The Effect of Low-Grade Hydrothermal Aging on the Shade Stability of Monolithic CAD/CAM Dental Ceramic Restorations

Abstract

Translucency and color stability are key factors for the long-term success of dental ceramics. The aim was to compare the translucency parameter (TP) and color stability (ΔE) of CAD/CAM ceramics, including a lithium disilicate (E; IPS e.max CAD), a zirconia-reinforced lithium-silicate (S; VitaSuprinity), and a zirconia-based ceramic (Z; Ceramill Zolid HT+), before and after low-grade hydrothermal aging (134 °C and 2 bars for 20 h). Ninety disks (n = 30/group, A2, 1.2 ± 0.02 mm) were fabricated and their L*, a*, and b* values were recorded against black and white backgrounds to calculate TP, contrast ratio (CR), and opacity (OP). ANOVA, Bonferroni post hoc, and paired t-tests (α = 0.05) showed that after aging, the Z group showed ↓L and ↑a values; the E group showed ↓L with ↑ a and b; and the S group showed only ↑a. All ceramics exhibited ΔE values below the clinical acceptability threshold of 3.7. E presented the highest TP, whereas Z demonstrated the highest CR and masking ability. Aging significantly increased CR and OP but did not alter TP. Within the limitations of this study, all tested ceramics maintained clinically acceptable shade stability and translucency, with E showing superior initial translucency and Z offering improved masking potential.

1. Introduction

In the ever-evolving landscape of modern dentistry, the pursuit of perfection in esthetic restorative materials has reached unprecedented heights. The advances of computer-aided design and computer-aided manufacturing (CAD/CAM) technology have revolutionized dental ceramics, elevating them from mere substitutes for natural dentition to sophisticated biomimetic materials that seamlessly emulate the optical and mechanical properties of enamel and dentin [1]. Among the defining characteristics of these advanced materials, the shade gradient, together with translucency, stand as the cornerstone providing a delicate balance between structural integrity and the sublime interplay of light [2].

The journey toward optimal translucency in dental ceramics has been the main focus for refinement, guided by high esthetic demands. Early iterations of zirconia, known for their exceptional strength, were often accused of having excessive opacity [3]. However, through continuous innovation, a new generation of high-translucency zirconia (e.g., 5-8Y-TZP) has emerged, characterized by a predominance of the cubic crystalline phase and reduced light-scattering properties [4]. Similarly, lithium disilicate and zirconia-reinforced lithium silicate ceramics have set new benchmarks in both translucency and machinability, with their fine-grained microstructures permitting light transmission [5].

However, the true measure of an exceptional restorative material lies not only in its initial presentation but in its ability to maintain those properties over time. The oral environment is considered a harsh environment, subjecting dental ceramics to thermal fluctuations, moisture exposure, and cyclic masticatory forces—all of which may compromise optical stability [6]. Hydrothermal aging, a well-established method for simulating long-term intraoral conditions, serves as a critical evaluative tool, revealing the susceptibility of these materials to low-temperature degradation and chromatic shift [7].

To date, most studies have evaluated lithium disilicate or zirconia separately, but comparative analyses including zirconia-reinforced lithium silicate remain limited. This study addresses this gap by directly comparing IPS e.max CAD, Ceramill Zolid HT+, and Vita Suprinity under identical hydrothermal aging conditions. The aim of this study is to perform a comparative analysis of these three leading CAD/CAM ceramic materials, with a focus on their translucency and shade stability before and after simulated hydrothermal aging. By observing their performance under controlled aging protocols, we aim to elucidate which material best upholds the dual mandates of immediate esthetic supremacy and enduring clinical resilience.

2. Materials and Methods

2.1. Fabrication of Test Specimens

Ninety disk-shaped samples (n = 30 per material group) were milled from commercial CAD/CAM blocks using a Ceramill Motion II system (Amann Girrbach, Mäder, Austria). The materials evaluated included lithium disilicate glass-ceramic (IPS e.max CAD, Ivoclar Vivadent, Schaan, Liechtenstein), high-translucency zirconia (Ceramill Zolid HT+, Amann Girrbach, Koblach, Austria), and zirconia-reinforced lithium silicate (Vita Suprinity, VITA Zahnfabrik, Bad Säckingen, Germany). All specimens were processed to identical dimensions (10 mm diameter × 1.2 ± 0.02 mm thickness) and underwent manufacturer-recommended sintering protocols using dedicated furnaces for each material type.

2.2. Accelerated Aging Protocol

To simulate long-term intraoral conditions, specimens underwent controlled hydrothermal aging in a steam autoclave (Euronda, Vicenza, Italy) at 134 °C under 200 kPa pressure for 20 h. This protocol replicates approximately 5–7 years of clinical service through accelerated low-temperature degradation [7].

2.3. Colorimetric Analysis

Color parameters (L, a, b*) were recorded using a calibrated VITA Easyshade^® spectrophotometer against both black and white reference backgrounds. Measurements were taken at baseline and post-aging. Color differences (ΔE) were computed using the CIEDE2000 formula (Equation (1)):

$$\Delta \mathrm{E}=\sqrt{[{(\Delta \mathrm{L}*)}^2+{(\Delta \mathrm{a}*)}^2+{(\Delta \mathrm{b}*)}^2]}$$

(1)

where Δ values represent differences between pre- and post-aging measurements. Translucency parameters (TP) were derived from Equation (2):

$$\mathrm{TP}=\sqrt{\left[\right({{\mathrm{L}}_{\mathrm{b}}-{\mathrm{L}}_{\mathrm{w}})}^2+({{\mathrm{a}}_{\mathrm{b}}-{\mathrm{a}}_{\mathrm{w}})}^2+({{\mathrm{b}}_{\mathrm{b}}-{\mathrm{b}}_{\mathrm{w}})}^2]}$$

(2)

with subscripts denoting measurements against black (b) or white (w) backgrounds.

In addition to translucency (TP) and color stability (ΔE) analysis, contrast ratio (CR) and opacity (OP) values were measured before and after hydrothermal aging to further evaluate the optical behavior of the tested ceramics. CR was determined using spectrophotometric measurements over black and white backgrounds and calculated using the standard formula (Equation (3)):

CR = Y_b/Y_w,

(3)

where Y_b and Y_w represent the reflectance over black and white surfaces, respectively.

OP opalescence (Equation (4))

OP = ∣b*_transmitted − b*_reflected∣

(4)

2.4. Statistical Evaluation

Data analysis was performed using SPSS Statistics 19.0 (IBM Corp., Armonk, NY, USA). Normality was verified using Shapiro–Wilk tests. Between-group comparisons employed one-way ANOVA with Bonferroni post hoc correction, while paired t-tests assessed aging effects within groups. Statistical significance was set at α = 0.05. All continuous variables are reported as mean ± standard deviation. Effect sizes were calculated for significant findings to determine clinical relevance beyond statistical significance.

3. Results

3.1. Comparison of Shade Coordinates

All specimens were fabricated using the A2 shade. Among the three groups, the highest (L) value—indicating lightness—was observed in the E group, while the S group exhibited the lowest (L) value. Regarding the red–green axis, the lowest (a) value was recorded in the E group, whereas the S group showed the highest. Similarly, for the yellow–blue axis, the (b) value was also lowest in the E group and highest in the S group.

When comparing pre- and post-aging measurements, the Z group exhibited a statistically significant decrease in (L) and increase in (a) values. The E group demonstrated statistically significant reductions in (L) and increases in both (a) and (b) values. In contrast, the S group showed a significant increase only in the (a) value following aging (

Table 1. Means and standard deviations (SD) of shade coordinates (L, a, and b) for each group before and after aging, the amount of change between before/after aging values, and statistical comparison of the before and after aging values. (Bonferroni, n = 30, * p < 0.05).

Group	Coordinate	Mean (SD) Before Aging (J)	Mean (SD) After Aging (K)	Mean (SD) Difference (K-J)	Sig.
Z	L	87.78 (±0.41)	87.52 (±0.39)	−0.25 (±0.26)	0.002 *
	a	3.78 (±0.39)	4.10 (±0.49)	0.4 (±0.44)	0.003 *
	b	31.68 (±0.99)	31.56 (±1.00)	−0.12 (±0.48)	0.33
E	L	90.3 (±0.78)	89.36 (±0.73)	−0.93 (±0.50)	0.00 *
	a	0.7 (±0.26)	1.00 (±0.33)	0.3 (±0.24)	0.00 *
	b	25.76 (±0.55)	26.74 (±0.34)	0.98 (±0.56)	0.00 *
S	L	85.58 (±1.16)	85.44 (±1.18)	−0.14 (±0.62)	0.4
	a	3.95 (±1.33)	4.08 (±1.37)	0.133 (±0.22)	0.04 *
	b	43.51 (±4.94)	43.82 (±4.84)	0.31 (±0.62)	0.07

).

3.2. Color Difference (ΔE)

The calculated ΔE values were 1.46 for the E group, 0.83 for the S group, and 0.75 for the Z group, resulting in the ranking E > S > Z (

Table 2. ΔE values calculated for each group.

Material	ΔE
E	1.46
S	0.83
Z	0.75

).

Statistical comparison between groups revealed that the ΔE value of the E group was significantly higher than both the S and Z groups (p < 0.05), whereas no significant difference was observed between the S and Z groups (

Table 3. ΔE comparison between materials, (Bonferroni, n = 30, * p < 0.05).

Groups (J)	Compared Group (K)	Mean (SD) (J-K)	Sig.
Z	E	−0.070 (±0.18)	0.002 *
	S	−0.07 (±0.18)	1.000
E	Z	0.70 (±0.18)	0.002 *
	S	0.62 (±0.18)	0.005 *
S	Z	0.07 (±0.18)	1.000
	E	−0.62 (±0.18)	0.005 *

).

3.3. Translucency Parameter (TP)

The mean TP values and corresponding standard deviations for each group, both before and after aging, are presented in

Table 4. The mean TP values calculated for each group for before and after accelerated aging readings.

Group	Aging	Mean (SD)	Sig.
E	Before	17.75 (±0.99)	0.876
	After	17.73 (±0.69)
S	Before	17.74 (±1.22)	0.535
	After	17.67 (±2.96)
Z	Before	12.62 (±0.03)	0.416
	After	12.56 (±0.06)

. At baseline, the mean TP values were 17.75 for the E group, 17.74 for the S group, and 12.62 for the Z group, with a general translucency ranking of E > S > Z.

Following aging, the TP values slightly changed to 17.73 (E group), 17.67 (S group), and 12.56 (Z group). Despite minor variations, the overall ranking remained consistent.

Statistical analysis confirmed that the Z group exhibited significantly lower TP values than the E and S groups (p < 0.05) at baseline, after aging, and when evaluating the change in TP values due to aging (

Table 5. The mean and SD of the TP values before and after aging and the amount of change in the TP values because of aging compared between groups, (Bonferroni, n = 30, * p < 0.05).

	Group (I)	Compared Group (J)	Mean Difference (SD) (I-J)	Sig.
Before Aging	Z	E	−5.13 (±0.33)	0.000 *
		S	−5.12 (±0.33)	0.000 *
	E	Z	5.13 (±0.33)	0.000 *
		S	0.01 (±0.33)	1.000
	S	Z	5.12 (±0.33)	0.000 *
		E	−0.01 (±0.33)	1.000
After Aging	Z	E	−5.17 (±0.28)	0.000 *
		S	−5.10 (±0.28)	0.000 *
	E	Z	5.17 (±0.28)	0.000 *
		S	0.06 (±0.28)	1.000
	S	Z	5.10 (±0.28)	0.000 *
		E	−0.06 (±0.28)	1.000
Mean after/before value	Z	E	−5.15 (±0.30)	0.000 *
		S	−5.11 (±0.30)	0.000 *
	E	Z	5.15 (±0.30)	0.000 *
		S	0.04 (±0.30)	1.000
	S	Z	5.11 (±0.30)	0.000 *
		E	−0.04 (±0.30)	1.000

).

Statistical analysis revealed significant differences in CR and OP values among the groups at baseline and after aging (p < 0.001). Before aging, the highest CR was recorded for the zirconia group (0.74), followed by Suprinity (0.68), and the lowest in IPS e.max CAD (0.63). A similar ranking persisted after aging. Paired sample t-tests confirmed a statistically significant increase in CR for all materials post-aging (p < 0.001), with a mean increase of 0.0055 units. OP values followed the same trend, where Suprinity showed the highest opalescence before (mean = 12.77) and after aging (mean = 12.99), while zirconia consistently showed the lowest (pre = 7.80; post = 7.97). All intergroup comparisons were statistically significant using Bonferroni and Games–Howell post hoc tests (p < 0.001).

4. Discussion

CAD/CAM ceramics represent a critical frontier, offering clinicians materials that balance optical performance with mechanical integrity. This study aimed to evaluate and compare the translucency and color stability of three commercially available CAD/CAM ceramics—a lithium disilicate, zirconia, and a zirconia-reinforced lithium silicate—before and after exposure to low-grade hydrothermal aging. The results revealed clinically relevant distinctions in baseline translucency, shade coordinate behavior, and color changes upon aging, reflecting the influence of material composition and microstructure on long-term optical outcomes.

4.1. Shade Coordinates Comparison (CIE L*a*b* Value)

In this study, all samples were prepared using the same A2 shade to maintain consistency. Before the aging process, we observed some clear differences between the materials. IPS e.max CAD showed the highest L* values, which means it appeared the brightest or lightest in color compared to the others. On the other hand, Vita Suprinity had the highest a* and b* values, which indicates that it looked slightly more reddish (a*) and yellowish (b*). These differences suggest that even when the same shade is selected (A2), the inherent material composition and structure can influence how the color is actually perceived.

Following low-grade hydrothermal aging, all groups showed an increase in the (a*) value, indicating a shift toward a redder hue. A reduction in the (L*) value was observed in the Z and E groups, suggesting that these materials became darker. An increase in the (b*) value, indicating a yellower appearance, was only evident in the E group. Therefore, regarding materials, the Z group became darker and redder, the E group became darker, redder, and yellower, and the S group showed only a redder shift (Table 1). Similar changes were found to be indicative of darkening and increased chroma—commonly attributed to water absorption and microstructural alterations [8]. And these changes are in line with studies suggesting zirconia-reinforced lithium silicates maintain their color better over time compared to pure lithium disilicate [9].

These findings align with previous studies [10,11]. However, Bagis and Turgut reported reductions in both (L*) and (a*) values with an increase in (b*) after aging [11], while Hamza et al. observed only a decrease in the (a*) coordinate [12].

Direct comparison of CIE Lab* values across studies remains challenging due to variability in numerous factors, including specimen design, shade selection [13,14], thickness [15,16], aging procedures [17], zirconia composition—such as the type and concentration of stabilizers, cubic phase content [18], porosity [19], grain size [20], coloring method [21], sintering conditions [19,22,23,24], background color for measurement [25], number of porcelain firings [26,27], spectrophotometer used [21], and accepted color difference thresholds [28].

4.2. Delta E (ΔE)

Clinical color matching is often evaluated through ΔE values, which quantify the perceptible difference between two colors under typical, uncontrolled clinical conditions. The perception thresholds for ΔE have been well established in the literature:

• 0–1: Color difference is generally imperceptible, even to trained observers.
• 1–2: A very slight difference, noticeable only to trained eyes.
• 2–3.5: A moderate difference, perceptible to both trained and untrained observers.
• 3.5–5: An obvious color difference.
• >6: A pronounced and easily noticeable difference.

The clinically accepted threshold for color acceptability is commonly cited as ΔE ≤ 3.7 units, supported by multiple studies [29,30,31]. In this study, all tested groups exhibited color changes well below this threshold after accelerated hydrothermal aging, indicating clinically acceptable color stability consistent with prior reports [7].

Although all materials passed the acceptability benchmark, IPS e.max CAD (E group) experienced the largest color shift, with a mean ΔE of 1.46—classified as a “very slight difference” detectable only by trained evaluation. In contrast, the Ceramill Zolid HT+ (Z group) displayed the least discoloration (ΔE = 0.75), with Vita Suprinity (S group) at 0.83 ΔE—both within the “normally invisible” range (Table 2). Statistical analysis confirmed that the ΔE for the E group was significantly greater than those of the Z and S groups, while the difference between Z and S was not significant.

This disparity in color behavior likely stems from microstructural differences. The IPS e.max CAD’s predominantly glassy, lithium disilicate matrix appears to be more vulnerable to hydrothermal-induced alterations in color. In contrast, both Zolid HT+ and Suprinity contain fine zirconia particles that may strengthen the ceramic structure, reducing susceptibility to grain pull-out and surface roughening, known contributors to optical degradation [32,33]. Additionally, the dissolution of silica networks and breakdown of colorant oxides during aging may further affect translucency and shade, particularly in glass-rich ceramics [34,35].

Vita Suprinity’s intermediate performance may be attributed to its dual-crystal network comprising lithium silicate and uniformly dispersed zirconia. While limited research exists on the aging effects of zirconia-reinforced lithium silicate, this composite structure may inhibit silica dissolution and prevent colorant degradation, explaining its superior stability compared to IPS e.max CAD. This suggests a protective synergy between zirconia reinforcement and lithium silicate matrices that preserve color fidelity under hydrothermal stress.

4.3. Translucency Parameter (TP), Contrast Ratio CR and OP

Translucency is the property of a material by which a major portion of the transmitted light undergoes scattering [36]. It is an essential optical property that must be considered when choosing restoration in the esthetic zone. Optimal translucency is required to achieve lifelike restorations [37]. However, in situations where restoration is required to mask discolored teeth or metal posts and cores, material with lower translucency and higher masking ability are required [38]. Therefore, good knowledge about the translucency of the newly introduced monolithic CAD-CAM materials is essential to choose the appropriate material for a specific case. It was documented in the literature that the translucency of dental ceramics is affected by chemical composition, crystalline structure, grain size, additives, and pores [39,40].

In the present study, accelerated aging has no significant effect on the TP values of the tested groups (p > 0.05), (Table 4).

Higher TP values correspond to materials with higher translucency, whereas lower TP values correspond to materials with lower translucency. TP values can range from zero (for a totally opaque material) to 100 (for a totally transparent material). The highest TP value was recorded for the E group, followed by the S group, and the Z group scored the lowest TP value (Table 4). Niu et al. [15] stated that the higher strength ceramic system tends to be opaquer because of the required increased crystalline content.

In the present study, statistically different values were obtained at baseline for the ceramic materials regarding TP values. The Z group was found to have a significantly lower statistical difference in translucency compared to the other groups (p < 0.05). On the other hand, no significant statistical difference was found between the E and S groups. Therefore, according to the results of the present study, it can be said that zirconia-reinforced lithium silicate ceramic materials have a greater translucency than zirconia materials (Table 5).

Grain size is a major influence on the material’s TP value. A small number of large crystals are present in the high translucency materials, whereas the low translucency materials contain a large number of smaller crystals [41]. This explains the higher TP values of the large Lithium crystal-containing materials compared to those of the materials containing the four to eight times smaller Zirconia crystals [42].

Kim and Kim [43] reported that TP values increased with increasing aging time for both zirconia and lithium disilicate. Fathy et al. [44] and Alghazzawi [8] stated that the Z group’s translucency of colored specimens decreased significantly after accelerated aging. On the other hand, Kurt et al. [45] reported that the TP values decreased in the zirconia group after aging, but this decrease was not statistically significant. Abdelbary et al. [46] stated that the TP values of 0.5 mm-thick specimens exhibited statistically significant decreases, whereas the TP values of 0.8 mm, 1 mm, and 1.2 mm-thick specimens exhibited statistically insignificant changes.

This variation in the outcomes could be attributed to the variation in the sample’s preparation process, the brand of zirconia, the aging protocol, or the samples’ thickness.

Few studies have reported the TP values of newly introduced monolithic CAD-CAM restorative materials [37,41,42,47], but none has discussed the effect of accelerated aging on the zirconia-reinforced lithium silicate materials.

The findings from CR and OP analyses complement the TP data by highlighting the inherent differences in light-scattering and masking ability across the materials. As expected, zirconia demonstrated the highest contrast ratio and lowest translucency, confirming its superior masking ability but reduced optical blending potential [48]. Suprinity, combining zirconia and lithium silicate, presented intermediate CR and OP values, indicating a balance between translucency and opalescence suitable for a wider range of clinical scenarios. The statistically significant increase in CR and OP after aging may be attributed to microstructural changes such as surface roughening, phase interface alteration, or water absorption, all of which can enhance light scatter and reduce transmission [49,50]. These results support previous findings that artificial aging affects not only color parameters but also the depth and behavior of light penetration in ceramic restorations.

The observed differences in optical properties across materials can be further explained by underlying microstructural characteristics. Factors such as porosity, grain size, refractive index mismatches between crystalline and glassy phases, and the intrinsic birefringence of polycrystalline phases strongly influence light scattering and transmission in dental ceramics [51]. For example, materials with smaller grain size and reduced porosity tend to scatter less light, resulting in higher translucency. Conversely, greater disparities in refractive indices between adjacent phases, as well as increased birefringence in anisotropic crystals, can enhance light scattering and reduce translucency.

4.4. Clinical Implications

The findings of this study offer valuable insights into clinical material selection, particularly when balancing esthetic demands with aging behavior. IPS e.max CAD exhibited the highest baseline translucency and lightness values, indicating its suitability for anterior restorations where initial brightness and visual appeal are of paramount importance. However, its higher ΔE value and susceptibility to color change after aging, especially with increased (a*) and (b*) values and decreased (L*), highlight a potential limitation in long-term color stability. Even minor changes in L*, a*, and b* coordinates can subtly affect the overall appearance of restorations over time, influencing brightness, hue, and chroma. For example, a slight decrease in L* (darkening) combined with increases in a* and b* (redder and yellower tones) could gradually alter the perceived harmony with adjacent teeth, particularly in anterior restorations. These findings highlight that material selection should consider both baseline optical properties and potential long-term shifts to optimize esthetic outcomes.

The observed differences in TP, CR, and OP have important clinical implications for restorative decision-making. Materials with higher TP, such as IPS e.max CAD, allow greater light transmission and blending with surrounding tooth structure, making them ideal for highly esthetic anterior restorations. In contrast, the lower TP and higher CR of the zirconia group (Zolid HT+) indicate reduced translucency and greater opacity, which enhances masking of discolored substrates but may limit seamless integration in highly translucent areas. Vita Suprinity, with intermediate TP and CR values, offers a balance between translucency and masking ability, suitable for premolars or restorations requiring both esthetics and durability. Regarding intraoral visibility, the observed optical differences are subtle, and while trained clinicians may detect slight variations under standard lighting, they are generally within clinically acceptable perceptibility thresholds, particularly when restorations are properly polished and glazed. These findings underscore the importance of selecting materials based on both optical properties and the specific esthetic demands of the restoration site.

4.5. Limitations and Future Directions

While the current study provides important comparative data on the esthetic and optical properties of ceramic materials, several limitations should be acknowledged. First, the study was conducted entirely in vitro, under standardized and controlled laboratory conditions. These settings do not fully replicate the complex oral environment, which includes dynamic variables such as temperature changes, saliva, mastication forces, and variable pH levels. Thus, the extrapolation of results to real-life clinical scenarios must be approached with caution.

Additionally, the hydrothermal aging protocol, though useful in simulating long-term changes, may not encompass all aspects of intraoral aging. Future studies may benefit from incorporating more comprehensive artificial aging protocols or longitudinal in vivo analysis. Another limitation lies in the use of a single shade (A2) across all groups. While this standardizes comparisons, it may not reflect the behavior of other shades, particularly darker or more translucent ones, which could respond differently to aging and exhibit distinct optical behaviors.

The use of a single specimen thickness (1.2 mm) may indeed limit the generalizability of our translucency results, as clinical restorations often vary in thickness depending on tooth morphology and preparation design. Optical properties such as TP, CR, and OP are known to be thickness-dependent, with thinner ceramics generally appearing more translucent and thicker restorations exhibiting increased masking ability [13,14,15,17]. The current findings should be interpreted as representative of a standard restoration thickness. Future studies incorporating multiple thicknesses would provide a more comprehensive understanding of how ceramic optical behavior varies with restoration geometry, improving clinical applicability.

Finally, the optical differences observed among IPS e.max CAD, Vita Suprinity, and Zolid HT+ were interpreted mainly at the macroscopic level (ΔE, TP, CR, OP) without direct microstructural verification. Because this study did not employ microstructural characterization techniques—such as SEM for porosity and grain size, XRD for phase composition, or refractometry for refractive index analysis—it was not possible to directly correlate the optical findings with underlying microstructural features. This gap limits the depth of interpretation, and future investigations should incorporate these methods to provide a clearer link between structure and optical performance. In addition, evaluation of defect states (e.g., oxygen vacancies or color centers) that may evolve during hydrothermal aging would add further insight into color stability mechanisms.

5. Conclusions

Within the limitations of this study—being in vitro and using only a single A2 shade—the results demonstrated that the optical properties of ceramic materials, including lightness, translucency, color coordinates, contrast ratio, and opacity, are significantly influenced by material composition and hydrothermal aging. IPS e.max CAD showed the highest initial translucency and brightness but was the most affected by aging in terms of color change. Vita Suprinity presented a balanced performance, offering good esthetics with moderate stability, while Ceramill Zolid HT+ exhibited the greatest resistance to color and translucency changes, although with lower initial translucency. These findings have direct clinical implications: IPS e.max CAD may be preferred in anterior restorations where initial brightness is critical, but caution is needed in patients requiring long-term color stability; Vita Suprinity offers a compromise suitable for premolars or situations demanding both esthetics and durability; and Zolid HT+ may be best suited for posterior restorations or cases where masking ability and long-term stability are prioritized. Evaluation of ΔE, CR, OP, and TP values provides a comprehensive understanding of material behavior over time. Future studies should include multiple shades, in vivo validation, and detailed microstructural characterization—such as SEM for porosity and grain size, XRD for phase composition, or refractometry for refractive index analysis—to directly correlate optical performance with underlying structural changes and further enhance clinical applicability.