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% was adopted for all analyses. RESULTS: The post-cure treatments increased the hardness of conventional composites (

Diferentes métodos para restauração de canais alargados: análise da resistência de união e resistência à fratura

O objetivo deste estudo foi comparar diferentes técnicas para restauração de canais alargados, através de ensaios de resistência à fratura e resistência de união. Sessenta dentes humanos unirradiculares foram distribuídos nos seguintes grupos: (EC) pino de fibra de vidro n°1 (Exacto Cônico, Angellus); (ECA) pino de fibra de vidro n°1 (Exacto Cônico, Angellus) juntamente com dois pinos acessórios (Reforpin, Angellus); (WP) pino de fibra de vidro n°4 (White Post, FGM). Após remoção da porção coronária a 14mm do ápice, os condutos radiculares foram preparados com a broca do sistema de pinos White Post n°4 (FGM), as raízes foram embutidas e os pinos, cimentados (Rely-X Arc). Para o teste de resistência à fratura, núcleos de preenchimento em resina composta foram confeccionados (n=10). Para o teste de resistência de união por push-out, as raízes (n=10) foram fatiadas com 1mm de espessura. Os testes de fratura e de push-out foram realizados na máquina de ensaios universal (EMIC DL 2000) com velocidade de 0,5mm/min. Os dados obtidos foram submetidos à Análise de Variância, sendo encontradas diferenças estatísticas significantes (p<0,001). O grupo WP levou a maiores valores de resistência à fratura do que o grupo EC (p<0,05), mas não foi diferente do grupo ECA. Com relação ao padrão de fratura, o grupo EC levou ao maior número de fraturas radiculares e o grupo WP, a nenhuma. Apenas 13,33% das fraturas foram radiculares, sendo todas favoráveis. Para a resistência de união, o grupo EC levou a menores valores do que os grupos WP e ECA, e este último, menores valores do que o grupo WP (p<0,05). A resistência de união da porção apical foi menor do que a da porção cervical e média dos condutos radiculares (p<0,05). Conclusão: Pinos de fibra de vidro mais adaptados ao conduto radicular levam a maiores valores de resistência de união e à fratura, sendo que o emprego de pinos de menor diâmetro predispõe à fraturas radiculares. O uso de pinos acessórios com pinos desadaptados também foi eficiente em aumentar a resistência à fratura e de união, quando comparados ao grupo que utilizou pinos desadaptados ao condutoThe aim of this study was to compare different techniques proposed for restoration of canals enlarged, when analyzing the fracture resistance and bond strength. Sixty single-rooted human teeth were divided into three groups: (EC) fiberglass posts nº 1 (Exacto Cônico, Angellus); (ECA) fiberglass posts nº 1 (Exacto Cônico, Angellus) with two accessory posts (Reforpin, Angellus) and (WP) fiberglass posts nº 4 (White Post, FGM). After removing the coronal portion of the 14mm limit amelo-cemental, the root canals were prepared with the drill post system White Post 4 (FGM), the roots were embedded and the posts were cemented (Rely X-Arc). To test the resistance to fracture filling cores in composite were prepared (n = 10). To test the push-out bond strength, the roots (n = 10) were sliced with 1mm thickness. The fracture test and push-out were performed in a universal testing machine (EMIC DL 2000) with a speed of 0.5 mm / min. Data were subjected to ANOVA and statistically significant differences were found (p<0,001). The WP group led to higher fracture resistance than the EC group (p <0.05) but was not different from the ECA group. With respect to fracture pattern, the EC group had the highest number of root fractures and the WP group had none. Only 13.33% were root fractures, none for WP group, all favorable . The bond strength of the EC group led to lower values than the groups WP and ECA, and the latter, lower than the WP group (p<0,05). The bond strength of the apical portion was lower than that of the cervical portion of root canals (p<0,05). Conclusion: fiberglass posts more suited to root canal lead to higher bond strength and fracture, and the use of more maladaptive posts predisposes to root fractures. The use of one main post with two accessory posts also was effective in increasing the fracture resistance and bond strength, when compared with the group that used pins maladjusted72 f