Background and objective: Severe periodontal disease is prevalent among patients with schizophrenia and is caused by the side effect of their medication, poor dental hygiene and smoking. The objective of this study was to evaluate whether the rate of periodontal disease could be modulated by changing the salivary flow rate (SFR) because of the use of antipsychotic medications in patients with schizophrenia. Methods: Group A (n=33) included patients who used medications that may cause xerostomia, or dry mouth and Group B (n=20) included patients who used medications that may cause sialorrhea, an excessive secretion of saliva. The participants' periodontal status was assessed using the plaque index (PI), assessing bleeding on probing (BoP), probing pocket depth (PPD) and clinical attachment levels (CAL). Results: The mean of PI and BoP was significantly higher in Group A than in Group B (P<0.001), but the PPD, CAL and decayed, missing and filled teeth (DMFT) scores were not significantly different in the two groups according to the statistical results (0.05). Conclusions: The researcher concluded that there is a high risk of periodontal disease among patients with schizophrenia, and there is an even higher risk of periodontal disease induced by medication that increased SFR. Preventive dental protocol should be increased during the dental health care of this disadvantaged patient group.