This study aimed to determine the optimum orthodontic force from a broader perspective. Interleukin (IL)-1β levels in human gingival crevicular fluid (GCF), pain intensity, and the amount of tooth movement were measured during canine retraction using different magnitudes of continuous orthodontic force. Sixteen subjects (two males and 14 females), aged 18-24 years, diagnosed with Class I bimaxillary protrusion and treated with first premolar extractions participated in this study. The upper canines were retracted with continuous forces of 50 or 150 g using nickel-titanium coil springs on segmented archwires. One of the lower canines was used as a control. GCF was collected from the distal site of each tooth at specific time points. IL-1β concentrations, pain intensity, using the visual analogue scale (VAS), and the amount of tooth movement were evaluated. One-way analysis of variance, Friedman, and paired t-tests were used for comparisons of IL-1β in GCF, the plaque and gingival indices, and the efficiency of tooth movement on pain perception, respectively. IL-1β concentration in the 150 g group showed the highest level at 24 hours and 2 months with significant differences compared with the control group (P < 0.05). The mean VAS score of pain intensity from the 150 g force was significantly greater than from the 50 g force at 24 hours (P < 0.01). However, no significant difference in the amount of tooth movement was found between these two different magnitudes of continuous force at 2 months. A 50 g force could effectively induce tooth movement similar to 150 g with less pain and less inflammation.
Objective: To quantify the amount of tooth movement and orthodontically induced root resorption (OIRR) in ovariectomized rats. Materials and Methods: Five 10-week-old female Wistar rats undergoing ovariectomy (OVX) were investigated as the experimental group, and the other five without ovariectomy served as the control group. Four weeks after ovariectomy, 25-g nickel-titanium closed-coil springs were applied mesially to the maxillary left first molars. Micro-computed tomography was taken at day 0, 1, 3, 7, 14, 21, and 28. At day 28, the molars were extracted. The surface area of root resorption craters, depth, and volume were measured using electron and laser scanning microscopes. Results: Tooth movement gradually increased with time throughout 28 days. There was a significant difference in the amount of tooth movement between the control group and the OVX group. For OIRR, the OVX group showed wide and shallow root resorption craters scattered on the mesial root. The deep resorption craters were observed on the distal roots distributed in the cervical, middle, and apical thirds of the roots. Statistically significant differences were found between the control and the OVX groups in the depth and the volume of root resorption craters in the distal roots and the total volume of root resorption craters in all three roots. Conclusion: Ovariectomy affected not only tooth movement but also OIRR. Tooth movement in the OVX group was more rapid than the control group. Furthermore, the amount of OIRR in the OVX group was more severe than the control group. (Angle Orthod. 2011;81:570-577.)
The aim of this study was to investigate the metal ion release and cytotoxicity of MU orthodontic miniscrews as well as two other brands of orthodontic miniscrews over time. Twenty-four orthodontic miniscrews were tested, divided into three groups of eight. Each sample extraction was performed following the ISO 10993-12:2012 method. Solutions were collected after 1, 7, and 30 days (T1, T2, and T3). The supernatants extracted from these three groups were added and exposed to mouse L929 fibroblastic cell line using an MTT cytotoxicity test. They were also tested for ion release by inductively coupled plasma-mass spectrometry (ICP-MS). Element analysis by energy-dispersive X-ray spectroscopy (EDS) was used to analyze the surfaces of the miniscrews. The quantification of three elements, namely, titanium (Ti), aluminum (Al), and vanadium (V) were assessed. The results indicated that there were no statistical differences between the self-made orthodontic miniscrews and those from two commercial groups (p<0.05). Throughout the testing period, the quantity of ions increased from T1 to T3. After 24 h, vanadium was the first to appear on the surface in small quantities in other two commercial groups. The self-made orthodontic miniscrews exhibited no toxic effects on living cells.
Objectives:
The objective of this study was to find the cephalometric measurements that correlate with the visual perception.
Materials and Methods:
A total of 250 lateral cephalograms of patients from the year 2016 to 2018 were hand traced and analyzed. Thirty-six hard- and soft-tissue measurements were obtained from the lateral cephalometric analysis. Silhouettes obtained from cephalometric films were rated by 10 orthodontists based on their level of convexity. For each sample, the rating of visual perception was correlated with all the cephalometric (hard and soft) measurements.
Results:
ANB, AF-BF, L1-NB (mm), overjet, anterior maxillary alveolar height, posterior maxillary alveolar height, lower lip to E plane, and H angle were positively correlated with the visual perception. On the contrary, Pg. to N perpendicular and Pg. to NB (mm) were negatively correlated with the visual perception. However, the measurements in the vertical dimensions did not have any significant correlations with visual perception. H angle showed a higher correlation with visual perception than the nasolabial angle, facial contour angle, and lower lip to E plane.
Conclusion:
The agreement between objective cephalometric measurements and subjective visual perception was less than expected. In general, only 27% of the cephalometric measurements had a significant correlation with visual perception. Therefore, orthodontic treatment planning based solely on cephalometric analysis can result in unsatisfactory treatment outcomes. An inclusion of subjective measures such as visual perception in orthodontic diagnosis and treatment planning is necessary.
Objective: The aim of this study was to evaluate the adhesion ofStreptococcus mutans (S. mutans)on different types of orthodontic brackets commonly used in Thailand. Materials and Methods: The adhesion ofS. mutanson 7 types of orthodontic brackets (Clarity, Spirit MB, Inspire Ice, 3M, Tomy, Ormco and W&H) was investigatedin vitro. The saliva-coated brackets were immersed in a flat-bottomed 96-well plate containingS. mutanssuspension (108CFU/ml) and incubated at 37 ̇C in 10% CO2and 100 rpm for 2 hours. The adhered bacterial cells were fixed by 99% methanol and stained with 0.5% crystal violet. The quantity of adhesion was determined by measuring optical density (OD) at 590 nm. The data were analyzed with Kolmogorov-Smirnov test, Levene test, one way ANOVA and Games-Howell post hoc test. Results: Significantly higher bacteria adhesion was found on Clarity, Spirit MB, Tomy, Ormco and W&H compared to Inspire Ice and 3M Gemini. However, there were no significant differences among the different types of bracket materials (ceramic, plastics and metal). Conclusion: The amount of bacteria adhesion was independent of the type of bracket materials. The size and shape of brackets also played an important role in the amount of adhesion of microorganism.
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