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Introduction: Determining age on posthumous dental remains is one of the forensically demanding procedures. By analyzing teeth, we can determine the age of unknown human remains, living people or archaeological dental remains. No method for determining age in adults is completely accurate and can give an approximate result ranging from 5 to 10 years. The introduction of infrared spectrometry with Fourier transformation in the analysis in this pilot study opens the possibility to add another method to the current forensic methods that could relatively quickly determine the dental age of an unknown human body. Materials and methods: A total of twenty tooth samples were used, which are part of the archive of the Department of Dental Anthropology, Faculty of Dentistry, University of Zagreb. The teeth were extracted, cleaned of blood and soft tissue residues, and disinfected in 2% H2O2 solution. After drying at room temperature, the teeth were embedded in quick-setting acrylate and cut into 0.5-1.1 mm thick cuts with a precision cutter. The samples were divided into five age groups: 10-19, 30-39, 40-49, 50-59, 60-69 years. Each group had 4 samples, each from a different person, different sex and different teeth. The samples were then placed in a spectrometer, and sampling was performed using attenuated total reflectance. A spectrum analysis of 400-4000 cm-1 in the area of tooth dentin was performed. As a control, the analysis of the acrylate spectrum was performed in order to eliminate possible contamination of the images. Results: After reducing the dimensionality of the spectrum by analyzing the main components of the spectrum and analyzing linear discriminants, no statistically significant difference between the absorption coefficients between groups (p> 0.05) was proven, but wherein the maximum values of absorption between groups the difference is observed. Wave numbers () 823, 1000, 1400, 1540 and 1650 cm-1 were isolated, with the largest increase in the absorption coefficient (present in all age groups). Differences in absorbance coefficients between groups for each of these wave numbers were tested by analysis of variance with post-hoc Holm-Šidak correction. The results showed a difference between groups 50- 59 and 60-69 at 873 cm-1. Conclusion: In this pilot study, there is a statistically significant difference between two of the 5 groups: 50–59 and 60–69 years. We conclude that it is necessary to increase the number of samples in order to obtain a statistically significant difference between other groups

Introduction: The aim was to investigate the effects of curing mode with a high-power LED curing unit in terms of shear bond strength (ISO 29022) of bulk composite bonded to dentin using universal adhesive. Materials and Methods: To create flat bonding substrates ; a mid-coronal section of tooth was made using a low-speed saw, dentin surface was embedded in an acrylic resin and wet-polished. Composite cylinders studs of four bulk composite materials (n=15) ; Tetric Power Fill, Tetric Power Flow (Ivoclar Vivadent), Filtek One (3M), SDR Plus (Dentsply Sirona) were bonded upon dentin substrates using universal adhesive Scotchbond Universal Plus (3M). In the first group, adhesive was cured using Bluephase PowerCure unit (Ivoclar Vivadent) for 20 s (1, 200 mW/cm2) and bulk materials were polymerized with 3 s mode (3, 000 mW/cm2), while in the second group composites were cured using 20 s mode. Specimens were stored at 37 °C in distilled water and fractured in shear mode after 1 month. Results: The highest bond strength was identified for Tetric Power Flow using 20 s mode (26, 75 MPa), whilst the lowest bond strength was observed for Filtek using 20 s mode (15, 52 MPa). A statistically significant effect of the curing protocol was identified only for Tetric Power Flow, which showed significantly lower bond strength for the 3 s protocol. Conclusions: In the experimental model adopted for this study, specimens polymerized with a high- power LED curing unit in 3 s mode didn't significantly differ in shear bond strength compared with specimens cured with 20 s mode except Tetric Power Flow. Keywords: dentin bond strength, shear bond strength, curing mode, high-power LED

INTRODUCTION: Scientific research often compares the final values of the mechanical properties of individual materials without considering the preparation of specimens in various moulds. Thus, in this study, the emphasis was on comparing two methodologies: the use of silicone and Teflon moulds. The research aimed to compare the results of flexural strength and modulus of identical materials made in different moulds. MATERIALS AND METHODS: Five bulk-fill composite materials were tested, including three high-viscosity materials (Tetric PowerFill, Ivoclar Vivadent ; Filtek One Bulk Fill Restorative, 3M ; QuiXfil Posterior Restorative, Dentsply Sirona) and two low- viscosity (Tetric PowerFlow, Ivoclar Vivadent ; SDR Plus Bulk Fill Flowable, Dentsply Caulk). Specimens (n = 10) were made in an orange silicone mould or a white Teflon mould. Two types of polymerisations were used: (I) according to ISO 4049 (2x2x16 mm, polymerised with Bluephase® PowerCure (Ivoclar Vivadent) 6x20 on both sides, average intensity 1079 mW/cm2) or (II) 3s protocol (2x4x16 mm polymerised 3x3 s, unilaterally, with an average intensity of 2602 mW/cm2). The specimens were stored in distilled water at 37ºC for 24 h and subjected to a three-point bending test. The results were analysed by Wilcoxon Matched Pairs Test (p

Aim: This research evaluates the fracture resistance of endodontically treated teeth with extensive MOD cavities based on different types of restorative material. The purpose of this study is to determine whether short fiber reinforced composite resign (SFRC) can compensate the loss of dental tissue in extensive MOD cavities or if crown placement is fully necessary. Materials and methods: In the study, 40 extracted molars were divided into four groups (n = 10). One group (CG) was left intact to serve as a control. Teeth inside the three experimental groups received extensive MOD cavity preparation and root canal treatment. The approximal tooth surfaces were restored with hybrid composite by using the incremental technique. The specimens were prepared and restored with their respective core materials as follows: (i) EX - EverX Posterior (GC Japan) + high-level microhybrid com- posite ; (ii) BF - Filtek One Bulk Fill (3M, USA) + high-rise microhybrid composite ; (iii) GIC - Fuji II LC (GC Japan) + high-level microhybrid composite. Restored teeth were embedded into resin molds and subjected to thermocycling. The specimens were scanned with an extraoral scanner to evaluate the tooth surface for the stress calculation. Fracture resistance was tested using the universal testing machine. The results were statistically analysed using ANOVA and Tukey’s HDS post hoc tests. Results: The control group (CG) showed a significant difference from experimental groups within maximum and break force (p < 0.01). The only difference between the experimental groups was made between the EX group and the GIC group where the maximum force values were statistically significantly lower in the SIC group compared to the EX (p < 0.05). Conclusion: The greatest fracture resistance was demonstrated by the control group (CG), while the SFRC restoration did not show a significant difference in resistance compared to other groups. The most probable cause may be MOD preparation with an isthmus greater than 2/3 of the vestibulooral width.

Parodontitis je jedna od najzastupljenijih bolesti koja pogađa svjetsku populaciju. Inicijalna ne- kirurška terapija je prvi korak i zlatni standard u liječenju parodontitisa. Uz inicijalnu terapiju, mogu se koristiti dodatne metode liječenja. U današnje vrijeme interes se usmjerio prema alternativnim metodama liječenja, na koje bakterije ne bi mogle razviti otpornost i jedna od tih metoda mogla bi biti upotreba Manuke meda. Materijali i metode: U ovom kliničkom istraživanju 45 ispitanika sa parodontitisom stadij III podvrgnuto je full-mouth inicijalnoj ne-kirurškoj terapiji i nakon randomizacije apliciran je Manuka med na 23 ispitanika, a 22 ispitanika dobilo je placebo pripravak. Učinkovitost Manuke meda ispitala se na način da se usporedio postotak zatvorenih džepova nakon 3 mjeseca uzevši u obzir početnu dubinu sondiranja (PPD). Rezultati: Rezultati su pokazali statistički veći postotak zatvorenih džepova nakon 3 mjeseca kod ispitanika kojima se aplicirao Manuka med za svaku početnu dubinu sondiranja (PPD). Za početnu dubinu sondiranja od 6mm (82.6% Manuka / 72.8% placebo), 7mm (68.2% Manuka/52.4% placebo), 8mm (62.0% Manuka/33.9% placebo), 9mm (44.7% Manuka/29.7% placebo) Zaključak: Upotreba Manuke meda kao dodatak inicijalnoj terapiji pokazao je obećavajući potencijal te iako malu ipak statističku značajnu razliku u većem postotku zatvorenih džepova nakon 3 mjeseca. Klinički je bitano jer će pacijenti potencijalno biti manje podvrgnuti kirurškim zahvatima.

Cilj: Cilj ovog istraživanja bio je odrediti prosječnu debljinu dentinskog zida gornjega središnjega sjekutića potrebnu za izradu modela rasta i razvoja korijena metodom konačnih elemenata. Materijali i metode: Pregledano je 137 intraoralnih rendgenskih snimki gornjega središnjega sjekutića u djece dobi od 7 do 11 godina indiciranih iz dijagnostičkih razloga na Zavodu za dječju i preventivnu stomatologiju KBC-a Zagreb koje su zatim bile podijeljene u 5 skupina prema stadijima razvoja korijena a uključivale su stadije u kojima je (1) razvijena jedna polovina korijena zuba, (2) tri četvrtine korijena zuba, (3) više od tri četvrtine korijena zuba, (4) potpuno razvijeni korijen s otvorenim apeksom te (5) potpuno razvijeni korijen sa zatvorenim apeksom. Debljina dentinskog zida u korijenu izmjerena je na tri referentne (horizontalne) linije: na udaljenosti 1 mm od apeksa (M), 4 mm od apeksa (L) te na razini cervikalne linije (K). Izmjerena je debljina distalnog zida dentina (M1, L1 i K1), debljina pulpe (M2, L2 i K2), debljina mezijalnog zida dentina (M3, L3 i K3), te dodatno i debljina samog apikalnog otvora (N) u dijagnostičkom softveru Soredex Scanora 5.1.2.4. U statističkoj analizi uspoređene su vrijednosti parametara K, L i M između pojedinih razvojnih stadija (multivarijatna ANOVA) te linearne korelacije između parametara (Pearsonova korelacijska analiza). Sve analize provedene su na razini značajnosti α=0.05. Rezultati: Parametri L i M statistički su se značajno razlikovali između razvojnih stadija, dok za parametar K nisu opažene značajne razlike. Većina korelacija između parametara bila je statistički značajna, a vrijednosti Pearsonovog koeficijenta korelacije R>0, 6 smatrane su praktično značajnim. Svi parametri za debljinu pulpe međusobno su dobro korelirali (R = 0.61 – 0, 99) kao i s debljinom korijena na udaljenosti 4mm i 1mm od apeksa (R = 0, 60 – 0, 95) dok nisu statistički značajno korelirali s debljinom korijena u razini cervikalne linije, osim parametra K2 (R = 0, 64). Svi parametri za debljinu dentinske stijenke prema distalno i mezijalno kao i za debljinu kanala međusobno su dobro korelirali na svojoj referentnoj liniji (R = 0, 46 – 0, 68) dok nisu statistički značajno korelirali s ukupnom debljinom na svojoj referentnoj liniji, osim parametra K3 (R = 0, 42). Debljina korijena na udaljenosti 4 mm od apeksa je dobro korelirala s debljinom pulpe (R = 0, 90) ali nije statistički značajno korelirala s debljinom dentinske stijenke prema distalno i mezijalno. Parametri K i K1 pokazali su značajno manje korelacija od svih ostalih parametara dok je parametar K2 korelirao sa svim izmjerenim parametrima (R = (-0, 26) – 0, 70). Zaključak: Unatoč ograničenjima ovog istraživanja, srednje vrijednosti odabranih parametara veličine zubnog korijena za 5 skupina stadija razvoja kod gornjega središnjega sjekutića mogu se koristiti za modeliranje debljine dentinskog zida pomoću analize konačnih elemenata (eng. FEA, finite element analysis).

Introduction: To evaluate flexural strength (FS) and flexural modulus (FM) of dual-cure resin cements polymerized using different curing protocols. Materials and methods: Four dual-cure cements and one light-cure cement were investigated. The specimens for the three-point bending test (2x2x16 mm) were prepared using the following three curing protocols: (I) 1200 mW/cm2 for 10 s immediately adjacent to the specimen surface, (II) 1200 mW/cm2 for 20 s through a 1-mm layer of disilicate ceramics, and (III) without light illumination. The specimens were artificially aged using 30-day immersion in water followed by 7-day immersion in absolute ethanol. Mechanical testing was performed in a universal testing machine at a crosshead speed of 1 mm/ min until fracture. Results: The investigated materials demonstrated a wide range of FS (11.4– 111.1 MPa) and FM (0.65–5.5 GPa). FS and FM values were notably material-dependent and significantly affected by curing protocols in all tested materials. The self-curing protocol resulted in up to 25% poorer mechanical properties compared to the corresponding maximum values attained by the maximum light exposure provided by curing protocol (I). In addition to being significantly affected by curing protocols, mechanical properties of the lightcure resin cement were at the low-end of all investigated materials. For all materials, FM was more affected by different curing protocols than FS. Conclusions: The dual-cure resin composite cements should be additionally light-cured in order to attain optimal mechanical properties. Also, direct exposure to the curing light resulted in improved mechanical properties compared to the light exposure through a 1-mm thick ceramic layer.

Introduction: The aim of this study was to investigate mass changes of experimental composites over a long-term immersion in distilled water. Materials and methods: Two series of experimental composites were prepared by replacing their reinforcing fillers (total: 70 wt%) with 0, 5, 10, 20, and 40 wt% of either bioactive glass 45S5 or a low-sodium fluoride-containing bioactive glass. Three ion-releasing commercial materials were used as references. A gravimetric method adapted from the ISO 4049 protocol was used to evaluate mass changes of cured material specimens after water immersion for 1, 28, 42, 63, and 180 days. Results: Mass changes during immersion were generally more pronounced for the composite series functionalized with bioactive glass 45S5. Within both experimental composite series, the materials with the highest bioactive glass amount (40 wt%) showed a time- dependent mass decrease, indicating a solubilization that continued beyond the 180-day observation period. The final weight changes were as follows: 1.8% for the control composite, 1.4– 3.0% for the experimental composites containing bioactive glass 45S5, and 0.6– 2.1% for the experimental composites with low-sodium bioactive glass. Among the reference materials, the glass ionomer increased its mass for 5.6%, while the weight changes for the giomer and the alkasite were comparatively lower (1.1% and 0.7%, respectively). Conclusions: Both series of experimental composites demonstrated a higher extent of water sorption and solubility compared to the control composite, whereas the composite series with the low-sodium fluoride-containing bioactive glass showed lower extents of water sorption and solubility compared to the composites with bioactive glass 45S5. This study was supported by Croatian Science Foundation, project IP-2019-04-6183.

Introduction: This study investigated the development of the degree of conversion (DC) over a 30-day period for dual-cure resin composite cements. Materials and methods: Four dual-cure resin cements were investigated. A light-cure resin cement was used as a reference. A thin layer of resin cement (0.1 mm) was cured using the following three curing protocols: (I) 1200 mW/cm2 for 10 s immediately adjacent to the specimen surface, (II) 1200 mW/cm2 for 20 s through a 1-mm layer of disilicate ceramics, and (III) without light illumination. DC was evaluated using attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) after 1, 7, and 30 days. Results: The measured DC values ranged from 44.3–77.8%. A statistically significant DC increase up to 30 days was identified in three materials, with the post-cure DC improvements up to 26.2%. Only one of the investigated materials showed no significant postcure DC increase. The response of the materials to different curing protocols was material- dependent, with self-cure protocol resulting in up to 13.9% lower DC values compared to the light-curing protocol (I). On the other hand, one of the tested materials showed no significant reduction of the DC due to different curing protocols. Conclusions: The behavior of the investigated dual-cure composite cements regarding their long-term polymerization and sensitivity to different curing protocols proved to be highly material-dependent. While for the most of the materials the DC values were dependent on the curing protocol and a long-term DC increase was observed, a different behavior was also possible, including no significant post-cure increase and insensitivity to curing protocols.

Aim: After removing dental restorative materials, their dust goes into the wastewater, and enters the aquatic ecosystems. Previous studies based on the study of (eco)toxic potential of dental materials were mostly based on cell lines while neglecting the effects on model vertebrate organisms. For this reason, this research aims to determine the influence of microparticles of composite materials and their eluates on the embryonic development of the zebrafish Danio rerio. Materials and methods: This study included two types of composite materials: commercial composite (Tetric EvoCeram, Ivoclar Vivadent) and laboratory composite (30% BisGMA/TEGDMA 60:40, 70% filler). Composite samples (d=6mm, h=2mm) were polymerized with Bluephase G2 (Ivoclar Vivadent ; 1200mW/cm2) for 10s. The samples were then ground, their powder collected, and dispersed in zebrafish medium. Samples were incubated on a shaker for 48h and 7 days, after which an embryotoxicity test was performed on Danio rerio embryos. In addition to mortality rates and morphological abnormalities, the cardiotoxic and neurotoxic potential was monitored. The chemical composition of the eluates was determined by high-performance liquid chromatography (Agilent 1260 Bioinert) to identify released monomers. Results: Only UDMA at a concentration of 1.21mg/ml was detected in the 48h-eluates of Tetric EvoCeram, which was present at a reduced concentration of 0.69mg/mL in 7d- eluates. TEGDMA (0.016mg/mL) was detected in the laboratory composite after 48h, with the same concentration after 7 days. Composite microparticles showed a negative effect on the embryonic development of zebrafish depending on the tested concentration. The most commonly observed developmental abnormalities during exposure were pericardial edema and scoliosis. Both tested composites caused increased heart activity. The reduction of the individuals length, the lack of pigmentation, and the accelerated pectoral fin movement were more pronounced in the commercial composite. Conclusion: The embryotoxicity of the tested eluates of dental composites was largest after 48h of incubation in the medium. The obtained results highlight the potentially negative impact on aquatic ecosystems and emphasize the importance of timely removal and disposal of these materials.

Objectives: The aim of the study was to examine the impact of rapid high-intensity polymerization on water sorption and solubility of a new generation of bulk-fill composite materials. Materials and methods: Five materials were tested: a conventional composite Filtek Z250 (3M, St. Paul, USA) and four bulk-fill composites, Filtek One Bulk Fill (3M), Tetric PowerFill (Ivoclar Vivadent, Schaan, Liechtenstein), Tetric PowerFlow (Ivoclar Vivadent), SDR Plus (Dentsply, Konstanz, Germany). Composite specimens with a 9-mm diameter and a 2-mm height (n = 6) were polymerized with a high- intensity curing unit (Bluephase® PowerCure, Ivoclar Vivadent). The control group was polymerized for a total of 40 s on both sides (1193 mW / cm2) and 3s group for 3 s on one side (3053 mW/cm2). Water sorption and solubility were measured by ISO 4049 method up to 30 days of immersion. The results were statistically analyzed using one- way ANOVA with Tukey post-hoc correction. Different polymerization protocols for the same material were compared by t-test (p < 0.05). Results: The 3s polymerization protocol increased the solubility of all materials. Filtek One Bulk Fill showed the highest water sorption and solubility values, and Tetric PowerFlow proved to be a stable material with low values of tested parameters. During immersion, a saturation of specimens was achieved in low-viscosity bulk-fill composites within two weeks, while in other materials it was not achieved within 30 days, or more, following the immersion. Conclusions: Rapid polymerization caused an increase in solubility, which could affect the biocompatibility of the investigated materials not intended for the 3s curing. SDR Plus and Filtek One Bulk Fill should not be polymerized with rapid high-intensity curing due to increased solubility that exceeds ISO 4049:2009 limits.

INTRODUCTION: Composite restorations are constantly exposed to water which negatively affects their longevity. In this study, the long- term water sorption and solubility of new generations of bulk-fill composites were examined during three months. MATERIALS AND METHODS: Seven composite materials were tested, of which five bulk-fill ma-terials (Tetric PowerFill, Ivoclar Vivadent ; Filtek One Bulk Fill Restorative, 3M ; Fill-Up !, Coltene / Whaledent AG ; Tetric PowerFlow, Ivoclar Vivadent ; SDR Plus Bulk Fill Flowable, Dentsply Caulk) and two conventional composites (Tetric EvoCeram and Tetric EvoFlow, Ivoclar Vivadent). Compo-site specimens with a diameter of 6 mm and a height of 2 mm (n = 6) were polymerized using a LED curing unit (Bluephase® PowerCure, Ivoclar Vivadent, 950 mW/cm2) for 20 s on each side. Water sorption and solubility were measured by the modified ISO 4049 method after 1, 7 and 90 days of immersion. RESULTS: Fill-Up! had the highest water sorption, followed by Filtek One Bulk Fill Restorative and Tetric EvoFlow which have statistically similar results with values above 20 μg / mm3. Tetric PowerFlow showed the lowest values of water absorption. Negative solubility values were obtained with Tetric EvoFlow, Tetric EvoCeram and Tetric PowerFill, and for Tetric PowerFlow the solubility value was almost equal to zero. CONCLUSION: After 90 days of immersion in water, composites with a lower inorganic filler con-tent generally showed higher absorption values, with the exception of Filtek One material which had the highest proportion of agglomerated fillers that hydrolyzed more easily. Tetric PowerFlow was the most stable material in this study. This research was funded by the Croatian Science Foundation, project IP-2019-04- 6183.

Introduction: This study aimed to investigate polymerization kinetics of resin composites light- cured using a rapid high-intensity curing protocol. Materials and methods: Two composites specifically designed for high-intensity light- curing and four reference composites were investigated. Composite specimens were prepared using Teflon molds (diameter = 6 mm, height = 2 mm) on top of a diamond ATR crystal and light- cured using the following protocols: (I) 3, 000 mW/cm2 for 3 s ; (II) 2, 000 mW/cm2 for 5 s ; and (III) 1, 000 mW/cm2 for 10 s. Real-time degree of conversion (DC) changes were continuously measured over 5 min after the initiation of light-curing using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). The data collection rate of 2 spectra/s enabled the evaluation of kinetic parameters. First derivatives of time-dependent DC curves were calculated to characterize the reaction rate. Results: DC at the end of the 5-min observation period amounted to 40.0–67.2%. Out of all kinetic parameters, maximum reaction rate (5.6–25.7%/s) was the most affected by different curing protocols. Highly significant differences in maximum reaction rates caused by variable radiant exitances were identified in five out of six investigated composites. Time of the maximum reaction rate (1.7–3.3 s) was the least discriminative parameter, mostly showing statistically similar values among the curing protocols. Partial eta-squared statistics identified that material type was more influential for all kinetic parameters compared to curing protocols. Significant interactions between material type and curing protocol were identified, indicating material-dependent responses to high- intensity light-curing. Conclusions: High- intensity light-curing significantly increased the polymerization rate, with possible implications on the development of polymerization shrinkage stress.

Objectives: To evaluate mechanical properties of a new commercially available bioactive restorative material and compare it to established bioactive and inert materials after artificial aging for up to 3 months. Methods: Four materials were tested: alkasite Cention (Ivoclar Vivadent) in self-cure (Cen-SC) or light-cure (Cen-LC) mode, giomer Beautifil II (Shofu ; BII), conventional glass ionomer Fuji IX (GC ; FIX), and resin composite Tetric EvoCeram (Ivoclar Vivadent ; TEC) as a control. For flexural strength (FS) and flexural modulus (FM) testing according to ISO 4049, Cen- LC, BII, and TEC were polymerized with 950 mW/cm2 for 20 s in 6 overlapping exposures on both sides, while Cen-SC and FIX were left to set for 15 min. The specimens (n=60/material) were dark stored in distilled water at 37°C, divided into three groups (n=20) and tested at 24h, 3 months, and 3 months+3 days in ethanol. FS and FM were measured using a customized universal testing machine at 1mm/min crosshead speed. The data were statistically analyzed using the Kruskal-Wallis test, and one- way ANOVA with Bonferroni post-hoc test, p < 0.05. Results: BII (121.8-142.1 MPa) and TEC (107.8- 132.2 MPa) had the highest FS at all time points of measurement, followed by Cen-LC (84.0-104.6 MPa) and Cen-SC (62.1-86.9 MPa). FIX had significantly lowest FS (7.9-12.0 MPa) and the lowest FM (0.5-2.7 GPa). FS and FM decreased at 3mo and after additional aging in ethanol for all materials except BII and Cen-SC. Contrary to other materials, Cen-SC had an increase in FS and FM at 3mo and 3mo+3 compared to 24h. Conclusions: In this study, BII behaved similarly to a composite material and had the best resistance to aging. Alkasite Cention showed better mechanical properties than FIX. Cention should be used in the light-cure mode. This study was supported by Croatian Science Foundation, grant IP-2019-04- 6183.

Ciljevi. Cilj istraživanja bio je ispitati stavove i mišljenja studenata Stomatološkog fakulteta Sveučilišta u Zagrebu o provođenju nastave za vrijeme trajanja izvanrednih mjera u ljetnom semestru akademske godine 2019./2020. koje su nastupile zbog pandemije COVID-19. Materijali i metode. Istraživanje je provedeno korištenjem anonimnog upitnika. Upitnik je podijeljen u nekoliko skupina pitanja kojima su se prikupljali demografski podaci te stavovi i mišljenja ispitanika o provedbi i održavanju on-line nastave za vrijeme izvanrednih mjera. Napravljena je deskriptivna statistička analiza, te faktorska analiza u SPSS-u. Rezultati. Od ukupnog broja ispitanika (357), 13.1% bilo je s prve, 19.0% s druge, 15.1.% s treće, 17.9 s četvrte, 20.2% s pete te 14.8% sa šeste godine studija. Više od 60% ispitanika izjavilo je da je iskusilo osjećaje nesigurnosti i zabrinutosti kad su na snagu nastupile izvanredne mjere na području Republike Hrvatske. Više od 17% ispitanika izjavilo je kako je u to vrijeme učenje bilo teže nego inače, a 19.3% zbog neizvjesnosti situacije nije bilo jednako motivirano za učenje. Kod 8% ispitanika polaganje ispita s mjerama za- štite (maske i rukavice) predstavljalo je izvor stresa, a 13% je polaganje ispita on-line predstavljalo izvor stresa. 16% ispitanika smatra kako bi gradivo bolje svladalo u neposrednom kontaktu s nastavnikom. Više od 88% izjavilo je kako je zbog pandemije COVID -19 osvijestilo rizik stomatološkog zanimanja. Zaključak. Zbog novonastale situacije uslijed pandemije COVD-19 nastava se održavala isključivo on-line. Dobiveni rezultati ukazuju kako je teoretski dio nastave održan on-line jednakovrijedan onome održanom uživo, a izostanak praktičnog dijela nastave većina studenata smatra nenadoknadivim.

AIM This research aimed to examine the long-term water sorption and solubility of commercially available bioactive restorative materials during one year. MATERIALS AND METHODS Four materials were investigated: alkasite Cention (Ivoclar Vivadent), auto-polymerized (CA) and photo-polymerized (CP), giomer Beautifil Il (Shofu ; BII), glass-ionomer Fuji IX (GC ; FIX), and composite Tetric EvoCeram (Ivoclar Vivadent ; TEC) as a reference. Specimens (n=10) had 6 mm in diameter and 2 mm high. TEC, BII, and CS were photo- polymerized on both sides with 1047 mW/cm2 for 20 s. CA and FIX were auto-polymerized for 10 minutes. After initial drying, specimens were individually placed in 4 ml of distilled water and dark stored at 37°C. During immersion, changes in specimen mass were measured after 1, 7, 14, 90, 180, and 365 days, and after drying. Sorption and solubility were calculated according to ISO 4049. One-way ANOVA and Tukey post-hoc test were used for statistical analysis (p

Polimerizacija kompozitnih materijala temeljno je i klinički značajno svojstvo koje određuje mnogobrojna fizička svojstva materijala poput čvrstoće, tvrdoće, elastičnosti, biokompatibilnosti, apsorpcije vode, hrapavosti površine i promjene boje. Postoje izravne i neizravne metode određivanja stupnja konverzije. Izravne metode temelje se na vibracijskoj spektroskopiji te izravno određuju količinu neizreagiranih C=C veza. U izravne metode pripadaju Ramanova spektroskopija te spektroskopija s Fourierovom transformacijom infracrvenog spektra (FTIR).

Objectives: To investigate the effect of two types of bioactive glass (BG) on polymerization kinetics of experimental resin composites. Methods: Resin composites were based on a photo-curable Bis- GMA/TEGDMA (60:40 in wt%) resin system. The composites with a total filler load of 70 wt% were functionalized with varying amounts (5, 10, 20, and 40 wt%) of either BG 45S5 or a low-sodium fluoride-containing BG. Uncured composites were cast in Teflon molds (n= 6, diameter=6 mm, height=2 mm) on top of a diamond ATR crystal and light-cured using 1, 100 mW/cm2 for 20 s. Real- time changes in degree of conversion (DC) occurring during light-curing and 5 min post-cure were monitored at the data collection rate of 2 s- 1 using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). From the time-dependent DC curves, the first derivative was calculated to represent reaction rate. Results: At the end of the 5-min observation period, DC values for the composites functionalized with BG 45S5 ranged from 59.2– 66.5%, and were significantly reduced by increasing BG amounts. In contrast, the 5-min DC values for the low-sodium fluoride-containing BG (64.7–67.0%) were not significantly affected by BG amounts. The polymerization rate for BG 45S5 (6.3– 12.5 %/s) decreased as a function of higher BG amounts. The composites functionalized with low- sodium fluoride-containing BG had comparatively higher polymerization rates (12.7–14.3 %/s) and showed a statistically significant reduction of polymerization rate only for the highest BG amount (40 wt%). Maximum polymerization rate occurred within 0.8–1.4 s from the start of light-curing and represented a less discriminative parameter due to high data scattering. Conclusions: The 5- min DC values and polymerization rate were significantly diminished by the addition of BG 45S5, while the addition of a low-sodium fluoride- containing BG showed a minor effect on kinetic parameters.

Aim: Copper-doped mesoporous bioactive glass nanospheres (Cu- MBGN) are developed to ensure remineralization and antibacterial properties. This study investigated the influence of Cu-MBGN on resin composites' depth of cure (DoC). Materials and methods: Eight materials were tested in the study: giomer as a reference material (Beautifil II, Shofu) and seven experimental materials with 45% photoactive resin (60/40 BisGMA / TEGDMA) and 65% filler. Inert barium glass was combined with 10% Cu-MBGN, silica, or conventional 45S5 bioactive glass in the bimodal group. In the trimodal group, the fillers consisted of 0, 1, or 5% Cu- MBGN or 45S5 glass, silica, and inert silanized barium glass fillers. The materials were fed into 4 mm diameter and 10 mm high cylindrical molds and cured with 920 mW/cm2 for 20 s. The unpolymerized excess material was removed, the length of the remaining part was measured with a movable gauge and divided by 2 to obtain DoC according to ISO 4049. Data were statistically processed by one-way ANOVA and Tukey post-hoc test (p

Introduction: This study is a pilot investigation of weight changes during water immersion of experimental composites functionalized with two types of bioactive glass (BG). Materials and methods: Experimental resin composites were prepared using a Bis-GMA/TEGDMA resin system (60:40 by weight). The photo-curable composites were functionalized with 0, 5, 10, 20, and 40 wt% of either BG 45S5 or a low-sodium fluoride- containing BG. The total filler load for all composites was 70 wt%. Three commercial restorative materials (giomer, glass ionomer, and alkasite) were used as references. According to a modified ISO 4049 gravimetric method, cured material specimens were immersed in distilled water and their weight changes were measured after 1, 3, 7, 14, 21, and 28 days. Results: Non- monotonous time-dependence of weight changes characterized by an initial increase followed by a peak and a subsequent decrease were identified for the experimental composites with the highest amounts of BG (40 wt%). At the end of the observation period (28 days), relative weight changes were as follows: 2.6% for the control composite containing only inert fillers, 2.0–3.8% for the experimental composites functionalized with BG 45S5, and 0.9–1.7% for the experimental composites with low-sodium fluoride-containing BG. The highest weight change was identified for the glass ionomer (6.1%), while weight changes for the giomer and the alkasite amounted to 1.0% and 0.4%, respectively. Conclusions: Different patterns of weight gain and loss were identified by subsequently weighing the specimens of water- immersed composite materials, indicating that uptake of water and release of material constituents occurred simultaneously. This study was supported by Croatian Science Foundation, project IP-2019-04-6183.

Objectives: Copper-doped mesoporous bioactive glass nanospheres (CuMBGN) with antibacterial and calcium/phosphate releasing properties were used as fillers in experimental resin composites. The effect of CuMBGN addition on the polymerization kinetics and the short-time degree of conversion (DC) was investigated. Methods: Seven experimental materials were prepared with increasing non-silanized CuMBGN amount (0, 1, 5, and 10%) and identical photoactive resin composition (60/40 BisGMA/TEGDMA). The total filler load was kept constant at 65wt.%, and the remaining filler share consisted of inert silanized barium-glass fillers or a combination of silanized barium-glass and silanized silica. Control materials were filled with conventional 45S5 bioactive glass (45S5). Specimens (n=5) were light-cured for 20 s with 950 mW/cm2. DC was measured in real-time for 5 min using attenuated total reflectance Fourier transform infrared spectroscopy at the data collection rate of 2 s-1. DC, maximum reaction rate, and time of maximum reaction rate were calculated. The data were statistically compared using ANOVA and Tukey post-hoc test (p

Cilj: Ciljevi su istraživanja utvrditi količinu otpuštenih fluorida iz bioaktivnih dentalnih materijala i promjene u pH vrijednosti otopine te ustanoviti postoji li razlika u količini otpuštenih fluorida prilikom korištenja različitih adhezivnih sustava ili premaza kod stakleno ionomernih cemenata. Materijali i metode: U ovome su istraživanju korištena četiri različita dentalna materijala: giomer Beautifil II (Shofu Dental GmbH, Ratingen, Germany), alkasitni kompozitni materijal Cention (Ivoclar Vivadent, Schaan, Liechtenstein), konvencionalni kompozit Filtek Z250 (3M Deutschland GmbH, Neuss, Germany) kao negativna kontrola te konvencionalni stakleno ionomerni cement Fuji IX Extra (GC Europe, Leuven, Belgium) kao pozitivna kontrola. Svjetlosno polimerizirani uzorci kompozitnih materijala premazani su dvama adhezivnim sustavima. Korišteni adhezivni sustavi bili su: univerzalni adheziv Gaenial Bond (GC Europe, Leuven, Belgium) i univerzalni adheziv koji otpušta fluoride Clearfil Universal Bond Quick (Kuraray Europe, Hattersheim am Main, Germany). Premaz korišten za stakleno ionomerni cement bio je Fuji IX coat (GC Europe, Leuven, Belgium). Pripremljeni su uzorci pohranjeni u 5 ml deionizirane vode i čuvani u laboratorijskom inkubatoru na 37 °C. Kvantitativno otpuštanje fluorida ispitivalo se standardnom metodom ion- selektivnom elektrodom Orion 9609BNWP (Thermo Fisher Scientific, Massachusetts, USA). Određivanje pH vrijednosti tekućine u kojoj su bili pohranjeni uzorci, vršilo se pomoću InLab Expert Pro pH elektrode (Mettler Toledo, Columbus, Ohio). Količine otpuštenih fluorida i pH vrijednosti mjerile su se u vremenskim intervalima: 1 sat, 24 sata, 48 sati, 7 dana, 1 mjesec i 3 mjeseca. Rezultati: Kumulativna količina otpuštenih fluorida nakon 3 mjeseca razlikovala se među ispitivanim materijalima bez adheziva ili premaza navedenim redoslijedom: Filtek Z250 < Beautifil II < Cention < Fuji IX (0 ppm, 1.01 ppm, 10.8 ppm i 45.7ppm). Materijali sa Clearfil Universal Bond Quick adhezivom otpustili su manje količine fluorida te je raspon kumulativnih vrijednosti nakon 3 mjeseca bio: Filtek Z250 < Beautifil II < Cention (0.00076 ppm, 0.082 ppm te0.24 ppm). Materijali sa Gaenial Bond adhezivom također su otpustili manje količine fluorida s rasponom kumulativnih vrijednosti nakon 3 mjeseca: Beautifil < Cention (0.322 ppm i 3.09 ppm). Filtek Z250 priređen bez adheziva i sa Gaenial Bond adhezivom nije otpustio fluoride. Gaenial Bond pokazao je u svim skupinama niske vrijednosti pH u vremenskim intervalima 1 sat i 24 sata. Nakon 1 sata su se pH vrijednosti među materijalima povećavale sljedećim redoslijedom: Filtek Z250 < Cention < Beautifil II (4.42, 4.53 i 4.75). Nakon 24 sata su se pH vrijednosti među materijalima povećavale sljedećim redoslijedom: Filtek Z250 < Beautifil II < Cention (5.39, 5.67 i 5.73). Zaključak: Količina otpuštenih fluorida razlikovala se među dentalnim materijalima te je ovisila o aplikaciji adhezivnih sustava i premaza.

Introduction: The composition of contemporary composite materials is changing and polymerization is shifting from classic cross-polymerization to short-chain polymerization, which opens the possibility of shortening the polymerization time with increasing light emission. The purpose of this study was to investigate the efficiency of a new generation LED curing unit with very high radiant emittance in short-time polymerization of contemporary bulk-fill composite materials. Materials and Methods: Four materials were investigated, three bulk-fills: Filtek One Bulk Fill (3M, St. Paul, USA), Tetric PowerFill (Ivoclar Vivadent, Schaan, Liechtenstein) and Tetric PowerFlow (Ivoclar Vivadent), with Tetric EvoFlow (Ivoclar Vivadent) as a reference. The materials (n=5) were polymerized for 3s with 3050 mW/cm2 (Bluephase Power- Cure, Ivoclar Vivadent). The degree of conversion (DC) was measured immediately after light curing at the surface and after 24h at surface, 1, 2, 3 and 4mm using a Raman spectrometer (Spectrum GX Perkin-Elmer, Waltham, MA, USA) with laser power 850mW and resolution 4cm-1 with 80 scans/measurement. Mean values were statistically compared using one-way ANOVA with Tukey adjustment for multiple comparisons, at an overall level of significance of 0.05. Results: All tested materials presented a significant increase in DC at the sample surface after 24h compared to DC immediately after light curing. Flowable materials achieved higher DC than sculptable. 3s curing was sufficient for adequate polymerization of Tetric PowerFlow up to 4mm (surface-70.12±2.98% and 4mm-58.23±5.87% after 24h). Tetric PowerFill at 3mm depth reached 60.80±6.74%, which was statistically similar to surface (66.66±1.21%) after 24h, but dissimilar to 4mm depth after 24h (47.77±5.26%). Filtek One demonstrated the lowest DC values at 4mm depth after 24h (29.96±6.11%). Surprisingly, the reference material Tetric EvoFlow reached very high DC values (surface- 87.86±1.21% and 4mm- 83.03±2.38% after 24h). Conclusion: Using a very high light emission for a short-time polymerization of bulk-fill composites is an innovative approach that should be used with caution for materials other than those specifically designed for such use.

Aim: Bioactive glasses (BGs) can be used to render resin composites anti-cariogenic. This pilot study aimed to investigate the protective effect of experimental BG-composites on enamel immersed in a repeatedly replenished acidic solution. Materials and methods: Three experimental composites based on a photo-curable resin (60:40 wt% bisphenol-A- glycidyldimethacrylate and triethylene glycol dimethacrylate) and a total filler ratio of 70 wt% were prepared by replacing 0, 10, and 20 wt% of silanized reinforcing fillers (barium glass and silica) with unsilanized BG 45S5. Enamel blocks (3x3x1 mm, n=9) were prepared from intact human third molars. Light-cured composite specimens (diameter=7 mm, thickness=2 mm, n=3 per material) were immersed with enamel blocks in a lactic acid solution (5 mL, pH=4.0). The immersion medium was replenished every four days. Knoop microhardness (MH ; load=100 g, dwell time=20 s ; n=5 per measurement) and pH of the immersion medium were assessed at the following time points (days): 0, 4, 8, 12, 16, and 20. Statistical analysis was performed using a nonparametric one-way ANOVA on ranks (Kruskal–Wallis). Results: The enamel blocks immersed with the 0 wt%-BG composite showed a statistically significant MH decline after 4 days, whereas the MH of enamel blocks immersed with the 10 wt%-BG composite remained unchanged up to 8 days. The enamel blocks immersed with the 20 wt%- BG composite showed no statistically significant MH change throughout the whole observation period. The pH value of the immersion medium was unchanged by the 0 wt%-BG composite, for the 10 wt% BG composite a transient pH increase was observed, while the 20 wt%-BG composite showed an extensive increase up to pH=9.8, which was maintained throughout the whole observation period. Conclusions: A dose-dependent protective effect against repeated acid attacks was identified for experimental composites functionalized with 10–20 wt% of BG 45S5.

Introduction: Final adjustment and polishing or removal of dental fillings produce particles of restorative materials of various sizes that can reach the wastewater. The purpose of this study is to investigate the effect of particles of restorative materials and their degradation products on the environment and non-target organisms using Danio rerio zebrafish embryos. Materials and methods: The study included dental amalgam (Amalcap plus, Ivoclar Vivadent), commercial composite (Tetric EvoCeram, Ivoclar Vivadent ; A2) and laboratory composite (BisGMA / TEGDMA, 70wt% filler). After polymerization of the composite materials (Bluephase G2, Ivoclar Vivadent ; 1200mW / cm2, 10s), or hardening of the amalgam (1h), micrometer particles were made and suspended in artificial water at various dilutions. Samples were continuously shaken during 48-h and 7-days incubation, followed by determination of embryotoxicity using Danio rerio embryos. Within 96 h of embryonic development on tested samples, lethal and sublethal (developmental abnormalities, cardiotoxicity, melanogenesis, etc.) endpoints were monitored. Results: All tested samples revealed high embryotoxicity. The commercial composite showed the lowest toxicity (1.5g of the composite caused 90% mortality, while in the other tested materials the same effect was observed already during the 250mg test). The laboratory composite showed higher toxicity in comparison to the commercial one, but its toxicity was reduced after 7 days of incubation compared to 48-h. Unlike the composite, the amalgam showed increased toxicity after 7 days of incubation (100%) versus 48-h (60%). High mortality on amalgam was present at all tested dilutions (0.25-4g). Conclusion: The highest percentage of composite-induced embryotoxicity was observed after 48 h of material incubation, while the highest percentage of amalgam-induced mortality was recorded after 7-days of material incubation. The obtained results emphasize the importance of such research and contribute to the establishment of biomarkers at different levels of biological organization in order to determine their safety for environment and non-target organisms.