Recent Advances in Shade Selection in Dentistry

ABSTRACT

Aesthetic dentistry has become one of the leading trends in modern dental practice, driven by the increasing demand for restorations that closely mimic the natural appearance of teeth. Achieving a color match between the restoration and the natural teeth is particularly crucial when restoring or replacing anterior teeth by using composite or ceramic materials. The instrumental method of color evaluation minimizes the subjective errors associated with human perception of shades.

INTRODUCTION

Restorative dentistry combines both scientific knowledge and artistic skill. For optimal aesthetics, four key factors must be considered in order: position, contour, texture, and color. Effective color combinations not only enhance aesthetics but also ensure that restorations look natural and appealing. Particularly in anterior restorations, it is essential for the restoration’s shade to match that of the neighboring tooth.[1]

Tooth color results from a combination of intrinsic and extrinsic factors. Intrinsic color is influenced by the light-scattering and absorption characteristics of enamel and dentine. Extrinsic color, on the contrary, stems from the absorption of substances such as tea, red wine, chlorhexidine, and iron salts on the enamel surface, particularly on the pellicle coating, leading to surface stains.[2]

Traditionally, shade selection has been done visually using commercial shade guides, However, shade determination can also be performed using various instruments, such as spectrophotometers, spectrocolorimeter, color meters, spectroradiometers, and digital cameras. Instrumental analysis offers the advantage of objective, accurate, and reproducible shade determination.[3] The recommended protocol for both traditional and digital shade matching should be followed to ensure a better understanding of the complexities involved in the process.[4]

GUIDELINES FOR SHADE SELECTION

1. Clean the teeth to be matched by removing all debris and stains. Perform a prophylaxis before selecting the shade.

2. Remove any brightly colored lipstick or makeup, Cover bright clothing with a gray napkin, and paint the operating walls gray.

3. View the patient at eye level and at arm’s length to use the most sensitive part of the retina.

4. Make shade comparisons under different lighting conditions. Start with a color-corrected fluorescent light and then confirm the shade in natural daylight by taking the patient to an operative window.

5. Perform shade comparisons at the beginning of the patient’s visit. Teeth become lighter when they are dry due to desiccation.

6. Make shade comparisons quickly (within 5 seconds), placing shade tabs just under the lip and adjacent to the teeth to be matched.

7. Between each shade evaluation, look at a gray wall or the patient’s napkin to reset your visual perception.[5]

Step 1: Hue selection

The operator should choose the hue that most closely matches the natural tooth. Use the area of the tooth with the highest chroma for selecting the hue.

Step 2: Chroma selection

After selecting the hue, for example, B, choose the chroma from the gradations within the B tabs (B1, B2, B3, and B4). Make several comparisons and avoid retinal fatigue by resting the eyes between comparisons (look at gray walls).

Step 3: Value selection

It is recommended to use a value-oriented shade guide. The guide includes B1, A1, B2, D2, A2, C1, C2, D4, A3, D3, B3, A3.5, B4, C3, A4, and C4. Select the final value by using a second shade guide, arranging samples from light to dark. Determine value by observing the guide and teeth from a distance, standing slightly away from the chair, and squinting. Squinting reduces light reaching the retina, making the rods more sensitive and helping to determine the achromatic conditions. Focus on which fades first—the tooth or the shade tab. The one that fades first has the lower value.

Step 4: Final check/revision

After selecting the value, the tabs chosen for hue and chroma may not match the value shade tab. If the value of the shade tab is lower than the natural teeth, select a new shade tab with a higher value, as you cannot increase the restoration’s value with extrinsic staining without increasing opacity. If the value of the shade tab is higher than the natural teeth, select a new shade tab with a lower value or adjust the difference with intrinsic or extrinsic staining.[6]

RECENT ADVANCES IN COLOR MEASUREMENT FOR SHADE SELECTION

Currently available devices

1. Shofu’s Shade Chroma Meter

2. Vita Easyshade

3. ShadeScan

4. ShadeRite Dental Vision System

5. SpectroShade[6]

Shofu’s Shade Ncc (Natural Color Concept) Chroma Meter (Shofu Dental, Menlo Park, California): The device features a freestanding, handheld contact probe approximately 3 mm in diameter. When the probe is placed against a tooth and the activation button is pressed, a flash of light is emitted from the probe’s periphery. The reflected light is then channeled through the probe’s center to the detector, where it is evenly distributed through color filters that simulate the three standard observer functions. The data are transmitted to the docking unit via an infrared signal.[7]

The Vita Easyshade (Vident, Brea, California) is a handheld spectrophotometer featuring a handpiece connected to a base unit by a monocoil fiberoptic cable assembly. The contact probe tip, approximately 5 mm in diameter, contains 1-mm-diameter fiber optic bundles. Various filters and photodiode arrays receive the light through return fibers in the probe tip’s center, measuring spectral reflectance in 25-nm bandwidths. Before measurement, the user selects a mode (tooth, crown, or shade tab). The display then shows the closest Vita shade in the classical or 3D shade guide designation.[8]

SHADE SCAN: It is a handheld device with a color LCD screen to assist in image location and focus. It uses a fiberoptic cable to direct a halogen light source onto the tooth surface at a 45° angle, collecting the reflected light at 0°. Light intensity and calibration to gray and color standards are continuously monitored and adjusted to ensure consistent color reproduction.[9] The data can be downloaded to a computer by using Shade Scan software. Shade and translucency mapping can be sent to the dental laboratory via email or by including a printout or flashcard with the clinical items.[10]

Shade Rite Dental Vision System (X-Rite Inc., Grand Rapids, Michigan): It is a handheld device with its own light source and an LCD screen to aid in positioning on the tooth. Measurements are taken through rotating filters that simulate the CIE (Commission Internationale de l’éclairagestandard) observer functions. The device is freestanding and placed in a docking station for calibration and data transmission to a computer.[11]

Spectroshade: Light from a halogen source is delivered through fiber optic bundles and lenses to the tooth surface at a 45° angle. The image of the tooth is displayed on a computer screen for positioning verification. The incident light is monochromatic when it strikes the tooth, and as it reflects back, the spectral scanning process is completed at 10-nm bandwidths by a black-and-white and a color-filtered CCD. The software includes shade guide references for most porcelain systems, with the ability to add more. It specifies the closest shade and the magnitude of the color difference from that reference.[12]

CONCLUSION

Digital shade-matching tools improve accuracy and reproducibility, complementing traditional visual methods. Innovations such as Vita Easyshade and SpectroShade ensure consistent results, enhancing aesthetics and clinical efficiency.[3]

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.