Critical Communication with Well-Documented Digital Photography Esthetic Shade Matching for a Single Full-Ceramic Crow

A 26-year-old female with an unremarkable medical history presented with a chief cosmetic complaint of a dislodged upper right central incisor with an exposed root surface (Figs 1 & 2). Tooth #8 had fractured due to an accident five years earlier and had been treated with a root canal and crown.1,2 

The patient exhibited good oral hygiene and periodontal health. The gingival margin of #8 was incisal to the contralateral #9. The crown at #8 was narrower and smaller than #9 mesiodistally and shorter than #9. The incisal embrasure of #8 and the line angle was not balanced with #9. The crown at #8 was monochromatic and the value  was slightly higher than the contralateral #9. Radiographic examination revealed that #9 had been treated with a root canal and had been fitted with a post and crown.

A new full-ceramic crown was planned to replace the ceramic metal crown. A provisional crown was planned to mold the soft tissue architecture first. 

To fabricate a single restoration that blends harmoniously with the adjacent dentition, shade matching is of the utmost importance.3 Shade matching is recommended at the start of the appointment, as dehydrating teeth will change color. Appropriate documentation and photography is critical for communication between the dentist and ceramist, especially when the dentist and the ceramist are a great distance from each other.4

Correct exposure is critical; photographs must not be overexposed as this will result in the loss of tooth details and color. The dentist can check with the histogram in the panel of the camera (Figs 3a & 3b). In a slightly underexposed photograph, there is more detail of the color of the tooth. Figure 4 was deliberately slightly underexposed to show maximum detail of the natural tooth.5

The camera must be angled in the correct position toward the tooth perpendicular to the long axis; otherwise, ring and even dual flashes will produce undesirable highlights. Shade tabs must also be correctly placed in the same plane as the tooth to be matched (Fig 5).

For flash photography, the author recommends using dual flash (Fig 6) instead of ring flash (Fig 7). The dual flash can alter the angulation and distance of the flash to the tooth and produce a different effect (i.e., a different reflection compared with ring flash). 

A dual point flash bracket allows for positioning of the flash heads on either side of the lens for intraoral views, or separates them by as much as 22 inches for anterior esthetic views and laboratory communication (Figs 8 & 9). The direct light from a flash can be unduly harsh. Using a bouncer that fits to a flash unit is recommended as the bounced light softens and diffuses the light.

Correct room lighting color temperature is recommended as it influences the perception of color. The ideal light  color temperature is 5500-6000K. The author uses the DIALITE lamp (Eickhorst; Hamburg, Germany) with two 5500k bulbs to provide correct environmental light for shade matching.6 The VITA 3D Master Linearguide (Vident; Brea, CA) was used in this case. It consists of two steps: First the right value from five value tabs is chosen, then the proper mix of chroma and hue is selected within the chosen value range. Once the gingival, body, and incisal shade tabs were selected, photographs of each of the tabs were taken next to the tooth to be matched (Figs 10a-10c). A black-and-white photograph with shade tab was also taken to allow for accurate evaluation of value (Fig 11).

A cross-polarized photograph was taken (polar_eyes,PhotoMed; Van Nuys, CA).7 This eliminates unwanted specular reflections that obscure the fine details of the tooth while providing a glare-free, in-depth image. This photograph enhanced and facilitated visualization of the base dentin shade and the subtle enamel characteristics, providing a chromatic map with a naturally enhanced contrast (Fig 12).

The human eye can make mistakes in shade matching. Because of this, a spectrophotometer (SpectroShade Micro, Medical High Technology; Verona, Italy) was used for final shade matching. With the help of a digital shade analysis, a more accurate shade match and detailed shade-mapping prescription was produced for the ceramist (Fig 13). The author performed digital shade matching only after traditional shade matching was done so as to eliminate bias.8-12 

“ Appropriate documentation and photography is critical for communication between the dentist and ceramist, especially when the dentist and the ceramist are a great distance from each other.” 

The VITA 3D shade guide can be used only for the value, chroma, and hue. But tooth color is complicated, as it  involves translucency, opalescence, and also the internal incisal edge effects. Vita VM9 has a special shade guide for those special color effects. This special effects shade guide was used for detailed shade matching. Margin effect (M) mimics the internal incisal edge effect. Effect enamel (EE) mimics the translucent layer. Other effects are effect opalescence (EO), effect fluorescence (EL), and effect chroma (EC). Special effect shade tab photographs were also taken for the ceramist (Figs 14-17). The ceramist will have additional ideas about special effects and can select the corresponding porcelain powders to create those effects.

The crown at #8 was removed and the crown margin was modified to 0.5 mm subgingivally. A provisional crown was fabricated by the index with Luxatemp (DMG America; Englewood, NJ) and the soft tissue was molded to balance the gingival architecture of #9. Photographs and study models of the patient-approved provisional were sent to the laboratory.

Once the preparation was finished, the tooth was cleaned and a stump shade photograph was taken for reference (Fig 18). A double cord technique was then used to prepare the teeth for impression-taking. A final polyvinyl silane impression was taken.  

A full-ceramic crown with Lava Plus transparent zirconia coping (3M ESPE; Seefeld, Germany) was tried in and layered with VITA VM9 powder (Figs 19a & 19b). 

The patient was satisfied and agreed to cementation. The temporary crown was removed and the full-ceramic crown was cemented with RelyX (3M ESPE; St. Paul, MN).  Photographs taken three months after the fitting appointment show excellent color integration. The extraoral and smile images show that the crown harmonizes with the natural dentition (Figs 20a-Fig 22).

Replacement of a single central incisor with a ceramic crown is one of the most challenging situations in esthetic dentistry. Communication between the dentist and technician with digital photography can facilitate the procedure and achieve an excellent result.