Final answer:
The success of a direct pulp cap is significantly increased by the complete sealing ability of the capping and restorative material, which helps prevent contamination and supports the natural healing process.
Step-by-step explanation:
The probability of success of a direct pulp cap is increased by the ability of the capping and restorative material to seal dentin completely. A proper seal prevents microorganisms from infiltrating the pulp space, thus reducing the risk of pulp inflammation or infection following the procedure. A direct pulp cap is meant to preserve the vitality of the potentially exposed pulp following minor injury or caries removal near the pulp. Using biocompatible materials that provide a hermetic seal is crucial for the success and longevity of the pulp cap. It is a misconception that a larger exposure or copious bleeding would be beneficial; in fact, both would likely increase the risk of failure. The material used should not promote swelling but rather facilitate the natural healing process without additional irritation or inflammation.