Comparison of rate of tooth movement, bone metabolism markers and salivary leptin levels between normal and overweight patients

Obesity, which is known to carry many metabolic diseases, is a common prevalent health problem that can cause serious health problems at any age. Serum leptin concentrations of obese people are quite high compared to non-obese people. Since leptin has cytokine-like effects responsible for bone remodeling, it is possible to think that leptin level may have an effect on the rate of orthodontic tooth movement. Therefore, the aim of this study is to evaluate the rate of orthodontic tooth movement between normal and overweight individuals requiring upper first premolar extraction and canine distalization, to compare saliva leptin concentration and to investigate the correlation between the amount of tooth movement and leptin. In addition, the changes of Osteoprotegerin (OPG) and Receptor activator of nuclear factor kappa B ligand (RANKL) levels obtained from gingival crevicular fluid (GCF) will be examined during the dental movement. For the study, 32 patients were selected between the ages of 12 and 18 from the adolescent patients who applied for orthodontic treatment, with 10 girls and 6 boys in each group. The average age of the patients is 15.58 ± 1.55 years. According to body-mass index (BMI) data, patients between 25-29.9 kg/m2 comply with the definition of overweight and therefore constitute the overweight group, and the normal group of patients between 18.5–24.9 kg/m2 constitute the control group. The patients were recorded before orthodontic treatment (T0), the day distalization begins (T1), the 1st day of distalization (T2), the 1st month (T3), and every following month until distalization is completed. These records are intraoral photographs, upper jaw dental cast, GCF samples taken from the distal of the tooth which randomly selected right or left upper canine and a non-stimulated saliva sample. After the leveling is completed, 0.016 x 0.022 steel wires were placed and canine distalization was performed by applying 150 g force with NiTi closed coil springs extending from canine to the first molar teeth. All saliva and GCF samples collected were stored at -80 ° C until biochemical analysis. Upper jaw dental casts were converted to digital models. In the ruga region on digital models, which is known to show the least change, the medial ends of the third rugaes and the posterior end of the incisal papilla were marked, 3-dimensional superimposition was made and the amount of tooth movement was measured. The data obtained were statistically evaluated at 95% confidence interval using independent sample t test, Mann Whitney U Test and Pearson correlation test. As a result of the analyzes, the saliva leptin level of patients with high BMI value was found to be approximately 3 or 4 times higher than normal weight patients (p≤0,01). It was determined that patients with high leptin levels had reduced rate of tooth movement and longer treatment time (p≤0,01). The amount of tooth movement (1.03 ± 0.09) of overweight patients is lower than the individuals (1.25 ± 0.13) whose BMI is within normal limits (p≤0.01). In both individuals with high BMI and normal values, a higher correlation was found between the amount of tooth movement and the saliva leptin level, although it was stronger in overweight individuals (p <0.05). It was found that GCF OPG level decreased and then increased slightly in both groups during the tooth movement. OPG levels of normal weight individuals were found higher than overweight patients in all time periods. It was found that GCF RANKL level first increased and then slightly decreased during tooth movement. RANKL levels of normal weight individuals were lower than overweight patients in all time periods. Keywords: BMI, Rate of tooth movement, Saliva leptin, GCF, OPG, RANKL