Posterior_Direct_Restorations Salvatore_compressed

FIG 4-2 (a) Pac-Dams. (b) Dam sheet to be perforated. (c) Pac-Dam application. (d) PacDam 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.