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Influence of chemical degradation and abrasion on surface properties of nanorestorative materials
de Paula, Andréia Bolzan; Alonso, Roberta Caroline Bruschi; de Araújo, Giovana Albamonte Spagnolo; Rontani, Julia Puppin; Correr-Sobrinho, Lourenço & Puppin-Rontani, Regina Maria
Abstract
Aim: The aim of this in vitro study was to investigate the synergistic effect of chemical degradation
(erosion) and three-body abrasion (mechanical degradation) on the surface roughness (Ra) and
hardness (KHN) of two nanorestorative materials and two conventional materials. Methods: Discshaped
specimens (5 mm in diameter, 2 mm thick) of Filtek Z350TM and TPH SpectrumTM composites
and Ketac NanoTM and VitremerTM light-curing glass ionomer cements, nanomaterials and conventional
materials were prepared according to the manufacturer’s instructions. After 24 h, polishing procedures
were performed and initial measurements of Ra and KHN were taken in all specimens. The specimens
were divided into 12 groups (n = 10) according to material and storage media: artificial saliva,
orange juice, and Coca-Cola®. After 30 days of storage, the specimens were submitted to mechanical
degradation and re-evaluated for Ra and KHN. Data were tested for significant differences by
repeated-measure three-way ANOVA and Tukey’s tests (p<0.05). Results: Erosion and abrasion
wear significantly decreased hardness of all materials. Only Filtek Z350 roughness, however, was
not affected by erosion and abrasion. All materials showed a significant increase in surface roughness
after erosion and abrasion, except for Filtek Z350. After chemical and mechanical degradation, the
KHN of all samples had decreased significantly. After mechanical degradation, the acidic drinks
(Coca-Cola® and orange juice) were more aggressive than artificial saliva to all materials.
Conclusions: A synergistic effect was observed by the increase in roughness for all materials,
except for Filtek Z350; hardness values decrease for all materials, regardless of whether they were
nanofilled or not. The RMGICs were more susceptible to degradation than the composites, considering
both hardness and roughness surface parameters.
Keywords
nanotechnology; tooth erosion; tooth abrasion
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