Any relationship between dental caries and stress?

Possibly: Stress may affect the gingival tissues causing sore, swollen, red and bleeding gums. It's even seen often in students around exam time. If your oral hygiene is poor and you ignore the plaque buildup then you may be susceptible to caries.

Possibly: We know that stress affects your immunity. So you are more prone to infection, including dental and periodontal infections, if you have extreme stress. Also, high and sustained stress can cause diminished salivary flow, which helps neutralize acids in your mouth. Grinding/clenching is another issue related to stress, which can cause excessive tooth wear, losing the protective enamel layer.