Surface hardness development in light-cured composites

Watts, D.C.; Amer, Omar; Combe, E.C.

doi:10.1016/s0109-5641(87)80085-4

Cited by 85 publications

(50 citation statements)

References 19 publications

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“…This increase can be related to the post-irradiation polymerisation caused by the remaining free-radicals in the resin matrix. Postirradiation polymerisation is supported by the fact that the maximum degree of polymerisation needs a long period of time to be reached [27,28,50].…”

Section: Discussionmentioning

confidence: 99%

“…For a given matrix, the most likely effect of a solvent is to decrease its mechanical properties [18,26] nevertheless, hardness of resin-composites have been shown to progressively increase over a period of time of at least 30 ds. Therefore, it is possible that some opposing trends could be operating during the period of solvent storage: first, the softening effect of the solvent and secondly the hardening effect due to the elevated degree of conversion [27][28][29][30].…”

Section: Introductionmentioning

confidence: 99%

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Surface and bulk properties of dental resin- composites after solvent storage

2016

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Surface and bulk properties of dental resin- composites after solvent storage

2016

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“…Hardness is a surface property defined as the resistance of a material to permanent indentation or penetration. The composite's surface hardness and the effect of post-irradiation aging have been studied extensively by many investigators [12][13][14] . It has been reported that the hardness of inorganic fillers has a direct effect on the material's hardness 15 .…”

Section: Introductionmentioning

confidence: 99%

Post-irradiation vickers microhardness development of novel resin composites

Marghalani

2010

Mat. Res.

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The aim of this study was to evaluate the effect of post-irradiation dry aging at different periods of time on Vickers microhardness of some dental composites based on various resin matrices. Sixty four disc-shaped specimens of the resin composites were prepared in a split Teflon mold (8 × 2 mm) and irradiated by Optilux 501 light cure (500 mW.cm -2 for 40 seconds) on their top side. The specimens were aged-dry in dark at 23 and 37 °C for the following storage periods; immediate, 1/2 an hour, 1, 6, 12, 24, 48 and 168 hours. The microhardness values were recorded using a Vickers Hardness Tester at 300 g load for 15 seconds. Results showed that Filtek ® P90 and Definite expressed the highest hardness value followed by Tetric Evoceram and then Premise Enamel. At each aging period, all materials demonstrated significant differences between hardness values of top and base surfaces as well as both temperatures examined (P < 0.05). In conclusion, surface hardness developed gradually in most of the materials reaching optimum after 168 hours post-irradiation aging. Dental composites based on silorane and ormocer resin matrices achieved higher Vickers microhardness than those based on dimethacrylates resin.

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“…Samples were kept in saline, at 37 8C, for 14 days, to maximize postpolymerization [8,9]. Consequently, the five samples of each group were embedded, face to face, in a slow selfcuring resin, producing a maximal exothermic temperature of 21 8C during curing (Epo-Thin, Buehlers).…”

Section: Groupsmentioning

confidence: 99%

“…Surface hardness is a good predictor for resin conversion [9]. It is especially sensitive to small changes of the polymer cross-linkage in areas of high conversion and is quite simple to use [18].…”

Section: Micro-hardness Measurementsmentioning

confidence: 99%

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

2003

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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.

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Surface hardness development in light-cured composites

Cited by 85 publications

References 19 publications

Surface and bulk properties of dental resin- composites after solvent storage

Surface and bulk properties of dental resin- composites after solvent storage

Post-irradiation vickers microhardness development of novel resin composites

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

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