Objectives This study investigated the curing efficiency, the extent of atmospheric oxygen inhibition to the polymerization reaction and the mechanical properties of a new resin-infiltration system for caries treatment. Methods The curing efficiency was estimated by measuring the percentage degree of cure (%DC) of thin resin films (h: 150 μm, Ø: 5 mm, n = 3), 10 min after 40 s exposure to a quartz halogen bulb (750 mW/cm2) light curing unit (Optilux 501, Demetron/Kerr, USA), in the absence of O2, by micro ATR-FTIR spectroscopy. The extent of O2 inhibition on resin film setting (width in μm) was assessed by transmission optical microscopy on thin films (h: 150 μm, Ø: ∼7 mm, n = 5) placed between two transparent cover slips and exposed to air from lateral sites. For each sample the extent of inhibition was measured at 5 different locations. The mechanical properties were tested employing Instrumented Indentation Testing according to ISO 14577:2002. Resin specimens (h: 2 mm, Ø: 10 mm, n = 5) were prepared employing cylindrical teflon moulds enclosed in transparent matrix strips and glass slides as before. The measurements were performed employing a Vickers indenter attached to a universal hardness testing machine (ZHU2.5/Z2.5 plus test Xpert software, Zwick/Roell, Ulm, Germany). The parameters tested were Martens Hardness (MH), Vickers Hardness (VHN), Indentation Elastic Modulus (EIT) and elastic to total ratio of indentation work (ηIT). For all these tests, specimens of a conventional light-curing bonding resin (HB-Heliobond, Ivoclar-Vivadent, FL) prepared as above were used as control. Student t-test was used to identify statistically significant differences between the two materials in the parameters tested (a: 0.05). Results The results of the materials tested were: (a) [% DC]; IC: 57.4 ± 1.5, HB: 59.8 ± 2.4, (b) [Width of O2 inhibition/μm]; IC: 33.1 ± 6.5, HB: 23.6 ± 4.4, (c) [MH/N/mm2] IC; 116 ± 16, HB: 261 ± 35, (d) [VHN]; IC; 15.4 ± 2.5, HB: 22.1 ± 1.8, (e) [EIT/(GPa)]; IC; 2.3 ± 0.4, HB: 7.5 ± 0.5, and (g) [ηIT (%)] IC; 50.3 ± 3.4, HB: 35.1 ± 1.9. The IC presented no significant difference in terms of % DC, higher thickness of the inhibited layer, lower MH, VHN, EIT and greater ηIT values than HB. Conclusions and Clinical Significant The resin-infiltrating system for incipient caries treatment demonstrated the same curing efficiency with a conventional unfilled bonding resin, but exhibited higher extent of oxygen inhibition, lower hardness, lower elastic modulus and higher plastic to elastic indentation energy. © 2015 Elsevier Ltd.
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