Effect of infiltrants composition and pre-heating on physical properties and penetration in initial enamel caries lesions

Author(s)

Lívia Aguilera Gaglianone

• Document type: Doctoral Thesis
• Press: Piracicaba, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Odontologia de Piracicaba
• Defense date: 2014-10-31

Examining board members

Giselle Maria Marchi; Maria Beatriz Freitas D'Arce; William Cunha Brandt; Vanessa Cavalli; Marcelo Giannini

• Advisor: Giselle Maria Marchi

Abstract

The aim of the present study was to evaluate the composition of infiltrant blends and the pre-heat effect on degree of conversion (DC), physical properties and penetration depth into enamel white spot caries lesions. Groups were set up as follows: [commercially available product Icon®]; [INF 1 - 25% BisEMA, 75% TEGDMA]; [INF 2 - 25% BisEMA, 65% TEGDMA, 10% etanol]; [INF 3 - 25% BisEMA, 65% TEGDMA, 10% HEMA]; [INF 4 - 100 % TEGDMA; INF 5 - 90% TEGDMA, 10% etanol]; [INF 6 - 90% TEGDMA, 10% HEMA]; and each one of these resins was tested under different temperature conditions (25°C and 55°C). DC (n=3) was measured using infrared spectroscopy and calculated by comparing the spectra from samples before and after light activation (LED Bluephase 5i ¿ Ivoclar Vivadent, 1000 mW/cm2, for 60 s). For water sorption (WS) and solubility (SL) test, the same DC samples (n=3) were subjected to water degradation method. After desiccation, polymerized samples were initially weighed (m1), stored in distilled water for 7 days (m2), and, after further drying, a constant mass (m3) were obtained. For the mechanical test (elastic modulus - E / flexural strength - FS), ten bar shaped specimens (7 mm X 2 mm X 1 mm) were prepared to be tested using the three-point flexural test, at a crosshead speed of 0.5 mm/min. Unpolymerized infiltrants contact angle in relation to a polished solid surface were obtained using a goniometer. Penetration depth into artificial enamel white spot caries lesions was evaluated using dual fluorescence confocal microscopy (rodhamine and sodium fluoroscein). All data were subjected to 2-way ANOVA and Tukey¿s test, and the significance level was set at a = 0.05. Pre-heated condition presented no influence in E and FS. Higher E values were attributed to INF3 while low ones were obtained by INF 5. At 25oC, DC did not reach 50% of conversion for all resins tested, but, with the pre-heating, all DC increased to more than 60%. There was significant WS reduction at 55oC. Analysing SL, INF 5 (TEGDMA + etanol) presented high values, and low means were found for heated Icon. Most of the groups were associated to increased contact angle, at 55oC. In contrast, the presence of HEMA led to a decrease of this parameter after material pre-heating. Finally, there was no statistical difference between temperatures for penetration depth. TEGDMA-based material (INF 4) presented more homogeneous penetration whereas Icon was associated to shallow infiltration. It can be concluded that the increase of infiltrant¿s temperature, prior polymerization step, was able to affect some of the evaluated properties (mainly DC and WS/SL). Overall, this approach was mostly beneficial for blends containing hydrophobic monomers (AU)

• FAPESP's process: 11/22114-2 - Effect of low viscosity resins composition and pre-heating on degree of conversion, mechanical properties and influence on penetration in inicial enamel caries lesions.
• Grantee: Lívia Aguilera Gaglianone
• Support Opportunities: Scholarships in Brazil - Doctorate