Posterior_Direct_Restorations Salvatore_compressed
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FIG 4-17 (a) Two things remain to be done after applying the dam: arranging the clamp and inverting the dam (red arrows). (b to f) The dam can be inverted around the cervical portions of the teeth using a spatula or pointed instrument. (g to k) Refitting the clamp at the end of isolation.
The dam almost always fails to fit properly near the clamp (Fig 4-17g). This causes infiltration of saliva and makes isolation essentially
ineffective. This problem can be solved by opening the clamp and refitting it (Figs 4-17h to 4-17k). During this procedure, tension on the dam must be maintained in order to keep the hole open and allow the clamp to re-engage.
Clamp first technique
In the technique described in the previous section, the clamp engages with the rubber dam, and winged clamps are used for this purpose. When the clamp is tested or when the “clamp first” technique described below is used, the clamp will have to be ligated with dental floss in order to recover it if it becomes disengaged from the tooth or breaks. A simple ligature (knot) may not be enough. Figure 4-18a shows a broken clamp, which can become dangerous if it is ingested, and Fig 4-18b shows a method for tying a clamp safely.
FIG 4-18 (a) A broken clamp may constitute a danger due to the risk of ingestion. (b) A safely ligated clamp.
In the “clamp first” technique, after tying the clamp (which should be wingless with this technique), it is positioned on the tooth (Figs 4-19a to 4-19c). The diameter of the most distal hole to be fitted around the clamp must be greater (although this depends on the flexibility of the dam). Once the dam has been fitted over the clamp (Figs 4-19d to 4-19g), the holes are arranged on the teeth, and the septa are positioned as described in the dam and clamp together technique (Fig 4-19h).
FIG 4-19 (a to c) Applying a clamp using the clamp first technique. Although it is not shown here, note that the clamp must be ligated in case it breaks or becomes dislodged from its site. (d to h) The dam is fitted around the clamp bow and then arranged on the other teeth.
Dam first technique
In the “dam first” technique, an assistant must position the dam around the last tooth, keeping the last hole stretched and extended (Fig 4-20a). The operator can then position the clamp (Fig 4-20b), which can be winged or wingless in this case, on the tooth. Once the clamp is stable, the dam tension can be released (Fig 4-20c). Then the holes are arranged over the teeth, and the interdental septa are fit as described in the dam and clamp together technique.
FIG 4-20 (a) In the dam first technique, the dam is initially stretched by an assistant. (b) The