How to isolate?

Absolute isolation in the posterior segment

This sequence shows step by step details for implementing absolute isolation in the posterior segment. Although each situation has its particularities that eventually require modifications in the art, the general background and the steps involved are constant in all cases.

In this case, an occlusal caries lesion in the lower left first molar can be seen in the photograph. In order to facilitate the procedures for preparation and restoration, one should avoid the adaptation of the clamp directly on the tooth to be restored. Therefore, we chose to adapt the clamp to the second molar.
Initially, the rubber dam should be adapted to the young frame, and slightly stretched until it catches on the claws which exist along with the frame. Then the frame/rubber dam assembly is positioned over the mouth cavity and the dam is pressed against the teeth to be isolated until their edges are readily noticeable through the rubber. At this point, a felt tip pen is used to mark each tooth planned to be isolated. It is important that the sheet is kept stable, from the first to the last mark, since they determine the sites to perforated and consequently define the distance from one hole to another. Ideally, one should start by marking the last tooth of the hemiarch- in this case, the second molar- and move towards the midline. After concluding this step note that all teeth- from the second molar to the canine of the opposite hemiarch can be easily identified. The extent of the isolation until the opposite hemiarch, although seemingly unnecessary at first sight, dramatically improves access and visualization, and is highly recommended.

After the marking of the rubber dam, it should be punished - one hole per tooth. Since the teeth have a range of anatomical and dimensional variations throughout the arches, accordingly the punch should present orifices with varying diameters, specific to each group of teeth. The largest orifice is assigned to the tooth that receives the clamp, the second is used for molars, the third for premolars and canines, the fourth is for incisors and finally the fifth and the last, smallest hole is for the mandibular incisors.

The perforations should be made with firm movement, so as not to tear the rubber. Before inserting the sheet, the proximal contacts should be checked with floss and, if necessary, be adjusted with abrasive strips. Next, the selected clamp should be stabilized on the tooth, being careful not to inadvertently compress the gingival tissues. Clamp #26 without side wings is the most commonly used when choosing the clamp prior to the insertion of the rubber dam.

With the clamp appropriately adjusted on the second molar, it is time for the placement of the frame/sheet assembly. First, however, the inner surface of the dam should be lightly lubricated with a water-soluble agent - the shaving cream is perfect for this purpose. Then the assembly frame/sheet is brought into position and with a slight tension of rubber, the dam is passed over the clamp. This step must be performed carefully to minimize the risk of rupture of the sheet.

The next step is to stabilize the most anterior tooth of the isolation. In this case the right canine. For this purpose, simply insert a small section of rubber - trimmed from the dam itself - between the canine and the sheet or, alternatively, you can make a loop with floss. With both ends stabilized, the orifices automatically assume their position on each of the teeth -as long as the marking of perforations has been carried out carefully, then with gentle tension place the rubber sheet to allow for its passage through the interproximal contact points.

Obviously, there may be resistance with the passage of the rubber sheet through the interproximal contacts, especially in places where they are very tight. Such resistance is normal even in those situations where the contacts were fitted with abrasive strips before isolation. To allow the passage of the sheet in these situations, it is essential to use tooth floss or ribbon. Although this is a simple maneuver, it is important that it is performed properly in order to accelerate the isolation and minimize the risk of rupturing the sheet in inter-proximal areas - implying the necessity to restart the isolation, from the marking of points before punching.
Notice this schematic diagram and the photographs, the dental floss should be positioned on the tooth and sild towards the proximal region, to promote the passage of rubber through the point of contact. If the floss was simply pressed on the rubber festoon, it's passage is much more difficult, and is accompanied by the increased risk of rupturing the sheet.

After the passage of the rubber dam through the points of contact, it is important that it is probably invaginated in the gingival sulcus region in order to improve sealing for this, the combined use of dental floss and a spatial with a blunt tip will be of interest.
At the same time that the floss is tightened around the tooth and tensioned to-words the cervical aspect, with the aid of a spatula on the opposite side. This procedure is repeated on every tooth, completing the absolute isolation.

The removal of the absolute isolation begins by withdrawing the clamp, followed by cutting the rubber sheet with scissors. After the removal of the dam, it is important to note that it is not torn at some points, which may mean that some pieces of rubber remain stuck between the teeth, and should also be removed.

Alternatively, the complete isolation can be accomplished with simultaneous insertion of the clamp and rubber dam. For this, a clamp with side wings is necessary as well as a #200 clamp. The clamp is adapted to the sheet through the wings - note that they are covered by the rubber. Below the dam, the frame and clamp, with the help of the clamp forceps are brought together towards the teeth to be isolated.

With the clamp in position, a blunt-tipped spatula is positioned under the portion of the rubber sheet which still covers the side wings in order to promote the displacement of the sheet down from the clamp wings. To ensure good adaptation and invagination of the sheet on other teeth are performed according to the protocol already demonstrated.