PMC:2854328 / 20511-22361 JSONTXT

{"project":"MyTest","denotations":[{"id":"20396441-16546248-28965147","span":{"begin":1635,"end":1638},"obj":"16546248"}],"namespaces":[{"prefix":"_base","uri":"https://www.uniprot.org/uniprot/testbase"},{"prefix":"UniProtKB","uri":"https://www.uniprot.org/uniprot/"},{"prefix":"uniprot","uri":"https://www.uniprot.org/uniprotkb/"}],"text":"The resin matrix of composites might become chemically degraded by the concentration or repeated application of peroxide. In addition, if the bleaching agent degraded the coupling agent of resin composites, the resultant roughness would be exaggerated.36 In the current study, it was observed that the type of bleaching system had a significant effect on roughness. The bleaching agents used differed in pH and duration of application. The low pH of the LumaWhite-Plus bleaching system could have been the reason why significantly higher surface roughness was obtained after the second bleaching session with shade A2. It appears that the effect of pH was, on the other hand, surpassed by the effect of the duration of application of the bleaching agent. When Opalescence Boost bleaching, which has a neutral pH but a longer gel contact time (45 minutes), was applied, it resulted in significantly higher surface roughness compared to the other bleaching agents (24 minutes of gel contact time) after initial bleaching in the A4 shade. However, after re-bleaching, no significant difference was found between Opalescence Boost and LumaWhite. Both had higher values than Beyond and the control groups. Nevertheless, it was surprising to find that Beyond, having an acidic pH and the same contact time as the LumaWhite-Plus, resulted in significantly lower surface roughness, even when compared to the controls, particularly after re-bleaching. It has been postulated that peroxides might induce oxidative cleavage of polymer chains and, therefore, any un-reacted double bonds are expected to be the most vulnerable parts of the polymer.37 In case of Beyond, the high intensity light used during bleaching might have resulted in greater double bond formation in the resin matrix, rendering it less vulnerable to the detrimental effects of the peroxide."}

{"project":"2_test","denotations":[{"id":"20396441-16546248-28965147","span":{"begin":1635,"end":1637},"obj":"16546248"}],"text":"The resin matrix of composites might become chemically degraded by the concentration or repeated application of peroxide. In addition, if the bleaching agent degraded the coupling agent of resin composites, the resultant roughness would be exaggerated.36 In the current study, it was observed that the type of bleaching system had a significant effect on roughness. The bleaching agents used differed in pH and duration of application. The low pH of the LumaWhite-Plus bleaching system could have been the reason why significantly higher surface roughness was obtained after the second bleaching session with shade A2. It appears that the effect of pH was, on the other hand, surpassed by the effect of the duration of application of the bleaching agent. When Opalescence Boost bleaching, which has a neutral pH but a longer gel contact time (45 minutes), was applied, it resulted in significantly higher surface roughness compared to the other bleaching agents (24 minutes of gel contact time) after initial bleaching in the A4 shade. However, after re-bleaching, no significant difference was found between Opalescence Boost and LumaWhite. Both had higher values than Beyond and the control groups. Nevertheless, it was surprising to find that Beyond, having an acidic pH and the same contact time as the LumaWhite-Plus, resulted in significantly lower surface roughness, even when compared to the controls, particularly after re-bleaching. It has been postulated that peroxides might induce oxidative cleavage of polymer chains and, therefore, any un-reacted double bonds are expected to be the most vulnerable parts of the polymer.37 In case of Beyond, the high intensity light used during bleaching might have resulted in greater double bond formation in the resin matrix, rendering it less vulnerable to the detrimental effects of the peroxide."}