The document summarizes various abnormalities and diseases that can affect the dental pulp and periapical tissues, including: 1) Pulp calcification, which involves mineralization within the pulp chamber or root canals and can occur as denticles, pulp stones, or diffuse linear calcifications. 2) Resorption of teeth, which can be physiological for deciduous teeth but pathological for permanent teeth. 3) Diseases of periapical tissues including periapical abscesses, granulomas, radicular cysts, phoenix abscesses, and condensing osteitis. These conditions are responses to dental infection and inflammation and can develop from other lesions if left untreated.