OBJECTIVE: Orthodontic root resorption (ORR) due to orthodontic tooth movement is a difficult treatment-related adverse event. Caspases are important effector molecules for apoptosis. At present, little is known about the mechanisms underlying ORR and apoptosis in the cementum. The aim of the present in vivo study was to investigate the expression of tartrate-resistant acid phosphatase (TRAP), caspase 3, caspase 8, and receptor activator of nuclear factor kappa-B ligand (RANKL) in the cementum in response to a heavy or an optimum orthodontic force. METHODS: The maxillary molars of male Wistar rats were subjected to an orthodontic force of 10 g or 50 g using a closed coil spring. The rats were sacrificed each experimental period on days 1, 3, 5, and 7 after orthodontic force application. And the rats were subjected to histopathological and immunohistochemical analyses. RESULTS: On day 7 for the 50-g group, hematoxylin and eosin staining revealed numerous root resorption lacunae with odontoclasts on the root, while immunohistochemistry showed increased TRAP- and RANKL-positive cells. Caspase 3- and caspase 8-positive cells were increased on the cementum surfaces in the 50-g group on days 3 and 5. Moreover, the number of caspase 3- and caspase 8-positive cells and RANKL-positive cells was significantly higher in the 50-g group than in the 10-g group. CONCLUSIONS: In our rat model, ORR occurred after apoptosis was induced in the cementum by a heavy orthodontic force. These findings suggest that apoptosis of cementoblasts is involved in ORR.
Acid Phosphatase ; Animals ; Apoptosis ; Caspase 3 ; Caspase 8 ; Caspases* ; Dental Cementum ; Eosine Yellowish-(YS) ; Hematoxylin ; Humans ; Immunohistochemistry ; Male ; Models, Animal ; Molar ; Osteoclasts ; Rats ; Rats, Wistar ; Root Resorption* ; Tooth Movement

BACKGROUND: Food allergy (FA) is a common disease in children, and its prevalence has increased in developed countries. The impact of overweight on children health also becomes an important social problem. However, the relationship between overweight and FA is still unclear. We examined the association between overweight and the prevalence of FA among Japanese children. METHODS: We analyzed data obtained using a self-administered questionnaire from 1772 Japanese children. Weight groups according to body mass index cutoff points proposed by the International Obesity Task Force were used to create two groups: overweight and non-overweight. Children were separated into four age groups (3-6 years, 6-9 years, 9-12 years, and 12-15 years) to examine age differences. We performed univariate and multivariate logistic models to examine the association between overweight and FA. RESULTS: The prevalence of FA was significantly higher in boys (10.6%, p = 0.014) than girls (4.5%) and girls (7.9%, p = 0.012) than boys (2.5%) for 6-9 and 12-15 age groups, respectively. While the prevalence of FA was significantly higher in overweight than non-overweight girls (26.1%, p = 0.005) in the 12-15 age group, no significant difference was found in boys. In girls, overweight was significantly associated with FA after adjustment for age and asthma (odds ratio 1.99, 95% confidence interval 1.01-3.89, p = 0.046). CONCLUSIONS Our results showed that being overweight was significantly associated with a higher prevalence of FA in girls, but not in boys. Further prospective studies are necessary to find the causal relationship between overweight and FA.
Adolescent ; Body Mass Index ; Child ; Child, Preschool ; Cross-Sectional Studies ; Female ; Food Hypersensitivity/epidemiology* ; Humans ; Japan/epidemiology* ; Male ; Overweight/epidemiology* ; Prevalence ; Sex Factors