ABSTRACT
Background: The degree of conversion of dental adhesive is an important parameter since poor mechanical properties are related to low percentage of monomer-to-polymer conversion within resin-based materials. Objectives: To evaluate the influence of polymerization time and light guide distance on the degree of conversion (DC) of three contemporary dental adhesives. Materials and Methods: The spectral data of ExciTE DSC, Single Bond ® , and Adper ® Prompt L-Pop were analyzed using FTIR spectroscopy after 20 s, 40 s, and 60 s of photoactivation times. Light tip distances were kept at 1, 3, and 6 mm during the exposures. Statistics: Data were analyzed using ANOVA and Tukey's test (α = 0.05). Results: Within groups, greater DC values were found using a tip distance of 1 mm or a 60-s curing time for Single Bond ® (59%) and Adper ® Prompt L-Pop (65%). No statistically significant difference (P > 0.05) was found using either 1 mm or 3 mm tip distances after 20 s, 40 s, and 60 s of light curing time for Single Bond ® . ExciTE ® DSC showed the greatest DC values with light tip distances of 1 mm (90%) and 3 mm (89%), using 60 s of light curing. Conclusion : The self-etch adhesive Adper ® Prompt L-Pop could be applied in shallow cavity preparations and must be light cured for at least 40 s. The light-cured total-etch adhesive ExciTE ® DSC could be applied in every restorative scenario if the curing time is extended up to 60 s or if the tip distance is extended up to 3 mm.
ABSTRACT
Objectives: To evaluate the effect of Opalescence PF home bleaching gel on the color stability ofAmelogen Plus microhybrid composite resin. Material and method: Thirty disks were fabricated fortesting using three different shades (A1, A2 and A3.5) of Amelogen Plus composite. Standardized L*a*b*parameters were determined and the specimens were subjected to 15% carbamide peroxide. The L*a*b*parameters were measured again and the color change (ΔE) in the composite disks were calculated. Thedata were analyzed using the One-way ANOVA and Tukey tests. (α = 0.05) Results: In all specimens themean of ΔE was more than 3.3. There was a signifi cant difference between shade A3.5 and A2 and withshade A1, as A1 showed the lowest values of color change with bleached composites being lightened incomparison with the unbleached specimens. The greatest change occurred in the red-green (a*) parameter.Conclusion: 15% carbamide peroxide bleaching gel (Opalescence® PF) caused a clinically detectable colorchange with each of three different shades (A1, A2 and A3.5) of Amelogen Plus (ΔE> 3.3) tested. Thegreatest color change occurred with the A3.5 shade and the least change was associated with the A1 shade.
Objetivos: Avaliar o efeito do gel de clareamento doméstico Opalescente® na estabilidade de cor do microcompósitoAmelogen® Plus. Material e método: Parâmetros L*a*b* foram determinados e os espécimes foram sujeitos a peróxidode carbamida a 15%. Os parâmetros L*a*b* foram medidos novamente e a alteração de cor (ΔE) nos discos de compósitofoi calculada. Os dados foram analisados pelos testes One-way ANOVA e Tukey (α = 0.05). Resultados: Emtodos os espécimes o valor médio de ΔE foi maior do que 3.3. Não houve diferença signifi cante entre cores A3,5, e A2A1. A1 mostrou o mais baixo valor, sendo mais claros os compósitos submetidos ao agente clareador em comparaçãoaos espécimes não submetidos. A maior alteração ocorreu no parâmetro vermelho-verde (a*). Conclusão: O gelde peróxido de carbamida a 15% (Opalescente® PF) causou uma alteração de cor clinicamente detectável em cadauma das diferentes cores (A1, A2 e A3,5) do compósito Amelogen® Plus testado. A maior alteração de cor ocorreucom a cor A3.5 e a menor foi associada à cor A1.
Subject(s)
Color , Composite Resins/chemistry , Peroxides/pharmacology , Tooth Bleaching Agents/pharmacology , Tooth Bleaching/methods , Urea/analogs & derivatives , Analysis of Variance , Time FactorsABSTRACT
Objectives: This study evaluated the infl uence of mechanical and thermal cycling on the nanoleakageof Class V composite resin restorations with and without enamel beveling. Material and method:Using 60 Class V cavities prepared on the buccal surfaces of human molars, specimens were dividedinto two groups (n = 30) based on the confi gurations of the enamel cavosurface margins. (beveled andnon-beveled) After restoring the cavity preparations with a fl owable composite, half of the specimenswere mechanically load-cycled. The specimens were sealed leaving a 1 mm window around the cervicaland enamel margins. Specimens were placed in a 50% (W/V) silver nitrate solution then immersedin photodeveloping solution and exposed to fl uorescent light for 8h. The teeth were buccolinguallysectioned, gold sputter coated and examined with a SEM to evaluate the nanoleakage values. The datawere analyzed using two-way ANOVA (α = 0.05). Results: Enamel margin confi guration had no significant effect on nanoleakage (p > 0.05). However, the nanoleakage value was signifi cantly higher inthe load-cycled group than in the group not load-cycled (p < 0.05). Conclusion: Since enamel margin confi guration does not affect nanoleakage, there is no need to bevel enamel margins of Class V cavitypreparations for composite restorations.
Objetivos: O presente estudo avaliou a infl uência dos ciclos de carga mecânico e térmico na nanoinfi ltração derestaurações Classe V em resinas compostas, com e sem biselamento do esmalte. Material e método: Os espécimes(60 cavidades Classe V preparadas na superfície vestibular de molares humanos) foram divididos em dois grupos(n = 30) baseados nas confi gurações das margens cavosuperfi ciais do esmalte (biseladas e não biseladas). Após restauraçãodos preparos cavitários com um compósito tipo fl ow, metade dos espécimes foi carregada mecanicamente.Os espécimes foram selados mantendo janela de 1 mm em torno das margens cervical e de esmalte. Os espécimesforam colocados em solução de nitrato de prata (50%), imersos na sequência em solução processadora fotográfi cae expostos à luz fl uorescente por oito horas. Os dentes foram cortados em sentido vestíbulo-lingual, revestidos emouro e observados em microscopia eletrônica para avaliar os valores de nanoinfi ltração. Os dados foram analisadospelo ANOVA (α = 0,05). Resultados: A confi guração das margens do esmalte não teve efeito signifi cante nananoinfi ltração (p > 0,05). Entretanto, os valores da nanoinfi ltração foram signifi cativamente mais altos no grupode carga que no grupo sem carga (p > 0,05). Conclusão: Uma vez que a confi guração da margem do esmalte nãoafeta a nanoinfi ltração, não há necessidade de biselar as margens do esmalte nos preparos de cavidades Classe V emrestaurações de compósitos.