<prompt> Calcium hydroxide is used in deep cavities in order to:Form dentin bridgeTo kill microorganismTo cause necrosisAs a base under restoration  <response>: A deep caries excavation close to the pulp, which may result in either an undetected pulpal exposure or a visible pulpal exposure, should be covered with a calcium hydroxide liner that can stimulate formation of dentin bridges reparative dentin over the exposure.If used, the calcium hydroxide liner should always be covered with a glass ionomer or resin-modified glass ionomer liner before the tooth is restored.Sturdevants Art and Science of Operative Dentistry. Edition 6. Page: 83 