Radiographs are an essential tool for diagnosing periodontal disease by assessing bone loss. Early periodontitis appears on radiographs as localized bone erosions while advanced cases show generalized horizontal bone loss. Vertical bone defects can also be seen, appearing as widened ligament spaces or loss of cortical plates. Furcation involvement initially widens the ligament but may progress to deep vertical defects. Aggressive periodontitis in young people causes rapid, widespread bone destruction and early tooth loss. Follow-up radiographs after treatment can demonstrate bone fill-in and sharpening of bony contours.