Dental Impression and Isolation Materials: Silicone Impression and Rubber Dam

In dentistry, the successful planning of prosthetic, orthodontic, or surgical treatment depends on the precise and dimensionally accurate reproduction of intraoral tissues. Silicone-based impression materials used for this purpose, and rubber dam (kofferdam) systems that isolate the working area from saliva and moisture during treatment, are two fundamental material groups that directly affect clinical success. This article addresses the technical properties and usage principles of both material groups. Selecting both material groups correctly and using them with the correct technique prevents errors that may occur at the first stage of treatment from carrying over into subsequent stages.

The Purpose of Taking Impressions in Dentistry

Taking an impression is the process of reproducing a negative mold of the tooth and soft tissue anatomy inside the mouth using an impression material, and obtaining a plaster model from this mold. The resulting model is the basic reference source for the precise laboratory fabrication of crowns, bridges, dentures, or orthodontic appliances in a dental laboratory. Even the smallest dimensional error in the impression can cause the restoration produced in the laboratory to not fit properly in the mouth. For this reason, taking an impression is considered a critical clinical step that requires a level of dimensional precision difficult to detect with the naked eye.

Today, intraoral digital scanners are becoming increasingly widespread as an alternative to traditional silicone impression materials; however, in many clinical situations, especially in cases of multiple missing teeth or deep subgingival margins, traditional silicone impression techniques are still frequently preferred.

Condensation Silicone Impression Materials: Putty and Wash Technique

Silicone-based impression materials are examined in two main groups: condensation type (C-silicone) and addition type (A-silicone). Putty-consistency condensation silicones are generally used with a two-stage technique: first, a general preliminary impression is taken with the thick putty material, and then fine details are reproduced over this preliminary impression using a flowable wash material. Condensation-type putty silicone products such as Optosil are examples of this technique; materials of this type, thanks to their high elastic recovery property, help the impression retain its original form without deforming when removed from the mouth. Some condensation silicones may show slight dimensional shrinkage over time after polymerization; therefore, it is recommended that the model be poured within a reasonable time after the impression is taken.

If the mixing ratio, working time, and intraoral setting time of silicone impression materials are not followed according to manufacturer instructions, dimensional deviations may occur in the impression; therefore, the application protocol must be followed meticulously. In addition, selecting an impression tray large enough to fully cover the tooth and soft tissue boundaries is also a determining factor in obtaining a complete and accurate impression.

What Is the Rubber Dam (Kofferdam) Isolation System?

Rubber dam is a rubber sheet system used to isolate the tooth being treated from surrounding tissues and saliva during root canal treatment, composite filling, and many other restorative procedures. Thanks to this system, the working area is kept dry, materials are prevented from losing their properties due to moisture, patient safety is increased, and the risk of instruments being swallowed or aspirated is reduced. One-piece, framed rubber dam products such as OptraDam are examples of isolation solutions developed as an alternative to the traditional clamp-and-frame system, aiming to shorten application time. In traditional rubber dam application, small metal retainers called clamps keep the sheet fixed in place around the tooth.

The use of rubber dam is considered an important standard practice, particularly for infection control in endodontic treatments, and whether it will be used is assessed by the dentist according to the conditions of the case. In some patients, conditions such as temporomandibular joint disorders or difficulty breathing through the nose may make rubber dam use difficult, so such special conditions should be shared with the dentist before treatment.

Points to Consider When Selecting Impression and Isolation Materials

When selecting an impression material, criteria such as dimensional stability, detail reproduction accuracy, hydrophilic property (ability to work in a moist environment), and shelf life are considered; when selecting a rubber dam, properties such as whether it contains latex (important for patients with latex allergies), flexibility, and ease of perforation are taken into account. Patients with a history of latex allergy must always inform their dentist of this before treatment. The intraoral setting time of the impression material must also be followed meticulously according to manufacturer instructions; removing it too early or leaving it in place too long can cause the impression to become permanently deformed.

Access to Dental Materials and Laboratory Services

The success of treatment is affected not only by the procurement of consumables such as impression materials, plaster model pouring, and rubber dam, but also by the correct processing of the impressions taken in dental laboratories. Working with an experienced laboratory regarding model pouring, tray selection, and storage conditions helps prevent small errors that may occur in the impression from being reflected in the restoration. By reviewing the dental laboratory and technical service companies listed by city in the Medikalfirma.com catalog, you can easily reach business partners in your region.