# The effect of coffee thermocycling and color correction serum on the colorimetric properties and hardness of CAD‐CAM restorative materials

## TL;DR

This study compares how different dental materials respond to coffee staining and color correction, finding that zirconia-reinforced materials perform best.

## Contribution

The study introduces a novel comparison of colorimetric and mechanical properties of CAD-CAM materials under coffee thermocycling and color correction.

## Key findings

- Zirconia-reinforced lithium silicate showed the best stain resistance and hardness.
- Color correction serums effectively reversed coffee-induced staining in some materials.
- Resin nanoceramic exceeded the perceptibility threshold for color change after coffee exposure.

## Abstract

To compare the stainability, translucency, opalescence, whiteness, gloss, and hardness of 4 computer‐aided design and computer‐aided manufacturing (CAD‐CAM) restorative materials after simulated coffee drinking and color correction.

Four CAD‐CAM blocks were investigated (n = 40): resin nanoceramic (Cerasmart, CS), polymer‐infiltrated ceramic network (Vita Enamic, VE), lithium disilicate glass ceramic (IPS e.max CAD, EC), and zirconia‐reinforced lithium silicate glass ceramic (Vita Suprinity, VS). The color stability (ΔE
00), relative translucency (RTP), opalescence (OP), and whiteness stability (ΔWID) were measured with a spectrophotometer. Gloss (GU) was recorded with a gloss meter, and hardness (HM) was detected with a Martens hardness testing device. The specimens were observed at baseline (T0), after coffee thermocycling (CTC) (T1), and after color correction (T2). ΔE
00 was analyzed by two‐way ANOVA, ΔWID was analyzed with one‐way ANOVA, and RTP, OP, WID, GU, and HM were assessed with repeated ANOVA to evaluate the effects of material type, treatment, and their interactions on the tested properties. Post hoc pairwise comparisons were assessed by Tukey HSD and Student t‐tests (α = 0.05).

ΔE
00, WID, OP, GU, and HM outcomes were significantly impacted by material type (p < 0.001) and treatment (p ≤ 0.028), whereas ΔWID and RTP were affected by material type (p ≤ 0.03). CS exceeded the ΔE
00 perceptibility threshold at T1. VS exhibited the highest stain resistance, RTP, and HM, and the least was in VE and CS. Color correction serums reversed CTC‐induced staining among VS and VE (p < 0.001).

Zirconia‐reinforced lithium silicate glass‐ceramics demonstrated superior color stability and hardness when subjected to coffee thermocycling and color correction serum.