Objective The objective of this study was to evaluate the root canal morphology of third molars in the Bosnia-Herzegovina population. Materials and methods A total of 241 extracted third molars (105 maxillary and 136 mandibular) were subjected to a clearing procedure. The specimens were categorized into ten groups based on the Alavi classification for maxillary third molars (MaxTMs), and six groups were based on the Gulabivala classification for mandibular third molars (ManTMs). Root canal type according to the Vertucci classification, the presence and position of lateral canals, and intercanal communication were analyzed using a stereomicroscope x15. Results MaxTMs had three roots in 77.13% of the samples. Among MaxTMs, the most common morphology was three fused roots (33.33%) and Vertucci’s type VIII (54. 28% of samples in Alavi’s Group IV). 60.29% of ManTMs have two separate roots (Gulabivala's Groups II and III). The most prevalent types in mesial roots were type I (41.46% in Group II) and type IV (48.78% in Group III), although type I predominated in distal roots (91.24% and 100% in Groups II and III, respectively). Conclusion Single-rooted third molars usually have a root canal morphology that is more favorable for endodontic treatment. In contrast, third molars with fused roots often have more complex root canal morphology.

The study explores the polymicrobial nature of primary endodontic infections using Illumina Next Generation Sequencing. Samples involved in research have been collected from root canals of the patients suffering from pulp and periapical inflammations with no history of endodontic interventions on affected teeth. The study revealed prevalence of different bacterial phyla, classes, orders and species. Further work will show potential correlations between individual microbiotas and clinical diagnosis.

Introduction: Composite materials may be exposed to chemicals in food and beverages in the oral cavity, which can lead to changes in surface roughness. The aim of this in vitro study was to evaluate the surface roughness of two restorative materials after exposure to coffee and green tea followed by a dental bleaching procedure. Methods: For nanofilled composite and microhybrid composite, 15 samples each were fabricated. Five specimens from each composite were stored in instant coffee and green tea for 4 h a day. After 30 days of immersion, specimens received dental at-home bleaching, using 16% carbamide peroxide (CP), for 7 h a day. The control group was stored in deionized water for 30 days. Surface roughness was determined by profilometry 24 h after polymerization, after 30 days of immersion, and after bleaching. The data were analyzed using a t-test for paired samples and mixed analysis of variance, at a 0.05 significance level. Results: Neither beverages nor CP treatment significantly altered the surface roughness of the composites. There was no difference between the tested composite materials regarding roughness. Conclusion: Surface roughness of the microhybrid and nanohybrid composites was not modified by coffee, green tea, and subsequent whitening treatment.

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.

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.

OBJECTIVES The goal of this study was to determine the sealing ability of MTA, Biodentine, and Fuji IX as root-end materials after ultrasonic retrograde preparation using a dye penetration method. MATERIALS AND METHODS Seventy permanent anterior teeth were used in this study. Root canals were prepared using rotary endodontic files, and obturated using the lateral condensation technique. The resection of the root apices was performed perpendicularly to the long axis, and 3 mm deep retrocavities were made by ultrasonic tips. The samples were randomly divided into three experimental groups (N=20) and two control groups (N=5). The root-end cavities were filled with mineral-trioxide aggregate (Rootdent MTA, TehnoDent, Russia) in Group 1, Biodentine (Septodont, Saint Maur des Fossés, France) in Group 2 and Fuji IX GP (GC Corporation, Tokyo, Japan) in Group 3. The retrocavities of the positive control group were left unfilled, while retrocavities in the negative control group were sealed using a flowable composite material. The samples were made transparent, and dye penetration was assessed under a stereomicroscope (x10). The data were analyzed with the Kruskal-Wallis test and the Mann-Whitney U-test. RESULTS The Biodentine group had a lower mean leakage value than the MTA and Fuji IX groups, and the difference was statistically significant (P<0.01). No statistical difference in apical microleakage was found between the MTA and Fuji IX groups (P>0.05). CONCLUSION Within the limitations of this study, it was concluded that Biodentine provides better sealing ability as a root-end material than MTA and Fuji IX. There was no statistically significant difference between the sealing ability of MTA and Fuji IX as root-end materials.

s of the 4th International Congress of the Department of Endodontics and Restorative Dentistry, School of Dental Medicine, University of Zagreb in coorganizing the Croatian Society for Minimal Interventional Dental Medicine CMA October 23-24, 2020, Zagreb, Croatia Sinergija znanosti i kliničkog rada Sažetci IV. kongresa s međunarodnim sudjelovanjem Zavoda za endodonciju i restaurativnu stomatologiju Stomatološkog fakulteta Sveučilišta u Zagrebu u suorganizaciji Hrvatskog društva za minimalno intervencijsku dentalnu medicinu HLZ-a 23. i 24. listopada 2020., Zagreb, Hrvatska Voditeljice • Leader: Prof.dr.sc. Goranka Prpić Mehičić Prof.dr.sc. Ivana Miletić Organizacijski odbor • Organizational board: Prof.dr.sc. Goranka Prpić Mehičić Prof.dr.sc. Ivana Miletić Izv.prof.dr.sc. Anja Baraba Znanstveni odbor • Scientific board: Prof.dr.sc. Silvana Jukić Krmek Prof.dr.sc. Zoran Karlović Izv.prof.dr.sc. Jurica Matijević Urednici knjige sažetaka • Editors of Book of

Objective : The aim of this study was to investigate the impact of inflammation on expression of MMP-2 and MMP-9, as well as to identify the cellular sources of these enzymes in human dental pulps using immunohistochemistry. Methods : Fifty-four irreversibly inflamed samples of dental pulp were used as the experimental group. Fifty-one healthy pulps, obtained from teeth extracted for orthodontic reasons, were used as the control group. The tissue samples were formalin-fixed, paraffin-embedded, and cut into sections at 3- 4 μm. An immunohistochemical study was performed using monoclonal antibodies against MMP-2 and MMP-9. Evaluation of the immunohistochemical expression was determined by the semi-quantitative method and scored as follows: no staining (score 0), less than 10% of stained cells (score 1), less than 30% of weakly stained or strongly but incompletely stained cells (score 2), and more than 30% of strongly and completely stained cells (score 3). Results : Immunohistochemical analysis revealed a significantly greater expression of MMP-9 in inflamed than in healthy dental pulps (Mann–Whitney U, p=0.0001). In contrast, there was no difference in the expression of MMP-2 between these two groups (Mann–Whitney U, p=0.907). MMP-2 and MMP-9 immunoreactivity was detected the most frequently in endothelial cells. Conclusions : MMP-9 is highly overexpressed in inflamed dental pulps. There are no differences in the expression of MMP-2 between healthy and inflammed dental pulps. Endothelial cells represent the major cellular source of MMP-9, as well as MMP-2, in healthy and inflamed dental pulps. Keywords : dental pulp, inflammation, MMP-2, MMP-9, immunohistochemistry

Aim: The aim of this study was to compare time of preparation and canal aberrations in a simulated root canals after using three different rotary systems: Endostar E5, Endostar E3 and T One File Gold. Materials and Methods: A total of 90 endodontic training blocks were used in this study and divided into three groups consisting of 30 each (n = 30). Blocks processing was performed by thirty dentists without any prior experience in rotary instrumentation techniques. In the first group blocks were prepared using Endostar E5, in second one with Endostar E3 and in third one with T One File Gold system. The preparation time was measured. The postoperative image of each block was taken by stereomicroscope and canal aberrations (ledge and instrument fracture) was recorded. Statistical analysis was done by SPSS software. Results: Instrumentation with T One File Gold system is significantly faster compared to instrumentation with Endostar E5 and Endostar E3 systems (p <0.05). There are no statistically significant differences in the type and number of procedural errors between Endostar E5, Endostar E3 and T One File Gold systems when the operators have no previous experience in rotary instrumentation techniques. Conclusion: Under the conditions of this study, the incidence of examined canal aberrations were similar for all tested systems. The preparation time was significantly shorter with single file system.

Objective: The present study aims to investigate the influence of presence and shape of cervical lesions on biomechanical behavior of mandibular first premolar, subjected to two types of occlusal loading using three-dimensional (3D) finite element method (FEM). Materials and Methods: 3D models of the mandibular premolar are created from a micro computed tomography X-ray image: model of sound mandibular premolar, model with the wedge-shaped cervical lesion (V lesion), and model with saucer-shaped cervical lesion (U lesion). By FEM, straining of the tooth tissues under functional and nonfunctional occlusal loading of 200 (N) is analyzed. For the analysis, the following software was used: CTAn program 1.10 and ANSYS Workbench (version 14.0). The results are presented in von Mises stress. Results: Values of calculated stress in all tooth structures are higher under nonfunctional occlusal loading, while the functional loading is resulted in homogeneous stress distribution. Nonfunctional load in the cervical area of sound tooth model as well as in the sub-superficial layer of the enamel resulted with a significant stress (over 50 [MPa]). The highest stress concentration on models with lesions is noticed on the apex of the V-shaped lesion, while stress in saucer U lesion is significantly lower and distributed over wider area. Conclusion: The type of the occlusal teeth loading has the biggest influence on cervical stress intensity. Geometric shape of the existing lesion is very important in the distribution of internal stress. Compared to the U-shaped lesions, V-shaped lesions show significantly higher stress concentrations under load. Exposure to stress would lead to its progression.