Thermo-mechanical degradation of composite restoration photoactivated by modulated methods-a SEM study of marginal and internal gap formation.
Acta Odontol Scand
; 71(5): 1341-7, 2013 Sep.
Article
em En
| MEDLINE
| ID: mdl-23445245
OBJECTIVE: To evaluate the influence of thermal-mechanical degradation on superficial and internal gap formation of composite restorations photoactivated using modulated methods. MATERIALS AND METHODS: An experimental composite was prepared using a resin matrix containing 65wt% Bis-GMA and 35wt% TEGDMA. Camphorquinone (0.5wt%) and dimethylaminoethyl-methacrylate (0.5wt%) were dissolved in the resin as a photo-initiator system and 65wt.% silanized glass fillers were added to the matrix. Ground buccal surfaces of bovine lower incisors were used to make 160 preparations (3 mm × 3 mm × 2 mm in depth). An adhesive system (Adper Single Bond 2) was applied and the specimens were assigned into 16 groups (n = 10), according to the photoactivation method [high intensity (HI), low intensity (LI), soft-start (SS) and pulse-delay (PD)] and the degradation protocol [(control/no degradation; thermal cycling (TC); mechanical loading (ML); thermo-mechanical loading (TC+ML)]. Marginal and internal interfaces of bonded restorations were replicated in epoxy resin and analyzed by SEM. Gaps were expressed as a percentage of the total length of the margins. Data were submitted to 2-way ANOVA and Tukey's test (α = 0.05). RESULTS: For the control group no significance was noted among the photoactivation methods. TC had no effect in gap formation. ML and TC+ML increased the incidence of superficial gaps for both HI and SS groups as well as increased the internal gaps for all groups. CONCLUSION: Although photoactivation methods do not influence gap formation at first, composite restoration photoactivated by low intensity or modulated methods showed improved resistance to thermo-mechanical degradation. Mechanical loading is determinant for interfacial degradation of composite restorations, while thermal cycling has no effect on gap formation.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Microscopia Eletrônica de Varredura
/
Resinas Compostas
Limite:
Animals
Idioma:
En
Revista:
Acta Odontol Scand
Ano de publicação:
2013
Tipo de documento:
Article
País de afiliação:
Brasil
País de publicação:
Reino Unido