1,720,963 research outputs found
Rabbit bone behavior after orthodontic and pulsed low-frequency electromagnetic field treatments
No full textThe effect of low-frequency pulsed electromagnetic fields (PEMF) on bone was studied after an orthodontic treatment. A spring was positioned between the incisors and the first molar on both sides of the rabbit mandible for 14 days. A PEMF treatment was performed 6 h/day on the right side only. A greater distance between the first and the second molar was recorded in the PEMF treated side with respect to the left side. In addition, analysis of undecalcified sections shows a lower number and width of erosion cavities and a greater amount of newly formed (fluorescent) bone on the right side. In conclusion, PEMF treatment not only appears to increase bone formation, as previously reported in the literature, but, acting on osteoclast activity, also seems to improve bone quality during orthodontic treatment
Computerized casts for Orthodontic purpose using powder-free intraoral scanners: accuracy, execution time and patient feedback.
Full text linkIntroduction. Intraoral scanners allow direct images of oral situation, with fewer steps than conventional impressions.The purpose
of this study was to compare the accuracy of digital impressions, traditional impressions, and digitalization of full-arch gypsum
models, to evaluate timing of differentmethods and finally to study perception of patients about conventional and digital impression
techniques. Methods. Dental arches of fourteen patients were evaluated by alginate impression, titanium dioxide powder-free
intraoral scanning (Trios, 3Shape), and digitalization obtained from gypsum models using the same scanner. Conventional and
digital techniqueswere evaluated throughmeasurements (lower and upper arch anteroposterior length, lower and upper intercanine
distance, and lower and upper intermolar distance) with a caliber for analogic models and using a computer software for digital
models (Ortho Analyzer, Great Lakes Orthodontics). In addition, chairside and processing times were recorded. Finally, each
patient completed a VAS questionnaire to evaluate comfort. Statistical analyses were performed with ANOVA and Tukey tests
for accuracy measurements and paired -test for times and VAS scores. Significance was predetermined at < 0.05. Results. The
measurements obtained with intraoral scanning, gypsum models after conventional impression, and digitalized gypsum models
were not significantly different. Both chairside and processing times of digital scanning were shorter than the traditional method.
VAS reporting patients comfort were significantly higher when evaluating digital impression. Conclusions. Intraoral scanners used
for orthodontic applications provide useful data in clinical practice, comparable to conventional impression. This technology is
more time efficient than traditional impression and comfortable for patients. Further evolution with more accurate and faster
scanners could in future replace traditional impression methods
Consistency of diet and its effects on mandibular morphogenesis in the young rat
No full textThe purpose of this study was to evaluate the relationship between mandibular morphogenesis and masticatory function in 30 male Sprague-Dawley rats, 28 days of age. Animals were randomly divided into three groups and they received diets of different consistency: liquid, normal (as control group) and elastic diet. The experiment lasted 28 days, at the end of which lateral radiographs of the cranium and photographs of the hemimandibles were made. These images were magnified fourfold and analysed in two dimensions (V = vertical dimension; S = sagittal dimension). Condylar morphology was also assessed. The photographic analysis of the hemimandible showed a significantly higher growth of the mandibular ramus stimulated by the elastic diet: V2 2.4 mm, V3 2.4 mm, V4 1.9 mm, V5 4.1 mm (p < 0.05). In contrast, a statistically significant (p < 0.05) lengthening of the mandibular corpus occurred in the rats subjected to liquid diet (S1 4.5 mm, S2 2.7 mm, S3 1.6 mm, S4 2.6 mm). Measurements were taken on both the radiographic and the photographic records. The variation coefficient showed that photographic analysis was more accurate than the radiographic analysis. From these data it appears that an increase in the tonus of the protrusive muscles could be beneficial in mandibular hypoplasia and the increased tonus of the masticatory muscles in skeletal open bite
Buccolingual Inclination Control of Upper Central Incisors of Aligners: A Comparison with Conventional and Self-Ligating Brackets
No full textObjective. The upper incisorstorque expression is essential for the orthodontic treatment accuracy.Various orthodontic devices areclaimedtohavedifferentinclinationcontrolcapacity.Thepurposeofthisretrospectivestudywastocomparetheradiographic buccolingualinclinationof upperincisorsinpatientstreatedwith three differentorthodontictechniques.Material andMethods. Conventional brackets (Victory, 3M), self-ligating appliances (Damon Q, Ormco), and aligners (Invisalign, Align Technology) were tested. Cephalometric data of 25 patients with similar skeletal and dental pretreatment parameters were collected for each technique.Position changesof upper centralincisorswere assessed with radiographic evaluationbefore and after therapy.Three different parameters were considered: 11∧SnaSnp, 11∧Ocl and I+ TVL. All variables were measured before (T0) and after (T1) treatmentandtheirvariationovertreatmentwasassessed.Results.Whenevaluatingangularmeasurements,11∧SnaSnpand11∧Ocl anglesshowedthehighestnumericvariationwithconventionalbrackets.Lowestvalueswerereportedwithaligners.However,the differences among various techniques were not significant for both angles (P>0.05). Also I+ TVL linear value variation did not showsignificantdifferencesamongthedifferentgroupstested(P>0.05).Conclusion.Conventionalmultibracketsapplianceshowed thehighestincisalpositionvariationsovertreatment,butthedifferencesamongvariousgroupswerenotsignificantlydifferent
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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