People with depression may experience low energy, lack of motivation, and difficulty concentrating, which can lead to neglect of oral hygiene practices.  

They may also be more likely to engage in unhealthy behaviours that can harm their oral health, such as smoking, excessive alcohol consumption, and overeating sugary foods.

Mental health conditions, on the other hand, can cause teeth grinding and jaw clenching, known as bruxism or clenching. This can lead to tooth damage, jaw pain, and headaches. 

People with depression may be more likely to experience dry mouth, which can increase the risk of tooth decay and gum disease. 

Additionally, certain medications used to treat mental illnesses can have side effects that affect oral health.

Therefore, it is crucial to address mental health issues to prevent further damage to oral health.