The use of 5% pomegranate peel extract and green tea increases the shear bond strength of composite to bleached teeth. [ABSTRACT FROM AUTHOR]

Background and Aims: The white color of teeth is one of the most essential factors in smile esthetics. Therefore, various whitening agents such as bleaching mouthwashes have been produced in response to the people’s high demand for having whiter teeth. The present study evaluated the efficacy of three whitening mouthwash products on tooth enamel whiteness. Materials and Methods: In the present in vitro study, 32 bovine incisors were assigned to four groups in terms of the mouthwash used (n=8): control (C); Xenon Smart White (ZSW), containing pyrophosphate and triphosphate; Signal White Now (SWN), containing Blue Covarine; and Pasta Del Capitano whitening mouthrinse (PCW), containing Plasdone. Colorimetry was carried out using a spectrophotometer at the baseline and 2, 4, 8, and 12 weeks after treatment with mouthwashes. Data were analyzed using CIELab parameters with ANOVA, RM two-way ANOVA, and post hoc Tukey tests (α=0.05). Results: The results showed that the whiteness created by the SWN mouthwash was clinically visible (ΔE>3.3). However, the functions of all the mouthwashes were statistically similar with no significant differences from the control group (P>0.05). Conclusion: Although, Blue Covarine-containing mouthwash was somewhat effective in whitening of tooth enamel, none of the mouthwashes had significant efficacy compared to distilled water. [ABSTRACT FROM AUTHOR]

Background and Aim: One of the most noticeable problems of composite restorations is color change of them over the time Due to this the most important advantage of composites which is providing esthetic is gone, so restorations need to be changed.The purpose of this study is to evaluate the effect of aging on color stability of two types of Bleached shade composites. Materials and methods: In this in vitro study 10 disk shape samples of each two nanohybride composit es DBl XL( IPS Empress Direct,Ivoclar Vivadent, Schaan, Liechtenstein)and Ebl L( IPS Empress Direct,Ivoclar Vivadent, Schaan, Liechtenstein in same size werefabricated.The primary color assessment was done by spectrophotometer matched which CIEI*a*b.Samples were done by the 10000 cycles of aging process which was equal to 1 clinical year. and then had the final test with her spectrometer. The results were evaluated with one way Anova. Results: the color change wasn’t perceptible( p=0.136),while the difference in a* parameter between composites was perceptible and DBI was more than EBI.( p=0.000) The differences of b and ΔE parametres were not significant for two evaluated composites (p=0.377 and 0.136, respectively) Conclusion: .The color change of bleached shade enamel and dentin resin composites after aging was acceptable clinically. (ΔE ≥ 3/3). [ABSTRACT FROM AUTHOR]

Background and Aims: The bleaching agents can lead to color and translucency changes in composite resins. Due to the increasing use of the nano composites and the silorane-based composites, this study aimed at examining the color and translucency changes of these restorations after bleaching agents. Materials and Methods: In this experimental - laboratory study, 198 composite discs were divided into three groups of 66 specimens using three types of composite: the microhybrid composite Z250, the nanohybrid composite Z350 and the siloranebased composite P90. After acid etching, half of the specimens in each group were covered by a resin rebounding agent. Then, the color and translucency assessment was done by reflectance spectrophotometer, using CIE LAB system. Each group was divided into three subgroups of bleaching agents: the 40% hydrogen peroxide and 20% carbamide peroxide bleaching agents and the control group. After applying bleaching agents, the final color and translucency changes were assessed. Data were analyzed using Mann Whitney and Kruskal Wallis tests. Results: The effect of composite and bleaching agent type and bonding agent were significant (P<0.001). The color changes in the microhybrid composite were higher than nanohybrid and silorane-based composites (P<0.001) (ΔE>3.3). Also, the color changes by 20% carbamide peroxide were higher than that of hydrogen peroxide and control groups (P<0.001). The results of translucency changes were generally consistent with color-change measurements (ΔE>3.3). Conclusion: According to the present study, the most color changes appeared in the microhybrid composite and by 20% carbamide peroxide bleaching agent. Rebound samples were generally less affected by bleaching agents. The least color and translucency changes were related to nanohybrid composites. [ABSTRACT FROM AUTHOR]

Background and Aims: Bleaching agents not only affect the tooth structure, but also may alter the properties of restorative materials. The aim of this in vitro study was to evaluate the effect of different bleaching regimens on the microhardness of four tooth-colored restorative materials. Materials and Methods: Eighty specimens of four restorative materials (Microhybrid resin composite (Z250 (3M, ESPE), nanohybrid composite Z350 (3M, ESPE), packable composite P60 (3M, ESPE), and resin modified glass ionomer Vitremer (3M, ESPE)) were fabricated and were polished after 24 h with Soflex discs (3M,ESPE). Then the specimens were divided into two groups: In office bleach group, 40 specimens (10 of each restorative material) were bleached with hydrogen peroxide 37.5% for 30 min in two sessions with 7 days interval. In home bleaching group, 40 specimens were bleached with carbamid peroxide 22%, 6 h a day for 14 days. Vickers microhardness test were done before and after bleaching (baseline). Finally data were evaluated using analysis of Variance. Results: Two bleaching regimens were significantly decreased the microhardness values. In Z250 resin composite, the microhardness values before and after bleaching were 95.30 and 92.67 kg/mm2, respectively. for office bleaching (P=0.011) and 95.38 and 92.39 kg/mm2 for home bleaching (P<0.001). In Z350 resin composite, the microhardness values before and after bleaching were 98.29 and 92.41 kg/mm2, for office bleaching (P<0.001) and 97.35 and 93.44 kg/mm2 for home bleaching (P<0.001) respectively. In P60 resin composite, the microhardness values before and after bleaching were 103.10 and 96.16 kg/mm2, respectively. for office bleaching (P=0.045) and 102.61 and 98.16 kg/mm2 for home bleaching (P=0.001). In resin modified glass ionomer (Vitremer), the microhardness values before and after bleaching were 56.79 and 49.41 kg/mm2, respectively. for office bleaching (P=0.004) and 54.17 and 46.50 kg/mm2 for home bleaching (P<0.001). There was no significant difference between two bleaching agents (P=0.365). Conclusion: Dental bleaching agents decrease the microhardness of tooth-colored restorative materials. [ABSTRACT FROM AUTHOR]

Introduction: During application of bleaching materials, they may come into contact with existing amalgam restorations resulting in changes in amalgam structure. The aim of the present study was to evaluate the influence of rebonding and bleaching on the release of metallic ions and microstractures of admixed and spherical amalgams. Materials and Methods: This experimental in vitro study was performed on 96 Class V cavities (3.5 mm in length, 2 mm in width and depth) prepared on sound human premolars and restored with amalgams containing spherical and admixed particles. In half of the samples of each amalgam type rebonding procedure was carried out with Scotchbond Multi-purpose adhesive system and Guardian Seal resin sealant. Then half of the amalgam restorations, with or without rebonding, were exposed to 30% carbamide peroxide (n = 12). The amount of metallic ions released from amalgams was determined by atomic absorption spectrometry. Surface topography and compositions of two samples in each group were observed under a scanning electron microscope (SEM). Data were analyzed by t-test and multivariate ANOVA (α = 0.05). Results: 30% carbamide peroxide gel caused a significant increase in Hg released from amalgams in non-rebonded groups (p value < 0.001). There was no significant difference in ion release from spherical and admixed amalgams (p value = 0.73). Rebonding resulted in significant reduction in Hg release (p value = 0.007). Conclusion: Exposure of spherical and admixed amalgams to 30% carbamide peroxide gel, without rebonding, caused a significant increase in Hg release from amalgam and changed amalgam microstructure. [ABSTRACT FROM AUTHOR]