CATEGORY 120 AUSTRALASIAN DENTIST LABS Expert Q&A: Mastering zirconia restorations Ian Feigen By Ian Feigen, Technical Services Director, Avant Dental Ian Feigen is Technical Services Director at full-service dental lab, Avant Dental. Ian qualified as a Dental Technician in 1981, and developed new implant and ceramics techniques that shaped the industry. Ian operated his own lab for 25 years, before joining the Avant Dental team in 2014. Zirconia restorations have quickly become a go-to choice for many clinicians. Their strength, durability, and aesthetics make them suitable for a wide range of restorative applications. In this Q&A, Ian Feigen, Technical Services Director at Avant Dental, explains how material selection, preparation, and clear lab communication can help dentists achieve high-quality zirconia restorations. What makes zirconia such a popular choice for restorations today? Zirconia’s strength gives excellent longterm durability, while its low-wear properties help protect opposing dentition when handled correctly as in hand polishing. Avant’s Aesthetic Zirconia is also chip-resistant and wears at a similar rate to natural enamel. Advances in manufacturing have also greatly improved translucency and strength, which makes zirconia suitable for both functional and aesthetic restorations. That means dentists can achieve lifelike results without compromising structural performance. When is zirconia the right material, and when is it not? Zirconia is ideal for posterior crowns, single crown and bridge implants, bonded bridges, and traditional bridges with abutments on either side. It can also be used for inlays and onlays when the dentist is comfortable with the technique. Veneers can also be made from zirconia. What are the most common preparation mistakes dentists make with zirconia? The most frequent errors involve inadequate occlusal clearance, poor taper, or rough margins. Zirconia requires a specific amount of space to achieve its full strength potential. If there isn’t enough clearance, the restoration may be weak or prone to fracture. Sharp angles or feather-edge margins can also lead to stress points and cracking. Smooth chamfer margins and rounded internal line angles distribute stress more evenly and reduce the risk of failure. How should dentists approach anterior vs posterior zirconia crown preparations? For anterior crowns, allow 0.6–0.8 mm minimum wall thickness, ideally 1–1.5 mm, and 1.0–1.5 mm incisal reduction. Use a clearly visible circumferential chamfer with 0.5–0.7 mm gingival reduction, keep preparation angles around 8°, round incisal edges, and avoid undercuts. For posterior crowns, maintain at least 0.8 mm wall thickness, ideally 1–1.5 mm, with 1.0–1.5 mm occlusal reduction. Chamfer margins of 0.5–0.7 mm and a 4–8° taper are ideal. All occlusal edges should be rounded and chamfer preparations are typically preferred. Why are smooth margins and correct occlusal clearance so important? Smooth edges and sufficient clearance reduce stress concentrations in the crown to improve fit and longevity. Zirconia’s strength increases significantly above 1.3 mm of occlusal thickness, so aiming for 1.5 mm provides a comfortable safety margin. Zirconia can, however, be used in thinner layers at the lingual surface – down to about 0.7 mm – where less load is applied. This combination of precision and balance is key to long-term performance. How can digital scanning and lab communication improve outcomes? Digital scans provide instant feedback on tooth reduction and preparation design, which allows immediate corrections before fabrication. This minimises fit issues, reduces chair time, and improves overall precision. Effective communication with the dental lab is also essential. Dentists should confirm zirconia type, provide clear margin visibility, and include supporting photos for shade matching. The lab can then design broad contact areas and smooth transitions to prevent food impaction and caries formation. What are the key steps to ensure strong bonding with zirconia? After cleaning the restoration, apply an MDP-based primer to create a strong chemical link between the zirconia and the resin cement. Following this sequence helps achieve a durable, long-lasting bond.
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