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Introduction. This study aimed to assess the effect of serum level of vitamin D on external apical root resorption (EARR) in maxillary anterior teeth in patients under fixed orthodontic treatment. Materials and Methods. This retrospective cohort was conducted on patients under fixed orthodontic treatment who were between 12 to 30 years of age. All patients underwent the same treatment technique by the same orthodontist using a 0.022 MBT system. EARR in maxillary anterior teeth was evaluated on pre- and postoperative panoramic radiographs. Blood samples were also collected from patients, and their serum level of vitamin D was measured after the completion of treatment. Data were analyzed by independent t-test and Chi-square test (alpha = 0.05). Results. A reduction in root length was noted in all patients, which was significant ( P < 0.0001 ); 75% of patients showed EARR in at least one maxillary incisor. EARR had no significant correlation with the serum level of vitamin D ( P = 0.423 ). Conclusions. Serum level of vitamin D had no significant correlation with the occurrence of EARR. However, the high prevalence of EARR calls for measures to minimize it.

The biomass concentration of conventional activated sludge (CAS) process due to low sludge sedimentation in clarifiers is limited to 3000 mg/L. In this study, high-frequency ultrasound wave (1.8 MHz) was applied to enhance the CAS process performance using high Mixed Liquor Suspended Solid (MLSS) concentration. The study conducted using a pilot scale CAS bioreactor (with and without ultrasound) and their performance for treating a hospital wastewater were compared. Experimental conditions were designed based on a Central Composite Design (CCD). The sets of data analyzed, modeled and optimized using Response Surface Methodology (RSM). The effect of MLSS concentration 3000-8000 mg/L and hydraulic retention time (HRT) 2-8 h are considered as operating variables to investigate on process responses. The obtained results showed that high-frequency ultrasound was significantly decreased the sludge volume index (SVI) 50% and effluent turbidity about 88.5% at high MLSS. Also, observed that COD removal of both systems was nearly similar, as the maximum COD removal for sonicated and non-sonicated systems were 92 and 92.5% respectively. However, this study demonstrates that the ultrasound irradiation has not had any negative effect on the microbial activity.

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AIM: In recent years, miniscrews are extensively used for anchorage in orthodontic treatments. This study aimed to assess the frequency of using miniscrew anchorage by the Iranian orthodontists in 2020. MATERIALS AND METHODS: This descriptive, cross-sectional study evaluated 70 Iranian orthodontists. After obtaining their written informed consent, a questionnaire was emailed to them. The validity of the questionnaire was confirmed by four faculty members and its reliability was determined to be 75% by calculating the Cronbach’s alpha after administering it among 40 orthodontists. Data were analyzed using SPSS version 22. RESULTS: Of 97 administered questionnaires, 70 were filled out and returned (response rate=72.16%) by 42 males and 28 females. Of participants, 62.3% reported using miniscrews in their practice. Furthermore, 96.6% of the orthodontists reported that they would place the miniscrews by themselves. The majority of orthodontists (98.3%) were completely or relatively satisfied with the efficacy of miniscrews, and 93.5% recommended the use of miniscrews to their colleagues. Factors such as poor expertise in miniscrew insertion, doubts about its advantages, high cost, and time-consuming placement were the main reasons for reluctance of some orthodontists in using miniscrews. CONCLUSION: Considering the high efficacy of miniscrews for orthodontic treatment and high satisfaction level of Iranian orthodontists with miniscrews, their application is expected to rise by the Iranian orthodontists after eliminating the existing limitations against their widespread use.