A study on the characteristics of resin composites for provisional restorations

T800/high-temperature epoxy resin composites with different hole shapes were subjected to hygrothermal ageing and thermal-oxidative ageing, and the effects of these different ageing methods on the open-hole properties of the composites were investigated, including analyses of the mass changes, surface topography changes (before and after ageing), fracture morphologies, open-hole compressive performance, dynamic mechanical properties and infrared spectrum. The results showed that only physical ageing occurred under hygrothermal ageing (70°C and 85% relative humidity), and the equilibrium moisture absorption rate was only approximately 0.72%. In contrast, under thermal-oxidative ageing at 190°C, both physical ageing and chemical ageing occurred. After ageing, the open-hole compressive strength of the composite laminates with different hole shapes decreased significantly, but the open-hole compressive strength after thermal-oxidative ageing was greater than that after hygrothermal ageing. Among the aged and unaged laminates, the laminates with round holes exhibited the largest open-hole compressive strength, followed by those with the elliptical holes, square holes and diamond holes. The failure modes of the laminates were all through-hole failures. The unaged samples had a glass transition temperature ( T g) of 226°C, whereas the T g of the samples after hygrothermal ageing was 208°C, which is 18°C less than that of the unaged samples, and the T g of the samples after thermal-oxidative ageing was 253°C, which is 27°C greater than that of the unaged samples.

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The Effects of Toothbrush Wear on the Surface Roughness and Gloss of Resin Composites with Various Types of Matrices

Dentistry Journal ◽

10.3390/dj9010008 ◽

2021 ◽

Vol 9 (1) ◽

pp. 8

Author(s):

Murtadha AlAli ◽

Nikolaos Silikas ◽

Julian Satterthwaite

Keyword(s):

Surface Roughness ◽

Pairwise Comparisons ◽

Resin Composites ◽

Hybrid Resin ◽

Before And After ◽

Post Hoc ◽

Main Effects ◽

Toothbrush Wear

Objective: To evaluate and compare the surface roughness and gloss of a DMA-free composite and Bis-GMA-free composite with a DMA-based composite before and after toothbrushing simulation. Materials and Methods: Fifteen dimensionally standardised composite specimens of three nano-hybrid resin composites (Tetric EvoCeram, Admira Fusion, and Venus Diamond) were used. Five specimens from each composite were polished and then subjected to a toothbrushing simulator. Surface roughness (Ra) and gloss were measured before toothbrushing and after 5000, 10,000, 15,000, and 20,000 toothbrushing cycles. The data was analysed using 5 × 3 ANOVA to assess surface roughness and gloss values and pairwise comparisons in the form of Tukey post hoc tests were performed to interpret main effects. Results: For all tested materials, surface roughness increased, and gloss decreased after toothbrushing abrasion. Surface roughness (Ra) values ranged from 0.14 to 0.22 μm at baseline and increased to between 0.41 and 0.49 μm after 20,000 toothbrushing cycles. Gloss values ranged between 31.9 and 50.6 GU at baseline and between 5.1 and 19.5 GU after 20,000 toothbrushing cycles. The lowest initial Ra value was detected in Venus Diamond and the highest initial gloss value was detected in Tetric EvoCeram. Conclusions: Simulated toothbrushing abrasion led to an increase in surface roughness and a decrease in gloss for all tested materials. Venus Diamond had the smoothest surface and Tetric EvoCeram had the glossiest surface after polishing and following 20,000 cycles of toothbrushing abrasion. Admira Fusion demonstrated the roughest surface and had the lowest gloss values before and after toothbrushing abrasion.

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