Identify the statements which are true with respect to periodontal diseases:
1. Presence of calculus
2. Bleeding or swollen gums
3. Formation of pockets and loosening of teeth
4. Oro-dental trauma

Correct option is C

Periodontal diseases are infections affecting the gums and supporting structures of the teeth. The following statements are true:
· (1) Presence of calculus – Correct, as calculus (hardened plaque) buildup leads to gum inflammation and periodontal disease.
· (2) Bleeding or swollen gums – Correct, as inflammation of the gums (gingivitis) is an early sign of periodontal disease.
· (3) Formation of pockets and loosening of teeth – Correct, as advanced periodontal disease leads to deep gum pockets and tooth mobility.
· (4) Oro-dental trauma – Incorrect, as periodontal disease is primarily caused by bacteria and plaque, while oro-dental trauma is caused by injury or impact.