Abstract Objective  This study investigated biomechanical behavior of custom post core made of six different materials on the tooth with and without the ferrule under different occlusal load. Materials and Methods  Three-dimensional models of mandibular first premolar, with and without ferrule, reconstructed from micro-computed tomography image are restored with different custom post core and zirconia crowns. By using the finite element analysis, von Mises stress shown in MPa was measured under simulated axial and oblique load of 200 [N]. To compare the stress distribution, six different custom post core materials were chosen: zirconia, Ni-Cr alloy, gold alloy, glass fiber-polyether ether ketone, polyether ether ketone, and carbon fiber-polyether ether ketone. Results  Custom post cores with a higher modulus of elasticity showed higher measured stress in the posts, but less stress in dentin. Measured stress in custom post core under oblique loading was approximately three times higher compared with axial loading. Stress in custom post core and in dentin under both types of loads was slightly higher in teeth without ferrule effect. Conclusion  The use of custom cast post cores made of different alloys is recommended in restoration of endodontically treated teeth, with extensive loss of tooth structure especially in teeth without ferrule effect.

Introduction: Stress among students is a growing problem. As emotional stress increases, the limbic structures and hypothalamus are stimulated, activating the gamma efferent system, which ultimately leads to an increase in muscle tone or additional muscle activity that can become repetitive behaviors such as bruxism. The aim of the study was to investigate the stress level that students are exposed to, to determine the difference between students in terms of gender, faculty, and year of study, and to evaluate the possible relationship between stress level and self-reported bruxism in college students during the pandemic COVID-19. Methods: In April 2022, a cross-sectional study was conducted on a sample of students from the Faculty of Dentistry and the Faculty of Pharmacy at the University of Sarajevo (BiH). The students answered a questionnaire consisting of two parts: The first part contained questions on basic personal data and data on self-reported bruxism and the second part contained questions on the perceived stress scale (PSS). Results: The study included 756 students from both faculties. Analysis of stress levels among students revealed higher stress levels. Female students were more likely to be under stress than male respondents. Students in the Faculty of Pharmacy were more likely to be stressed than students in the Faculty of Dentistry. At the Faculty of Pharmacy, there was no difference in stress levels between the different years of study, while at the Faculty of Dentistry, the individual score for PSS was highest among 1st-year students. A high prevalence (46.8%) of self-reported bruxism was found among students in both faculties. Conclusion: A slight positive correlation between self-reported bruxism and stress suggests that it is important to implement stress management strategies during academic education and to prevent bruxism and its consequences.

(1) Background: This study evaluates the effect of a conventional/low-voltage light-curing protocol (LV protocol) (10 s with 1340 mW/cm2) and high-voltage light-curing protocol (HV protocol) (3 s with 3440 mW/cm2) on the microhardness (MH) of dental resin-based composites (RBCs). Five resin composites were tested: conventional Evetric (EVT), Tetric Prime (TP), Tetric Evo Flow (TEF), bulk-fill Tetric Power Fill (PFL), and Tetric Power Flow (PFW). (2) Materials and Methods: Two tested composites (PFW and PFL) were designed for high-intensity light curing. The samples were made in the laboratory in specially designed cylindrical molds; diameter = 6 mm and height = 2 or 4 mm, depending on the type of composite. Initial MH was measured on the top and bottom surfaces of composite specimens 24 h after light curing using a digital microhardness tester (QNESS 60 M EVO, ATM Qness GmbH, Mammelzen, Germany). The correlation between the filler content (wt%, vol%) and the MH of the RBCs was tested. For the calculation of depth-dependent curing effectiveness, the bottom/top ratio for initial MH was used. (3) Conclusions: MH of RBCs is more dependent on material composition than on light-curing protocol. Filler wt% has a greater influence on MH values compared to filler vol%. The bottom/top ratio showed values over 80% for bulk composites, while for conventional sculptable composites, borderline or suboptimal values were measured for both curing protocols.

Objectives The study aimed to compare the color stability of two different light-cured composites after immersion in three liquids and the effectiveness of 16% carbamide peroxide (CP) in removing the discoloration. Material and methods Color stability of a microhybrid (Z250, 3M ESPE) and nanocomposite (Z550, 3M ESPE) was evaluated after immersion in instant coffee, tea, Coca-Cola, and deionized water as a control group (n=5). Samples were kept in liquids for four hours daily at 37°C for 30 days. Furthermore, 16% CP was applied for the following 14 days, simulating night whitening. A digital spectrophotometer was used for color measurement based on the CIEL*a*b* color coordinates. The color changes (∆E) were measured at baseline, after immersion in the beverages, and also after the teeth whitening procedure. Mixed and factorial ANOVA followed by Bonferroni’s post-hoc test were used for statistical evaluation (p≤0.05). Results Tested resin composites showed a color change over the acceptability threshold (ΔE*> 3.48) after immersion in coffee and tea. Nanocomposite reported a significant increase in discoloration in coffee after 30 days (p <0.05). The color of both materials significantly changed (p<0.05) along all three L*a*b* axes in coffee and tea to darker, yellow, and red. Whitening with 16% CP was effective in removing external discoloration in both examined composite materials. Conclusion Coffee and tea induced clinically detectable color changes in dental composites tested, with cumulative effects. Whitening represents an efficient method for the removal of surface discoloration in composite restorations.

Abstract Objectives  The aim of the study was to analyze the occurrence of stress on teeth with abfraction lesions restored with six different restorative materials, and by introducing the tensile strength parameters to calculate the safety factor of the material under the load (ratio between the strength of the material and the maximum stress). Materials and Methods  Three-dimensional models of the mandibular premolar are created from a microcomputed tomography images. An abfraction lesion is modeled on the tooth. The stress of the dental tissues and six restorative materials under functional and nonfunctional occlusal loading of 200 (N) are analyzed by finite element method. Statistical Analysis  CTAn program 1.10 and ANSYS Workbench (version 14.0) were used for analysis. Results are presented in von Mises stress. Results  Oblique loads caused ≈ four times higher stress in restorative materials than the axial ones. It is noticeable that high values of von Mises stress are measured at the bottom of the sharp lesion, even up to 240 MPa, that are significantly reduced after the restoration. The highest stresses at the restorative material are present at the lower (gingival) margin of the restoration. The highest stresses under both types of loads are measured in nanohybrid composite (Tetric EvoCeram, Ivoclar Vivadent). The lowest values of the stress are measured in the flowable composite (Tetric Flow, Ivoclar Vivadent), but at the same time, the highest value of the stress is measured in the surrounding dental tissues on the tooth restored with the flowable composite. The microhybrid composite (Herculite XR, Kerr), with the highest safety factor, is the material that best withstands the stresses it is exposed to. The obtained safety factor did not exceed the critical limit, except for the glass ionomer cement, with the safety factor lower than 1. Conclusion  The type of tooth loading has the greatest influence on the intensity of stress. The value of the obtained stresses in the restorative material and dental tissues differ due to the different mechanical properties of the materials. Restoration of noncarious lesions significantly reduces extremely high stress values at their bottom.

OBJECTIVES To test the influence of a bleaching procedure using 16% carbamide peroxide (CP) on the colour of composite materials and their consecutive subjection to discolouration in beverages. MATERIALS AND METHODS Nanocomposite Z550 (3M ESPE) and the microhybrid Z250 (3M ESPE) composite materials were selected for the research. 16% CP was applied to composite plates (15 samples each material) for seven hours a day for 14 days simulating at-home nightguard vital bleaching. The test samples were then divided randomly into three sub-groups and submerged in instant coffee, green tea and Coca Cola for 30 days. The control group (N=5) samples were kept in deionized water. Determination of the L*a*b* dimensions of colour of the polymerized discs was performed by calibrated spectrophotometer 24 hours later, after the bleaching procedure, and on days 7, 15 and 30 after immersion in the beverages. RESULTS After application of 16% CP, there were perceptible changes in the colour of both test materials, which did not exceed the boundaries of acceptability (ΔE<3.48). Coca-Cola did not cause discolouration of the tested composites, but coffee and tea changed their colour above the level of perceptibility already seven days after immersion. A statistically significant difference in the change in colour was established between the materials when they were immersed in coffee (P<0.05). CONCLUSIONS 16% CP does not affect the basic colour of the composites. Immersion in a beverage led to an unacceptable change in the colour of both test materials in coffee and tea, primarily towards black. The greatest discolouration after bleaching was shown by Z550 when immersed in coffee.

Introduction: Perceptions of the esthetic appearance of teeth vary in different individuals and can affect satisfaction with the dental appearance, attitudes, and the need for appropriate dental treatment. The research aims to examine the factors influencing the satisfaction with the appearance of the dentition and the attitude toward treatments which improve dental esthetics among students of the faculty of dentistry in comparison to the attitudes of students of non-dental faculties.Methods: The research included a total of 358 students of the Faculty of Dentistry and Faculty of Architecture in Sarajevo who voluntarily filled out a questionnaire created for this research. The questionnaire contained questions related to satisfaction with the appearance of teeth in general, tooth color, tooth position, questions related to the previous, and future desired esthetic restorations and treatments.Results: Female subjects expressed statistically significantly greater dissatisfaction with the appearance of the dentition and did or plan to do treatments that could improve dental esthetics compared to male subjects. Students of the Faculty of Dentistry at final years were significantly more satisfied with the general appearance of teeth and tooth color compared to freshmen students of the Faculty of Dentistry and students of the Faculty of Architecture.Conclusion: Satisfaction with dental appearance is a subjective experience that is influenced by various factors, level, and type of education is among them.

OBJECTIVE To evaluate and compare the solubility of three luting cements in three different solutions: distilled water and artificial saliva with different pH values (7.4 and 3.0). MATERIALS AND METHODS Resin-modified glass-ionomer cement (GC Fuji Plus) and two resin cements (Multilink Automix and Variolink II) were used. A total of 45 specimens, 15 specimens (15x1 mm) for each cement, were prepared according to ISO standard 4049:2009. The solubility of the cements was calculated by weighing the specimens before and after immersion and desiccation. Values of solubility in water (Wsl) in microgram/mm3 for each of the five specimens were calculated using the following formula (ISO 4049:2009): Wsl=(m1-m3)/V. The Mann-Whitney U nonparametric statistical method and Post hoc sample comparisons were applied. RESULTS GC Fuji Plus showed statistically significant higher solubility in comparison with Variolink II and Multilink Automix in all three solutions. In acidic artificial saliva (pH 3.0) Multilink Automix showed significantly higher values of solubility compared to Variolink II (P<0.016). By studying the effect of pH value on the solubility of GC Fuji Plus cement, significantly higher values of solubility in pH 3.0 artificial saliva were confirmed (P<0.009). The influence of the surrounding pH value on the solubility of the resin cements Multilink Automix and Variolink II was researched. No statistically significant difference was found. CONCLUSION Solubility values were mainly influenced by the proportion of hydrophilic matrix, the type and composition of filler, and the pH value of the solutions.

OBJECTIVE To evaluate and compare the water sorption of three luting cements in three different solutions: distilled water and artificial saliva with different pH values (7.4 and 3.0). MATERIALS AND METHODS Resin-modified glass-ionomer cement (GC Fuji Plus) and two resin cements (Multilink Automix and Variolink II) were used. A total of 45 specimens - 15 specimens (15x1 mm) for each cement were prepared according to ISO standard 4049:2009. The water sorptions of the cements were calculated by weighing the specimens before and after immersion and desiccation. RESULTS . Nonparametric statistic methods were applied. GC Fuji Plus cement showed significantly higher values of water sorption in all three solutions of both resin cements (p<0.009) and significantly higher values of sorption in artificial saliva pH 3.0. Multilink Automix showed significantly higher values of water sorption compared with Variolink II in artificial saliva pH 7.4, and higher values of sorption in this solution compared with pH value 3.0. CONCLUSION Water sorption values are mainly influenced by the proportion of hydrophilic matrix, the type and composition of filler, and the pH value of solutions.

Objective: To check and compare the retenti on of cast posts cemented with three diff erent kinds of cement. Method: Forty fi ve 45 human permanent maxillary...