Avtor/Urednik		Jevnikar, Peter; Jarh, Orest; Sepe, Ana; Funduk, Nenad
Naslov		The effect of setting mode on water diffusion and flexural strength of resin modified glass ionomer cements
Prevedeni naslov		Vpliv načina strjevanja na difuzijo vode in upogibno trdnost steklasto ionomernih cementov z dodatki kompozitov
Tip		članek
Vir		Zdrav Vestn
Vol. in št.		Letnik 67, št. Suppl 2
Leto izdaje		1998
Obseg		str. II-19-23
Jezik		eng
Abstrakt		Introduction. Glass ionomer cements are susceptible to water contaminantion in the early stages of the setting reaction. Resin modified glass ionometer cements (RM GIC) were developed, where photopolymerization should prevent early contact with water. It is not known how susceptible these materials are when they set without photopolymerization. The purpose of the present study was to visualize the water penetration into RM GIC samples prepared in two different setting modes as a function of time using MR microimaging. In addition we wanted to answer the questions if the flexural strenght of the cement is impaired when the photopolymerization is excluded. Materials and methods. Resin modified glass ionomer cement Fuji II LC CAPSULE (GC, Japan) was used in this study. Half of the samples for MR microimaging were radially exposed to a light source and the other half were allowed to set without photopolymerization. Both groups of samples were then stored in distilled water at 37 degrees C and imaged at different times. The same cement was used for the preparation of samples for flexural strenght testing. Half of the samples for each test time were photopolymerized and the other half were stored in dark-room. All samples were subjected to the three-point bending flexural strenght test. Results. MR microimaging showed that the variation in the setting mode results in substantial differences in the water penetration dynamics into the resin modified glass ionomer cement. The water uptake was slower in VL cured than in only chemically cured material. The flexural strenght of VL cured cement was significantly higher than of chemically cured cement. Water storage lowered the values in all test points and in both setting modes significantly (p < 0.05) except for the chemical cured samples after 7 days. (Abstract truncated at 2000 characters.)
Izvleček		Izhodišča. Steklasto ionomerni cementi (SIC) so sodobni dentalni materiali na vodni osnovi, ki se vežejo na trda zobna tkiva, sproščajo fluorindne ione in ne dražijo zobne pulpe. Strjujejo se preko acido bazne reakcije pri čemer so občutjivi na vodo v začetni fazi strjevanja. V želji, da bi to slabost odpravili, so razvili nov tip SIC z dodatkom plastičnih mas, ki imajo dvojni mehanizem strjevanja. Poleg stekel, polielektrolitov in vode, torej sestavin značilnih za klasične SIC, vsebujejo ti materiali še plastično maso v monomerni obliki, ki svetlobno polimerizira. Fotopolimerizacija, ki zagotovi hitro strjevanje na začetku naj bi preprečile prazgodnji vdor vode v material, ni pa znano kako se prodiranju vode med strjevanjem upira cement, če fotopolimerizacijo izključimo.V našem delu smo sledili prodiranju vode n SIC z dodatkom plastičnih mas pri dveh različnih načinih strjevanja, za kar smo uporabili magnetno resonančno mikroslikanje. Želeli smo tudi odgovoriti na vprašanje ali se cementu, ki se strjuje v temi, t.j. brez fotopolimerizacije, spremenijo mehanske lastnosti, kar smo preverjali s trotočkovnim upogibnim testom. Metode in materiali. Za študij prodiranja vode v steklasto ionomerne cemente z magnetno resonančno mikroskopijo smo sveže namešan cement injicirali v valje iz kvarčnega stekla dolžine 10mm in notranjega premera 4 mm. Pripravili smo dve skupini vzorcev (n = 8): Vzorce prve skupine smo krožno obsevali 120 s z dentalno polimerizacijsko lučjo, vzorce druge skupine pa smo takoj po injiciranju v kvarčne valje shranili v temnem prostoru, ter tako izključili fotopolimerizacijo. Vzorce obeh skupin smo med poskusom hranili v vodni kopeli pri temperaturi 37 stopinj C. MR meritve smo opravili na tomografskem sistemu Bruker Biospec (Bruker, Nemčija), ki je bil opremljen z dodatnimi gradientnimi tuljavami za mikroslikanje. (Izvleček prekinjen pri 2000 znakih.)
Deskriptorji		GLASS IONOMER CEMENTS MAGNETIC RESONANCE IMAGING PLIABILITY WATER HARDNESS TESTS