BackgroundThe purpose of this study was to evaluate the stress patterns produced in mini-implant and alveolar bone, for various implant dimensions, under different directions of simulated orthodontic force, using a three-dimensional finite element method.MethodsEight finite element (FE) models of mini-implant and bone were generated with insertion angles of 30° and 60°, diameters of 1 and 1.3 mm, and lengths of 6 and 8 mm. A simulated constant orthodontic force of 2 N was applied to each of these FE models in three directions simulating anterior retraction, anterior intrusion and retraction, and molar intrusion.ResultsComparison of the maximum von Mises stress in the mini-implant showed that the 1-mm diameter produced significantly high stress, and the amount of stress produced was more for a mini-implant inserted at an angle of 60°. The cortical bone showed that high stresses were generated for the 1-mm-diameter mini-implant and on increasing the insertion angulation from 30° to 60°, the stress produced increased as well. The comparison of von Mises stress in the cancellous bone was insignificant as the amount of stress transmitted was very low.ConclusionsThe 1-mm-diameter mini-implants are not safe to be used clinically for orthodontic anchorage. The 1.3 × 6 mm dimension mini-implants are recommended for use during anterior segment retraction and during simultaneous intrusion and retraction, and the 1.3 × 8 mm dimension mini-implant is recommended for use during molar intrusion. All mini-implants should be inserted at a 30° angle into the bone for reduced stress and improved stability.

No abstract

Balasubramaniam A. Vacuum-formed retainers versus lingual-bonded retainers: A systematic review and meta-analysis of stability of treatment outcomes in orthodontically treated patients.

Background: The initial leveling and aligning phase of orthodontic treatment involve the use of nickel titanium wires. The nickel titanium wires exhibit unique properties like shape memory and superelasticity. In the beginning, conventional nitinol wires were used, which lacked the superelastic property. Nowadays, superelastic nickel titanium wires are being used commonly. This systematic review aims to evaluate the efficiency of Superelastic NITi in the initial alignment of orthodontic treatment in comparison with conventional NiTi and multistranded stainless steel archwires by measuring the amount of decrowding and the time taken for decrowding. Method: A systematic literature search was performed on Pubmed, Cochrane, Google scholar & Lilacs. Result: Thirty four studies were identified by the search and ten studies satisfied the inclusion criteria and one study was excluded after abstract reading. Finally nine articles were included for quality assessment. Conclusion: This systematic review concluded that there was no significant differences in the aligning efficiency of superelastic NiTi in comparison with conventional NiTi and multistranded stainless steel wires.

Introduction: Digital study models today, provide the state-of-art infrastructure for the diagnosis and treatment planning in orthodontic malocclusions. Its versatility and wide scope of application makes it a valuable alternative to conventional study models. However, affordability and lack of knowledge may be the reasons for its limited use, presently. Hence, it was aimed to assess the knowledge, awareness and practice of digital and conventional study models among orthodontists and post-graduate students. Methods: A close-ended self-constructed questionnaire comprising of fifteen questions was administered to 50 orthotists and 50 post-graduate students. Frequency distribution of the answers given by the participants in each domain (knowledge, awareness and practice) was presented graphically. Results: The orthodontists had a better understanding and also were more inclined to digital study model as compared to the post-graduates. Storage and sterilization are the main concerns addressed by the digital study model, whereas conventional study models still remain less expensive. Conclusion: Orthodontists as well as post-graduates possess sufficient knowledge about digital study models, with orthodontists having a slight edge over the post-graduate students.