Orthodontic removable appliances made of transparent thermoplastic materials—aligners—are becoming increasingly popular in contemporary orthodontic practice. It is important for the clinician to fully understand the mechanical properties and behavior of the appliance used. Because of that, the aim of our study was to investigate the changes in aligner surface after immersion in Coca-Cola and orange juice. For surface evaluation, fractal analysis, texture analysis, and wetting angle measurement were performed. Statistically significant changes were found between some of the groups in the fractal dimension analysis. In texture analysis, all but one intergroup comparison showed statistically significant differences. For wetting angle assessment, statistically significant differences were found. These were, however, more numerous when assessing glycol droplets, rather than water droplets. Fractal dimension analysis confirmed a correlation between the intensity of changes in the aligner surface with immersion time in the liquids assessed. Texture analysis showed a high sensitivity to the changes in aligner surface. It failed, however, to reveal changes relative to immersion time. Wetting angle analysis revealed aligner surface degradation for Coca-Cola. It did not, however, prove the dependence of the intensity of this degradation as a function of time. Both Coca-Cola and orange juice can cause aligner surface degradation.
Introduction: The aim of our cross-sectional study is to determine whether there is a link between sex, skeletal class and mandibular asymmetry in orthodontic patients, with tooth length and asymmetry in tooth length on contralateral sides of the mandible. Methods: As the source for relevant data to answer this question, 3D cone-beam tomography (CBCT) images of a total of 95 future orthodontic patients were retrospectively selected from private practice records and were analyzed. The CBCT images were part of routine orthodontic diagnosis. Patients were divided into three groups (Class I, Class III with asymmetry and Class III without asymmetry) based on skeletal variables assessed on orthodontic cephalometric images and frontal photos of the face. Three null hypotheses were developed, and a series of statistical tests was performed in order to support or reject them. Results: We have established that there exists a sexual dimorphism in some of the teeth’s lengths in our sample. Furthermore, we failed to find a link between mandibular asymmetry and asymmetry in tooth length. We have also found a link between skeletal class and tooth length differences in some of the analyzed measurements. Conclusions: Computational models used to design orthodontic appliances and to plan orthodontic treatment should be more individualized to consider a patient’s sex and skeletal class.
Background: There are various methods of controlling the inclination of the incisors during retraction, but there is no evidence as to the advantages of some methods over others. The purpose of this systematic review and meta-analysis was to determine the effectiveness of the methods used to control torque during anterior teeth retraction. Methods: In accordance with the PRISMA guidelines, the main research question was defined in the PICO format [P: patients with complete permanent dentition; I: the maxillary incisor torque after (I) and before I retraction with straight-wire appliance and different modes of torque control; O: statistically significant differences in torque values of the upper incisors after orthodontic treatment]. The MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials databases were searched for keywords combining: retraction orthodontics, torque control orthodontics, torque orthodontics, inclination orthodontics, torque control retraction. The articles were subjected to risk of bias and quality analyses with the ROBINS-I protocol and the modified Newcastle–Ottawa QAS, respectively. Meta-analyses were performed with both fixed- and random-effects models. Results: 13 articles were selected in which total number of 580 subjects took part. In all studies, incisors were retroclined during retraction by 2.46° (mean difference), which was statistically significant. Considering the articles separately, the differences in torque between the study group and the control group were statistically significant in six articles. The Q statistic was 36.25 with p = 0.0003 and I2 = 66.9%, which indicated a high level of study heterogeneity. Conclusion: Both properly performed corticotomy and en-masse retraction using orthodontic microimplants seem to be the most effective and scientifically validated methods of torque control. Further high-quality research is needed to perform better quality analyses and draw more reliable conclusions.
BackgroundThere are various methods to control the inclination of the incisors during retraction, but there is no evidence as to the advantages of some methods over others. The purpose of this systematic review and meta-analysis was to determine the effectiveness of the methods used to control torque during anterior teeth retraction.MethodsIn accordance with the PRISMA guidelines, the main research question was defined in the PICO format [P: patients with complete permanent dentition; I: the maxillary incisor torque after (I) and before (C) retraction with straight-wire appliance and different modes of torque control; O: statistically significant differences in torque values of the upper incisors after orthodontic treatment]. The MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials databases were searched for keywords combining: retraction orthodontics, torque control orthodontics, torque orthodontics, inclination orthodontics, torque control retraction. The articles were subjected to risk of bias and quality analyses with the ROBINS-I protocol and the modified Newcastle–Ottawa QAS, respectively. Meta-analyses were performed with both fixed and random effects models.Results13 articles were selected in which total number of 580 subjects took part. In all studies incisors were retroclined during retraction by 2.46° (mean difference), which was statistically significant. Considering articles separately, differences in torque between the study group and the control group were statistically significant in 6 articles. The Q statistic value was 36.25 with p = .0003 and I2 = 66.9% which indicate a high level of study heterogeneity.ConclusionBoth properly performed corticotomy and en-masse retraction using orthodontic microimplants seem to be the most effective and scientifically validated methods of torque control. Further high-quality research is needed to perform better quality analyses and draw more reliable conclusions.
Summary Background In recent years, digital models have become increasingly popular among orthodontists, both for clinical and scientific purposes. It is, therefore, crucial to appropriately investigate their reliability. To this date, however, there has been no scientific, statistical investigation of their reliability as compared to the traditional gold standard—plaster models in the form of a meta-analysis. Objectives To evaluate the reliability and reproducibility of measurements taken on digital orthodontic models obtained from scanning plaster models in laboratory scanners compared to measurements taken directly on plaster models. Search methods Multiple electronic databases (PubMed, Scopus, Web of Science, Google Scholar and Cochrane Central Register of Controlled Trials) were searched for articles with no year or language limitations. Selection criteria The included original papers should have dealt with the accuracy and repeatability of the measurements conducted on plaster and digital models derived from laboratory scanners. In order to provide an adequate statistical analysis, the studies should have provided sufficient data, that is the difference of means (MDs) with standard deviations (SDs) for analysed measurements. Data collection and analysis In total, 25 types of non-standardised measurements were found in the evaluated studies. The quantitative analysis included papers that compared at least one of the parameters: upper/lower intermolar width, upper/lower intercanine width, overjet and overbite and provided standard deviation of the mean differences between measurements obtained on plaster and digital models from a laboratory scanner. Results GRADE and QUADAS tools were used to assess the quality of evidence, and they revealed substantial heterogeneity. Random-effects meta-analysis revealed no statistically significant differences for analysed measurements. Four of the analysed papers reported differences that may be considered clinically significant. Conclusions No statistical significance between the direct measurements on plaster models and the digital ones taken from laboratory scanners could be identified by means of random-effects meta-analysis. Registration The systematic review was registered in the PROSPERO database (ID CRD42020215411).
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