Crowns: Impression Materials 360°: How to choose the right impression material

Accurate impressions depend on proper technique as well as desirable material characteristics. Elastomeric impression materials (polyethers, polyvinyl siloxanes, and hybrids) are popular impression materials because of their excellent physical and mechanical properties including excellent detail reproduction, high elastic recovery and good dimensional stability.

Accurate impressions depend on proper technique as well as desirable material characteristics. Elastomeric impression materials (polyethers, polyvinyl siloxanes, and hybrids) are popular impression materials because of their excellent physical and mechanical properties including excellent detail reproduction, high elastic recovery and good dimensional stability.

There are many impression materials available from many manufacturers to choose from. Making the right impression material choice for you helps avoid making a bad impression on your patients.

The preferred elastomeric impression materials on the market are polyvinyl siloxanes (PVS) and polyethers (PE). Polyethers are known for their hydrophilic properties and good flowability. Polyvinyl siloxanes, on the other hand, are known for their excellent elasticity, high tear strength and stability. The decision to use one over the other varies among clinicians and is based on personal preference.

In recent years, a new class of impression materials has emerged. The polyether/polyvinyl hybrids were developed to combine the best features of both materials.
Here’s a more detailed look at the two types of materials:

Polyvinyl siloxanes (PVS)
Addition silicones, also known as polyvinyl siloxanes (PVS), are the most commonly used impression material in the United States. They are available in a wide range of viscosities, colors, scents/tastes and can be used with all impression techniques. Additional characteristics include long shelf-life, adequate working times, fast set times and dimensional stability.

Although polyvinyl siloxanes meet many of the criteria for an ideal impression material, they are inherently hydrophobic. This can reduce accuracy in a moist or wet environment. Surfactants are added to PVS materials to make them more hydrophilic and result in better impressions.

Polyethers
Polyethers have been in the dental market for more than 40 years. While they have earned a reputation for being too rigid and bitter in taste, enhancements over time have made them more desirable. Polyethers remain popular among a large number of clinicians mainly because of their inherent hydrophilic nature.

The water-loving elastomeric material provides superior wettability and adherence to preparations, resulting in good surface detail. Their use is ideal in situations where it is difficult to maintain a dry environment and/or when tissue management is difficult.

Technical details
Strain in compression is a measure of the flexibility of an impression material. A medium (5%-8%) to high (>10%) value of strain in compression indicates the impression material is more flexible when removed from the teeth.

Elastic recovery describes the ability of an impression material to be removed from the teeth and tolerate being pulled past undercuts and away from interproximal spaces without being permanently distorted. A high value (>99%) of elastic recovery means very little distortion will occur.

Bite registration materials
Although not included in our product listing of impression materials, bite registrations orient the maxillary and mandibular relationship during the mounting of models, playing an extremely important role in the success of the final restoration. Restorations made on correctly mounted models require considerably fewer adjustments, resulting in a shorter seating appointment.
Most clinicians use polyvinyl siloxane (PVS) bite registration materials because of their ease of use, relative stiffness, accuracy and proven stability.

Detail reproduction
All impression material must reproduce the finest details of the oral tissues and be able to accurately transfer them to gypsum dies.

With the addition of CAD/CAM and digital impressions, many clinicians wonder about the future of impression materials. Even in the age of digital dentistry, impression materials will never disappear.

See the Market Leaders on the next page ...

Market Leader

Aquasil Ultra Smart Wetting® Impression Material
Aquasil Ultra Smart Wetting® Impression Material is said to be known best for its combination of high tear strength and very low contact angle. Use with B4® Pre-Impression Surface Optimizer for excellent detail with less stress. A complete portfolio of 5 tray and 3 wash material viscosities are available in 3 set time options. Delivery systems include the digit® Targeted Delivery System, a unidose system for easy wash material application, 50 mL and 380 mL cartridges.

DENTSPLY Caulk
800-532-2855 • aquasilultra.com

Alan M. Atlas, DMD, Private Practice, Philadelphia, Pa.

How long have you been using Aquasil Ultra Smart Wetting® Impression Material?
My first introduction to Aquasil Ultra Smart Wetting Impression Material was at the University of Pennsylvania School of Dental Medicine where I have been teaching for the past 14 years as a Clinical Associate Professor. Aquasil impression materials have evolved and improved over the past decade confirming its selection as the material of choice at Penn during my tenure at the school.

Why is it your impression material of choice?
As Co-Director of Restorative Dentistry Clinics and Director of Implant Dentistry, our department can select any impression material on the market. Aquasil Ultra is an elastomeric impression material designed for optimum viscosity at each stage of the impression technique, delivered as both a free-flowing syringe viscosity and a more viscous and thixotropic tray material.

Our decision to use it is based on the scientific evidence supporting its use as well as its incredible successful track record with dental students. As a researcher at Penn Dental in dental materials I look at specific characteristics of this material that make it standout amongst all others available. Hydrophilicity or wettability, dimensional stability and lack of tearing and distortion upon removal are significant attributes of Aquasil Ultra.

Why would you recommend the material to a colleague?
Aquasil Ultra Smart Wetting Impression Material is time tested, dental school tested and versatile to meet every clinician’s needs. Aquasil Ultra’s unique surfactants enable this PVS material to set accurately and produce excellent results. DENTSPLY Caulk went one step further to ensure even better outcomes in the most difficult oral conditions by introducing B4®, a pre-impression surface optimizer, as a precursor to the impression procedure to equalize surface tension of multiple substrates and allow for desired flowability and detail.

Aquasil Ultra comes in a large variety of viscosities, setting times and delivery systems to cover the full range of clinical situations whether it’s a single crown or a full mouth reconstruction. It can be supplied in a small targeted Aquasil Ultra digit® delivery system, which allows accurate intraoral syringe delivery around preparation margins, especially in difficult to access areas. This delivery system is more controllable and easier to manipulate than larger 50 mL automix guns. A single, disposable unit dose also facilitates cross-infection control.

Aquasil Ultra saves me time with ease of use delivery systems and fast 3 minute set-up times and, most importantly, saves me money and reduces stress by giving me the confidence in knowing I can consistently achieve quality impressions with no retakes necessary.

Market Leader

Take 1™ Advanced™
Take 1 Advanced vinylpolysiloxane (VPS) impression material employs Kerr’s expertise in developing high-performance impression materials, along with recent technological advancements, to deliver a system of VPS materials with an optimum combination of physical properties: strength, elasticity, dimensional stability and the ability to register detail in any environment. The material provides a wide selection of set times, delivery systems and consistencies for an optimal combination of mechanical properties.

Kerr Corp.
800-537-7123 • kerrdental.com

Ara Nazarian, DDS, DICOI, Premier Dental Center, Troy, Mich.

How long have you been using Take 1 Advanced?
I have been using Take 1 Advanced for the past three years.

Why is it your impression material of choice?
Take 1 Advanced is definitely my impression material of choice, whether I am doing impressions for a single crown, multiple crowns or full mouth reconstructions. In the past, I would use a variety of different impression materials from several different manufacturers, because a particular type would be best for crowns and another type for dentures or partials.

With Take 1 Advanced, the proprietary fillers and polyvinyl materials allow you to work in any field. Because of their formulation, the material handles very well while extruding around preparations. It has a very hydrophilic characteristic, which allows it to be used when water, saliva or even blood is present. Most importantly, it recovers from deformation very well compared with other materials on the market.

Most dentists and assistants don’t want to look through a variety of impression materials in their cabinets for various dental procedures. Instead, they prefer to have a universal impression material that can be used no matter what the procedure.

In addition, Take 1 Advanced comes in a variety of dispensing options whether it be a volume machine or extruding guns. The light body wash material of Take 1 Advanced has two types of consistencies including light or medium for those dentists who request a specific type. Also, the light body materials are available in unidose syringes taking up less counter space as well as making the procedure of extruding the material easier because the tip is much shorter and closer to the working field. These unidose disposable light body syringes cover about 2-4 units of C/B.

Why would you recommend it to a colleague?
I highly recommend Take 1 Advanced to any dentist who wants to use a universal type of impression material that over-performs in all the categories to produce consistent impressions every time.

Market Leader

3M™ ESPE™ Impregum™ Soft Polyether  Impression Material
3M™ ESPE™ Impregum™ Soft Polyether

Impression Material is said to provide the benefits of a polyether and convenience of VPS dispensing, allowing use among multiple operatories. Its hydrophilicity allows for superb impressions in moist conditions and its flow properties offer excellent precision and accuracy of fit. Impregum material’s snap-set is exceptionally forgiving, enabling detail reproduction without distortion. Impregum Polyether can be prepped in the syringe up to 12 hours prior to taking the impression, which provides major time savings to the dental team.

3M ESPE
800-634-2249
3MESPE.com/GreatImpressions

Michael Barr, DDS, Palm Beach Smiles, Boynton Beach, Fla.

How long have you been using 3M™ ESPE™ Impregum™ Soft Polyether Impression Material?
Most recently, I’ve been using it for two years, but I used it all through dental school way back when it only came in tubes and had to be expressed on a paper mixing pad. Recently, Impregum  material became available in a more convenient Pentamix™ automatic delivery system and that brought me back.

Why is it your impression material of choice?
What I like about it is that it’s the only truly hydrophilic material on the market. So it’s very compatible with moist environments. If there is any saliva or fluid present, the impression doesn’t get ruined. You also get a whole lot of detail with it.

The more accurate the impression the better the results; the better the lab can fabricate the restoration. If we have a better chance to get it done on the first try, it’s better for the patient, too.
With Impregum Polyether, I don’t have as many materials that set up more quickly. Impregum impressions are just beautiful. You can really see the detail that the impression material picks up. To a dentist, it’s very pretty.

Why would you recommend it to a colleague?
For the ability to capture all your margins with precision without being in a hurry, especially for cases with multiple units. You can achieve accuracy on the first try.

In years past, one of the objections from patients was the taste. The taste has been improved, according to my patients. Dentists should no longer be reluctant to use it because of the improved taste.

Fusion Alginate
Fusion Alginate impression material is a high quality chromatic, dustless alginate with superior quality for taking alginate impressions. The high quality alginate impression material is said to provide great water absorption, high elasticity and is easy to mix. The material is available in a one-pound bag with options of a fast setting impression or regular setting impression.

Clear Innova LLC
310-882-5251 • clearinnova.com

VPS Impression Material
VPS Impression Material is made with VPS, Silicone Vinyl Polysiloxane material said to be specifically formulated to deliver excellent wet ability, to significantly enhance accuracy by delivering impressions that capture and reproduce every last detail of the anatomy.

Talladium Inc.
800-221-6449 • talladium.com