Operative dentistry aje qualtrough, jd satterthwaite la morrow, pa brunton

MOISTURE CONTROL
The oral cavity is intrinsically a wet environment. The presence of 
oral fluids (saliva, blood, gingival crevicular fluid and water coolant
spray) on the surface of a preparation is likely to:
• Dilute or displace etchant or bonding materials.
• Impair the creation of a bond between tooth and restoration.
• Interfere with cohesion of successive increments of restorative
material.
• React with restorative material and thus impair its strength or
dimensional stability, e.g. with zinc containing amalgams leading
to porosity and expansion.
• Discolour tooth-coloured resin restorations, e.g. with blood 
contamination.
• Prevent the creation of a marginal seal where a cement lute is
employed, e.g. for an indirect restoration.
• Contaminate a site that should preferably have as low a bacterial
load as possible, e.g. pulp exposures and root canal therapy.
For these reasons it is necessary to isolate a preparation from mois-
ture, especially when placing restorative materials and undertaking
endodontic therapy.
Rubber dam
Rubber dam is the most effective method of moisture control
11–13
and tooth isolation (Fig. 1.10). Rubber dam is available in latex and 
Basic principles


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latex-free sheets, it can also be obtained in different colours, grades or
thickness. Rubber dam has distinct advantages over other methods 
of moisture control and tooth isolation in that it prevents preparation
contamination, protects the airway, aids visibility and reduces the
risk of cross infection from patient to operator
14
. The quality of 
restorations, particularly resin-bonded restorations, is significantly
improved by using rubber dam
15
. There is also evidence that patients
prefer rubber dam isolation.
It is usual practice, when carrying out restoration placement, to 
isolate a quadrant or sextant with the tooth under treatment being 
in the middle. Expertise and experience enhance its convenience. In
situations where close application to the cervical margin is difficult, a
seal can be obtained by application of a caulking agent or some other
sealant, such as light-activated resin.
There are many different techniques for placing and retaining rubber
dam. Traditionally, the rubber dam was retained using clamps; how-
ever, alternative methods are now available. These include ligatures,
such as dental floss or the placement of an alternative interdental
retainer such as a portion of rubber dam material, a wooden wedge or
commercially available rubber dam retaining aids. If a clamp is used,
three different techniques may be employed for placement. These
include application of the rubber dam and clamp simultaneously, 
the rubber dam before the clamp or the clamp before the rubber dam.