eng Oriental Scientific Publishing Company Biomedical and Pharmacology Journal 0974-6242 2018-09-21 11 3 1463 1470 10.13005/bpj/1512 22426 article Zaid Ali Alasadi 1 Alhan Ahmed Qasim 1 Department of Pedodontics and Preventive Dentistry, College of Dentistry, University of Baghdad, Iraq. The aim of the present study is to evaluate the early impact of fixed orthodontic therapy on some salivary physical and chemical characteristics of patients in relation to their weight status. The sample consisted of 54 patients (25 males and 29 females; age between 16-18 years old) going under the course of fixed orthodontic treatment. Patients were categorized according to their Body Mass Index (BMI) into 3 weight status groups (underweight, normal weight, overweight and obese), then unstimulated salivary samples were collected from each patient who met specific inclusion and exclusion criteria during three time intervals; before bonding (1^st visit), 2 weeks after bonding (2^nd visit), and 4 weeks after bonding (3^rd visit), then salivary samples are examined to evaluate some salivary physical properties (flow rate, pH) and some chemical properties (salivary calcium  concentration, salivary phosphate concentration). A significant increase in salivary flow rate for all weight status categories during the 2^ndvisit. A significant decrease in salivary pH for both underweight and overweight groups during 2^nd visit with no significant change for normal weight group. A significant decrease in salivary calcium concentration for all weight status groups. And a significant increase in salivary phosphate concentration for all weight status groups. Exposure to fixed orthodontic appliances causes significant changes in salivary physical and chemical characteristics in early stages of treatment. These changes differ among patients with different BMI weight status, but with lesser intensity on normal weight patients than underweight and overweight and obese patients. https://biomedpharmajournal.org/vol11no3/impact-of-fixed-orthodontic-therapy-on-salivary-characteristics-in-relation-to-weight-status/ Effect Orthodontic Treatment Saliva Weight Status