Abrasion resistance of composites polymerized by light-emitting diodes (LED) and halogen light-curing units

Janisse Martinelli,Luciana Assirati Casemiro,Camila Tirapelli,Fernanda De Carvalho Panzeri Pires-De-Souza,Heitor Panzer

doi:10.1590/s0103-64402006000100007

Janisse Martinelli, Luciana Assirati Casemiro + Show 3 more

Open Access

https://doi.org/10.1590/s0103-64402006000100007

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Abstract

This study compared the abrasion resistance of direct composite resins cured by light-emitting diodes (LED) and halogen light-curing units. Twenty specimens (12 mm in diameter; 1.0 mm thick) of each composite resin [TPH (Dentsply); Definite (Degussa); Charisma (Heraus Kulzer)] were prepared using a polytetrafluoroethylene matrix. Ten specimens per material were cured with the LED source and 10 with the halogen lamp for 40 s. The resin discs were polished, submitted to initial surface roughness reading (Ra initial - microm) in a roughness tester and stored in water at 37 degrees C for 15 days. The specimens were weighed (M1) and submitted to simulated toothbrushing using slurry of water and dentifrice with high abrasiveness. After 100 minutes in the toothbrushing simulator, the specimens were cleaned, submitted to a new surface roughness reading (Ra final - microm) and reweighed (M2). Mass loss was determined as the difference between M1 and M2. Data were recorded and analyzed statistically by one-way ANOVA and Tukey Test at 5% significance level. The composite resin with greater size of inorganic fillers (TPH) showed the lowest mass loss and surface roughness means, indicating a higher resistance to toothbrush abrasion (p<0.05). Definite cured with LED presented the least resistance to toothbrush abrasion, showing the highest means of surface roughness and mass loss (p<0.05). The LED source did not show the same effectiveness as the halogen lamp for polymerizing this specific composite resin. When the composite resins were cured a halogen LCU, no statistically significant difference was observed among the materials (p>0.05). It may be concluded that the type of light-curing unit and the resin composition seemed to interfere with the materials' resistance to abrasion.

Highlights

Esthetics has gained more importance day after day, which has made esthetic materials like composite resins the restorative materials of choice in many clinical situations
According to Mills et al [2], light-emitting diodes (LED) lightcuring units (LCUs) may be used in dental practice because their performance does not significantly reduce over time as do conventional halogen LCUs
The light-curing units yielded statistically significant results (p>0.05), except for Definite group in which the specimens polymerized with LED showed statistically significant higher roughness means (p

Summary

Introduction

Esthetics has gained more importance day after day, which has made esthetic materials like composite resins the restorative materials of choice in many clinical situations. There are several types of composite resins and most of them are cured by traditional halogen lightcuring units (LCUs). These devices, promote a high temperature rise that is felt by the operator during activation, and require the use of filters to protect the dental tissue. Conventional halogen LCUs present a decrease in light intensity over time. This limits their lifetime and demand lamp replacement, which is costly [1,2,3,4,5]

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