Provider: - Institution: - Data provided by Europeana Collections- Popravak DNA je ključni mehanizam održavanja integriteta genoma i obrane od posljedica učinka genotoksičnih zagađivala. Sposobnost i ...brzina popravka predstavljaju važan biomarker za praćenje kvalitete morskog okoliša i postoji potreba za jednostavnom i ekonomičnom metodom mjerenja učinkovitosti popravka DNA u bioindikatorskim vrstama. Optimizacijom uvjeta za fluorimetrijsku detekciju 3D metodom u ovom radu je uspostavljen protokol za mjerenje učinkovitosti popravka DNA u probavnoj žlijezdi i škrgama dagnje Mytilus galloprovincialis. Utvrđeno je da učinkovitost popravka DNA u probavnoj žlijezdi dagnje je viša nego u škrgama, što ukazuje na tkivnu specifičnost popravka DNA, a njihova međusobna korelacija ukazuje na usklađeni odgovor ovih organa na prisutnost genotoksina. Integritet DNA u hemocitima dagnje Mytilus galloprovincialis, kao pokazatelj genotoksičnog pritiska okoliša, korelira s učinkovitosti popravka DNA probavne žlijezde, koja se razlikuje za populacije dagnje koje naseljavaju područja s različitim antropogenim pritiskom. Zaključuje se da je 3D metodom moguće sustavno praćenje genotoksičnog rizika u prirodnim populacijama dagnje, čime se može unaprijediti procjena genotoksičnog rizika u ekotoksikološkim studijama.- DNA repair is a key mechanism for the genome integrity maintenance and defense against the consequences of genotoxic pollutants. The DNA repair capacity in marine bioindicator species is an important biomarker for the marine environment monitoring that demand a simple and economic method. Following optimization of the 3D method a new protocol was established that allows a fluorimetric measurement of the DNA repair capacity in the digestive gland and gills of mussel Mytilus galloprovincialis was tested. The DNA repair capacity in the digestive gland was higher than in the gills suggesting that DNA repair capacity is tissue specific. The correlation between the DNA repair capacities of investigated tissues indicates a coordinated response of the organism to genotoxic pressure. DNA repair capacity in digestive gland distinguished population living under different anthropogenic pressure as well as correlated with the DNA integrity in haemocytes as indicators of environmental genotoxic pressure. Introduction of the 3D method measurement of DNA repair capacity in to the ecotoxicological studies could improve the assessment of the genotoxic risks in the marine environment.- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Provider: - Institution: Josip Juraj Strossmayer University of Osijek. FACULTY OF FOOD TECHNOLOGY. Department of Applied Chemistry and Ecology. Sub-department of Biochemistry and Toxicology. - Data ...provided by Europeana Collections- Cilj ovoga rada bio je ispitati sadržaj polifenola u ekstraktima vrsta Echinacea purpurea (L.) Moench kao i Castanea sativa Mill. te odrediti njihov antioksidativni i antigenotoksični učinak. Antioksidativna aktivnost ekstrakata i glavnih sastavnica je utvrđena primjenom elektronske spinske rezonancije i spektrofotometrijskih metoda hvatanja DPPH, superoksidnog i hidroksilnog radikala. Ispitan je i redoks učinak i citotoksičnost ekstrakata u kulturi stanica raka kolona (SW480).
Antigenotoksični i antimutageni učinak procijenjen je kometnim i Amesovim testom uz mutagene i genotoksične mikotoksine – aflatoksin B1 (AFB1) i ohratoksin A (OTA). Provedena je i senzorska analiza tretiranih uzoraka kikirikija i grožđica za preliminarnu procjenu primjenjivosti tretmana ekstraktima. Ekstrakt herbe ehinaceje je sadržavao više ukupnih polifenola u odnosu na ekstrakt lista kestena (10,57 % prema 6,74 %). Ekstrakt ehinaceje je sadržavao višestruko veću količinu fenolnih
kiselina (prvenstveno cikorijska i kaftarinska kiselina), dok je ekstrakt kestena bio najbogatiji taninima i flavonoidima (derivati galne i elaginske kiseline). Ekstrakt kestena je pokazao znatno veću sposobnost neutralizacije DPPH radikala (EC50 = 1,87 μg/mL) u odnosu na ekstrakt ehinaceje (EC50 = 15,67 μg/mL). Slični rezultati utvrđeni i ispitivanjem hvatanja hidroksilnog i superoksidnog radikala, pri čemu je ekstrakt kestena bio desetak puta učinkovitiji. Utvrđena je i snažna antioksidativna
aktivnost dominantnih sastavnica koja ukazuje na fenolne kiseline (ehinaceja) i elaginsku kiselinu (kesten) kao sastojke koji najviše doprinose učinku ekstrakata. Inhibitorni učinak ekstrakata ehinaceje na mutageno djelovanje aflatoksina B1 zabilježeno je samo kod najniže koncentracije na soju bakterije Salmonella typhimurium osjetljivom na pomak okvira čitanja. S druge strane, utvrđen je snažan inhibitoran učinak ekstrakta kestena, izraženiji na soju osjetljivom na pomak okvira čitanja. Supresija
genotoksičnog učinka AFB1 i OTA utvrđena je i kometnim testom, pri čemu je ustanovljena značajna redukcija dužine repa, repnog intenziteta i repnog momenta u leukocitima istovremeno tretiranim mikotoksinima i različitim koncentracijama ekstrakata. Dok ekstrakt ehinaceje tek pri dužoj inkubaciji i višim koncentracijama djeluje citotoksično na stanice raka kolona, ekstrakt kestena je pokazao znatno snažniji učinak već kod najniže koncentracije. Ispitivanjem supresije oksidativnog stresa
ekstraktima u kulturi stanica raka zabilježeno je podsticanje oksidativnog stresa kod nižih koncentracija i redukcija pri višim koncentracijama, a slično djelovanje je ustanovljeno i u stanicama tretiranim vodikovim peroksidom. Rezultati upućuju na indukciju antioksidantne zaštite stanica. Senzorska analiza tretiranih kikirikija je utvrdila koncentraciju ekstrakta koja nije izazvala značajnije promjene organoleptike u odnosu na kontrolni uzorak. Tretirane grožđice su bile promijenjenog mirisa i arome, iako bez utjecaja na prihvatljivost samog proizvoda. Dodatak ovdje ispitanih ekstrakata potencijalnog antigenotoksičnog učinka hrani bi, dakle, pored uloge u povećanju održivosti samih namirnica antioksidantnim djelovanjem, mogao modulirati toksičnost prisutnih mikotoksina nakon konzumacije.- The purpose of this thesis is to examine polyphenol content in Echinacea purpurea (L.) Moench and
Castanea sativa Mill. extracts, and to determine antioxidant effects of those extracts, trough electron
spin resonance and colorimetric method of DPPH•; a superoxide hydroxyl radical. Redox effect and
cytotoxicity of the extract in colon cancer cell culture SW480 has also been tested. Antigenotoxic
antimutagenic effect has been evaluated using comet and Ames test, with mutagenic and genotoxic
micotoxines AFB1 and OTA present. Sensory analysis of peanut and raisin samples has also been
performed for the preliminary evaluation of extract treatment. Echinacea herb extract contained higher
total polyphenol content than chesnutt leaves extract (10,57% compared to 6,74%). Echinacea herb
extract had significantly higher phenolic acid content (cicoric and caftarinic acid), while chestnut
extract was rich in tanine and flavonide compounds. Chestnut extract had higher capability to
neutralize DPPH radicals (EC50 = 1,87 μg/mL) compared to Echinacea extract (EC50 = 15,67 μg/mL).
Similar results were obtained when hydroxyl and superoxide radical capture capability was examined;
chestnut extract was about 10 times more effective. Strong antioxidative activity of dominant
compounds has been established, which points out to presence of phenolic acids and elaginic acid in
Echinacea and chestnut respectively, as well as other compounds which contribute to the extract
effect. Inhibitory effect of Echinacea extract on mutagenic effect of aflatoxin B1 has been recorded at
the lowest concentrations, when Salmonella typhimurium bacteria has been treated. On the other hand
there was a strong inhibitory effect demonstrated by the chestnut extract, once it was applied to the
appropriate bacteria culture. The suppression of genotoxic effect of AFB1 and OTA has been
determined using the comet test, whereby significant reduction of the tail length has been determined,
as well as tail moment and intensity in leukocytes treated by mycotoxines and different concentrations
of extracts simultane ously. Chestnut extract has shown strong effects even at low concentrations,
while Echinacea extract had cytotoxic effect on colon cancer cells only after prolonged exposure at
high concentrations. When suppression of the oxidative stress trough extract application has been
examined, it has been established that there is oxidative stress relation with lower concentrations,
while reduction has been established at high concentrations; similar effects have been established once
cells were treated with hydrogen peroxide. The results suggest induction of antioxidative protection of
the cell. Sensory analysis of treated peanuts has established the concentration with no significant
effects on organoleptics compared with the control sample. Treated raisins had a change in aroma and
scent, but without substantial effect on the consumability of the product itself. These additives not only would extend the useful life of various food products; they can also serve as a modulator for toxicity of various micotoxins after those food products have been consumed.- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
U ovom je radu iznesen pregled najnovijih ihtioloških istraživanja u kojima se autori služe tzv. mikronukleusnim testom. Test se u znanstvenoj literaturi spominje već čitav niz godina kao jedno od ...osnovnih sredstava za utvrđivanje oštećenja na DNK organizma–modela. Znanstvenici se njime koriste radi dokazivanja genotoksičnih utjecaja različitih tvari na organizme, u ovom slučaju hidrobionte.
Provider: - Institution: University of Zagreb. School of Dental Medicine. Department of Endodontics and Restorative Dentistry. - Data provided by Europeana Collections- Kompozitni dentalni materijali ...nakon svoje primjene dolaze u izravan dodir s oralnim tkivima. Zbog ovog bliskog i dugotrajnog kontakta, kompozitne materijale bi trebao karakterizirati visok stupanj biokompatibilnosti. Svrha ovog doktorskog rada bila je utvrditi koliko su kompoziti biokompatibilni i sigurni za kliničko korištenje kroz procjenu njihovog citotoksičnog i/ili genotoksičnog djelovanja. Citotoksično i genotoksično djelovanje istraživalo se na stanicama humane kulture gingive i pulpe, ex vivo, ovisno o koncentraciji korištenog materijala primjenom diferencijalnog bojanja akridin-narančastom bojom i etidijevim bromidom te primjenom komet testa. Isti materijali ispitivani su i u in vivo uvjetima. Pacijentima su izrađene kompozitne restauracije klase V te se pratio genotoksični učinak materijala na epitelnim stanicama gingive uz rub postavljenog ispuna. Uzorci stanica za ispitivanje uzimani su 0, 7, 30 i 180 dana nakon postavljanja restauracije. Oštećenje DNK analizirano je dvjema metodama, mikronukleus i komet testom. Kompozitni materijali u testiranim koncentracijama pokazali su genotoksični učinak u uvjetima ex vivo za oba ispitivana parametra komet testa, dužina i intenzitet repa. Kompozitni materijal Kalore pokazao je veću genotoksičnost u odnosu na Vertise flow. Rezultati in vivo dijela istraživanja pokazali su značajno više parametre komet testa unutar razdoblja od 30 i 180 dana. Mikronukleus test za isto vrijeme ekspozicije pokazao je znatno veći broj stanica s mikronukleusom, kariolizom i nuklearnim pupovima. Među testiranim materijalima nije uočena razlika u djelovanju. Na temelju rezultata, možemo zaključiti da upotreba kompozita uzrokuje DNK oštećenje u stanicama pulpe i gingive, međutim uzimajući u obzir visoku učinkovitost mehanizama popravka DNK, rezultate ne bi trebalo smatrati apsolutnim pokazateljima genotoksičnosti.- Objectives: The most important requirement for the materials to be used in medical applications is its biocompatibility. Dental composite materials come into close contact with oral tissues, especially with gingival cells. Due to this close and long-term contact, the materials should exhibit a high degree of biocompatibility. The aim of this doctoral thesis was to certify that the modern composite materials are biocompatible and safe for clinical use and also, was to evaluate their cytotoxic and/or genotoxic effect on human fibroblasts ex vivo and gingival cells in vivo.
Materials and Methods: Ex vivo cytotoxicity and genotoxicity of two contemporary commercial composite materials (Kalore, Vertise flow) on human gingival and pulpal fibroblasts depending on the concentration of the used material (20 mg/ml, 40 mg/ml), were tested using the ethidium bromide/acridin orange viability staining and an alkaline single-cell gel electrophoresis technique (comet assay). Genotoxicity was also assessed in gingival epithelial cells in vivo. Class V composite restorations were placed in 30 adult patients using two different composite resins. Cell samples were collected by gentle brushing gingival area along the composite restoration prior to, 7 days, 30 days, and 180 days following the restoration of the tooth. DNA damage was analysed for each cell sample by comet and micronucleus assay.
Results: Ex vivo tested dental composites revealed statistically significant increase in the tail length and tail intensity in treated human gingival and pulpal fibroblasts, independent of the applied concentration. Cultures treated with nano-hybrid composite material Kalore (20 mg/ml) have been showed more genotoxic than those treated with self-adhesive flowable composite Vertise flow. In vivo results showed significantly higher comet assay parameters (tail length and % DNA in the tail) within 30, and 180 days of treatment. While the micronucleus tests for the same exposure time showed a higher number of cells with micronuclei, karyolysis and nuclearbuds. Results did not reveal the difference between the two composite materials for the same exposure time.
Conclusion: We can conclude based on the results that the use of composite resins causes cellular damage. However, taking into consideration the high efficiency of DNA repair mechanisms, the results should not be considered as an absolute indicator of genotoxicity potential. As dental composite resins remain in close contact with oral tissue over a long period of time, further research on their possible genotoxicity are desirable.- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Jedan od genotoksina, prisutnih u okolišu kao posljedica ratnih djelovanja u Bosni i Hercegovini jest osiromašeni uran. Njegovo porijeklo veže se za upotrebu radioaktivne antitenkovske municije s ...osiromašenim uranom. UNEP-ova mjerenja otkrila su povećanu radioaktivnost na nekoliko ispitanih lokaliteta od kojih je jedan na području Hadžića, u blizini Sarajeva. Naše istraživanje obuhvatilo je evaluaciju genetičkog opterećenja u humanim limfocitima periferne krvi osoba koje su bile nastanjene na području Hadžića te bile direktno izložene osiromašenom uranu. Kao kontrola u istraživanju, uzeta je krv od osoba nastanjenih na području zapadne Hercegovine, koja se smatra ekološki nekontaminiranom. Korištena je metoda mikronukleus-citokalazin B testa, a frekvencije mikronukleusa ispitanika iz obje populacije međusobno su komparirane. Rezultati istraživanja pokazuju povećanu frekvenciju mikronukleusa među ispitanicima eksponirane populacije.
Dugotrajna profesionalna izloženost niskim dozama plinovitih anestetika može imati različite nepoželjne učinke na zdravlje. Iako se zbog slabe topljivosti u krvi i tkivima brzo uklanjaju iz ...organizma, poznati su njihovi neurotoksični, hepatotoksični, a prema nekim istraživanjima i karcinogeni učinci. Istraživanja genotoksičnosti anestetika dala su različite rezultate. Citogenetske metode pokazale su se vrlo prikladnim pri istraživanjima na populaciji profesionalno izloženih osoba. Da bi se procijenio rizik od profesionalne izloženosti anesteticima u skupinama anesteziologa i anestezioloških tehničara analizirane su kromosomske aberacije i učestalost mikronukleusa. Istraživanje je obuhvatilo 28 anesteziologa i 16 anestezioloških tehničara pretežno izloženih dušičnom oksidu i halotanu. U kontrolnoj skupini analizirane su 32 osobe raznih profesija koje na svojim radnim mjestima nisu bile izložene fizikalnim ni kemijskim mutagenima. Skupine ispitanika usklađene su po spolu i duljini izloženosti anesteticima. Dob ispitanika nije mogla biti potpuno usklađena zbog različite dužine školovanja ispitanika, a u kontrolnoj skupini i zbog odabira mlađih, novozaposlenih osoba kako bi se izbjegla profesionalna izloženost mutagenima. U izloženim skupinama nije uočen utjecaj dobi, dužine izloženosti i pušenja na učestalost kromosomskih oštećenja. Porast broja kromosomskih oštećenja nađen je u obje izložene skupine u odnosu na kontrolu. Statistički značajan porast acentričnih fragmenata nađen je kod anesteziologa, a dicentrika kod anestezioloških tehničara. Učestalost mikronukleusa u binuklearnim limfocitima bila je značajno povišena u obje izložene skupine. Ovaj test pokazao se osjetljivijim od analize kromosomskih aberacija, pokazujući i statistički značajno povišenje u učestalosti oštećenja kod žena izloženih anesteticima.
U svrhu izravne usporedbe, provedeno je ispitivanje citotoksičnosti i genotoksičnosti nekih legura koje su u učestaloj uporabi u stomatologiji. Istraživanje je obuhvatilo kobalt-kromne, ...zlatnoplatinske legure i samarij-kobaltne magnete, čiji su pripravci bili valjkasta oblika, dimenzija 3,0 x 6,85 mm, pripravljeni po uputama proizvođača. U pokusima “in vitro” korištena je kvasnica Saccharomyces cerevisiae D7, dok su ”in vivo” pokusi obavljeni na
eksperimentalnim životinjama, albino-štakorima. Ispitivanje citotoksičnosti obuhvatilo je kinetiku diobe stanica gljivice i koloniformnost u mediju rasta oko uloženog pripravka legure. Ispitivanje genotoksičnosti obuhvatilo je istraživanje mutagenosti legura u izravnom dodiru sa stanicama, kao i mikronukleus-test. Rezultati su testirani analizom varijance. Istraživanje citotoksičnosti i genotoksičnosti pokazalo je male razlike među ispitivanim legurama, koje nisu statistički značajne, kako u ”in vitro”, tako i u ”in vivo” pokusima. Rizik uporabe različitih legura u stomatologiji, te neka nesuglasja glede biokompatibilnosti i odabira eksperimentalnih modela, opravdavaju daljnja istraživanja na tome području.
Provider: - Institution: University of Zagreb. Faculty of Pharmacy and Biochemistry. Department of microbiology. - Data provided by Europeana Collections- Fumonizin B1 (FB1), bovericin (BEA) i ...okratoksin A (OTA) su svjetski rašireni mikotoksini koji izazivaju čitav
niz patoloških promjena in vivo i in vitro, a čije je istodobno pojavljivanje u kukuruzu dokazano na području
Hrvatske. Stoga je u ovom radu ispitan mehanizam djelovanja FB1, BEA i OTA i njihove interakcije u PK 15
stanicama (epitel bubrega svinje), praćenjem preživljavanja stanica, integriteta plazmatske i mitohondrijske
membrane, razine lipidne peroksidacije i antioksidacijskog kapaciteta stanice te stupnja apoptoze i
genotoksičnog učinka niskih koncentracija mikotoksina (0,05 g/mL, 0,5 g/mL i 5 g/mL), tijekom 24 i 48
sati. Fumonizin B1, BEA i OTA su citotoksični za PK 15 stanice što se očituje smanjenjem vijabilnosti i
povećanjem katalitičke aktivnosti laktat dehidrogenaze i glutamat dehidrogenaze ovisno o dozi mikotoksina. Sva
tri mikotoksina u najvećoj koncentraciji značajno stimuliraju lipidnu peroksidaciju, a već pri nižim
koncentracijama smanjuju koncentraciju glutationa u PK 15 stanicama. Fumonizin B1, BEA i OTA uzrokuju
apoptozu PK 15 stanica pri čemu se značajnije morfološke apoptotičke promjene zamjećuju nakon 48-satnog
izlaganja. Okratoksin A ima jače djelovanje na aktivnost kaspaze-3 već nakon 24-satnog tretiranja u
koncentracijama od 0,5 i 5 g/mL, dok BEA i OTA uzrokuju značajnije povećanje aktivnosti ovog enzima
nakon duljeg izlaganja. FB1 i BEA su genotoksični za PK 15 stanice u koncentracijama od 0,5 i 5 g/mL, dok
OTA značajno povećava broj mikronukleusa već kod najmanje koncentracije. Sva tri mikotoksina imaju
klastogeni i aneugeni učinak pri čemu je klastogeno djelovanje OTA i BEA više izraženo. U koncentracijama
0,05 i 0,5 g/mL nakon 24- i 48-satnog izlaganja, kombinacije dva i sva tri mikotoksina mikotoksina pokazuju
uglavnom aditivane a manje sinergističke interakcije što se odražava na smanjenje vijabilnosti, narušavanje
integriteta stanične i mitohondrijske membrane, stimulaciju lipidne peroksidacije i smanjnje antioksidacijskog
kapaciteta te apoptozu i mutagenezu. Nakon 24-satnog izlaganja navedenim kombinacijama u koncentraciji 5
g/mL zapažen je aditivan, sinergistički i antagonistički učinak, a nakon 48-satnog tretmana u istoj koncentraciji
više je izražen antagonizam. Istodobni unos niskih koncentracija ovih mikotoksina putem hrane negativno se
odražava na antioksidacijski sustav te može pridonijeti imunosupresiji, nefrotoksičnosti i karcinogenezi u ljudi i
životinja tijekom dulje izloženosti.- Fumonisin B1 (FB1), beauvericin (BEA) and ochratoxin A are widespread mycotoxins, which cause a great
number of pathological changes in vivo and in vitro. Their co-occurrence was established in maize in Croatia.
The mechanism of action of FB1, BEA and OTA, as well as their interactions, were studied in the PK 15 cells
(porcine kidney epithelial cells). We examined the effects of low concentrations (0.05, 0.5 and 5 g/mL) of
individual and combined mycotoxins on cell viability, mitochondrial and plasma membrane integrity, lipid
peroxidation, antioxidative status, and apoptotic and genotoxic events in PK 15 cells. Decrease of cell viability
and increase of catalytic activity of LDH and GLDH show that FB1, BEA and OTA are cytotoxic to PK 15 cell
in dose dependent manner. Individual treatment of cells with 5 g/mL of FB1, BEA and OTA significantly
stimulated lipid peroxidation, while lower concentrations significantly reduced levels of glutathione. Significant
morphological apoptotic changes were observed after 48 hours of exposure to individual mycotoxins. Ochratoxin
A activated caspase-3 already after 24 hours of treatment with 0.5 and 5 g/mL, while BEA and OTA
significantly affected this enzyme after prolonged exposure. Fumonisn B1 and BEA are genotoxic to PK 15 cells
in concentrations of 0.5 and 5 g/mL, while OTA significantly increased the number of micronuclei already after
treatment with lowest concentrations. All of three mycotoxins mainly act as clastogens. Combined treatment
with two or all of three mycotoxins in concentrations of 0.05 and 0.5 g/mL during 24 and 48 hours, showed
mainly additive and less synergistic interactions on cell viability, mitochondrial and plasma membrane integrity,
stimulation of lipid peroxidation and decrease of antioxidative capacity, apoptotic and genotoxic events in PK 15
cells. After 24 hours of exposure to combined mycotoxins in concentration of 5 g/mL, additive, synergistic and
antagonistic effects were observed, while after 48 hours of exposure to same concentration we observed
antagonism. Simultaneous prolonged exposure to mycotoxins in low dietary concentrations can negatively affect
antioxidant status contributing the immunosuppression, nephrotoxicity and carcinogenicity in animals and
humans.- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Provider: - Institution: University of Zagreb. School of Dental Medicine. Department of Endodontics and Restorative Dentistry. - Data provided by Europeana Collections- Izbjeljivanje zubi je postupak ...kojim se tretiraju te u odreĊenom stupnju otklanjaju razliĉite diskoloracije zubi. Aktivni spoj svih sredstava za izbjeljivanje je vodikov peroksid. Mehanizam reakcije vodikovog peroksida nije u potpunosti razjašnjen, ali se smatra da je proces oksidacije, gdje se velike pigmentirane molekule razlažu u manje, odgovoran za izbjeljivanje. Izvori svjetlosti mogu poboljšati izbjeljivanje tako što fotokatalitiĉki ili termokatalitiĉki ubrzavaju aktivni raspad molekula vodikovog peroksida. U ovome istraživanju ispitivao se uĉinak novih izvora svjetlosti: LED405, OLED i femtosekundnog lasera, a kao kontrolni izvor svjetlosti koristio se ZOOM2. Od komercijalnih sredstva za izbjeljivanje koristili su se 10%, 16% i 30% gel karbamid peroksida te 25% i 38% gel vodikovog peroksida. Povišenje temperature pulpne komore iznad kritiĉne vrijednost od 5.5 C zabilježeno je prilikom korištenja fokusiranog femtosekundnog lasera i ZOOM2 izvora svjetlosti, dok nefokusirani femtosekundni laser, LED405 i OLED nisu pokazali znaĉajan porast temperature u pulpnoj komori i na površini. Aktivacija gelova za izbjeljivanje ranije navedenim izvorima svjetlosti nije pokazala veća oštećenja površine cakline i dentina, kao i pojaĉano smanjenje mikrotvrdoće, nego kada su se koristili smo gelovi za izbjeljivanje bez svjetlosne aktivacije. U kemijskom sastavu cakline i dentina nakon izbjeljivanja takoĊer su zabilježene promjene u kvantitativnom omjeru elemenata specifiĉnih za ova tvrda zubna tkiva dok su se preparatima amorfnog kalcijevog fosfata ili boravkom u umjetnom slini sve ranije navedene strukturne, kemijske i morfološke promjene vratile na približno poĉetne vrijednosti, odnosno došlo je i do znaĉajnog porasta odreĊenih kemijskih elemenata odgovornim za remineralizaciju i potencijalni karijesprotektivni uĉinak (Ca, F). Novi izvori svjetlosti LED405 i femtosekundni laser, u kombinaciji s gelovima za izbjeljivanje, doveli su do znaĉajnog poboljšanja u promjeni boje obojanih pastila hidroksilapatita u odnosu na OLED i mjerenja pri kojima smo koristili samo gelove bez svjetlosne aktivacije. Zakljuĉno, sredstava za izbjeljivanje, korištena u kontroliranim kliniĉkim uvjetima pokazala su potencijalni genotoksiĉni i karcinogeni uĉinak na stanice oralne sluznice. Genom stanica pri tome je narušen, ali ne do vrijednosti koja bi bila kliniĉki znaĉajna.- The purpose Tooth whitening is becoming one of the most popular esthetic and corrective treatments for discolored teeth. Bleaching can be performed internally on non-vital teeth or externally on vital teeth by applying hydrogen peroxide, sodium perborate or carbamide peroxide, the most common agents used for bleaching. For acceleration or more effective tooth whitening, different light sources may be used. When the bleaching agent is activated under the influence of light, some amount of light is absorbed and the resulting energy is converted into heat. This can be perceived as a possible side effect during this type of tooth whitening. Therefore, light sources can have photothermal effects which are then associated with the chemical effect of the bleaching materials. In light-activated tooth bleaching procedures, there is a great concern about the heat generated by the light source, which may cause pulp irritation or severe damage such as necrosis. One of the purposes of the present study was to evaluate the surface and intrapulpal temperature changes after bleaching treatment with different gels of hydrogen peroxide (in further text HP) and carbamide peroxide (in further text CP) subjected to different sources of light activation (LED405, OLED, focused and unfocused femtosecond laser and ZOOM2). Also, one of the aims was to evaluate the influence of five bleaching agents on surface microstructure, change in chemical structure and microhardness of human tooth enamel and dentine as well as the change in color of stained specimens before and after the bleaching with different bleaching agents supported by new light sources. Finally, a possible genotoxic effect of two bleaching gels with high concentration of hydrogen peroxide on oral mucosa was investigated. Materials and methods Light sources used in this study were: LED405, OLED, femtosecond laser and ZOOM2. Each experimental group was treated with one of the following: 25% and 38% HP gel and 10%, 16% and 30% CP bleaching gels. For intrapulpal and surface temperature measurements, K-type thermocouple and infrared thermometer were used to repeatedly measure the temperature increase. Tooth surface was treated with five bleaching agents and vaseline which served as a control. For temperature measurements, we used extracted human maxillary central incisors and canines. Vickers microhardness was measured with a load of 100 g for 10 seconds at the baseline, after the last bleaching treatment and after 2 weeks storage in artificial saliva and surface treatment with amorphous calcium phosphate gel (in further text ACP) or 2 weeks storage in deionized water. Enamel and dentine surface morphology was observed under scanning electron microscopy (SEM) while structural and chemical changes were evaluated using energy-dispersive X-ray spectroscopy (EDS). For microhardness as well as SEM and EDS measurements, extracted human third molars were used. Change in color was determined by RGB colorimeter and UV VIS NIS spectrophotometer. For color measurement, specially made pastilles of hydroxyapatite were used. Genotoxic effect of two bleaching agents was analyzed using micronucleus test and the research was conducted on 22 human subjects. Results The average increases in the pulp chamber and tooth surface temperatures for LED405, OLED and unfocused femtosecond laser were below the critical temperature threshold of 5.5C, contrary to the treatments involving ZOOM2 and focused femtosecond laser, regardless of bleaching gel application. All bleaching agents showed significant reduction in surface microhardness. ZOOM2, which had the lower pH value (pH=3.20), showed larger decrease in surface microhardness compared to BOOST (pH=6.75) and 30 %, 16% and 10 % CP (pH=7.0). The treatment with ACP and artificial saliva can increase microhardness and reduce the mineral loss after bleaching treatment. After the bleaching procedure with highly concentrated HP and CP gels, enamel and dentine surface microstructure showed mild or slight alterations with no loss of superficial structure, while low concentration CP gels show no change in morphological structure of tested hard dental tissue. A statistically significant increase in Ca and F ions was found after the bleaching treatment and after the additional treatment with ACP and artificial saliva. The change in color before and after the whitening treatment with different light sources was measured using RGB and UV VIS NIR spectral analysis. After 30 minutes of bleaching treatment with LED405, there was a statistically significant increase in RGB index in comparison to OLED and without light activation for 10% CP, 16% CP, 30% CP, 25 % HP and 38 % HP gels. For femtosecond laser, a statistically significant increase in RGB index was found only when 16 % CP and 38 % HP were used. Finally, the difference between LED405 and femtosecond laser was statistically significant only when 25 % HP gel was used. Both of the tested bleaching agents (25% HP and 38 % HP) demonstrated a potential genotoxic effect. Statistically significant increase of genotoxicity markers was relatively small in amount. Significance Focused femtosecond laser and ZOOM2 produced a large temperature increase in the pulp chamber and at the tooth surface. Caution is advised when using these types of light activation, whereas LED405, OLED and unfocused femtosecond laser could be safely used. Although the application of the bleaching agents reduced temperature variability, the type of the bleaching agent applied was largely irrelevant, indicating similar insulating properties of different gels of HP and CP. All of the used bleaching agents resulted in a reduction of surface enamel and dentine microhardness. The application of ACP remineralizing agents in combination with artificial saliva can cause an increase in surface microhardness. A change in chemical structure of enamel and dentine after bleaching with different bleaching gels and after ACP treatment was found for Ca and F ions which can be a sign of possible remineralization. In combination with the used bleaching agents, LED 405 showed the best effect in color change, followed by femtosecond laser. OLED light showed the weakest effect in color change. Regarding the genotoxic effect of bleaching agents used in this study, it is important to say that oral mucosa cells have a short lifespan and a one-time exposure to such mild genotoxic noxa has probably a negligible carcinogenic potential. Therefore, bleaching can affect the genome of mucosal cells to a certain extent; however, it is difficult to assess clinical significance of these findings.- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
