The method which gives the most complete control over moisture in the mouth is the rubber dam. The tooth or teeth to be treated, together with adjacent teeth, are placed through holes in a rubber sheet, leaving the crowns of the teeth on one side and the mouth with its moisture and infection on the other.
The advantages of the rubber dam are as follows:
• Complete isolation of the teeth from saliva, blood, or gingival ﬂuid exudate is possible. This is important with all restorations but particularly so in ‘bonded’ restorations.
• The rubber dam aids isolation from bacteria in saliva and so is indicated when infection for the rest of the month must be excluded, for example in direct and indirect pulp capping and endodontic treatment.
• The rubber dam protects the patient from swallowing or inhaling instruments. Dentine pins, fractured burs, pieces of amalgam, wedges, crowns, inlays, endodontic instruments, ﬂanges from saliva ejectors, and even hand-piece heads have all found their way into the trachea or oesophagus.
• The rubber dam protects the dentist from infection from the patient. Its use is indicated in all patients whose blood and saliva may potentially transmit disease to the dentist or their staff (e.g. carriers of hepatitis B).
• The rubber dam has the effect of psychologically, as well as physically, separating the dentist from the patient. Not only are water, air spray, dust, debris, and the high-velocity sucker on the dentist’s side of the rubber, but patients will frequently remark, with some surprise, that they feel safer with the rubber in position, or that they feel detached from what is going on, almost as if the dentist were not working on them. It is not unusual for a patient to fall asleep with a rubber dam in place.
• Once the rubber dam is in place, operative dentistry is quicker and more efﬁcient. Wet mouths, writhing tongues, contracting lips, and garrulous patients dis-appear behind the rubber dam.
However, the technique has its disadvantages:
• The patient can no longer speak easily. Conversations thus become one-sided and cease.
• A few patients dislike the rubber dam intensely, feeling claustrophobic when it is in position.
• The rubber is held on posterior teeth with clamps, and a tooth which has been clamped may be sensitive for some hours after the clamp has been removed.
• The rubber dam takes time to apply and remove, although the more experienced the dentist is in its use, the less time is taken. Once the rubber is in position, however, operating conditions are improved and there-fore time is saved.
RUBBER DAM EQUIPMENT
1. Rubber dam.
It is supplied in ready-cut 15 cm (6 inches) square sheets. The rubber is resistant to tearing and it grips the teeth well and retracts gingival tissue. A dark colour (green, blue, or black) is preferred because it contrasts well with the teeth, and fragments torn off and left behind are easily seen and removed.
2. Rubber dam punch
The punch must give a clean cut otherwise there will be a weak point at the edge of the hole from which a tear may arise. Some punches have holes of varying diameters: the larger the hole, the easier it is to stretch over a tooth; the smaller the hole, the tighter the grip. It is useful to punch a hole in one corner of the rubber dam – near the edge – to check that the hole is being punched cleanly. A ragged hole in the centre of the sheet wastes a whole sheet. Assuming that you always punch it in the same position, this hole also helps to orientate the rubber dam when it is being stretched over the rubber dam frame.
3. Rubber dam stamp for marking the positions of the holes. This inked rubber stamp produces a series of dots on the rubber corresponding to the average positions of the teeth. When the dam is in position it should reach up to a point just below the patient’s nose, thus covering the mouth but not the nose. To achieve this when applying the rubber to the maxillary teeth or mandibular third molars, the position of the upper central incisors should be stamped about 2.5 cm (1 inch) from the top edge of the rubber sheet. For mandibular teeth the holes should be placed further up the sheet so that the rubber does not cover the nose.
4. Rubber dam clamps
These are metal clips which ﬁt the neck of the tooth and hold the rubber dam in position. In addition, they may occasionally help to provide gingival retraction. The following clamps make a good basic set :
• BW, JW molar clamps, wingless; used when the clamp is positioned on the tooth before the rubber.
• K molar clamp, winged; the wings allow the clamp and rubber to be placed simultaneously.
• GW premolar clamp.
• EW clamp used on any small tooth.
• AW molar clamp, wingless; used on partially erupted teeth only. The jaws of this clamp are retentive and point gingivally, thus aiding retention on a tooth whose maximum bulbosity is subgingival.
• Cervical clamp, Ferrier pattern, for use on anterior teeth where retraction of rubber or gingivae is required to allow access to a cervical cavity.
5. Rubber dam clamp forceps.
An instrument for placing, adjusting, and removing clamps.
6. Rubber dam lubricant
A water-based gel is supplied for this purpose but brushless shaving cream is equally suitable. A little lubricant should be applied around the holes in the rubber before sliding it over the teeth.
7. Waxed dental ﬂoss or tape
This can be used to carry the rubber past a tight contact point.
8. Rubber dam holder or frame. This holds the free edges of the rubber and prevents them from falling into the mouth or back against the patient’s face.
Rubber Dam - A Lecture Note
Rubber Dam Placement Videos