Block & Disk HC

A new hybrid ceramic material for CAD/CAM-based dentistry

Sam Halabo, DMD

Today's CAD/CAM restorations require clinicians to use a multitude of materials to satisfy the needs of their patients. There are many different materials that can be used to create CAD/CAM restorations, including ceramics, hybrid ceramics, and CAD/CAM composites.

Historically, material selection was a simpler process for clinicians because the stronger materials were associated with poor esthetics and the weaker materials were associated with great esthetics. Porcelain, although esthetic, is brittle, has a low fracture toughness, and is prone to failure in the presence of flaws. To overcome these issues, new materials were created with higher flexural strengths than porcelain. When they are prepped, handled, and bonded correctly, these materials demonstrate a good success rate. However, in cases for which the margins are thin, there's a deficient bond to the underlying tooth, or an adjustment is needed, the failure rate of restorations with high-strength ceramics can potentially increase dramatically. In response to the limitations of high-strength ceramics, new polymer-based resin-composite materials such as Shofu's HC Blocks and Disks have been developed.

The HC Block/Disk has many unique characteristics, including a distinctive nanostructure and a homogenous formulation designed to minimize the flaws associated with esthetic and high-strength ceramics. The material is composed of 61% zirconium silicate embedded in a high-temperature/high-pressure polymer matrix. Additionally, the HC Block/Disk has a high flexural strength of 191 MPa and a Vickers hardness value of 66HV0.2, making it a great candidate for posterior restorations, implant-supported cases, and long-term provisionals. This hardness value is closer to the hardness of dentin; therefore, no excessive antagonistic wear is observed.

The proprietary microstructure of the HC Block/Disk's composite particles offers enhanced polishability and esthetic results that mimic nature. Due to the unique formulation of the material, restorations fabricated with the HC Block/Disk show better marginal integrity and less separation when compared with those fabricated from glass ceramics.

When compared with other CAD/CAM materials, the HC Block and Disk offer better machinability in terms of milling time, damage tolerance, wear of CAD/CAM instruments, and the ability to be milled with lesser thickness. This material demonstrates many great characteristics that satisfy the functional and esthetic needs of the CAD/CAM dentist.