Influence of Different Surface Treatments on the Bond Strength Between Composites and Resin Cement / INFLUÊNCIA DE DIFERENTES TRATAMENTOS DE SUPERFÍCIE NA RESISTÊNCIA DE UNIÃO ENTRE COMPÓSITOS E CIMENTO RESINOSO

The aim of this study was to evaluate the influence of different surface treatments on bond strength (BS) between composite and a resin cement trough microshear bond strength test. Seventy five discs (10x2 mm) of Filtek P90, Filtek Z250 and Filtek Z350 XT (3M ESPE), were divided into 5 groups according to the treatment: C= control - no treatment; sandblasting J= aluminum oxide (50µm); sandblasting JE = + 99.3% ethanol for 5 min; silica coating S = (3M-ESPE Cojet - 30 microns); SS = silica coating + silane. PVC tubes (0.5 x 0.80 mm) were attached on the composite disc, and then, inserted resin cement (3M ESPE-RelyX ARC). After 24 hours artificial saliva storage at 37oC, the specimens were tested for microshear crosshead speed of 1.0 mm/min. Data were evaluated in two-way ANOVA and Tukey's test (5%) for contrast. The results showed that sandblasting with aluminum oxide (J) was efficient in increasing the BS for composites Z350 and P90. For the Z250, there were no difference between treatments. Also, CS showed results similar to controls for all composites. SE showed the worst results for Z350 e P90. BS values were dependent on the type of composite and the surface treatment used. Sandblasting with aluminum oxide seems to be an effective surface treatment for composites and may lead to higher BS values, while the use of ethanol could be harmful.

O objetivo deste estudo foi avaliar a influência de tratamentos de superfície na resistência de união (RU) entre compósitos e um cimento resinoso. Setenta e cinco discos (10x2 mm) das resinas Filtek P90, Filtek Z250 e Filtek Z350 (3M ESPE) foram divididos em 5 grupos de acordo com o tratamento: N= sem tratamento; S= jateamento com óxido de alumínio (50µm); SE= jateamento de óxido de alumínio + 99,3% de etanol por 5 min; C= jateamento de sílica com Cojet - 30 microns (3M ESPE); CS= jateamento de sílica + silano. Tubos de PVC (0,5 x 0,80 mm) foram fixados nos discos e o cimento resinoso (RelyX ARC, 3M ESPE) foi inserido. Após 24 horas de armazenamento em saliva artificial a 37oC, os espécimes foram submetidos ao teste de microcisalhamento com velocidade de 1,0 mm/min. Os dados foram avaliados em ANOVA de dois fatores e no teste de Tukey (5%) para contraste. Os resultados mostraram que o tratamento com oxido de alumínio (J) foi eficiente no aumento da RU nos compósitos Filtek Z350 e P90. Não houve diferença entre tratamentos para a Z250. Grupo CS mostrou resultados semelhantes aos do controle para todos os compósitos. Já o SE mostrou os piores resultados de RU. Concluiu-se que os valores de RU foram dependentes do tipo de compósito e do tratamento de superfície utilizado. O jateamento com óxido de alumínio parece ser um tratamento de superfície eficaz e pode elevar os valores de RU, já o uso de etanol pode ser prejudicial

Can whitening toothpastes maintain the optical stability of enamel over time?

Abstract Besides the effects on the health of individuals, cigarette smoking can also interfere with the appearance of their teeth. Objective: To evaluate the effect of cigarette smoking-toothbrushing-cycling (CSTC) with whitening toothpastes on the roughness and optical behavior of bovine enamel for eight weeks. Material and Methods: Thirty bovine dentin/enamel discs, 8.0 mm in diameter and 2.0 mm thick, were randomly divided into three groups according to the toothpastes: whitening (Colgate Luminous White - CW and Oral B 3D White - OW), and a non-whitening (Colgate - C). The roughness, color (CIE L*a*b* system), translucency and gloss were measured before and after the specimens were submitted to CSTC. The topography of the specimens was analyzed by scanning electron microscopy. During the first week, the specimens were daily subjected to the consumption of 20 cigarettes and brushed (40 strokes/100 g) with the toothpastes' slurries. Thereafter, the CSTC was weekly applied in an accumulated model (140 cigarettes/280 strokes) for seven weeks. The data were submitted to two-way ANOVA, Tukey's HSD test, and paired-t test (α=0.05). Results: The three toothpastes produced significant changes in roughness, color, translucency and gloss (p<0.05). After eight weeks, the roughness and the gloss produced by the three toothpastes were similar (p>0.05), while OW produced the lowest color change and the translucency of C was lower than that of CW (p<0.05). The three toothpastes produced a significant decrease in L* values and a significant increase in a* values after eight weeks (p<0.05). No significant difference in the b* coordinate was found for OW (p=0.13) There were topographic changes in the enamel surfaces. Conclusions: The whitening toothpastes increased the roughness, changed the topography and were not able to maintain the optical stability of enamel exposed over eight weeks.

Marginal integrity of restorations produced with a model composite based on polyhedral oligomeric silsesquioxane (POSS)

Marginal integrity is one of the most crucial aspects involved in the clinical longevity of resin composite restorations.Objective To analyze the marginal integrity of restorations produced with a model composite based on polyhedral oligomeric silsesquioxane (POSS).Material and Methods A base composite (B) was produced with an organic matrix with UDMA/TEGDMA and 70 wt.% of barium borosilicate glass particles. To produce the model composite, 25 wt.% of UDMA were replaced by POSS (P25). The composites P90 and TPH3 (TP3) were used as positive and negative controls, respectively. Marginal integrity (%MI) was analyzed in bonded class I cavities. The volumetric polymerization shrinkage (%VS) and the polymerization shrinkage stress (Pss - MPa) were also evaluated.Results The values for %MI were as follows: P90 (100%) = TP3 (98.3%) = B (96.9%) > P25 (93.2%), (p<0.05). The %VS ranged from 1.4% (P90) to 4.9% (P25), while Pss ranged from 2.3 MPa (P90) to 3.9 MPa (B). For both properties, the composite P25 presented the worst results (4.9% and 3.6 MPa). Linear regression analysis showed a strong positive correlation between %VS and Pss (r=0.97), whereas the correlation between Pss and %MI was found to be moderate (r=0.76).Conclusions The addition of 25 wt.% of POSS in methacrylate organic matrix did not improve the marginal integrity of class I restorations. Filtek P90 showed lower polymerization shrinkage and shrinkage stress when compared to the experimental and commercial methacrylate composite.

Effects of different surface treatments on bond strength of an indirect composite to bovine dentin.

Background: Several surface treatments could be used to improve the bond strength (BS) between indirect composites and cement. Aim: To evaluate the BS of an indirect composite submitted to different surface treatments, cemented to bovine dentin. Settings and Design: One hundred and fifty conical cavities were prepared in slices of bovine dentin and bulk filled with the composite. Materials and Methods: After curing and removal from the cavity, the restorations were treated according to the groups (n = 10): C‑untreated, S‑Sandblasting; SS‑Sandblasting + silane; F‑hydrofluoric acid; FS‑hydrofluoric acid + silane; SF‑Sandblasting + hydrofluoric acid; SFS‑Sandblasting + hydrofluoric acid + silane; E‑ethanol; ES‑ethanol + silane; SE‑Sandblasting + ethanol; SES‑Sandblasting + ethanol + silane; P‑H2O2; PS‑H2O2 + silane; SP‑Sandblasting + H2O2; SPS‑Sandblasting + H2O2 + silane. After cementation, push‑out test was performed in a universal testing machine. Statistical Analysis: Data were submitted to nonparametric tests (Kruskal–Wallis and Mann–Whitney U‑tests, α = 0.05). The failure mode was observed under a stereomicroscope and the topography by scanning electronic microscopy (SEM). Results: Sandblasted groups led to the highest BS values, (P < 0.001), except for the SFS group. SE, SES, and SPS led to higher BS values than S and SS groups (P < 0.05). F, E and P groups showed the lowest BS values. The number of cohesive or mixed failures was related to higher BS values. SEM evaluation showed major irregularities only for sandblasted groups. Conclusions: Sandblasting was a safe surface treatment for the indirect composite, increasing the BS values. Hydrofluoric acid applied after sandblasting damaged the BS values and should not be recommended while ethanol and H2O2, when applied after sandblasting, were effective in increasing BS values.

Degradation of Resin Composites in a Simulated Deep Cavity

The aim of this study was to analyze the sorption and solubility of a nanofilled (Filtek Z350) and a midifilled (Filtek P60) resin composite in oral environment-like substances, in a simulated deep cavity. A cylindrical cavity prepared in a bovine incisor root was incrementally filled with resin composites. The obtained resin composite cylinders were cut perpendicularly to the axis to obtain 1-mm-thick discs that were divided into fifteen groups (n=5) according to depth (1, 2, 3, 4 and 5 mm) and immersion media (distilled water - DW, artificial saliva - AS and lactic acid - LA). The sorption and solubility were calculated based on ISO 4049:2000. Additionally, the degree of conversion (DC%) was calculated by FT-IR spectroscopy. Data were analyzed using multifactor analysis of variance (MANOVA) followed by Tukey's HSD post-hoc test and linear regression analysis (a=0.05). The DC% was higher for the midifilled resin composite and was negatively influenced by cavity depth (p<0.05). The nanofilled resin composite presented higher sorption and solubility than did the midifilled (p<0.05). The immersion media influenced the sorption and the solubility as follows: LA>AS>DW, (p<0.05). Both phenomena were influenced by cavity depth, with the sorption and solubility increasing from 1 to 5 mm (p<0.05). The degradation of resin composite restorations may be greater in the deepest regions of class II restorations when the composite is exposed to organic acids present in the oral biofilm (lactic acid).

O objetivo deste estudo foi analisar a absorção e a solubilidade de uma resina composta nanopartículada (Filtek Z350) e de uma híbrida (Filtek P60) em substâncias simuladoras do ambiente oral em um modelo de cavidade profunda. Uma cavidade cilíndrica, construída em uma raiz de um incisivo bovino, foi preenchida incrementalmente com as resinas compostas. Os cilindros obtidos foram seccionados perpendicularmente ao eixo para obtenção de discos com 1 mm de espessura, que foram divididos em 15 grupos (n=5) de acordo com a profundidade (1, 2, 3, 4 e 5 mm) e o meio de imersão (água destilada - AD, saliva artificial - SA e ácido lático - AL). A absorção e a solubilidade foram calculadas com base na norma ISO 4049:2000(E). Adicionalmente, o grau de conversão (GC%) foi calculado através de espectroscopia FT-IR. Os dados obtidos foram analisados usando análise de variância multifatorial, teste de Tukey HSD e análise de regressão linear (a=0,05). A resina composta híbrida apresentou o maior grau de conversão, sendo este influenciado pela profundidade da cavidade (p<0,05). A resina composta nanopartículada apresentou maiores valores de absorção e solubilidade (p<0,05). O meio de imersão influenciou a absorção e a solubilidade: AL>SA>AD (p<0,05). Ambos os fenômenos foram influenciados pela profundidade da cavidade, com os valores aumentando de 1 para 5 mm (p<0,05). A degradação de restaurações de resinas compostas pode ser maior em regiões profundas de restaurações classe II e quando o material é exposto à ácidos orgânicos produzidos pelo biofilme oral (ácido lático).

Long-term degradation of resin-based cements in substances present in the oral environment: influence of activation mode

Indirect restorations in contact with free gingival margins or principally within the gingival sulcus, where the presence of organic acids produced by oral biofilm is higher, may present faster degradation of the resin-based cement pellicle. Objectives To investigate the degradation of four resin-based cements: Rely X ARC (R), Variolink II (V), Enforce (E) and All Cem (A), after immersion in distilled water (DW), lactic acid (LA) and artificial saliva (AS) and to analyze the influence of the activation mode on this response. Material and Methods Two activation modes were evaluated: chemical (Ch) and dual (D). In the dual activation, a two-millimeter thick ceramic disk (IPS Empress System) was interposed between the specimen and light-curing unit tip. Specimens were desiccated, immersed in distilled water, artificial saliva and lactic acid 0.1 M at 37°C for 180 days, weighed daily for the first 7 days, and after 14, 21, 28, 90 and 180 days and were desiccated again. Sorption and solubility (µg/mm 3 ) were calculated based on ISO 4049. The data were submitted to multifactor analysis of variance (MANOVA) and Tukey's HSD test for media comparisons (α=0.05). Results Sorption was higher after immersion in LA (p<0.05) and increased significantly with time (p<0.05). Sorption was influenced by the activation mode: Ch>D (p<0.05). The lowest solubility was presented by R (p<0.05). Conclusions Lactic acid increased the degradation of resin-based cements. Moreover, the physical component of activation, i.e., light-activation, contributed to a low degradation of resin-based cements. .

A critical analysis of the degree of conversion of resin-based luting cements

OBJECTIVE: This study analyzed the degree of conversion (DC percent) of four resin-based cements (All Ceram, Enforce, Rely X ARC and Variolink II) activated by two modes (chemical and dual), and evaluated the decrease of DC percent in the dual mode promoted by the interposition of a 2.0-mm-thick IPS Empress 2 disc. MATERIAL AND METHODS: In the chemical activation, the resin-based cements were prepared by mixing equal amounts of base and catalyst pastes. In the dual activation, after mixing, the cements were light-activated at 650 mW/cm² for 40 s. In a third group, the cements were light-activated through a 2.0-mm-thick IPS Empress 2 disc. The DC percent was evaluated in a FT-IR spectrometer equipped with an attenuated total reflectance crystal (ATR). The data were analyzed by two-way ANOVA and Tukey's HSD test. RESULTS: For all resin-based cements, the DC percent was significantly higher with dual activation, followed by dual activation through IPS Empress 2, and chemical activation (p<0.05). Irrespective of the activation mode, Rely X presented the highest DC percent (p<0.05). Chemically activated Variolink and All Ceram showed the worst results (p<0.05). The DC percent decreased significantly when activation was performed through a 2.0-mm-thick IPS Empress 2 disc (p<0.05). CONCLUSION: The results of the present study suggest that resin-based cements could present low DC percent when the materials are dually activated through 2.0 mm of reinforced ceramic materials with translucency equal to or less than that of IPS-Empress 2.

Influence of post-cure treatments on hardness and marginal adaptation of composite resin inlay restorations: an in vitro study

OBJECTIVES: The purpose of this study was to evaluate the Vickers hardness number (VHN) and the in vitro marginal adaptation of inlay restorations of three hybrid composite resins (Filtek Z250, Opallis and Esthet-X) subjected to two post-cure treatments. MATERIAL AND METHODS: For the microhardness test, three different groups were prepared in accordance with the post-cure treatments: control group (only light cure for 40 s), autoclave group (light cure for 40 s + autoclave for 15 min at 130ºC); and microwave group (light cure for 40 s + microwave for 3 min at 450 W). To assess the marginal adaptation, the composite resin was inserted incrementally into a mesial-occlusal-distal cavity brass mold and each increment light-cured for 40 s. A previous reading in micrometers was taken at the cervical wall, using a stereomicroscope magnifying glass equipped with a digital video camera and image-analysis software. Subsequently, the specimens were subjected to the post-cure treatments (autoclave and microwave) and a reading was taken again at the cervical wall. Data were compared using ANOVA for the hardness test, split-plot ANOVA for the adaptation assessment and Tukey's test for multiple comparisons. A significance level of 5 percent was adopted for all analyses. RESULTS: The post-cure treatments increased the hardness of conventional composites (p<0.001) and the gap values of inlay restorations (p<0.01). Filtek Z250 showed higher hardness (p<0.001) and lower gap values than Opallis and Esthet-X (p<0.05). Gap values did not exceed 90 µm for any of the experimental conditions. CONCLUSION: The post-cure treatments increased the VHN and the gap values on the cervical floor of composite resin inlays. Moreover, Filtek Z250 showed the best results, with higher hardness and lower gap values.

Cytotoxicity of current adhesive systems: in vitro testing on cell culture of L929 and balb/c 3T3 fibroblasts / Citotoxicidade de sistemas adesivos atuais: teste in vitro em cultura de células fibroblásticas L929 e balb/c 3T3

Purpose: The aim of this study was to evaluate the cytotoxicity of three current adhesives: Prime&Bond NT (PBNT), Single Bond (SB) and XENO III (XENO). Methods: After embedding and curing circles of filter paper with the tested adhesives, the filters were placed in contact with the solidified agar surface over L929 monolayer cells plated in 6-well cell culture plate and incubated for 24 h. The inhibition zone around the filter papers was measured in mm. MTT assay was performed using fibroblasts Balb/c 3T3 cell lines in multiwell culture plates. All assays were done in triplicate. Results: All materials were cytotoxic (Kruskal-Wallis, P<0.05) in a similar level to latex (P>0.05). For intra-groups analysis, SB presented the lowest cytotoxicity (P<0.01), while there was no statistical difference between PBNT and XENO (P>0.05). MTT assay confirmed the cytotoxicity of the tested adhesives. Conclusion: Considering the limits of this work, all adhesives tested were as cytotoxic as latex.

Objetivo: O objetivo deste estudo foi avaliar a citotoxicidade de três adesivos: Prime & Bond NT (PBNT), Single Bond (SB) e XENO III (XENO). Metodologia: Após embebição e polimerização de filtros de papel com os referidos adesivos, estes foram colocados em contato com a superfície de agar solidificada sobre a monocamada de células L929 plaqueadas em cultura celular de 6-poços e incubadas por 24 h. A zona de inibição formada ao redor dos filtros de papel foi medida em milímetros. Outro teste realizado foi o do MTT, utilizando fibroblastos Balb / c 3T3 em placas de multi-poços, sendo os ensaios realizados em triplicatas. Resultados: Todos os materiais testados foram citotóxicos (Kruskal-Wallis, P < 0,05) e semelhantes ao látex (P > 0,05). Para a análise intra-grupos, o SB apresentou a mais baixa citotoxicidade (P < 0,01), enquanto não houve diferença estatística entre PBNT e XENO (P > 0,05). O ensaio de MTT confirmou a citotoxicidade dos adesivos. Conclusão: Considerando as limitações deste trabalho, todos os adesivos testados foram tão citotóxicos quanto o látex.

Restauração de dentes tratados endodonticamente com pino de fibra de vidro e acessório em canais amplos / Fiber glass post and accessory post to restore endodontically treated teeth with large root canal

Os pinos de fibra de vidro têm sido extensivamente utilizados em dentes com grande perda de estrutura dentária e canais endodonticamente tratados. Por apresentar seção circular, mesmo com diâmetros diversos, sua linha de cimentação torna-se muito espessa em canais mais elípticos ou alargados. Tal condição poderia aumentar o potencial para a microinfiltração, além de diminuir a resistência à fratura do núcleo. Este artigo mostra a resolução do caso clínico de um incisivo lateral superior com conduto radicular amplo tratado endodonticamente, a partir do emprego de um retentor intra-radicular de fibra de vidro cônico associado a um pino acessório, com objetivo de diminuir a linha de cimentação e aumentar a longevidade do procedimento restaurador.

Relationship between the degree of conversion, solubility and salivary sorption of a hybrid and a nanofilled resin composite

This study analyzed the relationship between the degree of conversion (DC), solubility, and salivary sorption of a hybrid (Filtek P 60) and a nanofilled resin composite (Filtek Supreme), and evaluated the influence of the light-activation mode on these properties. Two light-activation modes were used: Conventional (C; 850 mW/cm² for 20 s) and Soft-start (SS; 100-1,000 mW/cm² for 10 s + 1,000 mW/cm² for 10 s). The DC ( percent) was evaluated by FT-Raman spectroscopy. The solubility and salivary sorption were measured after immersion in artificial saliva for 7 days. Data were analyzed by ANOVA and Student-Newman-Keuls' test and linear regression analysis (a = 0.05). The DC varied from 50.52 percent (nanofilled composite) to 57.15 percent (hybrid composite), and was influenced by the light-activation mode: C > SS. The solubility (0.45 mg/mm³) and salivary sorption (8.04 mg/mm³) of the nanofilled composite were greater than those of the hybrid composite (0.40 mg/mm³ / 6.87 mg/mm³), and were influenced by the light-activation mode: SS > C. Correlation was found between DC and solubility (r = - 0.89, p<0.05), as well as between solubility and salivary sorption (r = 0.95). These findings suggest that nanofilled composites may present higher degradation in the oral environment than hybrid ones. Soft-start light-activation mode may increase the solubility of resin composites.

Relationship between the degree of conversion, solubility and salivary sorption of a hybrid and a nanofilled resin composite: influence of the light-activation mode

This study analyzed the relationship between the degree of conversion (DC), solubility, and salivary sorption of a hybrid (Filtek P 60) and a nanofilled resin composite (Filtek Supreme), and evaluated the influence of the light-activation mode on these properties. Two light-activation modes were used: Conventional (C; 850 mW/cm2 for 20 s) and Soft-start (SS; 100-1,000 mW/cm2 for 10 s + 1,000 mW/cm2 for 10 s). The DC (%) was evaluated by FT-Raman spectroscopy. The solubility and salivary sorption were measured after immersion in artificial saliva for 7 days. Data were analyzed by ANOVA and Student-Newman- Keuls’ test and linear regression analysis (= 0.05). The DC varied from 50.52% (nanofilled composite) to 57.15% (hybrid composite), and was influenced by the light-activation mode: C > SS. The solubility (0.45 µg/mm3) and salivary sorption (8.04 µg/mm3) of the nanofilled composite were greater than those of the hybrid composite (0.40 µg/mm3 / 6.87 µg/mm3), and were influenced by the light-activation mode: SS > C. Correlation was found between DC and solubility (r = - 0.89, p<0.05), as well as between solubility and salivary sorption (r = 0.95). These findings suggest that nanofilled composites may present higher degradation in the oral environment than hybrid ones. Soft-start light-activation mode may increase the solubility of resin composites.

Influência do protocolo de fotoativação no selamento de restaurações com compósitos / Influence of light-curing mode on the sealing of resin composite restorations

O propósito deste estudo foi avaliar a influência do protocolo de fotoativação no selamento de restaurações classe V com compósitos. Sessenta cavidades com margem oclusal em esmalte e margem apical em dentina, preparadas nas superfícies vestibular e lingual de pré molares humanos, foram hibridizadas com o sistema adesivo Single Bond e restauradas com três compósitos (A110, P60 e Point 4). Para cada compósito, foram produzidos dois grupos de acordo com os protocolos de fotoativação (n = 10): Convencional-500 mW/cm2/40 segundos e Softstart-250 mW/cm2/40 segundos + 500 mW/cm2/20 segundos. Após acabamento/polimento das restaurações e armazenagem durante 7 dias em água destilada a 37°C, os dentes foram submetidos à termociclagem. Os espécimes foram impermeabilizados com esmalte de unha e imersos em solução neutra de azul de metileno a 2 % por 24 horas. Os dentes foram seccionados e o grau de penetração do corante foi avaliado em uma escala ordinal de 0-3. Os dados foram submetidos aos testes de Kruskal-Wallis e Mann-Whitney (α = 0,05). Não houve diferença estatística entre os grupos ativados com os dois protocolos de fotoativação. A microinfiltração foi maior nas margens em dentina do que nas margens em esmalte (p < 0,01). Esses achados sugerem que o protocolo de fotoativação soft-start não apresentou influência no selamento de cavidades restauradas com compósitos fotopolimerizáveis

This study investigated the effect of light-curing modes on cervical sealing of resin composite restorations. Sixty cavities with the occlusal margins in enamel and the gingival margins in dentin, prepared on the labial and lingual surfaces of human premolars were treated with Single Bond adhesive system and restored using a bulk technique with three resin composites (A110, P60 and Point 4). For each composite, two groups of 10 cavities were created according to the two light-curing modes: Standard (S)-500 mW/cm2 / 40 seconds and Soft-start (SS) - 250 mW/cm2 / 40 seconds + 500 mW/cm2 / 20 seconds. The specimens were submitted to thermocycling prior to immersion in 2% neutral solution of methylene blue for 24 hours. The teeth were sectioned and the degree of dye penetration was scored on a 0-3 ordinal scale. The data were analyzed by Kruskal-Wallis and Mann-Whitney tests (α = 0.05). No significant difference in the microleakage scores was observed among the groups polymerized with the two light-curing modes. The microleakage was greater in dentin margins than in enamel margins (p < 0.01). These results suggest that soft-start light-curing mode did not have any influence on resin composite restoration sealing

Depth of cure of dental composites submitted to different light-curing modes

OBJECTIVE: This study evaluated the depth of cure of five dental composites submitted to different light-curing modes. MATERIAL AND METHODS: Canal-shaped cavities with 5mm of length were prepared on the buccal surfaces of extracted third molars, and restored using P-60, A-110, Admira, Z-250 and Supreme resin composites. Materials were light-cured from the top, according to three modes (Group 1- Conventional (C): 500 mW/cm² / 40 s; Group 2 - Soft-Start (SS): 250 mW/cm²/ 20 s + 500 mW/cm²/ 20 s + 500 mW/cm²/ 10 s and Group 3 - LED: 250 mW/cm²/ 40 s). After that, cavity longitudinal surfaces were polished and marked with a millimeter scale of 4mm of length. Depth of cure was evaluated by means of Knoop hardness number (KHN), so that five indentations were performed at each millimeter. Original data were submitted to three-way ANOVA and Fisher's LSD test (alpha = 0.01). RESULTS: All materials presented a significant reduction on KHN from first to third millimeter. Regarding depth of cure, the results obtained for Conventional and Soft-Start modes were similar, but statistically superiors to those found for group 3 (LED). CONCLUSION: This performance may be related to the differences among energy densities obtained with different light-curing modes.

OBJETVO: Este estudo avaliou a profundidade de polimerização de cinco compósitos fotopolimerizáveis submetidos a diferentes métodos de fotoativação. MATERIAL E MÉTODO: Cavidades em forma de canaleta com 5 mm de comprimento, preparadas nas faces vestibulares de terceiros molares, foram restauradas com os compósitos P-60, A-110, Admira, Z-250 e Supreme. Os materiais foram fotoativados pelo topo das cavidades com três técnicas (Grupo 1 - Convencional (C): 500 mW / cm² / 40 s; Grupo 2 - Soft-Start (SS): 250 mW / cm² / 20 s + 500 mW / cm² / 20 s + 500 mW / cm² / 10 s e Grupo 3 - LED: 250 mW / cm² / 40 s). Após a fotoativação, as superfícies longitudinais dos materiais foram polidas e marcadas com uma escala milimetrada com 4 mm de comprimento. A profundidade de polimerização foi avaliada através do número de dureza Knoop (NDK), com cinco indentações a cada milímetro. Os dados originais foram submetidos à Análise de Variância de três fatores e teste de Fisher para comparações entre médias (alfa = 0,01). RESULTADOS: Todos os materiais apresentaram diminuição do NDK do primeiro para o terceiro milímetro (p < 0,01). Os resultados obtidos com os Grupos Convencional e Soft-Start foram similares e superiores ao Grupo LED (p < 0,01). CONCLUSÃO: Este desempenho pode ser relacionado às diferenças nas densidades de energia obtidas com os métodos de fotoativação utilizados.

Depth of cure of dental composites submitted to different light-curing modes%Profundidade de polimerização de compósitos restauradores submetidos a diferentes métodos de fotoativação

OBJETVO: Este estudo avaliou a profundidade de polimerização de cinco compósitos fotopolimerizáveis submetidos a diferentes métodos de fotoativação. MATERIAL E MÉTODO: Cavidades em forma de canaleta com 5 mm de comprimento, preparadas nas faces vestibulares de terceiros molares, foram restauradas com os compósitos P-60, A-110, Admira, Z-250 e Supreme. Os materiais foram fotoativados pelo topo das cavidades com três técnicas (Grupo 1 - Convencional (C): 500 mW / cm2 / 40 s; Grupo 2 - Soft-Start (SS): 250 mW / cm2 / 20 s + 500 mW / cm2 / 20 s + 500 mW / cm2 / 10 s e Grupo 3 - LED: 250 mW / cm2 / 40 s). Após a fotoativação, as superfícies longitudinais dos materiais foram polidas e marcadas com uma escala milimetrada com 4 mm de comprimento. A profundidade de polimerização foi avaliada através do número de dureza Knoop (NDK), com cinco indentações a cada milímetro. Os dados originais foram submetidos à Análise de Variância de três fatores e teste de Fisher para comparações entre médias (a = 0,01). RESULTADOS: Todos os materiais apresentaram diminuição do NDK do primeiro para o terceiro milímetro (p < 0,01). Os resultados obtidos com os Grupos Convencional e Soft-Start foram similares e superiores ao Grupo LED (p < 0,01). CONCLUSÃO: Este desempenho pode ser relacionado às diferenças nas densidades de energia obtidas com os métodos de fotoativação utilizados

Influência de diferentes métodos de fotoativação na contração de polimerização linear e no módulo de elasticidade de resinas compostas e do fator-C na microinfiltração marginal / Influence of different light-curing methods on the linear polymerization contraction and elastic modulus of resin composite materials, and of C-factor on marginal microleakage

O objetivo desse estudo foi analisar a contração de polimerização linear (CP) e o módulo de elasticidade (ME) das resinas compostas Filtek A110/3M-ESPE (A), Durafill VS/Heraeus Kulzer (D), Heliomolar/Ivoclar-Vivadent (H), Heliomolar HB/Ivoclar-Vivadent (HB), Filtek Z250/3M-ESPE (Z), Filtek P60/3M-ESPE (P), Point 4/SDS-Kerr (P4) e Pyramid Dentin/Bisco (PD), variando o método de fotoativação (MF), e verificar a influência de diferentes fatores de configuração cavitária (fator-C) na microinfiltração marginal (MM). Para o teste de CP, um cilindro de resina composta foi inserido entre duas placas de vidro fixadas ao extensômetro de uma máquina de ensaios universal. Três MF, com mesma densidade de energia (24J/cm2), foram empregados: convencional (600mW/cm2 x 40s), alta intensidade (1000mW/cm2 x 24s) e softstart (200mW/cm2 x 15s + 600mW/cm2 x 35s). Quando da fotoativação, a aproximação das placas decorrente da CP foi registrada por 15min. O ME foi medido por meio de um teste de flexão no equipamento Dynamic Mechanic Thermal Analyzer (DMTA), no intervalo de temperatura de 25 2oC a 160 2oC, sob uma tensão cíclica de 1Hz. Os corpos-de-prova (2mm x 4mm x 50mm) foram fotoativados segundo os métodos já citados, sendo também incluída uma variável de baixa intensidade (200mW/cm2 x 15s). Os dados de CP e ME foram submetidos à análise de variância e ao teste de Tukey (5 por cento). O método softstart levou aos menores valores de CP (p < 0,05). As resinas compostas P4 e H apresentaram respectivamente, a maior e a menor CP (p < 0,05). A resina PD apresentou o segundo maior valor de CP comparada às demais resinas (p < 0,05). A variável de baixa intensidade levou aos menores valores de ME (p < 0,05). Entre os MF empregados, não houve diferença nos valores de ME. As resinas P, Z e PD apresentaram os maiores valores de ME (p < 0,05), sendo as duas primeiras semelhantes entre si (p=0). A resina D mostrou o menor ME, seguida das resinas A, H e HB e estas, da P4

Avaliaçäo de propriedades mecânicas de diferentes resinas compostas / Evaluation of the mechanical properties of different composite resins

Este estudo avaliou propriedades mecânicas de resinas compostas. Foram avaliadas as resinas ALERT, Filtek P60, Surefil e TPH. As propriedades avaliadas foram: resistência flexural (RF), módulo de elasticidade (ME) e dureza Vickers (DV) de acordo com as normativas internacionais (1,5). Os resultados demostraram que a resina Filtek P60 obteve os maiores valores de RF e DV, diferentes apenas para a ALERT (p<0,05). Em relaçäo ao ME, a ALERT obteve valores maiores em relaçäo aos outros materiais. Conclui-se que, apesar das diferenças, todos os materiais poderiam ser indicados em dentes posteriores