Rubber Dam: Instruments, Application and Hole Sizes
A rubber dam isolates one or more teeth from the rest of the oral cavity. The working field stays dry, saliva and germs stay out, and small instruments or irrigation fluids cannot reach the throat. Only a few instruments are needed to place it: punch, rubber dam clamps, clamp forceps, frame, dam sheet and template. This guide explains what each part does, how to choose the hole size and how placement works step by step.
Key points at a glance
- A rubber dam provides dryness, infection control, soft tissue protection and better visibility; in endodontics it is considered standard.
- The rubber dam punch punches holes in the sheet. There are two designs: Ainsworth (rotating table) and Ivory.
- Hole size: small holes for incisors, medium for canines and premolars, large for molars.
- Rubber dam clamps anchor the sheet to the tooth; there are winged and wingless clamps.
- The clamp forceps spreads the clamp for placement; the frame holds the sheet taut outside the mouth.
- Always secure clamps with floss so they cannot be swallowed or aspirated.
Why use a rubber dam?
A rubber dam provides a dry working field for long periods. This is a prerequisite for moisture-sensitive adhesive techniques. In endodontics it prevents saliva and bacteria from entering the root canal. At the same time it protects against swallowing or aspirating small instruments and against contact with irrigation solutions. Further advantages are protection and retraction of lips, cheek and tongue and a better overview. Typical indications are root canal treatments, adhesive restorations, removal of amalgam fillings and bleaching.
The instruments at a glance
Rubber dam punch
The punch makes clean, round holes in the sheet. A pointed plunger strikes a table with several hole sizes. On the Ainsworth punch, a rotating table is used to select the hole size. The Ivory punch is a second common design. Depending on the model, five to six hole sizes are available. Important for durability: punches whose plunger meets the table as vertically as possible show less wear over time. In our shop you will find the Ivory pattern rubber dam punch and the rubber dam punch.
Rubber dam clamps
The clamp anchors the sheet at the tooth neck. It consists of a bow and two jaws that grip the tooth below its greatest convexity. There are three basic forms:
- Winged clamps: Lateral wings hold the sheet in advance. Clamp, sheet and frame can be placed together in one step.
- Wingless clamps: They are smaller. The clamp is placed first, and the sheet is then pulled over it.
- Double-bow clamps: They are used mainly in the anterior region.
Clamps are numbered; each number stands for a particular tooth group or situation, for example small clamps for premolars and anterior teeth, larger ones for molars. Clamps with serrated jaws hold on partially erupted teeth, clamps with deeper jaws on badly broken-down teeth. A selection is offered by the rubber dam clamp set and the 11-piece rubber dam clamp set with forceps.
Clamp forceps
The clamp forceps (e.g. Brewer or Ivory pattern) is used to spread, place and remove the clamps. The tips of the forceps engage the holes in the clamp jaws. A lock on the handle keeps the clamp spread so that you can position it calmly. In our shop: rubber dam clamp forceps.
Rubber dam frame
The frame holds the sheet taut outside the mouth, retracts lips and cheeks and ensures free access. The U-shaped Young frame is widely used. For radiographs during treatment, radiolucent plastic frames are available. Available at MedToolPro: small rubber dam frame and large rubber dam frame.
Sheet and template
Rubber dam sheets come in different thicknesses. Thin sheets are easier to place but tear more quickly. Thick sheets retract tissue better and are often used in endodontics. Dark colours improve contrast with the tooth. Latex-free sheets are available for patients with latex intolerance. A template or stamp is used to mark the hole positions. In the case of malpositioned teeth or gaps, mark the positions individually.
Which hole size for which tooth?
The hole size depends on the diameter of the tooth neck. If the hole is too large, the sheet does not seal; if it is too small or the spacing is too narrow, it tears. As a rule of thumb:
| Tooth group | Hole size | Note |
|---|---|---|
| Lower and upper incisors | Small | Smallest holes on the table |
| Canines and premolars | Medium | Medium hole sizes |
| Molars | Large | Largest holes, usually for the clamped tooth |
| Thin sheet | One size smaller | Increases tension at the tooth neck |
The exact assignment of individual hole numbers differs from punch to punch. Follow the manufacturer's instructions and check after punching that every hole has been cut out completely.
Placing a rubber dam: step by step
The following steps describe the common winged technique with a winged clamp:
- Plan: Decide which teeth will be isolated and which tooth will carry the clamp (usually the most distal tooth).
- Mark and punch: Mark the tooth positions with the template and punch the holes in the right size and with sufficient spacing.
- Select and secure the clamp: Try the clamp on the tooth and tie floss through the bow.
- Pre-assemble: Stretch the sheet over the wings of the clamp and attach it to the frame.
- Place: Spread the clamp with the clamp forceps and place clamp, sheet and frame together. The clamp jaws sit at the tooth neck, on or just below the gingival margin.
- Release the sheet: Push the sheet off the wings with a blunt instrument so that it settles around the tooth neck.
- Further teeth: Pull the sheet over the remaining teeth and guide it through the contact points with floss.
- Invert and check: Invert the edge of the sheet at the tooth neck. If necessary, seal with liquid dam and stabilise with ligatures or wedges.
With wingless clamps, the clamp is placed first and the sheet is then pulled over clamp and tooth. For removal with several teeth, cut the interdental septa with scissors, remove the clamp with the forceps and take off sheet and frame together.
Care and storage
Punch, clamp forceps, clamps and metal frames are reusable instruments. Check clamps regularly for cracks, corrosion and loss of tension, and store them free of tension. A worn punch produces ragged holes that tear easily. Read more in our guide to instrument care and reprocessing. You will find further instruments for restorative dentistry and endodontics under endodontics and other dental instruments.
Frequently asked questions
What is a rubber dam used for?
A rubber dam keeps the working field dry and low in germs, protects against swallowing or aspirating small instruments and retracts lip, cheek and tongue. In root canal treatment it is considered standard.
What is the difference between an Ivory and an Ainsworth punch?
Both punch holes in several sizes. On the Ainsworth punch, the hole size is selected via a rotating table. The Ivory punch is a second common design; which one you prefer is mainly a matter of handling.
Which rubber dam clamp for which tooth?
Small clamps are intended for anterior teeth, canines and premolars, larger ones for molars. For partially erupted or badly broken-down teeth there are clamps with serrated or deeper jaws. Numbering varies by manufacturer.
Why is the clamp secured with floss?
If a clamp springs off, it can be retrieved immediately via the floss. This prevents it from being swallowed or inhaled.
When should a rubber dam not be placed?
Reasons against a rubber dam can include a latex allergy (use latex-free material instead), a very strong gag reflex, severe respiratory disease or a tooth on which no clamp will hold. In these cases the approach must be adapted individually.