Stress distribution in maxillary first molar periodontium using straight pull headgear with vertical and horizontal tubes: A finite element analysis

Background: One of the most effective ways for distal movement of molars to treat Class II malocclusion is using extraoral force through a headgear device. The purpose of this study was the comparison of stress distribution in maxillary first molar periodontium using straight pull headgear in vertical and horizontal tubes through finite element method. Materials and Methods: Based on the real geometry model, a basic model of the first molar and maxillary bone was obtained using three-dimensional imaging of the skull. After the geometric modeling of periodontium components through CATIA software and the definition of mechanical properties and element classification, a force of 150 g for each headgear was defined in ABAQUS software. Consequently, Von Mises and Principal stresses were evaluated. The statistical analysis was performed using T-paired and Wilcoxon nonparametric tests. Results: Extension of areas with Von Mises and Principal stresses utilizing straight pull headgear with a vertical tube was not different from that of using a horizontal tube, but the numerical value of the Von Mises stress in the vertical tube was significantly reduced (P 0/05). Conclusion: Based on the results, when force applied to the straight pull headgear with a vertical tube, Von Mises stress was reduced significantly in comparison with the horizontal tube. Therefore, to correct the mesiolingual movement of the maxillary first molar, vertical headgear tube is recommended

Examining the pattern of tooth agenesis in cleft lip and palate patients referred to Isfahan cleft palate clinic from 1389 to 1399

Objectives Tooth agenesis or hypodontia is a major problem that may occur in any person in any area of the mouth. However, it is of greater significance in patients with cleft lip and palate (CLP) because of their susceptibility to various problems. This study aimed to investigate the prevalence of tooth agenesis in both jaws among patients with CLP. Methods In this descriptive analytical study, a total of 150 unilateral CLP and 30 bilateral CLP patients (age range, 4-19 years) were randomly selected, and their panoramic radiographs were examined. The collected data were analyzed using Chi-square test, Mann-Whitney test, Fisher’s exact test, and logistic regression analysis. Results:The results of Chi-square test revealed that the prevalence of tooth agenesis was significantly higher in unilateral CLP patients compared to their bilateral CLP counterparts (P=0.039). The maxillary lateral incisors (26%), followed by right maxillary first premolars (20%), accounted for the highest number of hypodontia. The results of Mann-Whitney test did not indicate any significant differences in the number of hypodontia between unilateral and bilateral CLP patients (P=0.158). Conclusion The frequency of tooth agenesis in the evaluated CLP population of Isfahan (Isfahan Province, Iran) was similar to that of other populations around the world. According to the present findings, unilateral CLP was more frequent than bilateral CLP, and left-sided CLP was more frequent than right-sided CLP and bilateral CLP

Effect of Low-Level Laser on IL-17 Level in GCF during Orthodontic Treatment

Considering the role of inflammatory mediators in both orthodontic movements and the development of periodontal diseases and taking into accountthe role of Interleukin 17 as an important inflammatory mediator in orthodontic treatments and the impact of low-level laser therapy (LLLT) as a new and appropriate adjuvant therapy, the aim of the present study was to investigate the effect of LLLT on IL-17 levels in gingival cervicular fluid (GCF) during orthodontic treatment.Materials & Methods:In this clinical trial study, 12 patients in need of orthodontic treatment were selected. In these patients, one side of the mouth was randomly selected for laser irradiation and the other side as a control. Diode LLL irradiation with a wavelength of 810 nm was performed throughout the gingival Cervicular on days 0, 2, 18, and 30 after orthodontic treatment. Sampling was performed on days 0, 2, 18, and 30 by placing paper points in distal, mesial, palatal, and buccal sulcus of the maxillary fifth molar on the both sidesfor 30 seconds. All samples were then transferred to the laboratory and IL-17 level was determined by ELISA reader. Data were analyzed using Paired t-test and One-way ANOVA.Results:Mean IL-17 levels at day zero (p value = 0.62) and day 2 after orthodontic treatment (p value = 0.19) were not significantly different betweenthe control and laser treated sides, howeverthey were significantly lower in the laser-treated group than the control group on days 18 and 30 after orthodontic treatment (p value < 0.001). The mean IL-17 levels decreased in both groups during the treatment period, but this decreasewas significant on day 18.Conclusion:The results of the present study indicate thetherapeutic role of diode LLL in reducing inflammation, and Il-17 levels in both sides of the mouth gradually decreased over time, and thisdecrease was more pronounced in the laser-treated side than in the control sid

The effect of local injection of the human growth hormone on the mandibular condyle growth in rabbit

Background: The aim of this study was to evaluate the effect of local injection of human growth hormone (GH) in stimulating cartilage and bone formation in a rabbit model of temporomandibular joint (TMJ). Materials and Methods: In an experimental animal study, 16 male Albino New Zealand white rabbits aged 12 weeks were divided into two groups: In the first group (7 rabbits) 2 mg/kg/1 ml human GH and in the control group (9 rabbits) 1 ml normal saline was administered locally in both mandibular condyles. Injections were employed under sedation and by single experienced person. Injections were made for 6 times with 3 injections a week in the all test and control samples. Rabbits were sacrified at the 20th day from the beginning of study and TMJs were histologically examined. ANOVA (two-sided) with Dunnett post hoc test was used to compare data of bone and cartridge thickness while chi-square test was used to analyze hyperplasia and disk deformity data. P < 0.05 was considered as significant. Results: Cartilage layer thickness was greater in the GH-treated (0.413 ± 0.132) than the control group (0.287 ± 0.098) (P value = 0.02). Although bone thickness and condylar cartilage hyperplasia were greater in the GH-treated group, these differences were not statistically significant (P value = 0.189 and 0.083, respectively). There was no statistically significant difference between two groups regarding the disc deformity (P value = 0.46). Conclusion: Local injection of human GH in the TMJ is able to accelerate growth activity of condylar cartilage in rabbit