About violations of the work of which organs does the dentist warn of a smoker and why?

During the reception of the patient, the dentist first of all looks at the condition of the oral cavity (teeth, gums, tongue) Smoking can harm the mucous membrane of the mouth, due to tobacco smoke there can be yellow plaque on the teeth (caries can develop), and saliva is increasingly common produced (excreted), thereby poisonous particles get into the saliva and the person looks inside.