A 33 year old female patient complains of decayed tooth. IOPA reveals dentinal caries with 46 not involving the pulp. A composite restoration has been planned for the tooth. Following etching, how much time should the operator wait before the patient is allowed to rinse?
Once the tooth is etched, the acid should be rinsed away thoroughly with a stream of water for about 20 seconds, and then rinsed water must be removed.
When enamel alone is etched and is to be bonded with a hydrophobic resin (e.g. bisphenol A glycidyl methacrylate –based resin), it must be dried completely with warm air until it takes on a white, frosted appearance.
Dentin, in contrast, cannot withstand such aggressive drying, which would cause bond failure because of the formation of impermeable, collapsed collagen fibers.
In the total-etch technique, a dentin bonding agent and primer must be used that are compatible with both moist dentin and moist enamel.

Reference-  Sturdevant 6th ed Pg-310
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