Polyurock Provides Accuracy, Strength for Producing Models

Laboratories have long had a difficult choice to make between stone models and epoxy models. The former are very delicate and require extraordinary handling, and they often become stained during normal laboratory procedures. The latter are strong and have a hard surface, but they tend to trap air bubbles and take a long time to set—often several hours.

Sterngold Dental made the decision easier with a new option. Polyurock, a dual-component model resin, provides the strength and hardness advantages of the epoxy materials, but it is easy to pour without air bubbles, and it sets in about an hour, according to Sterngold Vice President of Sales and Marketing Ryan Mansfield.

“When a model breaks during the laboratory procedures, it often means that we need to bring the patient back in to make a new impression,” Mansfield says. “Even if we can pour a second model from an impression, some concerns exist about the accuracy of that second model. But, most importantly, it wastes time.”

The harder surface, Mansfield adds, means that the model surface does not become stained and therefore results in a better presentation.

Mansfield says Sterngold became aware of the new technology approximately 18 months ago. The company performed extensive in-house testing to confirm that it was better than the existing materials on the market.

“Along with hardness and strength testing, our testing involves using some extreme situations, such as making an impression of a coin, with all its sharp edges and fine detail, and then pouring a model with Polyurock,” Mansfield says. “We examine these under a microscope for any loss of detail and observe the surface texture, including any air inclusions. We also cut and grind the material to make sure that it can be used easily with normal laboratory tools. We compare setting time and ease of pouring.”

They found that impressions were easy to pour without bubbles due to Polyurock’s low viscosity and more than 4 minutes of working time. It is white, but the base can be tinted with blue or yellow colorants. The material is compatible with alginates, hydrocolloids, various types of silicones, and many other impression materials. Polyurock release spray should be used with polyethers, vinyl polysiloxanes, metals, and plastics.

The early feedback for Polyurock has been positive, Mansfield says.

“A number of large laboratories are using a lot of this material,” he says. “They say that it saves them time and eliminates the concern of a broken model. The clean appearance of the model is a feature that helps the dentists feel confident about the laboratories’ work.”