1,720,982 research outputs found
“ I casi clinici” “ Distalizzazione dei primi molari superiori con molle al nichel titanio senza collaborazione del paziente”
No full textla distalizzazione dei molari è una fase del trattamento che si prefigge lo scopo di ottenere un prima classe molare per recuperare lo spazio per posizionare i canini in una giusta posizione occluso-funzional
Contaminazione dello smalto dentario e resistenza al distacco dei bracket
No full textThe aim of this study was to assess the effect of water and saliva contamination on shear bond strength of APC Plus orthodontic brackets bonded with 3 different adhesives (Transbond XT, Transbond Moisture Insensitive Primer, and Transbond Plus Self Etching Primer) 24h after bonding and after thermocycling.
A total of 270 bovine permanent mandibular incisor were randomly divided into 18 groups (n=15). Each adhesive material was tested in 3 different enamel surface conditions: dry, water and saliva application after etching. As a result 9 groups were defined and debonded after 24h 9 other similarly partitioned groups debonded after thermocycling (1500 thermocycles: 5±2/50±5°C, bath 30", transfer 5"). The samples have been subjected to a shear bond test and data were statistically analyzed (ANOVA, Scheffè). The adhesive surfaces of enamel have been observed (16x) before bonding brackets and after the detachment to assess the quantity of adhesive left on the surface (ARI score; Kruskal-Wallis, Mann-Whitney tests).
Conventional adhesive had the highest bond strength on dry enamel surfaces and the lowest on moisture contemned surfaces (p<0.001). Transbond Plus Self Etching Primer and Transbond Moisture Insensitive Primer were less influenced by water and saliva contamination (p<0.05) without significant differences. Thermocycling led more frequently to adhesive failure at the bracket interface in comparison with groups tested after 24h, even though it didn't affect shear strength significantly
Is postural platform suited to study correlations between the masticatory system and body posture? A study of repeatability and a meta-analysis of reported variations.
No full textSurgical-Invisalign treatment of a patient with Class III malocclusion and multiple missing teeth.
No full textGingival crevicular fluid protein content and alkaline phosphatase activity in relation to pubertal growth phase
No full textObjective: To evaluate gingival crevicular fluid (GCF) protein content and alkaline phosphatase (ALP) activity in growing subjects in relation to stages of skeletal maturation, ie, the growth phase, as prepubertal, pubertal, and postpubertal.
Subjects and Methods: Fifty healthy growing subjects (31 girls and 19 boys; age range, 7.8– 17.7 years) were enrolled in this study that followed a double-blind, prospective, cross-sectional design. Collection of GCF was performed at the mesial and distal sites of both central incisors, for the maxilla and mandible. Growth phase was assessed through the cervical vertebral maturation method. GCF parameters were expressed as total protein content, total ALP activity, and normalized ALP activity.
Results: The total GCF protein content was similar between the different growth phases. On the contrary, the total ALP activity showed a peak for the pubertal growth phase. The normalized GCF ALP activity was only poorly associated with growth phase. No differences were seen between the maxillary and mandibular sites, or between the sexes, for any GCF parameter.
Conclusions: The total GCF protein content is not sensitive to the growth phase. However, GCF ALP activity has potential as a diagnostic aid for identification of the pubertal growth phase in individual subjects when expressed as total, but not normalized, values. (Angle Orthod. 2012;82:1047–1052.
La barra trans palatale secondo la tecnica di Norman Cetlin
No full textNon è previsto Abstract essendo Capitolo di libr
Combined aging effects of strain and thermocycling on unload deflection modes of nickel-titanium closed-coil springs. An in-vitro comparative study.
No full textIntroduction: There are no reports on the aging effects of thermocycling of nickel-titanium (NiTi) based coil springs, and few studies have investigated their superelasticity phases in full. In this study, we compared the mechanical properties of NiTi-based closed-coil springs after the combined aging effects of prolonged strain and thermocycling, as a reflection of the clinical situation. METHODS: Ninety NiTi-based closed-coil springs were used, 30 each of the following types: (1) Nitinol (3M Unitek, Monrovia, Calif), (2) Ni-Ti (Ormco, Glendora, Calif), and (3) RMO (Rocky Mountain Orthodontics, Denver, Colo); all had similar dimensions (length, 12 mm). In each sample group, 2 equal subgroups of 15 coil springs were extended by either 50% (to 18 mm) or 150% (to 30 mm), immersed in artificial saliva, and kept at 37°C for 45 days. All springs underwent sessions of 1000 thermocycles (1 minute long) from 5°C to 55°C on days 22 and 45. Unload deflection curves from both the 50% and 150% ex
Incidence and distribution of deciduous molar ankylosis, a longitudinal study.
No full textAim To study incidence and distribution of deciduous molar ankylosis.
Materials and methods Study design: longitudinal retrospective study A total of 512 consecutive subjects (aged 5 to 15 years) were examined at the Orthodontics and Paediatric Dentistry Department of the Genoa University School of Dentistry; for each subject an ortopantomography x-ray was taken.
Results Thirty-four children were affected by deciduous molars ankylosis (6.6%). A statistically significant difference was revealed between the distributions: the lower deciduous molars were ankylosed more frequently than the upper ones (P<0.001); the second deciduous molars were ankylosed more frequently than the first molars (P<0.001). No statistical significance was found between sex and number of infraoccluded teeth (P=0.74).
Conclusion This study found an incidence of deciduous molar ankylosis of about 6.6%; the lower deciduous molars and second deciduous molars were ankylosed more frequently (P<0.001)
Surface roughness of a microhybrid composite polished with abrasive pastes
No full textObjective: Occlusal surfaces of dental restorations should reestablish the anatomy of cusps, pits and fissures that has been lost. Since this complex area of the restoration is difficult to polish properly with rigid and semi-rigid rotary instruments, the benefits of polishing pastes have been highlighted and their use advocated. The present study aims to individuate a polishing protocol for a microhybrid composite using abrasive pastes with decreasing grit. Methods: Sixty composite discs (Filtek Z250, 3M ESPE, USA) were assigned to six experimental groups (n=10), each one established to be the sequential step of a polishing protocol based on abrasive pastes (Diamond ACI, ACII and Excel, FGM, Brazil): G1, simulated finishing with 40 μm diamond bur; G2, as G1 + 75-80 μm paste; G3, as G2 + 30-35 μm; G4, as G3 + 2-4 μm; G5a, as G4 + felt wheel; G5b, as G4 + resin coating (Seal Coat Fast, DEI Italia, Italy) and felt wheel. The profilometric superficial parameter Sa was taken into account as measure of the roughness on the treated surfaces. Non-parametric statistical analysis was used to assess differences among groups (α=0.05). Results: The registered mean Sa values ±SD expressed in μm were: G1, 0.31±0.06; G2, 0.11±0.01; G3, 0.11±0.02; G4, 0.12±0.02; G5a, 0.17±0.07; G5b, 0.09±0.03. The decrease in surface roughness among groups representing subsequent steps was statistically significant between G1 and G2 (p<0.001) and between G4 and G5b (p<0.01). Similar surface roughness was observed in groups 2 to 5a. Conclusion: Polishing pastes were effective in improving the surface smoothness of the composite after the finishing procedure. The 30-35 μm and the 2-4 μm pastes and the felt wheel alone did not influence the surface roughness obtained after the use of the 75-80 μm paste, which was already low. The resin coating yielded the smoothest surface
Is gingival crevicular fluid volume sensitive to orthodontic tooth movement? A systematic review of split-mouth longitudinal studies.
No full textTo assess the scientific evidence for detectable volume changes of gingival crevicular fluid (GCF) incident to orthodontic tooth movement (OTM). A literature survey of longitudinal split-mouth studies was performed searching PubMed, SCOPUS and the Cochrane Library, with the last access in 15 April 2012. After selection, 13 articles qualified for the final analysis. One study was judged to be of medium/high quality, six were of medium quality and the rest of low quality. Across all studies, there was very little or no statistically significant change in GCF volume incident to OTM. The changes seen were generally ascribed to the clinical or subclinical inflammation consequent to placement of the fixed orthodontic appliance. A reappraisal of the data provided in these studies was performed by comparing the GCF volume from the test (moved) and control (non-moved) teeth, in terms of effects-size (ES) coefficients and variations, as percentages. Generally, the ES coefficients and the variations were below 1.0 and 20%, respectively. Therefore, when using current methods to collect and measure GCF volume, there was no meaningful diagnostic potential for the GCF volume as an index of tissue remodelling incident to OTM. The GCF volume is not a reliable index for tissue remodelling incident to OTM
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