Today’s shift toward all-ceramic crowns requires a more accurate impression material. Not only is it important to accurately portray the marginal area, but the tooth’s entire surface must be captured.

An even thickness of cement between the crown and the tooth along with even ceramic thickness reduces internal stresses that might lead to premature fractures.

Beveled or light chamfered margins are easier to accurately impress because moisture at and slightly above the marginal area is more easily displaced along a smooth margin by the impression material. Shoulders, which are often required for all-ceramic crowns, are more difficult to impress because the fluids are not as easily carried past the abrupt joint created at the margin.

In an ideal world blood and saliva would not be a problem, gingival health would always be present, and preparations would not encroach upon biologic width.1,2 Unfortunately, this is not always possible. Making accurate impressions is a challenge. Dentists always are looking for a more forgiving material to help compensate for less than ideal intraoral conditions.

It has to be flexible

Flexibility is important when selecting an impression material. It is amazing how many different techniques dentists use to obtain their ideal impression. There is the no-cord, single cord, and the double cord technique with or without a number of astringents and medicaments. Some use a laser or electrosurgery to expose sub-gingival margins while others prepare supra-gingival or gingival margins eliminating the need for cord. Different viscosities are used from the all-in-one monophase to combine materials such as putty and extra-light. It is important to realize dentists like to do a procedure their way.

Panasil impression material is available in many viscosities, hardnesses, speeds and delivery systems. For example, in the heavy bodied tray material viscosities, there are traditional putty, a machine mixed putty viscosity, fast set heavy bodied, soft heavy bodied, and soft heavy fast-set materials. The syringable viscosity materials are available in regular viscosity, light viscosity, extra-light viscosity, and extra-light fast set viscosity. The available formulations should meet the needs of nearly every technique and preference.

The Panasil advantage

Addition reaction poly-vinyl siloxane impression materials are the most popular impression materials for fabricating fixed removable prostheses in North America.3 They achieve the best dimensional accuracy and stability of all available dental impression materials and exhibit an extremely low polymerization shrinkage of 0.04% at 24 hours.4

The ability of the unpolymerized, unset material to wet intraoral tissues has led manufacturers to add surfactants to increase their hydrophillicity.5 Not only is it important for an impression material to wet the surface of a tooth, it also must displace water away from the preparation and marginal areas. This is a physical property in which Panasil excels.

The evaluation
When members of the Catapult Group were asked to evaluate Panasil, they were most concerned about reducing the need for impression remakes because of missed margins, and bubbles and voids on the impression’s surface. They felt the material would need to exhibit better detail along the margins, especially sub-gingivally, and have fewer voids or bubbles before they would consider changing from their present-day impression material.

Eighty-eight percent of respondents rated Panasil as equal to or better than their current material, and 57% rated it better than their present in-office impression material. In particular, they rated the superior sub-gingival margins very high. Eighty-six percent said they would consider using the material in their offices. These are unusually high marks for a group that tests many available products and can make personal decisions for their offices from a high level of experience.

Case presentation

A patient presented with a discolored maxillary left central incisor that had undergone endodontic root canal therapy (Fig. 1). Another dentist had performed composite bonding on several occasions, and the patient was looking for a more long term solution.

Treatment options including bonding, veneering and an all-porcelain crown were presented. The patient elected to have an all-ceramic crown placed. The tooth was prepared and impressions made (Figs. 2 and 3). A custom shade guide along with photographs were sent to the laboratory (Fig. 4). The patient returned 2 weeks later and the crown was tried in, adjusted and bonded into place (Fig. 5).

Something to consider

Poor preparation and impression taking technique cannot be fully compensated with improved materials. However, with newer all-ceramic materials requiring precise impressions in difficult situations, anything that can improve the likelihood of success should be explored. Panasil offers a wide variety of products that should satisfy most dentists’ personal preferences. The group finds that the Panasil impression materials should be considered if you are thinking about using a new impression material.