BackgroundDifferent crown-root angulations of maxillary central incisors can be assumed as a potential reason for many underscored outcomes of orthodontic treatments. The aim of this study was to determine the effects of the different crown-root angles on stress distributions in the maxillary central incisor’s periodontal ligament (PDL) during application of intrusive and retraction forces using a 3D finite element method.MethodsTwo models of a maxillary central incisor were constructed using ANSYS software: the first one with an angle of 166.7° (as a sample of the maxillary central incisor in a class II, division 2 patient) and the other one with an angle of 173.4° (normal angulation). Each of the samples was loaded twice by an intrusive force (0.25 N) and a retraction force (0.5 N) through the ideal position of brackets.ResultsFEM results showed little difference between stress distributions in the two models during intrusion (ten thousandth) compared to retraction (thousandth). In the application of retraction force, the stress concentration on the curved tooth was less than the other.ConclusionTo produce similar patterns of stress in the PDL, orthodontists can apply 1.18 times heavier retraction forces on the maxillary central incisors in class II, division 2 patients compared to class I patients.

Approximating the ratio RCus-LCus/Ch-Ch to the divine proportion may definitely help in achieving a more pleasant smile. On the next level, altering the ratios Ls-LCus/LCh-LCus and Ls-RCus/RCh-RCus could also play a role in making a beautiful smile.

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Background:During sliding mechanics, the frictional force (FF) is an important counterforce to orthodontic tooth movement. The purpose of this in vitro study was to investigate the static and kinetic FFs of S silica-insert ceramic (SIC) brackets with Teflon-coated (TC) and conventional S stainless steel (SS) archwires.Materials and Methods:The target group of this study included 80 maxillary canine 0.022 inch slot SIC brackets. Forty SS brackets were used as the control. TC and conventional uncoated SS archwires of different dimensions (0.016, 0.018, 0.016 × 0.022, and 0.018 × 0.025 inch) were examined. All tests were carried out under artificial saliva injected condition. Scanning Electron Micrographs were prepared for two samples of coated and uncoated archwires. Analysis of variance and Tukey post hoc tests were used for statistical purposes (level of significance P < 0.05).Results:SIC brackets showed significantly lower levels of FFs than SS brackets. TC archwires had greater frictional values than conventional uncoated ones. They also exhibited an unusual behavior of increasing kinetic FFs with time. Indentation and delamination of coating were obvious under scanning electron microscopy observations.Conclusion:From the standpoint of friction, SIC brackets may serve well, even better than SS brackets, in sliding mechanics. The coating layer of the archwires may delaminate and lost, causing an impediment to tooth movement.

A bstract Introduction Guiding anterior crossbite to a normal position is one of the most important responsibilities of a pediatric dentist or orthodontist to gain both esthetic and function. Crossbite with dental etiology can be treated by a variety of appliances. We describe a removable appliance with a different spring design for proclination of more than one incisor in mixed dentition. Materials and methods This study is an observational study that was performed on sixteen children, 7–11 years of age, who needed incisor proclination in more than one tooth. In this study, patients were followed until the end of their orthodontic therapy. The variables evaluated were the maxillary arch length, arch depth, intercanine distance, and intermolar distance in pre- and posttreatment. To assess intra-examiner reliability, 10 plaster models were randomly selected and re-measured. Results In all the cases, the newly designed removable appliance was used and in all showed a significant increase in arch length, arch depth, intercanine distance, and intermolar distance. The correction was achieved within 1–9 months depending on the patient's compliance. Conclusion There was a significant increase in all aspects of arch length and depth after using this appliance. The procedure is a simple and effective method that is recommended for compliant patients needing proclination of more than one anterior tooth; especially in dental class III, pseudo-class III patients, and the first phase of class II division 2 skeletal treatments. How to cite this article Bozorgnia Y, Mafinezhad S, Pilehvar P. Introducing a Removable Orthodontic Appliance and Its Effects on Dental Arch Dimensions. Int J Clin Pediatr Dent 2021;14(S-1):S39–S43.