This study investigated the correlation between bone characteristics, the design of orthodontic mini-implants, the pull-out force, and primary stability. This experimental in vitro study has examined commercial orthodontic mini-implants of different sizes and designs, produced by two manufacturers: Tomas-pin SD (Dentaurum, Ispringen, Germany) and Perfect Anchor (Hubit, Seoul, Korea). The total number of 40 mini-implants were tested. There are two properties that are common to all tested implants—one is the material of which they are made (titanium alloy Ti-6Al-4V), and the other is the method of their insertion. The main difference between the mini-implants, which is why they have been selected as the subject of research in the first place, is reflected in their geometry or design. Regardless of the type of implant, the average pull-out forces were found to be higher for a cortical bone thickness (CBTC) of 0.62–0.67 mm on average, compared to the CBTC < 0.62 mm, where the measured force averages were found to be lower. The analysis of variance tested the impact of the mini-implant geometry on the pull-out force and proved that there is a statistically significant impact (p < 0.015) of all three analyzed geometric factors on the pull-out force of the implant. The design of the mini-implant affects its primary stability. The design of the mini-implant affects the pulling force. The bone quality at the implant insertion point is important for primary stability; thus, the increase in the cortical bone thickness increases the value of the pulling force significantly.
Background: Periodontal complications are one of the common side effects associated with orthodontic therapy. Objective: This study aimed to evaluate the periodontal changes in patients before, during, and after the therapy with a fixed orthodontic appliance. Methods: Out of 38 healthy adolescents with permanent dentition who were indicated for fixed orthodontic therapy were included in this study. Patients were selected from Class I, treated by non-extraction methods, by using conventional orthodontic braces. After their examination and treatment by an orthodontist, the patients were referred to the periodontist before the placement of a fixed orthodontic appliance. The patients underwent the application of a periodontal anamnestic-diagnostic protocol, and the clinical-radiological evaluation. After a fixed orthodontic appliance was placed, the respondents were referred to the periodontist for regular mandatory check-ups, initially, after three months, and later on–after 6 months, after 1 year and after 2 years until the end of orthodontic therapy. Results: An increase in the mean value of the Plaque Index and Sulcus Bleeding Index was found at each check-up after the placement of a fixed orthodontic appliance. There is a statistically significant difference in the presence of gingival hyperplasia found by monitoring the changes after three and six months, and after one and two years following the start of orthodontic therapy. Conclusion: The assessment of periodontal changes in patients before, during and after the completion of fixed orthodontic therapy revealed that there is a strong need for mutual and close cooperation between orthodontist and periodontist during orthodontic therapy.
Objectives The development of third molars can be helpful in dental age estimation of adolescents and in early adult period. We tested the repeatability and accuracy of the three dental age radiographic methods (Olze, Demirjian and Solari and Abramovitch) and evaluated which method is more useful. We also aimed at testing to find the correlation of estimated dental and chronological age by these three methods. Material and methods The orthopantomographs (OPGs) of 1007 individuals (8 - 25 years) were divided into two groups (cca 500 OPGs) - one group of OPGs has been presented with all four third molars, while another one was registered with third molar/s hypodontia. And all of OPGs were assessed, to verify the three methods (Olze, Demirjian and Solari and Abramovitch) for age estimation based on third molar development. Results There was a high Spearman's correlation coefficient between stages of development of wisdom tooth and chronological age of subjects by all these three methods. Conclusion We may recommend using third molars for assessing the dental age by Olze, Demirjian and Solari and Abramovitch dental method as well, on Bosnian and Herzegovinian population.
The main objective of this research is to establish a connection between orthodontic mini-implant design, pull-out force and primary stability by comparing two commercial mini-implants or temporary anchorage devices, Tomas®-pin and Perfect Anchor. Mini-implant geometric analysis and quantification of bone characteristics are performed, whereupon experimental in vitro pull-out test is conducted. With the use of the CATIA (Computer Aided Three-dimensional Interactive Application) CAD (Computer Aided Design)/CAM (Computer Aided Manufacturing)/CAE (Computer Aided Engineering) system, 3D (Three-dimensional) geometric models of mini-implants and bone segments are created. Afterwards, those same models are imported into Abaqus software, where finite element models are generated with a special focus on material properties, boundary conditions and interactions. FEM (Finite Element Method) analysis is used to simulate the pull-out test. Then, the results of the structural analysis are compared with the experimental results. The FEM analysis results contain information about maximum stresses on implant–bone system caused due to the pull-out force. It is determined that the core diameter of a screw thread and conicity are the main factors of the mini-implant design that have a direct impact on primary stability. Additionally, stresses generated on the Tomas®-pin model are lower than stresses on Perfect Anchor, even though Tomas®-pin endures greater pull-out forces, the implant system with implemented Tomas®-pin still represents a more stressed system due to the uniform distribution of stresses with bigger values.
Retention is a phase of orthodontic treatment devised to keep the teeth in a correct position once the orthodontic treatment has been completed. There are three main characteristics that each ideal retainer is required to have: to keep the teeth in the correct position after orthodontic therapy, to be long lasting and resistant to mechanical damage, and to have no adverse long-term effects on periodontal tissue. Through a computer-based browsing through a number of databases (such as, e.g. PubMed and Google Scholar) we have found and analysed various articles used in this research. The inclusion criteria to be met were: an overall availability of a research paper, the requirement that these research papers are published in English, that these research papers were published in the period 2007-2019, the requirement that the research papers should involve clinically randomized studies and that their titles contain one of the predefined keywords. The database browsing that is based on the said keywords and carried out within the above time frame has resulted in finding 165 relevant articles. A complete set of the inclusion criteria were met by 8 published research papers, but 7 articles were analysed in the end. The selected articles have compared different types of fixed and mobile retainers, different times of wearing the retainers, the impact that the retainers had on the periodontium, and the acceptability of different retention protocols for patients. The conclusion of this research paper is that bonded retainers prove to be most effective in stabilising the position of the incisors, particularly the lower ones, but that their disadvantages include the reopening of the extraction space and the retention of plaque due to difficulties in maintaining oral hygiene. Vacuum-formed retainers appear to be more effective than Hawley retainers in retaining the position of the incisors, and patients have indicated that they are more acceptable to wear. Hawley retainers prove to be most effective in preserving a closed extraction space, but they do now show solid results with regard to other segments. Changes in the overbite, overjet, arch length, and anterior and posterior widths did not show any significant statistical differences in the different types of retainers. Keywords: orthodontics, retention, stability, impact
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