Case Study
Multi-Layer Zirconia Restorations
Comprehensive aesthetic rehabilitation
This case study details a complex restorative treatment involving the use of high-translucency multi-layer zirconia (Zirconia Y-TZP), which was digitally designed and milled in-house at our Australian Digital Dentistry Academy (ADDA) lab. Our approach here showcases modern advancements in zirconia material, which offer high aesthetic value and durability. This case is testament to the evolution of dental restorations, which have come a long way in terms of bonding capacity and chairside precision.
Patient presentation
The patient presented with significant aesthetic and functional issues, including a severely darkened tooth (21) and a visually unappealing and functionally inadequate denture involving teeth 24 and 25. Seeking a comprehensive upper arch restoration, the patient prioritised a solution that would closely mimic natural teeth in colour, translucency, and aesthetics while ensuring durability and long-term stability.
Treatment plan
The treatment plan involved restoring the upper arch with a combination of pontics, crowns, and an overlay, with future implant restorations planned to replace the existing denture. Key elements of the treatment included:
- 16: MO (Mesio-Occlusal) overlay
- 14, 15, 12: Pontics
- 13, 11, 21, 22: Zirconia crowns
- 23: Natural tooth retained
The plan emphasised high-translucency multi-layer zirconia, milled directly from digital designs. This approach eliminated the need for hand finishing and instead relied on precise characterisation to achieve optimal aesthetics.
High-translucency multi-layer zirconia materials
Zirconia has long been a staple in restorative dentistry due to its superior mechanical properties, but recent developments in multi-layered zirconia blocks now allow for aesthetics that rival those of traditional lithium disilicate materials like e.max. In this case, we utilised high-translucency multi-layer zirconia (Y-TZP), which offers several key advantages:
- Aesthetic quality: The natural gradient within the block mimics the depth and opacity transitions found in natural teeth, providing translucency in incisal regions and opacity in cervical regions.
- Bonding capacity: These zirconia restorations can be bonded, a significant advancement in zirconia applications, offering improved retention and long-term stability in cases requiring adhesive techniques.
- Durability: Zirconia continues to offer superior strength, making it an excellent choice for long-span restorations such as the pontics in this case.
Digital workflow
The entire restorative workflow was digitally driven, from the initial scan to the final milling. We made use of CAD/CAM technology to ensure precision and efficiency:
Digital workflow
The entire restorative workflow was digitally driven, from the initial scan to the final milling. We made use of CAD/CAM technology to ensure precision and efficiency:
Digital imaging:
A comprehensive digital impression of the patient’s upper arch was taken using an intraoral scanner. This allowed for accurate capture of the remaining natural teeth and any anatomical nuances.
CAD modelling:
Using advanced software, we designed the restorations, ensuring optimal fit and aesthetics. The digital design allowed us to plan the pontics, crowns, and overlay with precision.
CEREC milling:
The restorations were milled from high-translucency multi-layer zirconia blocks using a 1:1 milling process directly from the digital design. No additional hand-finishing was necessary, as the multi-layer blocks already provided the aesthetic transitions required for a natural look.
Characterisation:
Post-milling, the zirconia restorations were characterised using stains and glazes to further enhance the natural appearance, ensuring seamless integration with the patient’s existing dentition.
Restorative work
This detailed 3D printed dental model of the patient’s upper arch displays mockups of the planned zirconia restorations.
Challenges and solutions
The most significant challenge was the darkened tooth 21, which required both a highly opaque yet translucent restorative material. Zirconia proved to be an excellent choice for masking the darkened substrate while providing the necessary aesthetic translucency to blend with the surrounding restorations.
Additionally, the existing denture involving teeth 24 and 25 posed a functional and aesthetic concern. Future implant placement will address this, but for the time being, the patient was satisfied with the provisional restorations.
Precision and efficiency of in-house zirconia
This case highlights the significant advantages of using high-translucency multi-layer zirconia in complex restorative treatments. The material’s unique ability to closely mimic natural tooth structure—while providing superior strength and the option to be bonded—represents a transformative development in restorative dentistry. By incorporating advanced digital design and in-house milling technology, we were able to achieve results that were not only fast and precise but also highly aesthetic, aligning with the patient’s functional and visual expectations.
Zirconia’s evolution now allows it to compete with traditional aesthetic materials like e.max, offering a reliable, durable, and natural-looking solution for patients with complex restorative needs. This case exemplifies how modern zirconia materials, combined with streamlined digital workflows, are revolutionising restorative dentistry, setting new standards for efficiency, predictability, and clinical success.