The aim of this study was to evaluate the effect of different number of thermal cycles on the shear bond strength (SBS) of metallic orthodontic brackets bonded to feldspathic ceramic by a composite resin. Twenty-five ceramic cylinders were etched with 10% hydrofluoric acid for 60 s and received two layers of silane. Brackets were bonded to the cylinders using Transbond XT and assigned to 5 groups (n=5): Group 1 -Control group (without thermal cycling); Group 2 -500 thermal cycles; Group 3 -5,000 thermal cycles; Group 4 -7,000 thermal cycles and Group 5 -10,000 thermal cycles. Light-activation was carried out by Radii Plus LED. SBS testing was carried out after 24 h of storage in deionized water and thermal cycling (5/55 o C and 30 s dwell time). Five brackets were bonded to each cylinder, totalizing 25 brackets for each group. Data were submitted to one-way ANOVA and Tukey's test (α=0.05). The Adhesive Remnant Index (ARI) was evaluated at 8× magnification. The SBS (MPa) of control group (9.3±0.8), 500 (9.0±0.7) and 5,000 (8.4±0.9) thermal cycles were significantly higher than those after 7,000 (6.8±0.6) and 10,000 (4.9±1.0) thermal cycles (p<0.05). The ARI showed a predominance of Scores 0 (adhesive failure) prevailed in all groups, as shown by the ARI, with increased scores 1 and 2 (mixed failures) for control group and 500 thermal cycles. In conclusion, thermal fatigue may compromise the bonding integration between metallic brackets and ceramic restorations. For in vitro testing, use of at least 7,000 cycles is advised to result in significant fatigue on the bonding interface. I n f l u e n c e o f T h e r m a l C y c l e s N u m b e r o n B o n d S t r e n g t h o f M e t a l l i c B r a c ke t s t o C e r a m i c
Aim:To evaluate the force decay of orthodontic elastomeric chains after immersion in disinfecting solutions. Methods: One-hundred and fifty segments of elastomeric chains were divided in 3 groups: Control group -no disinfection; Chlorhexidine group -disinfection in 0.12% chlorhexidine digluconate solution; and Peracetic acid group -disinfection in 0.2% peracetic acid solution. Elastomeric chains of 14 mm were stretched up to 20 mm and the given force (kgf) was evaluated in an Instron universal testing machine at the following intervals: 1 h, 1 day, 7, 14, 21 and 28 days after the immersion in the disinfecting solutions. Data (kgf) were analyzed statistically by Analysis of Variance and Tukey's test at a 5% significance level. Results: Both groups presented similar force decay along 7 days and remained stable up to 28 days. Force degradation was observed in the first hours of activation (~50%). Conclusions: It may be concluded that there were no significant differences among the investigated groups, in most interval times, indicating that both chemical solutions can be used for previous disinfection of orthodontic elastomeric chains.
The aim was to evaluate the flexural strength and the effects of deflection on the surface roughness of esthetic orthodontic wires. The sample consisted of 70 archwire 0.014-inch: polytetrafluorethylene (PTFE)-coated Nickel-Titanium (Niti) archwires (Titanol Cosmetic-TC, Flexy Super Elastic Esthetic-FSE, esthetic Nickel Titanium Wire-ANT); epoxy resin-coated Niti archwires (Spectra-S, Niticosmetic-TEC); gold and rhodium coated Niti (Sentalloy-STC) and a control group (superelastic Niti (Nitinol-NS). The initial roughness was evaluated with a rugosimeter. After that, the wires were submitted to flexural test in an universal testing machine. Each wire was deflected up to 2 mm at a speed of 1 mm/min. After flexural test, the roughness of the wires was evaluted on the same surface as that used for the initial evaluation. The data of roughness and flexural strength were analyzed by one-way ANOVA and Tukey's test (α=0.05). Student t-test compared roughness before and after deflection (α =0.05). The roughness of S and ANT (epoxy resin and PTFE-coated wires, respectively), before and after deflection, was significantly higher than the other groups (p<0.05). Wire deflection significantly increased the roughness of the wires S and STC (p<0.05). The flexural strength of groups FSE and NS (PTFE and uncoated) was higher compared with that of the other groups (p<0.05). We concluded that the roughness and flexural strength of the orthodontic wires does not depend on the type of the esthetic coating, but it is influenced by the method of application of this coating. The deflection can increase the roughness of the esthetic orthodontic wires.
Os objetivos desse trabalho foram determinar, em moradores assistidos pelo Programa Saúde da Família na cidade de Casa Branca – SP, a prevalência de más oclusões e suas relações as com alterações funcionais: respiração e deglutição. O estudo foi realizado na área assistida pela Unidade de Saúde da Família de Casa Branca, num total 652 crianças, de ambos os gêneros e com idade entre sete e quatorze anos. A oclusão foi avaliada de acordo com as relações anteroposterior, vertical e transversal. Para a análise estatística foram utilizados os testes Coeficiente de Correlação, Qui-quadrado e Fisher. Os resultados mostraram que 70,1% da amostra apresentam má oclusão. No aspecto funcional, 9,5% apresentaram respiração bucal e 10% deglutição atípica. Houve correlação positiva estatisticamente significante entre a má oclusão e as duas funções avaliadas (p<0,001). Concluiu-se que a prevalência da má oclusão foi elevada e esta apresentou correlação positiva com as alterações funcionais.
Background: Dental biofilm accumulation and poor personal oral hygiene are known major risk factors for gingivitis and halitosis. However, it is not clear how studies compare the effectiveness of hygiene regimens, associated with outcomes centered on patients. Methods: A randomized, blind, controlled clinical trial involving 58 participants aged from 12 to 17 years, who search the Department of Pediatric Dentistry of Universidade Metropolitana de Santos , will be conducted. Immediately, the volunteers will be inserted into Group 1 (commercially available hygiene regimen) or Group 2 (tooth brushing alone). In Group 1, participants will receive Colgate Total 12 toothpastes, Plax mouthwashes and Colgate Ultrasoft toothbrushes, while Group 2 will use Colgate Cavity Protection toothpastes and Colgate Ultrasoft toothbrushes. The interventions will be conducted in the periods of 1, 3, and 6 months after the baseline, when the evaluations will also be performed. Biofilm and halitosis indexes will be evaluated. Data regarding discomfort, satisfaction and the socioeconomic/individual characteristics will also be computed. Discussion: Although toothbrushing has shown positive effects in decreasing biofilm and in gingival health, there is no comparison in the literature of different brushing regimens with halitosis measurement in adolescents. In addition, the effectiveness of these protocols would be confirmed from the acceptability of the volunteers.
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