The implementation of standards for sanitation, hygiene, ventilation, and nutrition occurred during the ____ centuries

You arrive at the scene of a possible unconscious patient located in a lab setting. On the exterior of the room there is a NFPA diamond with a 4 in the blue portion of the diamond. This is an:

A. extreme health hazard B. extreme fire hazard C. extreme reactivity hazard D. extreme water reactivity

Which type of dentin is formed as a reaction to irritation, such as caries or attrition?

a. Secondary b. Tertiary c. Mantle d. Peritubular