objective: to evaluate qualitative and quantitative changes in the saliva of individuals undergoing orthodontic treatment with fixed appliances. methods: salivary samples were collected from 50 individuals divided in two groups: experimental group - patients with fixed orthodontic appliances (n=25); and control group - subjects with no orthodontic appliances (n=25). salivary flow rate, ph, buffering capacity, amylase activity, concentrations of total proteins, calcium and glucose were measured in all salivary samples. results: there was a reduction in salivary ph and buffering capacity and an increase in the concentration of calcium ions in the experimental group (p<0.05); there was also an increase in glucose, amylase and protein concentrations in the saliva of the experimental group, but the differences were insignificant. there was insignificant correlation between calcium ion concentration and salivary flow or between buffering capacity and salivary flow. conclusion: the saliva of individuals with fixed orthodontic appliances had lower ph, buffering capacity and calcium concentration than that of individuals without any type of orthodontic appliance. these oral changes are enough to cause tooth demineralization. patients with orthodontic appliances should adopt additional oral hygiene procedures.