Based on the images alone I would say it doesn't look like something we need to worry about. Other factors such a how much water you consume would also be factors causing dry mouth symptoms. The whitish area isn't looking alarming. However if you're feeling a burning sensation, pain etc, I would advise you to have a detailed consultation.
Next Steps
drink sufficient water throughout the day
eat fresh fruits and vegetables daily
consult with a dentist online or offline for further examination.