Ontiveros and Paravina / Light-emitting diode polymerization, Part II 671 LIGHT-EMITTING DIODE POLYMERIZATION: A REVIEW OF PERFORMANCE, PART II Joe C. Ontiveros, Rade D. Paravina UnIversIty Of texas DentaL Branch at hOUstOn; DePartment Of restOratIve DentIstry anD BIOmaterIaLs; UnIversIty Of texas DentaL Branch at hOUstOn, hOUstOn, tx 77030-3402, Usa acta stomatologica naissi jun/June 2007, vol. 23, broj/number 55 str./p 671 - 678 Abstract Several important properties associated with light-emitting diode (LED) polymerization lights and dental materials treated using LED technology, such as compressive and lexural strength, bond strength, temperature rise, power density, and material thickness and opacity, have been reviewed in this paper. Key words: polymerization, light-emitting diode, depth of cure, hard- ness, degree of conversion, compressive strength, lexural strength, bond strength Degree of Conversion the introduction of fourier transform in- frared spectroscopy (ftIr) of polymers has brought about a renewal interest in infrared spectroscopy as a method of determining de- gree of conversion. 1 the term degree of con- version describes the percentage of c=c double bonds that react during the free-radical polyme- rization process and is a major determinant for the properties of composite resin. the degree of conversion with photo initiation ranges from about 65 percent to 80 percent, whereas chemi- cal initiation results in values from 60 percent to 75%. 2 as described by asmussen et al. 3 , ftIr involves analyzing thin ilms of resin compos- ite which are immersed in strong solvents such as methanol, and the Ir absorption peak of the c=c double bond at 1,640 cm -1 and the absorp- PREGLEDNI RAD REVIEW ARTICLE Kratak sadržaj U ovom radu prikazano je nekoliko važnih osobina u vezi svetlosno- polimerizujuće diode (LED) polimerizacionog svetla i dentalnih ma- terijala tretiranih upotrebom LED tehnologije, kao što su kompresivna i leksuralna snaga vezivanja, porast temperature, gustina snage, de- bljina materijala i neprovidnost. Ključne reči: polimerizacija, svetlosno emitujuća dioda, dubina polime- rizacije, tvrdoća, stepen konverzije, kompresivna snaga, leksuralna snaga, snaga vezivanja Stepen konverzije Uvođenje Fourier transformacione infra- red spektroskopije (ftIr) polimera je ponovo oživelo interesovanje za infrared spektroskopiju kao metodu za određivanje stepena konverzije. 1 Pojam stepen konverzije opisuje procenat c=c dvogubih veza koje reaguju za vreme polim- erizacije slobodnih radikala i to je glavna de- terminanta za određivanje of composite resin. Stepen konverzije foto inicijatorima se kreće od 65% do 80%, dok hemijska inicijacija re- zultira vrednostima od 60% do 75%. 2 Kao što su to već opisali Asmussen i saradnici 3 , ftIr uključuje analizu tankih ilmova resin kom- pozita koji se potapaju u jake rastvarače poput metanola. Ir apsorpciona maksimalna vrednost c=c dvogube veze na 1,640 cm -1 i apsorpcija aromatičnog lepka od 1,610 cm -1 određuju se pre i posle polimerizacije.