Which type of infection causes fluids and byproducts to build up within the walls of the pulp chamber and root canals?

The type of infection that specifically causes fluids and byproducts to accumulate within the walls of the pulp chamber and root canals is a periapical abscess. This condition occurs as a result of a bacterial infection that typically stems from untreated tooth decay, trauma, or other dental issues that allow bacteria to infiltrate the pulp of the tooth. When the pulp becomes infected, it leads to inflammation and the formation of pus, which is composed of dead tissue, bacteria, and immune cells. This buildup of fluids creates pressure and can result in severe pain and discomfort.

In contrast, gingivitis is primarily an inflammation of the gums surrounding the teeth but does not directly involve the pulpal chamber or root canals. Root canal infection is a term that might seem closely related but is less specific and does not emphasize the accumulation of fluids in an abscessed state. Finally, periodontitis refers to an advanced form of gingivitis that affects the supporting structures of the teeth and generally involves the periodontium rather than specifically addressing the pulp chamber and root canals. Thus, a periapical abscess is the correct choice due to its direct link to fluid accumulation and infection within the tooth's interior structure.