What type of defect might indicate bone loss on tooth #4?

The presence of a crater defect, especially around tooth #4, is significant as it can indicate localized bone loss associated with periodontal disease. A crater defect is characterized by concavities found in the interproximal area between teeth, which are often indicative of the body’s response to bacterial infection in the periodontal tissues. When bone resorption occurs due to inflammation or other periodontal conditions, these crater-like lesions can form as the bone in the area is lost but often retains some of its normal outlines. This specific type of defect suggests that there has been a reduction in the supporting bone level around the tooth, thus reflecting bone loss.

In contrast, cupping defects are broader and more generalized bone loss that is not specific to the interproximal area. Horizontal bone loss refers to a more uniform resorption of bone across the arch, typically seen in more generalized periodontal conditions rather than localized defects. Vertical bone loss, while it indicates a type of bone resorption, usually suggests a more angular pattern of defect which may not specifically represent the crater configuration found between teeth. Therefore, the crater defect is the best indicator of localized bone loss around tooth #4, aligning with characteristics seen in periodontal disease.