29 research outputs found
Usporedba standardne i pulsno-laserske polimerizacije kompozitnih materijala
An ever growing amount of photo-curable materials is being used in different fields of dentistry. Standard photopolymerization devices produce about 60% o f monomer conversion in composite resin fillings. In order to improve the quality of polymerization, a series of experiments was made using pulsed laser, because continuous coherent light leads to a higher polymerization shrinkage caused by a temperature rise in the material. Three different experiments were carried out with different shades of composite resins Helioprogress and Heliomolar (Vivadent, Liechtenstein). In the first experiment, the wavelength was changed from 465 to 495 nm in steps o f 5 nm with 30s exposition time. In the second one, the wavelength was constant (470 nm) and the illumination time was changeable (10, 20, 30 and 40s). The cured part of the sample, situated in a specially prepared aluminum mould, was measured with Vernier micrometer. The best results were achieved at 470 nm regardless of the amount of filler and pigment. The results were compared with a commercial device (Heliomat). It is expected that pulsed laser polymerization will improve the degree of monomer conversion, decrease a temperature rise in the composite and in that way avoid wall-to-wall contraction.Zbog Å”irokog uporabnog spektra, jednokomponentni smolasti materijali postali su gotovo nezamjenjivi u raznim stomatoloÅ”kim disciplinama. Standardni polimerizacijski ureÄaji osiguravaju svega 60%-tnu konverziju monomera, dok argonski laser uzrokuje veÄi stupanj polimerizacijskog skvrÄavanja kao rezultat poviÅ”enja temperature na mjestu apsorpcije. Stoga su, prvi put, izvedeni
pokusi polimerizacije kompozita pulsnim laserom (XeCl Lambda- Physik L P X 100). KoriÅ”tene su razliÄite boje kompozitnih materijala Helioprogress i Heliomolar (Vivadent, Liechtenstein). U prvom pokusu, eksperimentirano je sa sedam valnih duljina u rasponu od 465-495 nm pri ekspoziciji od 30s, dok je u drugom valna duljina bila nepromjenljiva (470nm) uz razliÄito vrijeme osvjetljavanja od 10, 20, 30 i 40 s. Polimerizirani dio uzorka, smjeÅ”ten u posebno pripremljenom aluminijskom kalupu, mjeren je pomiÄnim mjerilom, nakon temeljitog odstranjenja mekog dijela kompozita. Zamjetna je najveÄa dubina polimerizacije u podruÄju oko 470 nm bez obzira na koliÄinu punila i pigmenta. Dobiveni rezultati usporeÄeni su s kontrolnim mjerenjima izvedenim halogenom žaruljom (Heliomat). Rad u pulsnom režimu pri odreÄenoj valnoj duljini, mogao bi znatno poboljÅ”ati stupanj konverzije monomera, smanjiti temperaturni porast u materijalu i na taj naÄm reducirati polimerizacijsko skvrÄavanje
Usporedba standardne i pulsno-laserske polimerizacije kompozitnih materijala
An ever growing amount of photo-curable materials is being used in different fields of dentistry. Standard photopolymerization devices produce about 60% o f monomer conversion in composite resin fillings. In order to improve the quality of polymerization, a series of experiments was made using pulsed laser, because continuous coherent light leads to a higher polymerization shrinkage caused by a temperature rise in the material. Three different experiments were carried out with different shades of composite resins Helioprogress and Heliomolar (Vivadent, Liechtenstein). In the first experiment, the wavelength was changed from 465 to 495 nm in steps o f 5 nm with 30s exposition time. In the second one, the wavelength was constant (470 nm) and the illumination time was changeable (10, 20, 30 and 40s). The cured part of the sample, situated in a specially prepared aluminum mould, was measured with Vernier micrometer. The best results were achieved at 470 nm regardless of the amount of filler and pigment. The results were compared with a commercial device (Heliomat). It is expected that pulsed laser polymerization will improve the degree of monomer conversion, decrease a temperature rise in the composite and in that way avoid wall-to-wall contraction.Zbog Å”irokog uporabnog spektra, jednokomponentni smolasti materijali postali su gotovo nezamjenjivi u raznim stomatoloÅ”kim disciplinama. Standardni polimerizacijski ureÄaji osiguravaju svega 60%-tnu konverziju monomera, dok argonski laser uzrokuje veÄi stupanj polimerizacijskog skvrÄavanja kao rezultat poviÅ”enja temperature na mjestu apsorpcije. Stoga su, prvi put, izvedeni
pokusi polimerizacije kompozita pulsnim laserom (XeCl Lambda- Physik L P X 100). KoriÅ”tene su razliÄite boje kompozitnih materijala Helioprogress i Heliomolar (Vivadent, Liechtenstein). U prvom pokusu, eksperimentirano je sa sedam valnih duljina u rasponu od 465-495 nm pri ekspoziciji od 30s, dok je u drugom valna duljina bila nepromjenljiva (470nm) uz razliÄito vrijeme osvjetljavanja od 10, 20, 30 i 40 s. Polimerizirani dio uzorka, smjeÅ”ten u posebno pripremljenom aluminijskom kalupu, mjeren je pomiÄnim mjerilom, nakon temeljitog odstranjenja mekog dijela kompozita. Zamjetna je najveÄa dubina polimerizacije u podruÄju oko 470 nm bez obzira na koliÄinu punila i pigmenta. Dobiveni rezultati usporeÄeni su s kontrolnim mjerenjima izvedenim halogenom žaruljom (Heliomat). Rad u pulsnom režimu pri odreÄenoj valnoj duljini, mogao bi znatno poboljÅ”ati stupanj konverzije monomera, smanjiti temperaturni porast u materijalu i na taj naÄm reducirati polimerizacijsko skvrÄavanje
Polymerization Contraction of Composite Resin Filling
Volumetrijska kontrakcija negativna je posljedica polimerizacije kompozitnih materijala. Uzrok je pojavi pukotine izmeÄu ispuna i zuba s posljediÄnim mikropropuÅ”tanjem, rubnim obojenjem, sekundarnim karijesom i moguÄom iritacijom zubne pulpe. Te pojave, inducirane dimenzijskim promjenama, kompromitiraju kakvoÄu, trajnost i estetiku kompozitnog ispuna. U svrhu prevladavanja polimerizacijske kontrakcije nužno je obratiti posebnu pozornost pripravi kaviteta prije postavljanja slojeva kompozitnog materijala. Potrebno je odstraniti ili preobraziti zaostatni sloj koji zatvara dentinske kanaliÄe mehaniÄki obraÄivanog dentina da bi se stvorili uvjeti za adheziju ispuna. Kod pliÄih se kaviteta, zatim, rabe dentinska ljepila (adhezivi), a kod dubljih svjetlosno polimerizirajuÄi stakleno-ionomerni cementi radi poboljÅ”anja ÄvrstoÄe sveze izmeÄu ispuna i kaviteta. Aplikacija kompozitnog materijala s visokim sadržajem anorganskog punila drugi je naÄin prevladavanja polimerizacijske kontrakcije. TreÄa je moguÄnost izbor polimerizacijskog ureÄaja s minimalnom indukcijom topline uz maksimalan polimerizacijski uÄinak, jer je porast temperature u kompozitnom materijalu izravan, uzrok dimenzijskih promjena. Kompenzacijom polimerizacijske kontrakcije onemoguÄuje se nastanak rubne p u kotine - najveÄeg problema pri rekonstrukciji zuba kompozitnim materijalima.Polymerization shrinkage is a negative consequence o f the setting o f composite materials. It usually leads to the formation o f gaps around cavity margins, which is resulting in microleakage, marginal discoloration, reccurent caries and possible tooth sensitivity. To overcome the polymerization contraction, it is necessary to treat the cavity walls before the composite material application. The removal or modification o f the dentin smear layer appears to play a significant part in the mechanism by which the dentin and resin become linked. In shallow cavities, it is sufficient to use dentin adhesives, but in deeper cavities use o f light-hardened glass-ionomer cements is required to improve the adhesive capacity and bonding strength o f the resin to the tooth structure. It enables penetration, impregnation and entanglement o f the methacrylate-based monomers into dentinal substrates, where they polymerize in situ and create zones o f resin-reinforced dentin or Ā»hybrid layersĀ«. Other ways o f prevailing the volumetric contraction are the application o f hybrid composite materials with high filler weight percentage and use o f light-curing device with minimal heat-generation and maximal polymerization effect. It is known that temperature elevation in a composite material directly leads to dimension changes. Thus, the marginal gap formation, the major problem in composite resin tooth restoration, can be prevented by overcoming the polymerization contraction
Noncarious Destructive Lesions of Dental Hard Tissue
Osim karijesa, parodontopatija i trauma kao najrasprostranjenijih bolesti Äovjeka, zube tijekom života oÅ”teÄuju mnogobrojni fiziÄkokemijski nefizioloÅ”ki podražaji koji postupno razaraju tvrdo zubno tkivo. Skupni im je naziv: nekarijesne kroniÄne lezije tvrdih zubnih tkiva. ZajedniÄko obilježje tih oÅ”teÄenja jest da se javljaju na zubnim povrÅ”inama bez plaka, nisu karijesne ni bakterijske prirode i imaju multikauzalnu etiologiju. OÅ”teÄenja tvrdih zubnih tkiva kod nekarijesnih kroniÄnih lezija su polagana i dugotrajna, izazivaju neugodnu preosjetljivost zubi, bolne senzacije, promjene u pulpi i konaÄno gubitak zuba. Pojavljuju se kao abrazija, atricija, abfrakcija i erozija. Kiseline koje otapaju zubna tkiva potjeÄu iz vanjskih, unutarnjih i nepoznatih izvora.Loss of tooth tissue occurs in a number of ways, dental caries and trauma being the more obvious ones, although tooth wear in its own right is assuming greater importance. Non-carious destructive processes affecting the teeth, including abrasion, attrition, abfraction and erosion, are presented. According to current knowledge, non-carious destructive processes appear on the dental surfaces free o f plaque. They are non-carious destructive lesions and have multifactorial etiology. The acids producing tooth destruction may be exogenous, endogenous or unknown origin
TOTAL CONTRIBUTION OF TOURISM TO CROATIAN ECONOMY: INPUT-OUTPUT MODEL AND TOURISM SATELLITE ACCOUNT
PromatrajuÄi turizam kao skup svih djelatnosti gospodarstva kojeg odreÄuje (turistiÄka) potražnja, ovaj Älanak ima za svrhu procijeniti ukupan, izravan i neizravan, doprinos turizma gospodarstvu Hrvatske. Osnovu za procjenu veliÄine turizma i njegovog izravnog doprinosa gospodarstvu u okviru statistike turizma, pruža satelitski raÄun turizma. Procjena neizravnog i ukupnog doprinosa pretpostavlja koriÅ”tenje razliÄitih stohastiÄkih ili deterministiÄkih modela. U ovom je radu procjena ukupnog doprinosa turizma zasnovana na input-output modelu kojeg sa satelitskim raÄunom turizma povezuje izbor djelatnosti (matrica ukupnih meÄufaznih tokova dimenzije 13x13) i podaci o turistiÄkoj potroÅ”nji. Postupkom prikazanim u radu dobivena je statiÄka procjena utjecaja turistiÄke potražnje na hrvatski BDP u baziÄnim cijenama za 2005. godinu. U svrhu unapreÄenja metoda procjena nužno je u buduÄnosti nastaviti daljnju intenzivniju suradnju turistiÄkih struÄnjaka i ānacionalnih raÄunovoÄaā Hrvatske, koja bi omoguÄila uspjeÅ”nu primjenu dinamiÄkih simulacijskih modela podržanih modernim informacijskim tehnologijama.Considering tourism as a set of demand driven economic activities which are de-termined by (tourism) demand, the purpose of this paper is to assess the total, direct and indirect, contribution of tourism to the Croatian economy. Within the system of tourism statistics framework, the basis for estimating the size of tourism and its direct contribution to the economy is provided by Tourism Satellite Account. Assessment of indirect and total contribution assumes the use of different stochastic or deterministic models. This paper uses input-output model for estimation of total tourism contribution. Input-output model is linked to Tourism Satellite Account through the selection of activities (dimension of matrix of total intermediate fl ows is 13x13) as well as through data on tourism expendi-tures. Procedures presented in this paper result in static assessment of the contribution of tourism demand to Croatian GDP at basic prices for 2005. In order to improve the method of these estimates it is necessary to further intensify cooperation of tourism experts and Croatian national accountants in the future. That would enable successful application of dynamic simulation models supported by modern information technologies
Povezanost stupnja konverzije i transmisije svjetla kroz uzorak kompozitnog materijala
Quantitative analysis of residual double bonds or free radicals in the polymer network is the most reliable method for determining the degree of conversion. In this study, measurements of the degree of conversion and light transmission of three different composite resin materials and two different shades (the lightest and the darkest shades) were evaluated. The correlation between the measurements of the degree of conversion and light transmission was observed. Absorption and scattering by filler particles would continue the light attenuation through a composite resin specimen and consequentially reduce the degree of conversion. There is a dependence on the amount of filler loading and composite resin shade. The results confirmed the hybrid materials and lighter shades to provide higher conversion than the microfilled composite resins as well as darker and more opaque shade. It was also found that illumination by a curing unit of low output (230 mW/cm2) should be prolonged and gradual
increments should not exceed one mm.Najpouzdaniji postupak odreÄivanja stupnja konverzije jest kvantitativna analiza zaostatnih dvostrukih sveza ili slobodnih radikala u polimerskoj mreži. Svrha ovoga rada bila je procjena ovisnosti stupnja konverzije i transmisije svjetla kroz razliÄite uzorke kompozitnih materijala. Stupanj konverzije odreÄivan je Fourier-transform infracrvenom (FTIR) spektroskopijom, a transmisija svjetla Minolta Chromametrom. Za polimerizaciju kompozita rabljena je standardna halo gena žarulja Heliolux II snage 230 mW/cm2. Rezultati potvrÄuju meÄusobnu ovisnost prethodno nave-denih parametara kao i ovisnost stupnja konverzije o koliÄini anorganskog punila i boji kompozitnog materijala. Znano je da hibridne kompozitne smole ostvaruju viÅ”i stupanj konverzije od onih s mikropunilom. Materijali tamnih boja ne osiguravaju dostatnu polimerizaciju dubljih slojeva kom-pozitnog ispuna. Stoga je, u tim sluÄajevima, nužno rabiti žarulje jaÄe snage, produžiti vrijeme izloženosti svjetlu i postavljati tanje slojeve kompozitnog materijala (1 mm)
Esthetic Reconstruction of the Incisal Edge of Upper Central Incisors
OÅ”teÄeni incizijski bridovi srediÅ”njih gornjih sjekutiÄa smatraju se znaÄajnim i razmerno složenim problemom u restorativnoj stomatologiji zbog minimalnoga stupnja oÅ”teÄenja, složenih estetskih zahtijeva te zbog osiguravanja dugotrajnosti provedene rekonstrukcije. Za opskrbu incizijskih defekata postoji niz tehnika. MeÄu njima je najmanje invanzivna izravna tehnika kompozitnim smolama.
Svrha rad bila je prikazati jednu od moguÄnosti rekonstrukcije traumom oÅ”teÄenog incizijskoga brida. Pacijent K.R., u dobi od 22 godine, imao je nakon udarca tvrdim predmetom frakture cakline i dijela dentina na incizijskome bridu. PrijaÅ”nji restorativni zahvat nije bio odgovarajuÄi pa se proveo nov postupak uporabom Artemis
(Vivadent, Schaan, Liechtenstein) mikrohibridnoga kompozitnoga
materijala s paletom estetskih nijansi za stimuliranje cakline, dentina i posebnih efekata. Opakne nijanse boja stimulirale su izgubljeni dentin, prozirne caklinske boje caklinu, a mamelonske i jasne transparentne boje posebne efekte. Rekonstrukcija je provedena u slojevitoj tehnici uz uporabu instrumenata za plasticiranje i
odgovarajuÄih kistova uz polimerizaciju svakoga sloja posebno.Damaged incisal edges of the upper central incisors are considered to be an important as well as a relatively complex problem in restorative dentistry because the degree of damage is minimal yet esthetical demand provision of long-lasting reconstruction complex. There are several techniques for provision of incisal defects, the least
invasive being direct technique with composite resins. The purpose of this study was to present one of the possibilities for reconstruction of trauma damaged incisal edge. A 22 year old patient after being strike by a hard object, sustained fractures od enamel and part of the dentin on the incisal edge. Previously performed restorative treatment
was not satisfactory, so a new procedure was undertaken, using Artemis (Vivadent, Schaan, Liechtenstein) microhybrid composite material with a wide spectrum of shades for enamel and dentin simulation as well as special effects. Opaque shades of colours simulated lost dentin, transparent enamel shades enamel, and mammelon and clear transparent shades special effects. Reconstruction was performed in layer technique with the use
of instruments for plasticizing including responding brushes and polymerization of each layer separately
Influence of Dentine Adhesive with Nanofiller on Postrestorative Sensitivity
Sve veÄi zahtjevi za dugotrajnoÅ”Äu ispuna i rubnog integriteta utjeÄu na razvoj novih materijala i tehnika rada u restorativnom postupku na caklini i dentinu. Ti zahtjevi potaknuli su razvitak nekoliko generacija kompozitnih materijala i caklinsko-dentinskih adheziva s tendencijom stalnog poboljÅ”anja. Adhezijska sveza restorativnog materijala za caklinu postiže se uspjeÅ”no s pomoÄu caklinskih adheziva, no tehnika sveze za dentin, zbog specifiÄne graÄe i vlažnosti dentinske povrÅ”ine, nije uvijek zadovoljavajuÄa i dugotrajna. Najnovije generacije dentinskih adheziva pokazuju bolje vrijednosti sveze i hermetskoga zatvaranja dentinske povrÅ”ine uz pojednostavljeniji postupak primjene od prijaÅ”njih. Svrha ovoga rada bila je na ukupno 453 mala, srednje duboka i duboka kaviteta kliniÄki utvrditi postojanje poslijerestorativne preosjetljivosti nakon aplikacije āExciteā(Vivadent, Schaan, Liechtenstein) caklinsko-dentinskog adheziva ispod kompozitnog ispuna mjesec dana i tri mjeseca nakon Å”to je postavljen ispun. Nakon mjesec dana 21 zub je pokazivao osjetljivost 1., 2. i 3. stupnja, a tri mjeseca poslije samo Äetiri zuba su pokazala osjetljivost 1. i 2. stupnja, Å”to potvrÄuje da āExciteācaklinsko-dentinski adheziv može uspjeÅ”no smanjiti pojavu poslijerestorativne osjetljivosti zuba.Increasing requirements for the longevity of filling and marginal integration has influenced the development of new materials in restorative procedure on enamel and dentine. These requirements have contributed to the development of several generations of composite materials and dentine adhesives. Adhesion of the restorative material on the enamel is succesfully enhanced with the use of enamel adhesives, while bonding to dentine, because of its specific constitution and wetness of its surface, is not always acceptable and longlasting. The latest generation of dentine adhesives shows better bonding values, better sealing of the dentine surface and is simpler to handle than earlier generations of dentine adhesives. The aim of this study was to determine in 453 small medium and deep cavities the clinical existence of postrestorative sensitivity after the application of āExciteā one-bottle enamel-dentine adhesive under a composite resin filling one and three months after the application of the composite filling. After one month 21 teeth showed sensitivity of 1st, 2nd and 3th degree, and after three months only four teeth showed sensitivity of 1st and 2nd degree. This confirmed the fact that āExciteā enamel-dentine adhesive can successfully decrease the presence of postrestorative sensitivity
Dental Erosions in Patients with Anorexia and Bulimia Nervosa
Dentalne erozije spadaju u skupinu kemijski uzrokovanih kroniÄnih lezija tvrdih zubnih tkiva. ZajedniÄko obilježje takvih oÅ”teÄenja jest da se pojavljuju na povrÅ”inama zuba bez plaka te da imaju nekarijesnu i nebakterijsku prirodu. Kao potencijalni riziÄni Äimbenici nastanka dentalnih erozija spominju se: promjena naÄina života i prehrane, poveÄano konzumiranje kisele hrane i piÄa, te razliÄiti gastrointestinalni poremeÄaji. Dugotrajno djelovanje izrazito kisela sadržaja uzrokuje postupnu demineralizaciju anorganske tvari tvrdih zubnih tkiva i nastanak erozijskih lezija. Ti defekti uzrok su brzem abrazijskom troÅ”enju i smanjivanju sveukupnog volumena zuba.Dental erosions belong to a group of chemically caused chronic lesions of hard tooth tissue. A common characteristic of these lesions are the appearance of a tooth surface without plaque as well as noncarious and nonbacterial etiology. As potentional risk factors for dental erosions are new life style, increased consumption of acid food and drinks and different gastrointestinal disorders. Long-lasting exposure to acid substances leads slowly to demineralization of the anorganic component of hard tooth tissue and the appearance of dental erosion. These defects lead to faster abrasion and decrease of whole tooth volume and greater tooth sensitivity
Degree of Conversion and Temperature Measurement of Composite Polymerised with Halogen and LED-Curing Unit
DanaÅ”nji kompozitni materijali polimeriziraju se vidljivim plavim svjetlom valne duljine oko 468 nm. Komercijalni ureÄaji za polimerizaciju kompozitnih materijala emitiraju plavo svjetlo razliÄite jakosti. Uporaba ureÄaja za polimerizaciju jaÄega intenziteta sa svrhom da se postigne veÄi stupanj konverzije neminovno poveÄava zagrijavanje i temperaturu u materijalu tijekom stvrdnjavanja te polimerizacijski skuplja materijal. Svrha rada bila je utvrditi postoji li razlika izmeÄu stupnja konverzije i porasta temperature triju ispitivanih kompozitnih materijala: Amelogen (Akeda Dental, Danska), Pertac II (ESPE, Seefeld, Germany), Z100 (3M Dental Products, St. Paul, Minessotta, USA), polimeriziranih eksponencijskim programom Elipar Trilight (ESPE, Seefeld, NjemaÄka) polimerizatora i Lux-o-Max (Akeda Dental, Danska) ureÄajem za polimerizaciju temeljenog na LED (light emitting diodes) tehnologiji. Rezultati su pokazali tek neÅ”to niži stupanj konverzije pri polimerizaciji Lux-o-Max ureÄajem u odnosu prema eksponencijskome programu Elipar Trilight polimerizatora. Temperaturni porast znatno je niži pri polimerizaciji Lux-o-Max ureÄajem za sve ispitivane kompozitne materijale u usporedbi s rezultatima dobivenima pri polimerizaciji eksponencijskim programom Elipar Trilight polimerizatora.Today available composite materials are polymerized by blue light, with a wavelength of about 468 nm. Commercially available curing units for composite resin polymerization emit blue light of different intensity. Using curing units of higher light intensity to reach a higher degree of conversion unavoidably leads to higher temperature rise in material during hardening, and also to polymerization shrinkage of material. The aim of this study was to determine if there is any difference between the degree of conversion and temperature rise in three composite materials: Amelogen (Akeda Dental, Denmark), Pertac II (ESPE, Seefeld, Germany) and Z100 (3M Dental Products, St. Paul, Minessotta, USA) polymerized with exponential program of Elipar Trilight curing unit (ESPE, Seefeld, Germany) and Lux-o-Max curing unit (Akeda Dental, Denmark) based on LED (light emitting diodes) technology. The results showed only a slightly lower degree of conversion, in the case of polymerization with Lux-o-Max curing unit. The temperature rise was significantly lower in the case of polymerization with Lux-o-Max curing unit for all tested composite materials