Rubber dam

Rubber dam - a thin sheet of rubber that is fitted over the mouth and perforated to expose certain teeth that acts as a moisture barrier during dental procedures. In 1864, S.C. Barnum, a New York City dentist, introduced the rubber dam into dentistry. Use of the rubber dam ensures appropriate dryness of the teeth and improves the quality of clinical restorative dentistry. The rubber dam is used to define the operating field by isolating one or more teeth from the oral environment. The dam eliminates saliva from the operating site and retracts the soft tissue.

Rubber dam

Advantages

Dry, clean operating field

For most procedures, rubber dam isolation is the preferred method of obtaining a dry, clean field. The operator can best perform procedures such as caries removal, proper tooth preparation, and insertion of restorative materials in a dry field. The time saved by operating in a clean field with good visibility may more than compensate for the time spent applying the rubber dam. When excavating a deep caries lesion and risking pulpal exposure, use of the rubber dam is strongly recommended to prevent pulpal contamination from oral fluids.

Access and Visibility

The rubber dam provides maximal access and visibility. It controls moisture and retracts soft tissue. Gingival tissue is retracted mildly to enhance access to and visibility of the gingival aspects of the tooth preparation. The dam also retracts the lips, cheeks, and tongue. A dark-colored rubber dam provides a non-reflective background in contrast to the operating site. Because the dam remains in place throughout the operative procedure, access and visibility are maintained without interruption.

Improved properties of Dental Materials

The rubber dam prevents moisture contamination of restorative materials during insertion and promotes improved properties of dental materials. Amalgam restorative material does not achieve its optimum physical properties if used in a wet field. Bonding to enamel and dentin is unpredictable if the tooth substrate is contaminated with saliva, blood, or other oral fluids. Some studies have concluded that no difference exists between the use of the rubber dam and cotton roll isolation as long as control of sources of contamination is maintained during the restorative procedures.

Protection of the Patient and the Operator

The rubber dam protects the patient and the operator. It protects the patient from aspirating or swallowing small instruments or debris associated with operative procedures. A properly applied rubber dam protects soft tissue from irritating or distasteful medicaments (e.g., etching agents). The dam also offers some soft tissue protection from rotating burs and stones. Authors disagree on whether the rubber dam protects the patient from mercury exposure during amalgam removal. However, it is generally agreed that the rubber dam is an effective infection control barrier for the dental office.

Operating Efficiency

Use of the rubber dam allows for operating efficiency and increased productivity. Excessive conversation with the patient is discouraged. The rubber dam retainer helps provide a moderate amount of mouth opening during the procedure. Quadrant restorative procedures are facilitated. Many state dental practice acts permit the assistant to place the rubber dam, thus saving time for the dentist.

Disadvantages

Rubber dam use is low among private practitioners. Time consumption and patient objection are the most frequently quoted disadvantages of the rubber dam. However, the rubber dam usually can be placed in less than 5 minutes. The advantages previously mentioned certainly outweigh the time spent with placement.

Certain situations may preclude the use of the rubber dam, including

1. Teeth that have not erupted sufficiently to support a retainer,
2. some third molars, and
3. extremely malpositioned teeth.

In addition, patients may not tolerate the rubber dam if breathing through the nose is difficult. In rare instances, the patient cannot tolerate a rubber dam because of psychological reasons or latex allergy. Latex-free rubber dam material is, however, currently available.

Materials and Instruments

Material

Rubber dam material (latex and nonlatex), as with all rubber products, deteriorates over time, resulting in low tear strength. The dam material is available in 5 × 5 inch (12.5 × 12.5 cm) or 6 × 6 inch (15 × 15 cm) sheets. The thicknesses or weights available are thin (0.006 inch [0.15 mm]), medium (0.008 inch [0.2 mm]), heavy (0.010 inch [0.25 mm]), and extra heavy (0.012 inch [0.30 mm]). Light and dark dam materials are available, and darker colors are generally preferred for contrast. The rubber dam material has a shiny side and a dull side. Because the dull side is less light reflective, it is generally placed facing the occlusal side of the isolated teeth. A thicker dam is more effective in retracting tissue and more resistant to tearing; it is especially recommended for isolating Class V lesions in conjunction with a cervical retainer. The thinner material has the advantage of passing through the contacts easier, which is particularly helpful when contacts are tight.

Frame

The rubber dam holder (frame) maintains the borders of the rubber dam in position. The Young holder is a U-shaped metal frame with small metal projections for securing the borders of the rubber dam.

Retainer

The rubber dam retainer consists of four prongs and two jaws connected by a bow. The retainer is used to anchor the dam to the most posterior tooth to be isolated. Retainers also are used to retract gingival tissue. Many different sizes and shapes are available, with specific retainers designed for certain teeth. When positioned on a tooth, a properly selected retainer should contact the tooth in its four line angles. This four-point contact prevents rocking or tilting of the retainer. Movement of the retainer on the anchor tooth can injure the gingiva and the tooth, resulting in postoperative soreness or sensitivity. The prongs of some retainers are gingivally directed (inverted) and are helpful when the anchor tooth is only partially erupted or when additional soft tissue retraction is indicated.

Suggested Retainers for Various Anchor Tooth Applications

Retainer	Application
W56	Most molar anchor teeth
W7	Mandibular molar anchor teeth
W8	Maxillary molar anchor teeth
W4	Most premolar anchor teeth
W2	Small premolar anchor teeth
W27	Terminal mandibular molar anchor teeth requiring preparations involving the distal surface

The jaws of the retainer should not extend beyond the mesial and distal line angles of the tooth because:

1. they may interfere with matrix and wedge placement,
2. gingival trauma is more likely to occur, and
3. a complete seal around the anchor tooth is more difficult to achieve.

Wingless and winged retainers are available. The winged retainer has anterior and lateral wings. The wings are designed to provide extra retraction of the rubber dam from the operating field and to allow attachment of the dam to the retainer before conveying the retainer (with dam) to the anchor tooth, after which the dam is removed from the lateral wings. The bow of the retainer (except the No. 212, which is applied after the rubber dam is in place) should be tied with dental floss approximately 12 inches (30 cm) in length before the retainer is placed in the mouth. For maximal protection, the tie may be threaded through both holes in the jaws of the retainer because the bow of the retainer could break. The floss allows retrieval of the retainer or its broken parts if they are accidentally swallowed or aspirated. It is sometimes necessary to re-contour the jaws of the retainer to the shape of the tooth by grinding with a mounted stone. A retainer usually is not required when the dam is applied for treatment of the anterior teeth except for the cervical retainer for Class V restorations.

Rubber dam isolation of upper left second premolar, held in place with a rubber dam retainer during endodontic therapy.

Punch

The rubber dam punch is a precision instrument having a rotating metal table (disk) with holes of varying sizes and a tapered, sharp-pointed plunger. Care should be exercised when changing from one hole to another. The plunger should be centered in the cutting hole so that the edges of the holes are not at risk of being chipped by the plunger tip when the plunger is closed. Otherwise, the cutting quality of the punch is ruined, as evidenced by incompletely cut holes. These holes tear easily when stretched during application over the retainer or tooth.

Retainer Forceps

The rubber dam retainer forceps is used for placement and removal of the retainer from the tooth.

Napkin

The rubber dam napkin, placed between the rubber dam and the patient’s skin, has the following benefits:

1. It improves patient comfort by reducing direct contact of the rubber material with the skin.
2. It absorbs any saliva seeping at the corners of the mouth.
3. It acts as a cushion.
4. It provides a convenient method of wiping the patient’s lips on removal of the dam.
5. The rubber dam napkin adds to the comfort of the patient, particularly when the dam must be used for long appointments.

Lubricant

A water-soluble lubricant applied in the area of the punched holes facilitates the passing of the dam septa through the proximal contacts. A rubber dam lubricant is commercially available, but other lubricants such as shaving cream also are satisfactory. Applying the lubricant to both sides of the dam in the area of the punched holes aids in passing the dam through the contacts. Cocoa butter or petroleum jelly may be applied at the corners of the patient’s mouth to prevent irritation. These two materials are not satisfactory rubber dam lubricants, however, because both are oil-based and not easily rinsed from the dam when the dam is placed.

Anchors (Other than Retainers)

Besides retainers, other anchors may also be used. The proximal contact may be sufficient to anchor the dam on the tooth farthest from the posterior retainer (in the isolated field), eliminating the need for a second retainer. To secure the dam further anteriorly or to anchor the dam on any tooth where a retainer is contraindicated, waxed dental tape (or floss) or a small piece of rubber dam material (cut from a sheet of dam) or a rubber Wedjet (Hygenic, Akron, OH) may be passed through the proximal contact. When dental tape is used, it should be passed through the contact, looped, and passed through a second time. The cut piece of dam material is first stretched, passed through the contact, and then released. When the anchor is in place, the tape, floss, dam material, or Wedjet should be trimmed to prevent interference with the operating site.

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