Effect of coffee thermal cycling on the surface properties and stainability of additively manufactured denture base resins in different layer thicknesses.

Çakmak, Gülce; Watson Asadolahi, Nura; Schimmel, Martin; Molinero Mourelle, Pedro; Akay, Canan; Donmez, Mustafa Borga; Yilmaz, Burak (2023). Effect of coffee thermal cycling on the surface properties and stainability of additively manufactured denture base resins in different layer thicknesses. (In Press). Journal of prosthodontics Wiley 10.1111/jopr.13803

Text Journal_of_Prosthodontics_-_2023_-_akmak_-_Effect_of_coffee_thermal_cycling_on_the_surface_properties_and_stainability_of.pdf - Accepted Version Restricted to registered users only until 15 November 2024. Available under License Publisher holds Copyright. Download (1MB) | Request a copy

PURPOSE

To compare the effect of coffee thermal cycling on surface roughness (Ra), Vickers microhardness (MH), and stainability of denture base resins additively manufactured in different layer thicknesses with those of subtractively manufactured denture base materials.

MATERIALS AND METHODS

Eighty disk-shaped specimens (Ø10×2 mm) were fabricated from two subtractively (Merz M-PM [SM-M] and G-CAM [SM-G]) and three additively (NextDent 3D+ [50 μm, AM-N-50; 100 μm, AM-N-100], FREEPRINT Denture [50 μm, AM-F-50; 100 μm, AM-F-100], and Denturetec [50 μm, AM-S-50; 100 μm, AM-S-100]) manufactured denture base materials (n = 10). Ra measurements were performed before and after polishing by using a non-contact optical profilometer, while MH values and color coordinates were measured after polishing. Specimens were then subjected to 5000 cycles of coffee thermal cycling, all measurements were repeated, and color differences (ΔE00) were calculated. A linear mixed effect model was used to analyze Ra and MH data, while one-way analysis of variance was used to analyze ΔE00 data (α = .05). Ra values were further evaluated according to a clinically acceptable threshold of 0.2 μm, while ΔE00 values were evaluated according to perceptibility (1.72 units) and acceptability (4.08 units) thresholds. The interaction between the material type and the time interval affected both Ra and MH (p ≤ 0.001). Tested materials had their highest Ra before polishing (p ≤ 0.029). Before polishing, AM-F-100 had the highest, and SM-M and SM-G had the lowest Ra (p < 0.001). After polishing and after coffee thermal cycling, SM-G mostly had lower Ra than those of other materials (p ≤ 0.036). SM-G mostly had higher MH than that of other materials before and after coffee thermal cycling (p ≤ 0.025). Coffee thermal cycling reduced the MH of SM-M and increased that of AM-S-100 (p ≤ 0.024). AM-N-100 had higher ΔE00 than AM-F, AM-S-100, and SM-G (p ≤ 0.009), while AM-F and SM-G had lower ΔE00 than AM-S-50 and AM-N-50 (p ≤ 0.024).

CONCLUSIONS

Polishing reduced the surface roughness of all materials, whereas coffee thermal cycling's effect was nonsignificant. Most of the tested materials had acceptable surface roughness after polishing and after coffee thermal cycling according to the reported threshold. Layer thickness only affected the microhardness of tested additively manufactured resins, which was material-dependent. Subtractively manufactured specimens mostly had high microhardness and that of nonreinforced subtractively manufactured resin decreased after coffee thermal cycling.  When reported color thresholds are considered, all materials had acceptable color stability. This article is protected by copyright. All rights reserved.

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