Overcoming Shade Challenges

Restoring teeth with dark underlying tooth structure poses a significant challenge. Achieving optimal esthetics and ensuring patient satisfaction while not compromising the health of the dentition necessitates a multidisciplinary approach that encompasses meticulous treatment planning, selection of proper materials, and utilization of various masking techniques by the dentist and the ceramist.

In the context of shade matching, the influence of the underlying tooth structure—also known as the stump shade—becomes a decisive aspect in achieving the desired final result.

Moreover, with the growing demand for all-ceramic restorations and minimally invasive approaches that closely mimic the natural tooth's shade and translucency, the challenge of addressing discolored teeth becomes even more pronounced. In such cases, ceramists are required to possess exceptional masking skills through layering techniques and a keen ability to select suitable materials.

Several techniques can simulate the underlying color of a discolored tooth, including the use of stump die materials such as light-curing substances, acrylic resin, permanent colored pens, and dentin color spacers (Figure 1 through Figure 4).

However, it is still preferable to consider treating the discolored tooth directly in the dental chair to achieve more predictable outcomes.

There are multiple ways to mask discolored dentition. One approach can be using a semi-translucent restoration with a semi-translucent resin cement, instead of using a translucent restoration with an opaque cement (Figure 5 through Figure 7). Opaque cements can show through the translucent restoration, revealing the preparation and compromising the overall esthetics.

The patient presented to the clinic and wanted a brighter, whiter smile. She had had severe tetracycline stains on her teeth since she was a child, and always had been conscious of her smile (Figure 8 through Figure 10). The patient bleached her teeth multiple times, but she was not satisfied with the result; she wanted a more dramatic and predictable result. She opted to restore from first premolar to first premolar both on the maxilla and the mandible to enhance the overall color and shape of her teeth.

The design of the restoration—whether it be a conventional labial veneer, three-quarter veneer, or crown—would be determined once the appropriate amount of tooth structure was removed to reveal the shade of the underlying tooth structure. In certain cases, the discoloration becomes more intense as the outer dentin is removed (Figure 11).

To mask the discolored tooth, more prosthetic space is needed; therefore, more tooth preparation must be performed. Once appropriate space has been created, the clinician must evaluate the amount of tooth structure left and finalize the geometry of the preparation.

Due to clinical attachment loss, the patient in this case had large interproximal spaces. It was decided that a three-quarter veneer would be needed to close the interproximal spaces without creating unnecessary interproximal overhangs. If the preparations were short, a full crown may have been considered in order to maximize the mechanical retention of the restoration. However, for this patient, her prepared teeth were long enough, and the margins could be placed subgingivally in the interproximal areas, so a three-quarter veneer preparation was performed. Composite foundation restorations were placed on all the prepared teeth in order to seal the dentin and improve the bond strength of the resin cement to the preparations.

When choosing the material for the definitive restoration, the restorative team must consider preparation design, preparation shade, inherent strength, and bond strength to the tooth structure. The restorative material should allow for maximum predictability when matching the color, value, and opacity.

The fabrication process of pressable ceramics allows for precise replication of the final tooth form via a digital wax-up (Figure 12 and Figure 13). The wax-ups for the final restoration in this case were fabricated on the basis of the patient's gender, age, adjacent teeth, personality, face shape, and tooth proportion. They were also designed to meet the patient's functional and esthetic expectations.

After careful consideration of various factors, a lithium disilicate-based press ingot (Amber Press, HASS Bio America, Inc.) with a press and stain technique was selected for the definitive restorations. The LT W4 ingot was chosen based on the patient's desired shade and preparation shade. A delicate divesting process was carried out using fine glass beads. After pressing, it is very critical to use the correct grinding instruments to avoid chipping and cracks.

Digital photography has become an invaluable asset in modern dentistry, facilitating enhanced communication, esthetic replication, and better overall treatment outcomes. Ceramists rely on digital photography to meticulously observe and analyze the intricate details of natural teeth (Figure 14). By capturing high-resolution images, they gain invaluable insights into tooth anatomy, color variations, and surface texture. This knowledge empowers ceramists to mimic nature's subtleties, resulting in restorations that closely resemble natural dentition.

After the divesting stage, final contouring and texture were provided by the ceramist. The integration of stain and glaze techniques into laboratory procedures enhances predictability and reproducibility. Ceramists can achieve consistent esthetic results by utilizing advanced materials that offer a higher level of control and reliability (Figure 15 and Figure 16). Skilled ceramists, armed with advanced stain and glaze materials, can replicate nature's intricacies and produce restorations that closely resemble layered techniques. In this case, the patient was exceptionally pleased with the final esthetic outcome provided (Figure 17 through Figure 20).

Successfully masking the dark underlying tooth shade for a brighter smile requires collaboration between the dentist and ceramist, meticulous planning, careful material selection, and advanced masking techniques. By incorporating these elements, dental professionals can achieve optimal esthetics and patient satisfaction in restoring teeth with discoloration, ultimately enhancing the patient's confidence and overall oral health.

Sung Bin Im, MDC, CDT, BS
CEO
SUNG BIN IM Dental Studio
Fort Lauderdale, FL

Jae Seon Kim, DDS, FACP, CDT
Owner
Pacific Modern Dentistry
Seattle, WA