BACKGROUND

Ceramics, such as zirconia, are the gold standard for permanent aesthetic dental restorations such as crowns, bridges, inlays, onlays, veneers, and pontics. These materials demonstrate high strength and, in the case of zirconia, can be engineered to undergo transformation toughening to reduce the risk of brittle fracture. Because the materials have low ductility and high hardness, the shape of the restoration is typically custom created to precisely match the dentition of the individual patient. This process often involves capturing the geometry of prepared tooth and subsequently designing and fabricating the restoration either at a dental laboratory or with in-office computer-aided manufacturing equipment. This process is expensive and time consuming for both the dentist and patient.

Preformed dental crowns are manufactured in a factory, shipped in kits to dentists, and can be shaped and adapted chairside to create custom dental restoration. Stainless steel and aluminum have been the favored material because they are strong, yet malleable. Thin wall stainless steel crowns, having a wall thickness of 150-200 microns, can be mass produced at low cost, require minimal removal of tooth structure, and can be trimmed and bent by the dentist at chair side to create a tight fitting and durable restoration. Unfortunately, the tooth-like aesthetics are not possible with stainless steel and attempts to substitute polymers, like polycarbonate, have yielded crowns with durability substantially less than ceramic or steel crowns.

Polymer-ceramic composites are alternative material for restoring teeth. These materials may be pre-shaped in a dental laboratory or delivered to the dentist in a form that allows shaping and curing of the restoration in the mouth of the patient. The cured form of these materials offers lower strength than native tooth enamel, but the incorporation of high amounts of ceramic filler can result in restorations that exhibit wear resistance comparable to natural tooth structure.

To date the availability of preformed ceramic dental restorations has been limited to a few preformed crowns have been offered for pediatric use. Those crowns typically have a wall thickness in excess of 0.4 mm and, therefore, require extensive preparation of the tooth prior to fitting. Further as zirconia is a very hard and tough material, they are not easily trimmed or otherwise adjusted at the dental chair. Accordingly, a need exists for new types of ceramic crowns, or other dental restorations, and ways to make such crowns.

SUMMARY

An additively manufactured dental crown, consistent with the present invention, includes a wall having a bottom edge and an occlusal portion joined with the wall opposite the bottom edge, where the wall and occlusal portion form an interior surface and an opposing exterior surface. A thinnest portion of the wall has a thickness of less than 300 microns, and the wall and occlusal portion both comprise an additively manufacturable material.

A method for making a dental crown, consistent with the present invention, includes receiving a design for a dental crown and making the dental crown using additive manufacturing. The dental crown has a wall having a bottom edge and an occlusal portion joined with the wall opposite the bottom edge, where the wall and occlusal portion form an interior surface and an opposing exterior surface. The wall has a thickness of less than 300 microns at the thinnest portion of it.

