Isolation

Patients with rubber dam at the dental clinic of The University of Iowa, 1890s. (Courtesy of the Frederick W. Kent Collection, The University of Iowa Libraries.)

Every day we are bombarded with new dental products. Everything is new, state-of-the-art. It belongs to the future and has no past. Today’s products must be a complete departure from the old. They must have evolved. Everything changes, advances, and (apparently) gets better.

But not rubber dam. Rubber dam has remained the same since March 15, 1864, when Sanford Christie Barnum of New York invented it.1 After more than one and a half centuries, there is no better method for absolute isolation.

Even though isolation with rubber dam offers many advantages,2 it is not used commonly.37 The main reason for this is clinician ability with rubber dam. If isolation is carried out quickly and effectively, very few patients refuse its use. However, if patients experience fumbled and failed attempts, they may ask for it not to be used. Therefore, it is recommended to practice for a long time on simulators or on colleagues and start with simple treatments such as Class 1 restorations.

Cases where positioning rubber dam is particularly tricky or even impossible are very rare:

  • Third molars with incomplete eruption or specific morphology
  • Malpositioned teeth
  • Some Class 5 lesions (in the cervical third)
  • Patients with psychologic disorders or breathing difficulties

Teeth that have not fully erupted can be successfully isolated with some assistance, even though it is difficult and complicated. Except for fissure sealing and small Class 1 lesions where single-tooth isolation is preferred, it is almost always advisable to isolate by sector. Even though a Class 2 restoration could be performed by isolating only two teeth, it is advisable to extend the isolation as far as possible in order to achieve better visibility and accessibility. Isolation by sextant is carried out from the first or second molar to the central incisor, and even if it is not necessary, it can be useful to extend the isolation to a tooth in the contralateral arch (as far as the canine).

Benefits to the clinician include:

  • Constant retraction of the lips and tongue (clinician does not need to hold in place)
  • Easy analysis of the tissue to be treated (aided by contrast with the dam color)
  • No noise from the aspirator (the patient can swallow)
  • Less conversation with the patient
  • Easier to treat by quadrant
  • Optimum performance of bonding materials
  • No contamination of the working field or adjacent tissues

Advantages for the patient include:

  • No swallowing of instruments/materials
  • Shorter working times
  • Protection of the tongue, soft tissues, and perioral tissues

Required Materials

Isolation requires dam sheets, dam punch, clamps, clamp forceps, frame, and dental floss (Fig 4-1). A template (see Fig 4-1e) is optional, but highly recommended. One of the most common mistakes, particularly at the beginning, is to space the holes too close together or too far apart. A template makes for fewer mistakes.

FIG 4-1 (a) Rubber dam sheets. (b) Dam punch. (c) Clamp forceps. (d) Dental floss. (e) Template. (f) Clamps. (g) Dam frame with seven retainers. The dam frame keeps the dam taut. It may be metal or plastic. Use of a very large bow (with nine retainers rather than seven) is advised to improve operating field visibility. The bow may be fitted externally or internally to the rubber dam.

Dam sheets

Different dam thicknesses (see Fig 4-2a) can be used for different purposes8:

FIG 4-2 (a) Pac-Dams. (b) Dam sheet to be perforated. (c) Pac-Dam application. (d) Pac-Dam aligned with corners. (e) Marking areas to be perforated. (f) Marked dam for the mandibular left sector.

  • Thin (0.127 to 0.178 mm)
  • Medium (0.178 to 0.229 mm)
  • Heavy (0.229 to 0.292 mm)
  • Extra heavy (0.292 to 0.343 mm)
  • Special heavy (0.343 to 0.394 mm)

In clinical practice, it is advisable to have one thin/medium dam and one heavy dam. The former can be used in situations where it is difficult to insert the dam through tight contacts. The latter can be used in other cases because it offers the benefit of flattening and apicalizing soft tissues (eg, papillae, marginal gingiva). Because some patients are allergic to latex, it is also advisable to keep latex-free dam material on hand.9

Template

Many templates and stamps are available for marking the ideal hole positions. One of the most common mistakes is to space the holes too close together or too far apart. This results in complicated, inaccurate isolation with stretched cervical areas and infiltration of oral fluids.

One such template is the Pac-Dam, which was designed by one of the book’s authors. The Pac-Dam is an open source project released with an international license that allows personal production of the Pac-Dam for noncommercial purposes. Anyone can download the source file and send it to a laser-cutting center; Pac-Dam is also sold online (visit www.pacdam.org for more information).

The Pac-Dam template (Fig 4-2) can be used to mark holes for the three most common isolation types:

  • Single-tooth (sealing, small Class 1 restorations, endodontics)
  • Posterior sector (several teeth, Class 2, indirect bonding, endodontics)
  • Anterior sector (Class 3 and 4, cementing of veneers, endodontics)

Aligning the straight portions of the “head” of the Pac-Dam with the sheet to be perforated (see Fig 4-2c) automatically centers the sheet for the type of isolation to be marked. A Pac-Dam can be used on both sides of the mouth and turned 180 degrees (Fig 4-3) into a total of four positions.

FIG 4-3 Positioning of Pac-Dam for specific scenarios. (a) Isolation of maxillary anterior sector, single tooth in mandibular right sector, and entire mandibular left sector. (b) Isolation of maxillary anterior sector, single tooth in mandibular left sector, and entire mandibular right sector. (c) Isolation of mandibular anterior sector, single tooth in maxillary left sector, and entire maxillary right sector. (d) Isolation of mandibular anterior sector, single tooth in maxillary right sector, and entire maxillary left sector.

After more than one and a half centuries, there is no better method for absolute isolation.”

Each template or stamp provides ideal sheet perforation positions. In situations such as crowding, tooth position may not coincide with the template. An eccentrically positioned tooth can be marked by hand, or ideal positions can be marked for the sector, and then the necessary changes can be made (Fig 4-4). The marks can be erased easily using alcohol.

FIG 4-4 (a) A sector with tooth misalignment requiring isolation. (b and c) The maxillary right sector is marked using the Pac-Dam, and a dot is added lingual to the second premolar site. (d to g) The buccal dot is deleted using alcohol, and the dam is perforated. (h and i) Dam application.

Dam punch

The dam punch (see Fig 4-1b) incorporates a disk with holes of different diameter (Fig 4-5). The wide range of holes can satisfy all needs. Beginners are advised to use only one diameter in the beginning (for molars or premolars) because this is simpler, wastes less time, and makes it possible to concentrate on intraoral maneuvers. Forceps with a longer slot allow it to reach further onto the dam when it is stretched on the frame (Fig 4-6). Perforating the dam once fitted to the frame is recommended for everyone, particularly beginners. The hole made by the punch must be accurate, otherwise the dam may tear during application. Worn or defective disks or punches can be replaced on some forceps.

FIG 4-5 Dam punch disk. The largest setting (A) is to be used mainly for the “clamp first” technique on molars. The molars or universal setting (B) is for clinicians who have never used isolation and should be used for all teeth, until learning how to be more selective. There are also premolar (C), canine (D), and incisor (E) settings.

FIG 4-6 (a) Although these two dam punches are both excellent, the one on the left (A) can be inserted 5 cm onto the dam as opposed to 2.4 cm for the other (B). (b) This greater extension allows for easier perforation of the dam when stretched over the frame.

Clamp forceps

IV-type or lightweight forceps (Fig 4-7a) offer considerable advantages over Palmer (Figs 4-7b and 4-8a) or Brewer (Fig 4-8b) forceps. Firstly, greater separation power can be achieved for the same effort because the fulcrum is closer to the clamp (see Fig 4-7). IV-type forceps also have horizontal surfaces at the terminals that fit into the clamp holes (arrows in Figs 4-8c and 4-8d). These prevent the clamp from tilting and angling, which makes it difficult to insert the clamp, particularly for more distal teeth.

FIG 4-7 Difference between IV-type (also called lightweight) forceps (a) and Palmer (or Brewer) forceps (b). The effort arm is longer in the IV-type (compare green bars).

FIG 4-8 Terminals of the Palmer (a), Brewer (b), and IV-type (c and d) forceps. The IV-type forceps have an anti-rotation feature (arrows).

Choosing a clamp

The purpose of a clamp is isolation. Clamps generally feature the common elements shown in Fig 4-9. There are not specific clamps for molars or premolars; there are only different shapes to coincide with different cervical morphologies. Therefore, the suggestions provided are merely general guidelines. The authors advise assessing the shape of the area between the jaws of the clamp (shown in red in Fig 4-10) and establishing whether it is consistent with the cervical anatomy of the tooth in question. If four points are in contact with the tooth at the same time, the clamp will be stable (rule of four). If only three points are in contact, the clamp may sometimes be stable (particularly if the two distal points are in contact), but the force exerted by the dam (which tends to tip the clamp over) must be taken into careful consideration.

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May 25, 2021 | Posted by in General Dentistry | Comments Off on Isolation
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