CURING EFFICIENCY OF DUAL-CURE RESIN CEMENT UNDER ZIRCONIA WITH TWO DIFFERENT LIGHT CURING UNITS

Abstract

Purpose: Adequate polymerization is a crucial factor in
obtaining optimal physical properties and a satisfying
clinical performance from composite resin materials. The aim
of this study was to evaluate the polymerization efficiency of
dual-cure resin cement cured with two different light curing
units under zirconia structures having differing thicknesses.
Materials and Methods: 4 zirconia discs framework in 4
mm diameter and in 0.5 mm, 1 mm and 1.5 mm thickness
were prepared using computer-aided design system. One
of the 0.5 mm-thick substructures was left as mono-layered
whereas others were layered with feldspathic porcelain
of same thickness and ceramic samples with 4 different
thicknesses (0.5, 1, 1.5 and 2.0 mm) were prepared.
For each group (n=12) resin cement was light cured in
polytetrafluoroethylene molds using Light Emitting Diode
(LED) or Quartz-Tungsten Halogen (QHT) light curing
units under each of 4 zirconia based discs (n=96). The
values of depth of cure (in mm) and the Vickers Hardness
Number values (VHN) were evaluated for each specimen.
Results: The use of LED curing unit produced a greater
depth of cure compared to QTH under ceramic discs
with 0.5 and 1 mm thickness (p<0.05).At 100μm and 300
μm depth, the LED unit produced significantly greater
VHN values compared to the QTH unit (p<0.05). At
500 μm depth, the difference between the VHN values of
LED and QTH groups were not statistically significant.
Conclusion: Light curing may not result in adequate
resin cement polymerization under thick zirconia
structures. LED light sources should be preferred
over QTH for curing dual-cure resin cements,
especially for those under thicker zirconia restorations.

Keywords

• Polymerization; translucency; resin cement; hardness; zirconia

Dual-Cure Reçine Simanın Zirkonya Seramikleri Altındaki Polimerizasyon Etkinliğinin İki Farklı Işık Kaynağı ile İncelenmesi

Abstract

Amaç: Kompozit reçine esaslı malzemelerin ideal fiziksel özelliklerinin ve klinik performanslarının elde edilmesi; yeterli polimerizasyonun sağlanmasına bağlıdır. Bu çalışmanın amacı, farklı kalınlıklardaki zirkonya esaslı restorasyonların altında kullanılan dual-cure reçine simanın polimerizasyon etkinliğinin iki farklı ışık kaynağı ile değerlendirilmesidir. Gereç ve Yöntem: 4 mm çapında disk şeklinde 4 adet zirkon alt yapı (2 adet 0.5 mm, 1 adet 1mm, 1 adet 1.5 mm kalınlığında) bilgisayar destekli tasarım sistemi kullanılarak hazırlandı. 0.5 mm lik disklerden biri alt yapı olarak bırakılırken diğer 3 diske aynı kalınlıkta üst yapı porseleni uygulanarak 4 farklı kalınlığa (0.5, 1, 1.5 ve 2.0 mm) sahip seramik örnek elde edildi. Politetrafloroetilen kalıp içine konulan reçine siman 4 farklı seramik disk üzerinde her bir grupta 12 adet örnek olacak şekilde Light Emitting Diode (LED) ya da Quartz-Tungsten Halogen (QTH) ışık kaynakları kullanılarak polimerize edildi (n=96). Polimerizasyon derinliği (mm) ve Vickers sertlik değerleri (VHN) her bir örnek için tespit edildi. Verilerin istatistiksel olarak analizinde tek yönlü varyans analizi, Tukey HSD ve Student t testi kullanıldı (p < 0.05). Bulgular: LED ışık kaynağının kullanımı ile 0.5 ve 1 mm.lik örnek gruplarında QTH’a oranla daha yüksek polimerizasyon derinliği sağlamıştır (p < 0.05). 100 µm ve 300 µm derinlikte LED ışık kaynağı QTH’a oranla istatistiksel olarak anlamlı derecede yüksek VHN değerleri göstermiştir (p < 0.05). Simanda 500 µm derinlikte, iki ışık kaynağının polimerizasyon etkinliği arasında Vickers sertliği açısından anlamlı bir fark bulunmamıştır. Sonuç: Zirkon esaslı restorasyonların kalınlığı arttıkça reçine simanın polimerizasyonu yetersiz kalabilir. Özellikle kalın zirkon esaslı restorasyonların altında bulunan dual-cure reçine simanlarının ideal olarak polymerize edilebilmesi için LED ışık kaynağı QTH ışık kaynağına tercih edilmelidir.

Keywords

• Polimerizasyon, translusentlik, reçine siman, sertlik, zirkon

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