G-CAM Crowns

G-CAM crowns are produced using a graphene-reinforced polymethyl methacrylate (PMMA) biopolymer, combining strength with aesthetic qualities. This material has been developed to offer improved mechanical properties and durability, alongside the enhanced aesthetics expected from modern restorative materials.

Graphene, a form of carbon arranged in a two-dimensional honeycomb structure, is known for its strength and flexibility. When incorporated into the PMMA matrix, graphene increases the crown’s elastic modulus to around 3200 MPa and boosts its flexural strength beyond 140 MPa. While these improvements make G-CAM crowns resistant to fractures, they are not as hard as zirconia and may wear more over time in certain clinical situations.

As a result, G-CAM crowns are generally suitable for posterior restorations but may be less ideal in patients with extreme parafunctional habits like bruxism, where higher-strength materials like zirconia might be preferred.

Aesthetic Properties and Customisation

The optical properties of G-CAM crowns are a key advantage, closely mimicking the translucency of natural enamel. The crowns come in a range of shades based on the VITA shade guide, which helps dental technicians achieve a precise match with the patient's existing dentition. This aesthetic stability ensures that G-CAM crowns maintain their pleasing appearance over time without significant discolouration or shade alteration.

Technicians can also customise the aesthetics of G-CAM crowns after milling, using traditional composite staining techniques to fine-tune the final appearance. This makes them ideal for anterior restorations where a natural look is essential. However, it's important to note that while G-CAM crowns offer good aesthetics, zirconia may offer superior masking for heavily discoloured or dark preps.

Fabrication Workflow in the Dental Lab

The fabrication process for G-CAM crowns follows a typical CAD/CAM workflow, starting with the milling of the crown from graphene-reinforced PMMA discs. These discs come in a variety of thicknesses and diameters and are compatible with most CAD/CAM systems. Once milled, the crowns undergo polishing and aesthetic refinement using surface stains to achieve the desired shade and finish.

This customisation process makes G-CAM crowns versatile, suitable for both single-unit restorations and more extensive rehabilitations. However, because of their lower hardness compared to zirconia, they may not be recommended for long-span bridges or cases where high compressive forces are involved.

Cementation of G-CAM Crowns

For cementation, G-CAM crowns require the use of resin-based cements to ensure optimal retention and longevity. These cements provide excellent bond strength and aesthetic outcomes, especially in cases where the underlying tooth is discoloured or dark. In such cases, opaque resin cements are often used to block out the underlying shade, ensuring that the final restoration maintains its aesthetic integrity.

Both dual-cure and light-cure cements are suitable for use with G-CAM crowns, depending on the clinical situation. Dual-cure cements are preferred for posterior restorations where light penetration is limited, while light-cure cements may be ideal for anterior cases.

Clinical and Laboratory Benefits

G-CAM crowns provide a range of clinical and laboratory benefits, including faster production times due to their monolithic structure, which eliminates the need for complex layering processes. This makes them more cost-effective compared to traditional ceramic or zirconia/pressed ceramic restorations.

However, G-CAM crowns may be less ideal in high-stress or heavy bruxism cases, where zirconia’s higher hardness and durability would be more appropriate. Moreover, for complex multi-unit restorations or long-span bridges, zirconia may provide better long-term stability due to its superior strength.