ABSTRACT
Statement of the Problem: Root resorption [RR] after orthodontic tooth movement [OTM] is known as a multifactorial complication of orthodontic treatments. Hormonal deficiencies and their effect on bone turnover are reported to have influences on the rate of tooth movement and root resorption
Purpose: This study was designed to evaluate the effect of female and male steroid sex hormones on tooth movement and root resorption
Materials and Method: Orthodontic appliances were placed on the right maxillary first molars of 10 ovariectomized female and 10 orchiectomized male Wistar rats as experimental groups and 10 female and 10 male healthy Wistar rats as control groups. NiTi closed-coil springs [9mm, Medium, 011"×.030", Ortho Technology[registered sign]; Tampa, Florida] were placed between the right incisors and the first right maxillary molars to induce tipping movement in the first molars with the application of a 60g force. After 21 days, the rats were sacrificed and tooth movement was measured by using a digital caliper [Guanglu, China]. Orthodontic induced root resorption [OIRR] was assessed by histomorphometric analysis after hematoxylin and eosin staining of sections of the mesial root
Results: The rate of tooth movement was significantly higher in all female rats, with the root resorption being lower in the experimental group. The rate of tooth movement in experimental male rats was significantly higher than the control group [p= 0.001] and the rate of root resorption was significantly lower in the experimental group [p= 0.001]
Conclusion: It seems that alterations in plasma levels of estrogen, progesterone, and testosterone hormones can influence the rate of OTM and RR. The acceleration in tooth movement increased OTM and decreased RR
ABSTRACT
Objective: Studies have demonstrates that physical properties of denture base affect patient satisfaction and acceptance. Thermal conductivity is among the most important properties of denture base influencing the sense of taste and gingival health. The conventionally used acrylic resin has a low coefficient of thermal conductivity. This study aimed to improve the thermal conductivity of acrylic resin by adding small concentrations of nanosilver
Methods: In this laboratory experimental study, 0.2wt% and 2wt% silver nanoparticles measuring 10-100 nm were mixed with the conventional denture base acrylic powder. Cylindrical samples were fabricated and thermal conductivity was measured. One-way ANOVA and Scheffe's post-hoc test were used to compare the mean thermal conductivity of different groups. Data were analyzed using SPSS 15 and p<0.05 was considered statistically significant
Results: The thermal conductivity of resins reinforced with nanosilver was significantly higher than that of the conventional resin. By increasing the amount of nanoparticles in the acrylic powder, thermal conductivity further increased
Conclusion: Addition of small amounts of nanosilver to denture base acrylic resin increases its thermal conductivity