RESUMEN
Polymer networks are considered to be largely affected by water and chemical absorption from environment. Objective: The aim of this study was to evaluate the hygroscopic expansion of bulk-fill composite. Material and Methods: Fifteen disks (5 in each group) with different thickness(4mm/2mm) of Tetric N-Ceram Bulk Fill composite(TB) and Tetric N-Ceram composite(TN) were made according to the manufacturer's instruction and stored in deionized water. The length of each specimen was recorded using a digital micrometer at baseline and at the end of 24 h, 1, 2, 4, 12 weeks intervals. Repeated measure ANOVA and Tukey HSD were used to determine the effect of variables. At 12 weeks, the mean hygroscopic expansion after water immersion ranged between 0. 33±0.09mm for TN to 0.41±0.07mm for TB with 2mm thickness. Repeated measure ANOVA revealed a significant increase in hygroscopic expansion over time (P <0.05). Results: The results indicated that at 24hours and 2weeks there was a significant difference among TN and TB with 4mm thickness (p=0.007 and p=0.023, respectively). The other differences were not significant. Hygroscopic expansion affected by the type of composite and the passing of time. Conclusion: The results showed that the time taken to reach stabilization in hygroscopic expansion was shorter for TN in comparison with TB. For 2mm thickness equilibrium was attained earlier. (AU)
Considera-se que as redes de ligações intrínsecas de polímeros são amplamente afetadas pela absorção de água e produtos químicos do meio ambiente. Objetivo: O objetivo deste estudo foi avaliar a expansão higroscópica do compósito bulk-fill. Material e Métodos: Quinze discos (5 em cada grupo) com diferentes espessuras (4mm / 2mm) de compósito Tetric N-Ceram Bulk Fill (TB) e Tetric N-Ceram (TN) foram confeccionados de acordo com as instruções do fabricante e armazenados em água deionizada. O comprimento de cada espécime foi registrado usando um micrômetro digital no início e no final de 24 h, 1, 2, 4, 12 semanas de intervalo. O teste de medidas repetidas ANOVA e Tukey foram usados para determinar o efeito das variáveis. Às 12 semanas, a expansão higroscópica média após imersão em água variou entre 0,33 ± 0,09mm para NT a 0,41 ± 0,07mm para TB com 2mm de espessura. ANOVA revelou um aumento significativo na expansão higroscópica ao longo do tempo (P <0,05). Resultados: Os resultados indicaram que às 24h e 2 semanas houve diferença significativa entre TN e TB com 4mm de espessura (p=0,007 e p=0,023, respectivamente). As outras diferenças não foram significativas. A expansão higroscópica foi afetada pelo tipo de compósito e pelo tempo. Conclusão: Os resultados mostraram que o tempo necessário para alcançar a estabilização na expansão higroscópica foi menor para TN em comparação com TB. Para 2 mm de espessura o equilíbrio foi atingido mais cedo. (AU)
Asunto(s)
Resinas Compuestas , Polimerizacion , AguaRESUMEN
Objective: Despite great advances made in dental composite resins, their use is associated with some concerns regarding their mechanical properties such as their flexural strength. Considering the introduction of different composite resins into the market, there is a need to compare their mechanical properties and particularly flexural strength. This study aimed to compare the flexural strength of 12 types of composite resins
Methods: In this in-vitro experimental study, 120 specimens were fabricated of 12 different composite resins using a mold according to ISO 4049 standard. Samples were then subjected to 3- point flexural test in Surface Mount Techniligy [SMT] device with a crosshead speed of 0.75+/-0.25 mm/min. Obtained data were analyzed using one-way ANOV A and Scheffe's test. P<0.05 was considered statistically significant
Results: Flexural strength of understudy composite specimens was significantly different [P<0.0001]. Pair-wise comparison of groups revealed significant differences between the following composite resins: Artemis and Swiss TEC [P<0.004], Venus and Swiss TEC [P<0.02], Charisma and Swiss TEC [P<0.0001], Charisma and Spectrum [P<0.03], Artemis and Z250 [P<0.0001], Synergy and Z250 [P<0.007], Point 4 and Z250 [P<0.02], CermaX and Z250 [P<0.02], Venus and Z250 [P<0.001], Charisma and Z250 [P<0.0001] and Charisma and Tetric Ceram [P<0.03]
Conclusion: All under study composite resins had the minimum required flexural strength according to ISO 4049 standard. Their flexural strength ranged from 134.0 MPa for Charisma to 263.0 MPa for Z250. Use of Tetric Ceram, Spectrum, Swiss TEC and Z250 is recommended for restorations in high stress-bearing areas due to their high flexural strength