Final answer:
Dental varnish is used in cavity preparation mainly to seal dentinal tubules and reduce leakage around a restoration, thus preventing sensitivity and protecting the dentin. It forms a protective barrier to promote the longevity of dental restorations and improves overall tooth integrity.
Step-by-step explanation:
The purpose of using dental varnish in cavity preparation is to seal dentinal tubules and reduce leakage around a restoration. While enamel serves as a protective layer for the underlying dentin and pulp cavity, it can still experience tooth decay due to bacterial acids that degrade the calcium crystals in the enamel. Dental varnish acts as a barrier, protecting the dentin from exposure to oral bacteria and reducing sensitivity. This protective effect is vital, especially considering the dangers of mercury in dental amalgams and the propensity of untreated dental caries to lead to abscesses and more severe infections.
Dental health treatments such as fluoride usage in toothpaste and water fluoridation help strengthen the calcium matrix of tooth enamel, rendering it more resistant to decay. Fluoride is not only bonestimulatory, reinforcing the tooth structure, but it also has antimicrobial properties that impede the growth of decay-causing bacteria. Thus, the application of dental varnish during cavity preparation is a focused method to enhance the longevity of restorations and maintain tooth integrity.