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Pre-heating mitigates composite degradation
Dental composites cured at high temperatures show improved properties and higher degrees of conversion; however, there is no information available about the effect of pre-heating on material degradation. OBJECTIVES: This study evaluated the effect of pre-heating on the degradation of composites, bas...
Autores principales: | , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Faculdade de Odontologia de Bauru da Universidade de São Paulo
2015
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4716695/ https://www.ncbi.nlm.nih.gov/pubmed/26814459 http://dx.doi.org/10.1590/1678-775720150284 |
Sumario: | Dental composites cured at high temperatures show improved properties and higher degrees of conversion; however, there is no information available about the effect of pre-heating on material degradation. OBJECTIVES: This study evaluated the effect of pre-heating on the degradation of composites, based on the analysis of radiopacity and silver penetration using scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS). MATERIAL AND METHODS: Thirty specimens were fabricated using a metallic matrix (2x8 mm) and the composites Durafill VS (Heraeus Kulzer), Z-250 (3M/ESPE), and Z-350 (3M/ESPE), cured at 25°C (no pre-heating) or 60°C (pre-heating). Specimens were stored sequentially in the following solutions: 1) water for 7 days (60°C), plus 0.1 N sodium hydroxide (NaOH) for 14 days (60°C); 2) 50% silver nitrate (AgNO(3)) for 10 days (60°C). Specimens were radiographed at baseline and after each storage time, and the images were evaluated in gray scale. After the storage protocol, samples were analyzed using SEM/EDS to check the depth of silver penetration. Radiopacity and silver penetration data were analyzed using ANOVA and Tukey’s tests (α=5%). RESULTS: Radiopacity levels were as follows: Durafill VS<Z-350<Z-250 (p<0.05). The depth of silver penetration into the composites ranked as follows: Durafill VS>Z-350>Z-250 (p<0.05). After storage in water/NaOH, pre-heated specimens presented higher radiopacity values than non-pre-heated specimens (p<0.05). There was a lower penetration of silver in pre-heated specimens (p<0.05). CONCLUSIONS: Pre-heating at 60°C mitigated the degradation of composites based on analysis of radiopacity and silver penetration depth. |
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