Final answer:
The classification discussed refers to dental caries on the occlusal and distal surfaces, which are caused by oral bacteria and can lead to severe tooth damage if untreated. X-rays are essential to identify the full extent of decay.
Step-by-step explanation:
The classification of caries on the occlusal two-thirds of a distal surface refers to a specific type of dental decay that affects the biting surface and the area toward the back of a tooth. Dental caries, more commonly known as cavities, are caused by oral bacteria, mainly Streptococcus and Actinomyces species, which thrive in the mouth when dental hygiene is insufficient. Plaque caused by these bacteria can lead to the breakdown of enamel and create lesions on the teeth, which can progress into the dentin and eventually to the pulp if not adequately treated.
Early detection and treatment of these caries are crucial to prevent further complications such as dental abscesses or systemic infection. The use of X-rays can help reveal the extent of decay inside the tooth, as enamel alone may not show external signs of the underlying damage. To address the issue, all affected areas of the tooth must be thoroughly removed before it can be filled and restored.