Comparative efficiency of plasma and halogen light sources on composite micro-hardness in different curing conditions

Abstract

Objectives. Recent developments have led to the introduction of high power curing lights, which are claimed to greatly reduce the total curing time. This study evaluated the effectiveness of a plasma-curing device (Apollo 95 E) and a halogen device (Heliolux DLX), in different curing conditions.Method. Vicker's micro-hardness values were performed on 1 and 2 mm thick composite discs cured in a natural tooth mold by direct irradiation or indirect irradiation through composite material (2 or 4 mm) and dental tissues (1 mm enamel or 2 mm enamel-dentin). Measures were, respectively, performed after a 1, 3, 6 s (SC, step curing mode) or 18 s (3 £ SC) exposure to the plasma light, and a 5, 10, 20 or 40 s exposure to the halogen light.Results. With the PAC light used, a 3 s irradiation in the direct curing condition was necessary to reach hardness values similar to those obtained after a 40 s exposure to the halogen light. Using the indirect curing condition, hardness values reached after an 18 s exposure (3 £ SC mode) with the plasma light were either equivalent or inferior to those obtained with 40 s halogen irradiation.Significance. Direct polymerization with the plasma light used requires longer exposure times than those initially proposed by the manufacturer. The effectiveness of plasma generated light was lowered by composite or natural tissues, and therefore requires an important increase in the irradiation time when applied to indirect polymerization. The practical advantage of this polymerization method is less than expected, when compared to traditional halogen curing.

Influence of Tooth Thickness on Degree of Conversion of Photo-Activated Resin Composite Irradiated Through the Tooth

“…Due to the use of different types of equipments, materials and test conditions, there is no study homogeneity among most available literature. In previous experiments; ceramic materials, artificial light filters and other analogs were applied to indirectly cure composite resin using a transmitted light beam [44,47], and then evaluated the effects on the depth of cure of composite resin. In this experiment freshly extracted human caries-free teeth were used to prepare dental slices of different thickness (Figure 1).…”

“…Some studies have shown that curing through enamel is just one-third to two-thirds as effective as direct curing and is appropriate only when there is no alternative [45,46]. Another research reported the least critical record situation when 0.5mm of composite Z100 was cured through 1mm enamel [47]. Although the experiments involved through-tooth-tissue curing, only the quantitative analyses of hardness-based measurements on the degree of polymerization were employed, no qualitative analyses were done.…”

“…The light intensity after transmittance through tooth tissue, depending on the thickness of the tooth tissue, may undergo different degree of scattering or absorption, resulting in minimized polymerization degree, thus reducing the DC. The least critical situation was recorded when 0.5 mm of composite Z100 was cured through 1mm enamel [47]. Although the experiments involved throughtooth-tissue curing, only the quantitative analyses of hardnessbased measurements on the degree of polymerization were employed, no qualitative analyses were done.…”

Kompozit rezinin yüzey sertlik değerleri üzerine farklı ışık cihazlarının etkisi

“…Yüzey sertli i yüksek dönü üm alanlar ndaki polimer çapraz ba lar n n küçük de i imlerine özellikle duyarl d r (6). Ayr ca örneklerin üst yüzeyi, orta bölgesi ve alt yüzeyi gibi örnek içerisindeki spesifik bölgelerin ölçümlerine izin verir (7). Di er bir avantaj ise sertlik de erleri ve dönü-üm derecesi aras nda, literatürde gösterilmi bir korelasyonun bulunabilmesidir (8,9).…”

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“…Surface hardness is an indirect measure of the degree of conversion, and important information can be obtained by comparing hardness values at the top and bottom surfaces (Dietschi, Marret & Krejci, 2003;Hofmann & others, 2002;Jandt & others, 2000;Mills & others, 1999). Many investigators have reported the top and bottom surface hardness of resin composites polymerized with different types of light curing units (Hofmann & others, 2002;Jandt & others, 2000;Leonard & others, 2002;Mc Cabe & Carrick, 1989;Mills & others, 1999).…”