“…However, in the present study sample's dimensions were set bigger to allow sufficient resolution in the μCT experiment and to provide sufficient data to probe the variables under study as function of depth. The polymerization contraction of the resinous materials is usually assessed by scanning in a microscope mechanically sectioned samples (Raskin et al, 2003), or by methods such as the use of dyes (Chiang et al, 2010), gas pycnometer (Amore & Lewgoy, 2003), biaxial stacked strain gauge (Damineni, Mashalkar, & Sharaschandra, 2014), and advanced video extensometer (Weig, Magalhães Filho, Costa Neto, & Costa, 2015). However, some of these techniques destroy the samples, depends on the ability of the experimentalist and provide limited assessment and resolution.…”
This research aimed to obtain the depth dependence of polymerization contraction and microporosity from irradiated dental resin cements by X-ray computed microtomography (μCT). Samples (n = 5) of commercial Relyx U200 (RU) and AllCem Core (AC) dual-cure resin cements were injected in a cylindrical Teflon sampler (25 mm 3 ) and separated according to polymerization mechanism: self-cured (not irradiated) and dual-cured (irradiated from the top surface with a LED device). The cement's volume was scanned with the μCT scanning conditions kept constant. To assess the depth dependence of polymerization contraction, it was measured the displacement of the cement mass from the sample holder at 30 vertical cuts (0.1 mm distant). To probe the microporosity, the percentage of area with presence of porosity by slice was obtained. All data were statistically treated. It was observed a positive linear correlation between depth and polymerization contraction in the irradiated groups. In the other hand, the concentration of micropores decreased with increasing depth. Furthermore, the composition of the resin cement was determinant for the correlation's coefficients of these physical properties with depth. The μCT technique showed to be useful to probe physical properties of dental restorative materials that influence in the clinical outcomes, revealing that, for thin specimens, when light cured the RU cement presented mechanical behavior more favorable for clinical applications.
“…However, in the present study sample's dimensions were set bigger to allow sufficient resolution in the μCT experiment and to provide sufficient data to probe the variables under study as function of depth. The polymerization contraction of the resinous materials is usually assessed by scanning in a microscope mechanically sectioned samples (Raskin et al, 2003), or by methods such as the use of dyes (Chiang et al, 2010), gas pycnometer (Amore & Lewgoy, 2003), biaxial stacked strain gauge (Damineni, Mashalkar, & Sharaschandra, 2014), and advanced video extensometer (Weig, Magalhães Filho, Costa Neto, & Costa, 2015). However, some of these techniques destroy the samples, depends on the ability of the experimentalist and provide limited assessment and resolution.…”
This research aimed to obtain the depth dependence of polymerization contraction and microporosity from irradiated dental resin cements by X-ray computed microtomography (μCT). Samples (n = 5) of commercial Relyx U200 (RU) and AllCem Core (AC) dual-cure resin cements were injected in a cylindrical Teflon sampler (25 mm 3 ) and separated according to polymerization mechanism: self-cured (not irradiated) and dual-cured (irradiated from the top surface with a LED device). The cement's volume was scanned with the μCT scanning conditions kept constant. To assess the depth dependence of polymerization contraction, it was measured the displacement of the cement mass from the sample holder at 30 vertical cuts (0.1 mm distant). To probe the microporosity, the percentage of area with presence of porosity by slice was obtained. All data were statistically treated. It was observed a positive linear correlation between depth and polymerization contraction in the irradiated groups. In the other hand, the concentration of micropores decreased with increasing depth. Furthermore, the composition of the resin cement was determinant for the correlation's coefficients of these physical properties with depth. The μCT technique showed to be useful to probe physical properties of dental restorative materials that influence in the clinical outcomes, revealing that, for thin specimens, when light cured the RU cement presented mechanical behavior more favorable for clinical applications.
“…14 Kompozit rezinlerde gerçekleşen bu büzülme materyal içeriğine bağlı olarak %1.5-5 arasında değişmektedir. 15 Polimerizasyon büzülmesi kompozit rezinde internal gerilimler oluşturur ve materyalin kavite duvarlarına balanarak sertleşmesi sırasInda diş-restorasyon ara yüzeyi ve diş yapısında stresler artar 16,17 Polimerizasyon büzülmesi ve gerilimleri şu faktörlerden etkilenmektedir: kompozit materyalin toplam hacmi, kompozit tipi, polimerizasyon hızı ve C faktör/diş preparasyonun konfigüras-yonu. 16 C faktör restorasyonların bağlandığı yüzeyle-rin serbest yüzeylere oranıdır ve büzülen restoratif materyale yüklenen basınç seviyesini ifade etmek için kullanılan bir göstergedir.…”
Section: 13unclassified
“…24 Polimerizasyon büzülmesini değerlendirmek için kullanılan yöntemler iki gruba ayrılabilir. 15 Yoğunluk ve hacimdeki değişikliği değerlendirenler (dilatometre ve piknometre) ve lineer ölçüm alanlar (linometre, interferometre, optik koherens tomografisi. 15,25 Bu yöntemlerin baz1lar1nda örnekle direkt temas varken (LVDT, dilatometre, piknometre ve gerilim ölçerler(strain gauge lar) gibi), bazıları ise non-kontakt (3D mikrotomografisi, dijital görüntü korelasyonu (DIC)) tekniklerdir.…”
Section: 13unclassified
“…15 Yoğunluk ve hacimdeki değişikliği değerlendirenler (dilatometre ve piknometre) ve lineer ölçüm alanlar (linometre, interferometre, optik koherens tomografisi. 15,25 Bu yöntemlerin baz1lar1nda örnekle direkt temas varken (LVDT, dilatometre, piknometre ve gerilim ölçerler(strain gauge lar) gibi), bazıları ise non-kontakt (3D mikrotomografisi, dijital görüntü korelasyonu (DIC)) tekniklerdir. 26 Polimerizasyon gerilimleri testlerinde temel prensip aynıdır; kompozit rezin iki yüzeye bağla-nır, polimerize edilir.…”
Section: 13unclassified
“…17 Piknometre ile ilgili temel hata kaynak gaz basıncının belirlenmesiyle ilişkili-dir bunun yanında bu yöntem sadece polimerizasyon öncesi ve sonrası ölçüm yapabilir. 15 Aynı zamanda monomerik ve polimerik hallerdeki materyal yoğunlukları eşitleyerek, polimerizasyonlardaki hacimsel büzülmeyi hesaplamak da mümkündür. 14,68 KOMPOZİT REZİNLERİN TERMAL ANALİZLERİ Çoğu polimerik materyal ağız içinde de maruz kaldığı, sıcaklığa karşı hassas olduğundan, fonksiyon sırasındaki sıcaklıkların bu materyallerin mekanik davranışı üzerine etkilerinin değerlendirilmesi önemlidir.…”
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