Color stability of nanohybrid and microhybrid composites after immersion in common coloring beverages at different times: a laboratory study

Abstract

Objective/aim: This in vitro study aimed to evaluate the color stability of microhybrid and nanohybrid restorative composites after exposure to immersion media common in Yemen for different periods.

Materials and methods: Two composite materials, nanohybrid Tetric N-Ceram and microhybrid Te-Econom Plus, were investigated. Six groups of 30 cylindrical specimens (n = 5/group; diameter, 10 mm; thickness, 2 mm; shade A2) of each restorative material were immersed for 1 week in distilled water, qat solution, Yemeni coffee, traditional Yemeni coffee (qishr), red tea, and Dilsi cola. Color changes were evaluated by colorimetry. The color data and pH were measured before and 1, 3, and 7 days after immersion. The data were statistically analyzed.

Results: Tetric N-Ceram showed lesser discoloration than did Te-Econom Plus. Qat, coffee, and red tea caused highly significant discoloration than did Dilsi cola and distilled water (p < 0.05). The role of low pH in discoloration depended on the colorant.

Discussion: Nanohybrid Tetric N-Ceram composites are more resistant to discoloration than are microhybrid Te-Econom Plus composites. Qat and coffee have the highest effect on composite discoloration.

Conclusions: These findings will aid in selecting composite materials and patient instruction.

Fig. 1. Composite specimen preperation in a metalic mold between two glass slides and a nylon film.

Each composite specimen was prepared separately in a metallic mold covered with a nylon film and held between two glass slides.

Fig. 2. Closed tubes containing specimens stored in distilled water.

Composite specimens were stored in closed glass tubes with rubber stoppers and concave bottoms containing distilled water for 24 h before immersion in staining media. The specimens were kept inside the plastic tube holders.

Fig. 3. The immersion media.

The six immersion solutions used in our study in glass cups with plastic droppers from left to right: coffee, Qishr, red tea, Dilsi Cola, qat, and distilled water.

Fig. 4. The mean color changes (∆E*) of the different experimental groups over time.

The mean color changes (∆E*) of the two types of micro and nano composites, indicated by the height of the vertical column, increasing proportionally with immersion times (1, 3, and 7 days) in different media. It is visible that qat (green column) had the highest discoloration on both types of composites.

Fig. 5. Specimens after 168 h of immersion. Specimens after 168 h of immersion in each type of immersion media had two rows.

The first from the left is micro and the second is nano. The highest value was for qat and red tea.

Fig. 6. The surface roughness of the samples after immersion in Dilsi Cola.

The surface roughness of the samples increased after immersion in Dilsi Cola. The effect of the acidity of Dilsi Cola on the surface of the samples proportional with the time of immersion (1, 3, and 7 days).