There is a vast range of shapes and sizes of rubber dam clamps, supposedly to suit every possible tooth and situation. In fact, this merely causes confusion, as an ill-fitting clamp may be quite unsatisfactory, and dislodge during treatment. When properly fitted, a clamp should have four point contact with the tooth. If not, it will either rock back and forward or dislodge completely.
Clamps are described as being either active , where the jaws slope downwards and positively slide into cervical undercuts, or passive when they tend to remain where placed. They may also be either winged or wingless, depending upon the chosen method of application.
The size 8A clamp is described by the manufacturers as a universal retentive molar clamp .It is an active clamp, and fits every molar tooth, even when these are quite broken down. The author would suggest therefore that all the other designs merely confuse the issue, and until the operator is very experienced only this clamp is used for all molar teeth. Likewise, the size 1 fits virtually all premolars (Fig. 6). If passive clamps are preferred size 0 or 00 are suitable for premolars, although they will not be as retentive. Rather than place aggressive clamps on anterior teeth, it is usually kinder to use interproximal wedges, either pieces of rubber dam or a commercial product such as Wedgets (Fig. 7). It is often easier to isolate several anterior teeth, giving a clear operating field.
Occasionally, a clamp may be dropped in the patient s mouth, or may fracture across the bow as seen in Figure 8, during application. All rubber dam clamps should be protected with a length of dental floss, about 50 cm, threaded through the holes on either side. It is not necessary for this to be wrapped around the clamp as was described in some early restorative textbooks. Indeed this should not be done since, once the clamp is in place above the rubber dam sheet and technically outside the mouth, the floss should be cut and withdrawn. If not it may act as a wick, drawing saliva into the operating field, or taking medicaments down into the mouth. Small voids around the dam may be sealed with a caulking agent such as Oraseal or Cavit (Fig. 9).