Search Results (75)

Objective: This in vitro study aimed to compare the layer-matched color compatibility of three 3Y/4Y/5Y multilayer zirconia grades marketed in shade A2. Materials and Methods: Disc specimens (18 mm × 1.5 mm) were milled from pre-shaded multilayer zirconia blanks (Katana™ Multi-Layered Zirconia; Kuraray Noritake Dental Inc., Tokyo, Japan) in three grades: UTML (5Y), STML (4Y), and HTML (3Y). Twelve discs per grade were polished and measured on a neutral-gray background (Munsell N7) using a dental spectrophotometer (VITA Easyshade Advance 4.0; VITA Zahnfabrik, Bad Säckingen, Germany) at the incisal, middle, and cervical thirds. Color differences were calculated using CIEDE2000 (ΔE₀₀). Yttria content (wt%) was determined using EDS (JSM-7800F; JEOL Ltd., Tokyo, Japan), and phases were assessed using XRD (X’Pert PRO; Malvern Panalytical, Almelo, The Netherlands); microstructure and grain size were examined using FE-SEM after thermal etching. Statistics: A two-way mixed-design ANOVA with Bonferroni adjustment (α = 0.05) was conducted. Results: A significant incisal-to-cervical gradient was observed within each grade (p < 0.001), whereas layer-matched inter-material differences were small (all ΔE00 < 1.0), i.e., below the commonly accepted perceptibility threshold. EDS confirmed the expected stepwise decrease in Y₂O₃ from UTML to HTML, accompanied by corresponding changes in phase constitution and grain size. Conclusions: Despite compositional and microstructural differences, the three multilayer zirconia grades showed no clinically perceptible layer-matched color differences, supporting their combined use in extended rehabilitations while maintaining the natural-like color gradient across the multilayer blank. Full article

Tooth bleaching improves dental esthetics but may cause color mismatch with existing resin composite restorations and complicate restorative treatment planning because tooth color may change during the post-bleaching stabilization period, sometimes requiring delayed restoration placement or replacement of existing restorations. Universal shade resin composite (UC) has been introduced to simplify shade selection; however, its ability to adapt to dynamic tooth color changes associated with bleaching has not been sufficiently documented. A 61-year-old male patient underwent tooth bleaching for esthetic improvement. One year later, secondary caries was detected on tooth #22 and restored using a UC. The restoration was placed prior to additional bleaching procedures. Clinical follow-up indicated that the UC restoration appeared to maintain shade adaptation after bleaching. Furthermore, at the two-year follow-up, generalized tooth discoloration was observed; however, the restoration remained harmonized with the surrounding tooth structure. Subsequent additional bleaching resulted in further lightening of the tooth structure while shade harmony with the restoration was preserved. Favorable shade adaptation was maintained throughout the three-year follow-up. This case suggests that a UC restoration placed before bleaching appeared to maintain shade compatibility over long-term follow-up, despite bleaching-induced color improvement and subsequent intrinsic and extrinsic discoloration. Full article

Achieving natural esthetics has become essential for successful dental restorations and supports the use of modern non-metal materials. However, complexity in esthetic features of natural teeth, determined by both inherent color factors and hierarchical and gradient microstructures, makes recording, determination, and reproduction difficult. This often leads to misunderstanding during manufacturing and dissatisfaction with the final outcome, even when using advanced digital tools. The aim of this study was to investigate a new, easy-to-handle digital tool for determining the color of restorative materials. An industrial-level handheld color identifier, the NCS Colourpin SE, together with the corresponding NCS color system, was tested on three materials: dental resin nanocomposite, self-glazed zirconia (SGZ), and Decore zirconia pellets. The repeatability and impacts of geometrical contributions such as surface roughness and thickness on different colors were measured. The Colourpin SE offered promising repeatability. Decore zirconia showed more than 90% repeatability for most of the colors, independent of thickness. The NCS scanner showed slightly better repeatability than earlier in clinical trials with an intraoral scanner. The shades A3.5 and A3 had lower repeatability, varying from 50 to 90%. It identified effects of material thickness and surface roughness, where the thicker samples were identified with higher blackness levels, and surface roughness seemed to be coupled with a lower blackness level in color identification codes. Small but consistent differences between materials were detected, suggesting that material and manufacturing methods affect the final shade. The NCS Colourpin SE shows potential to be developed into an affordable and easy-to-handle scanner for the identification of a patient’s tooth color, enabling synchronization with digital workflows and improving the match between restoration and the patient’s natural teeth. Nevertheless, further research and development in customized applications for color identification in esthetic dentistry is still required through multidisciplinary collaboration. Full article

The colour matching of ceramic restorations is sensitive to ceramic thickness, ceramic optical properties, the tooth region, the tooth/substrate basis colour, and the shade of the bonding agent. This in vitro study evaluates the influence of substrate darkening, resin cement shade and zirconia thickness on the final colour of monolithic Prettau^®2 zirconia restorations. An in vitro factorial design was used combining four resin substrates simulating increasing darkening (ND6–ND9), three shades of dual-cure resin cement (universal, transparent, white opaque) and three zirconia thicknesses (0.5, 1.0, 1.5 mm) of Prettau^®2 zirconia. Standardized photographs were taken under controlled conditions, and CIELAB coordinates (L*, a*, b*) were obtained in Adobe Photoshop. Colour differences relative to the Prettau^®2 A1 shade tab were calculated as ΔL*, Δa*, Δb* and ΔE*. An additive linear model on ΔE* and a main-effect MANOVA on ΔL*, Δa* and Δb* were fitted to assess the impact of each factor. The mean ΔE* was 6.67 ± 2.66, and all but two specimens showed a clinically perceptible colour difference (ΔE* > 2.7) from the A1 shade tab. Substrate shade accounted for 38.4% of the explained variance in ΔE*, cement for 27.6% and zirconia thickness for 6.7%. MANOVA confirmed significant multivariate effects of substrate and cement, but not of zirconia thickness. Translucent monolithic zirconia showed limited ability to reproduce the A1 reference shade over darkened substrates. Substrate shade was the main determinant of colour mismatch, followed by resin cement, whereas zirconia thickness within 0.5–1.5 mm played a minor role. White opaque cement reduced ΔE* and brought the final shade closer to A1, but residual mismatches often remained clinically relevant. These findings highlight the need to control and, when possible, modify the underlying substrate and to select high-opacity cements when shade matching is critical. Full article

Objective: This study aimed to assess the impact of different adhesive systems on the color stability of composite veneers following their exposure to various common beverages. Materials and Methods: A single layer of commercially available adhesives (4th and 7th generations) and two experimental adhesives based on hydroxyapatite and bioactive glass were applied, followed by composite restoration on incisor typodonts. The typodonts were prepared with depths of 0.3, 0.5, and 0.7 mm at the cervical, middle, and incisal regions, respectively. Samples from each group were immersed in coffee, Cola, and deionized water, and color stability was analyzed on days 1 and 60. One-way and two-way analyses of variance were performed. Results: The interaction between groups and solutions was statistically significant (p = 0.001) across all tooth regions. Coffee and Cola caused significant color changes (p = 0.001). The 4th generation demonstrated better color stability than the 7th generation in the middle and cervical regions (p-values = 0.083 and 0.003, respectively). The findings showed that the bioactive glass-based bonding agent exhibited greater discoloration than the hydroxyapatite-based adhesive (p = 0.001). Conclusions: The composite thicknesses are influenced differently by adhesives with respect to shade matching. Bioactive materials-based adhesives showed more resistance towards color change than commercial adhesives. Full article

Several studies have attempted to define the performance of most commercially available shade guides. The purpose of the present study was to compare the coverage errors of three commercial shade guides for a selected Greek population and to investigate whether there is a difference between the coverage errors of the three shade guides for different types of anterior teeth of the selected population. Adult participants with healthy maxillary anterior teeth were recruited for color assessment. Color coordinates were measured for central incisors, lateral incisors, and canines of 212 individuals. Tooth shades were measured at the middle third using the Spectroshade Micro spectrophotometer, and three shade guide systems (Ivoclar, Vitapan Classical, and 3D Master) were evaluated under standardized conditions for comparison. The coverage errors of Ivoclar and Vitapan classical shade guides were not significantly different from each other for all teeth and for the three tooth types separately. However, 3D Master shade guide exhibited significantly lower coverage errors for all teeth and for the three tooth types separately (p < 0.001). 3D Master performed better than the other two shade guides for shade matching with natural dentition in the selected population. Full article

Background: This study aimed to evaluate the agreement among different evaluators in assessing smile esthetics from frontal-view photographs of the lower third of the face during smiling, and afterwards to determine thresholds of perceptibility and acceptability of tooth and gingival shade changes on a single modified digital photograph. Methods: Sixty photographs of the lower third of the face of individuals with pleasing smiles were obtained. Evaluator groups included laypeople, general dentists, and specialists in periodontology, orthodontics, and prosthodontics. Esthetic assessment was performed using seven items from the Orofacial Esthetic Scale (OES). One photograph was digitally manipulated by altering the shade of the first maxillary incisor and the gingiva of the right maxillary second incisor. Perceptibility thresholds and acceptability of these modifications were assessed by all evaluator groups. Results: Specialists in periodontology and prosthodontics, although rating 60 photographs as more esthetically pleasing, detected changes in tooth and gingival color earlier and judged such deviations as unacceptable sooner than general dentists and laypeople, particularly for shifts in lighter shades. Laypeople noticed color changes later but classified them as unacceptable almost immediately showing greater tolerance for lighter shades. Conclusions: The study shows that laypeople prioritize brighter tooth shades, whereas dental specialists value a more natural appearance. Specialists’ early detection of subtle shade changes and discerning judgments reflects their clinical training and awareness of the challenges in achieving perfect esthetics. In contrast, laypeople, seeking bright teeth influenced by social esthetic norms, noticed changes later but judged them as unacceptable more quickly. Full article

Background/Objectives: Tooth colour perception is critical to aesthetic outcomes in restorative dentistry and patient satisfaction. Psychological and gender-related factors may modulate individual colour perception. This study evaluates the influence of gender and emotional state on tooth colour self-perception in healthy adults. Methods: A prospective observational study was conducted on 100 adults (50 women, 50 men; mean age 32.2 years) without anterior restorations or systemic disease. Tooth shade was assessed by (i) operator visual matching using the VITA Classical A1–D4 guide, (ii) patient self-selection with the same guide, and (iii) spectrophotometric measurement (Spectroshade Micro). Emotional state was measured using the abbreviated Profile of Mood States (POMS-SF); the OHIP-14 was administered to characterise oral health–related quality of life. Statistical analyses included the Chi-squared test, Kendall’s τ, and t-test, with p < 0.05 considered significant. Results: A significant association between gender and the magnitude of patient–operator discrepancy was found (p = 0.013): women showed higher rates of complete agreement or two-step differences, whereas men more frequently exhibited one-step differences. Positive mood parameters (feeling active, energetic, satisfied) correlated with greater patient–operator agreement (τ = 0.17–0.23, p < 0.05). Significant association was neither observed between patient self-selection and spectrophotometric measurement (p = 0.225), nor between facial undertone, facial colour contrast, or depressive mood levels. Conclusions: Gender and emotional state influence subjective tooth colour perception. Positive mood is associated with improved agreement between perceived and clinically assessed colour. These findings support a personalised, gender- and mood-informed approach to shade selection and patient management in aesthetic dentistry. Full article

Background and Objectives: The rapid increase of whitening products use raises questions about enamel safety. We compared three high-concentration protocols—Opalescence Quick (45% carbamide peroxide ≈ 15% H₂O₂), Opalescence Boost (40% H₂O₂), and BlancOne Ultra (35% H₂O₂ + LED)—under controlled conditions to balance color change (ΔE) with enamel integrity (microhardness, FTIR). We also constructed a qualitative cytotoxicity risk profile from published data; no biological assays were performed in this study. Methods: Seventy-two matched half-crowns were randomized to Control or one of the three protocols. Outcomes were a change in Vickers microhardness, spectrophotometric color difference, and FTIR carbonate-to-phosphate ratio after 24 h in artificial saliva. We also compiled a qualitative cytotoxicity risk profile from published evidence; no biological assays were performed. One-way ANOVA with Tukey HSD on Δ-scores, Shapiro–Wilk and Levene’s tests for assumptions, Welch’s t-tests for tooth-class comparisons, and Pearson correlation between ΔE and ΔMH. Results: All active protocols produced clearly visible whitening (mean ΔE 5.7–6.3). Hydrogen-peroxide gels showed greater hardness loss and carbonate depletion than the carbamide-peroxide gel under similar contact time. The association between greater shade change and hardness loss was moderate and not predictive for individuals. Conclusions: Under harmonized conditions, all systems whitened effectively. Pursuing changes beyond ~6 units offered little extra benefit while increasing enamel impact. Carbamide-based Opalescence Quick achieved comparable aesthetics with lower acute enamel effects. Clinicians should individualize exposure time and pair in-office whitening with short-term remineralising care. Cytotoxicity comments are qualitative and literature-based only. Full article

Accurate shade matching is essential in restorative and prosthetic dentistry yet remains difficult due to subjectivity in visual assessments. We develop and evaluate a deep learning approach for the simultaneous segmentation of natural teeth and shade guides in intraoral photographs using four fine-tuned variants of Segment Anything Model 2 (SAM2: tiny, small, base plus, and large) and a UNet baseline trained under the same protocol. The spatial performance was assessed using the Dice Similarity Coefficient (DSC), the Intersection over the Union (IoU), and the 95th-percentile Hausdorff distance normalized by the ground-truth equivalent diameter (HD95). The color consistency within masks was quantified by the coefficient of variation (CV) of the CIELAB components (L*, a*, b*). The perceptual color difference was measured using CIEDE2000 (ΔE00). On a held-out test set, all SAM2 variants achieved a high overlap accuracy; SAM2-large performed best (DSC: 0.987 ± 0.006; IoU: 0.975 ± 0.012; HD95: 1.25 ± 1.80%), followed by SAM2-small (0.987 ± 0.008; 0.974 ± 0.014; 2.96 ± 11.03%), SAM2-base plus (0.985 ± 0.011; 0.971 ± 0.021; 1.71 ± 3.28%), and SAM2-tiny (0.979 ± 0.015; 0.959 ± 0.028; 6.16 ± 11.17%). UNet reached a DSC = 0.972 ± 0.020, an IoU = 0.947 ± 0.035, and an HD95 = 6.54 ± 16.35%. The CV distributions for all of the prediction models closely matched the ground truth (e.g., GT L*: 0.164 ± 0.040; UNet: 0.144 ± 0.028; SAM2-small: 0.164 ± 0.038; SAM2-base plus: 0.162 ± 0.039). The full-mask ΔE00 was low across models, with the summary statistics reported as the median (mean ± SD): UNet: 0.325 (0.487 ± 0.364); SAM2-tiny: 0.162 (0.410 ± 0.665); SAM2-small: 0.078 (0.126 ± 0.166); SAM2-base plus: 0.072 (0.198 ± 0.417); SAM2-large: 0.065 (0.167 ± 0.257). These ΔE00 values lie well below the ≈1 just noticeable difference threshold on average, indicating close chromatic agreement between the predictions and annotations. Within a single dataset and training protocol, fine-tuned SAM2, especially its larger variants, provides robust spatial accuracy, boundary reliability, and color fidelity suitable for clinical shade-matching workflows, while UNet offers a competitive convolutional baseline. These results indicate technical feasibility rather than clinical validation; broader baselines and external, multi-center evaluations are needed to determine its suitability for routine shade-matching workflows. Full article

Background: The aesthetic performance of single-shade polymer-based restorative materials (SPRs) can be compromised by extrinsic stains. Understanding the effects of novel whitening interventions on SPRs is crucial. Objective: This in vitro study aimed to evaluate the effects of different whitening interventions, including a novel purple tooth serum and charcoal-based whitening toothpaste with and without in-office bleaching, on the color of a new coffee-stained SPR. Materials and Methods: Seventy disc-shaped SPR specimens were prepared, stained, and then divided into seven groups (n = 10). Three groups were subjected directly to 2500 cycles of brushing simulation with regular toothpaste (control), charcoal toothpaste, or purple tooth serum. The rest were divided into bleaching groups, and the four groups underwent a simulation of bleaching and then brushing with the three products. The color parameters were recorded at the stained baseline, after brushing, after bleaching, and after post-bleaching brushing. The color change (ΔE00) was calculated, and the data were analyzed statistically using the Kruskal–Wallis test and Dunn–Bonferroni pairwise comparisons (p < 0.05). Results: In-office bleaching without brushing had a statistically significantly higher ΔE00 value than all other groups (p < 0.001). Post hoc tests indicated that the ΔE00 values of the brushed specimens were not significantly different from each other when assessed with and without bleaching (p > 0.05). When using the charcoal toothpaste, the post-bleaching brushed specimens had a noticeable color change above the PT. Conclusions: Bleaching improved the stained SPR color initially, but other treatments may offer longer-lasting aesthetics. The charcoal toothpaste showed promising results when combined with bleaching. The purple serum showed limited effectiveness. Full article

Background: The rising demand for aesthetic dental treatments has spurred interest in peroxide-free color correctors as alternatives to traditional hydrogen peroxide formulations, which are associated with tooth sensitivity and potential enamel demineralization. This systematic review evaluates the whitening efficacy and safety profile of hydrogen peroxide-free color corrector (HPFCC) products, focusing on color change metrics, enamel and dentin integrity, and adverse effects. Methods: Following PRISMA guidelines, we searched PubMed, Scopus, and Web of Science throughout January 2025 for randomized controlled trials, observational studies, and in vitro experiments comparing HPFCC to placebo or peroxide-based agents. The data extraction covered study design, sample characteristics, intervention details, shade improvement (ΔE00 or CIE Lab), enamel/dentin mechanical properties (microhardness, roughness, elastic modulus), and incidence of sensitivity or tissue irritation. Risk of bias was assessed using the Cochrane tool for clinical studies and the QUIN tool for in vitro research. Results: Six studies (n = 20–80 samples or subjects) met the inclusion criteria. In vitro, HPFCC achieved mean ΔE00 values of 3.5 (bovine incisors; n = 80) and 2.8 (human molars; n = 20), versus up to 8.9 for carbamide peroxide (p < 0.01). Across studies, HPFCC achieved a mean ΔE00 of 2.8–3.5 surpassing the perceptibility threshold of 2.7 and approaching the clinical acceptability benchmark of 3.3. Surface microhardness increased by 12.9 ± 11.7 VHN with HPFCC (p < 0.001), and ultramicrohardness rose by 110 VHN over 56 days in prolonged use studies. No significant enamel erosion or dentin roughness changes were observed, and the sensitivity incidence remained below 3%. Conclusions: These findings derive from one clinical trial (n = 60) and five in vitro studies (n = 20–80), encompassing violet-pigment serums and gels with differing concentrations. Due to heterogeneity in designs, formulations, and outcome measures, we conducted a narrative synthesis rather than a meta-analysis. Although HPFCC ΔE00 values were lower than those of carbamide peroxide, they consistently exceeded perceptibility thresholds while maintaining enamel integrity and causing sensitivity in fewer than 3% of subjects, supporting HPFCCs as moderate but safe alternatives for young patients. Full article

Objectives: The aim of this study was to evaluate the effectiveness of spectrophotometers for objective tooth color measurement, particularly in bleaching procedures enhanced by digital positioning templates. Methods: Tooth color registration was conducted using both subjective methods with shade guides and objective methods with spectrophotometers. Spectrophotometers were chosen for their ability to provide objective, quantifiable, and reproducible results, crucial for monitoring color modifications accurately. Digital workflows were implemented to enhance the registration process further. These workflows included providing a precise positioning matrix for spectrophotometer sensors and optimizing working models to ensure high-quality therapeutic splints. Results: The use of spectrophotometers demonstrated superior performance in registering tooth color objectively compared to subjective shade guides. Digital workflows significantly improved the precision and efficiency of spectrophotometer measurements through a digital matrix, enhancing the quality of therapeutic splints obtained. Conclusions: Spectrophotometers are recommended for objective and precise tooth color registration, particularly in bleaching procedures. Integrating a digital positioning matrix enhances measurement accuracy and reliability, supporting effective monitoring and treatment outcomes. Full article

Image-assisted digital shade guides are increasingly popular for shade matching; however, research on their accuracy remains limited. This study aimed to compare the accuracy and reliability of color coordination in image-assisted digital shade guides constructed using calibrated images of their shade tabs captured by a mirrorless camera (Canon, Tokyo, Japan) (MC-DSG) and a smartphone camera (Samsung, Seoul, Korea) (SC-DSG), using a spectrophotometer as the reference standard. Twenty-nine VITA Linearguide 3D-Master shade tabs were photographed under controlled settings with both cameras equipped with cross-polarizing filters. Images were calibrated using Adobe Photoshop (Adobe Inc., San Jose, CA, USA). The L* (lightness), a* (red-green chromaticity), and b* (yellow-blue chromaticity) values, which represent the color attributes in the CIELAB color space, were computed at the middle third of each shade tab using Adobe Photoshop. Specifically, L* indicates the brightness of a color (ranging from black [0] to white [100]), a* denotes the position between red (+a*) and green (–a*), and b* represents the position between yellow (+b*) and blue (–b*). These values were used to quantify tooth shade and compare them to reference measurements obtained from a spectrophotometer (VITA Easyshade V, VITA Zahnfabrik, Bad Säckingen, Germany). Mean color differences (∆E₀₀) between MC-DSG and SC-DSG, relative to the spectrophotometer, were compared using a independent t-test. The ∆E₀₀ values were also evaluated against perceptibility (PT = 0.8) and acceptability (AT = 1.8) thresholds. Reliability was evaluated using intraclass correlation coefficients (ICC), and group differences were analyzed via one-way ANOVA and Bonferroni post hoc tests (α = 0.05). SC-DSG showed significantly lower ΔE₀₀ deviations than MC-DSG (p < 0.001), falling within acceptable clinical AT. The L* values from MC-DSG were significantly higher than SC-DSG (p = 0.024). All methods showed excellent reliability (ICC > 0.9). The findings support the potential of smartphone image-assisted digital shade guides for accurate and reliable tooth shade assessment. Full article

Cosmetic restorative dentistry focuses on restoring teeth affected by caries or trauma using materials that mimic natural teeth in shape, texture, and color. Composite resins, particularly nanofilled composites, are widely used due to their superior mechanical and aesthetic properties. Accurate tooth color selection is crucial, and methods include visual (shade guides) and instrumental (spectrophotometers, colorimeters, and intraoral scanners). Newer biomimetic composites, such as Admira Fusion 5 and Clearfil Majesty ES-2 Universal, simplify shade selection through advanced optical technologies. A randomized clinical study involving 30 patients compared the color-matching accuracy of two biomimetic composite resins: Admira Fusion 5 (Voco) and Clearfil Majesty ES-2 Universal (Kuraray). The study utilized the Vita Easyshade spectrophotometer and the Primescan intraoral scanner. Patients were treated following standardized protocols, and shade accuracy was evaluated pre- and post-restoration using Cohen’s Kappa index. Admira Fusion 5 showed higher shade-matching accuracy, with good agreement between pre- and post-restoration measurements using both instruments. Clearfil Majesty ES-2 Universal demonstrated lower reproducibility in shade matching, particularly in posterior teeth, with lower agreement in pre- and post-tests. Instrumentation Comparison: Primescan showed slightly better performance than Easyshade, but both provided comparable results. In conclusions, universal composites may not always achieve optimal shade matching in posterior teeth. Layered composites provide better color adaptability. While digital instruments enhance shade accuracy, combining them with visual methods yields the best clinical outcomes. Further research with larger sample sizes is needed to improve shade-matching techniques in aesthetic restorative dentistry. Full article