Influence of solvent evaporation on ultimate tensile strength of contemporary dental adhesives

Atsushi Kameyama,Takashi Muramatsu,Masashi Kojima,Akiko Haruyama,Yuichi Nakazawa,Hirokazu Abo

doi:10.1186/s40563-019-0120-0

Atsushi Kameyama, Takashi Muramatsu + Show 4 more

Open Access

https://doi.org/10.1186/s40563-019-0120-0

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Abstract

The aim of this study was to evaluate the influence of solvent evaporation on the ultimate tensile strength (UTS) of commercial adhesives. Two 1-step (OptiBond All-In-One and G-Premio Bond) and two 2-step (Clearfil SE Protect, OptiBond XTR) adhesives were selected. Two bottles of each adhesive were opened and stored at 37 °C in a dry oven with silica gel shielded from light for 2 weeks (“Desiccated”). Two unopened bottles were stored at room temperature (“Original”). After 2 weeks, the adhesives were used to fill an hour-glass shaped, metallic matrix mold and light-cured. Samples were weighed, and then immersed in a 37 °C water bath for 1 h or 7 days. The UTS of each sample was then measured at a cross-head speed of 1 mm/min (n = 10). The UTS for the Clearfil SE Protect was higher in the “Original” than “Desiccated” samples (p < 0.05). For the OptiBond XTR, no significant difference was found between the ‘Original’ and ‘Desiccated’ samples (p > 0.05). Neither of the two “Original” 1-step samples could be hardened, even after light-curing, yet the ‘Desiccated’ OptiBond All-In-One samples obtained high UTS values. Both OptiBond All-In-One and Clearfil SE Protect had an increase in weight after the 7-day immersion in water. In conclusion, residual solvent reduces the mechanical strength of the adhesive. The hydrophilicity of the adhesive resin might also affect its mechanical strength.

Highlights

Dental practice has been significantly revolutionized by the development of composite filling materials [1]
The mechanical property was measured in terms of ultimate micro-tensile strength (UTS), a variable that is frequently used to evaluate the performance of an adhesive in terms of its tensile bond strength with the local tissue [14, 15], which differs to the Young’s modulus or the nano-indentation value [16]
The Clearfil SE Protect contains the same proprietary self-etching, light-curing technology as the “gold-standard” Clearfil SE Bond, which has been well described in the literature [17], but the Clearfil SE Protect has some additional ingredients: an MDPB antibacterial monomer in the self-etching primer, and sodium fluoride and hydroxyethyl methacrylate (HEMA) in the adhesive agent [18, 19]

Summary

Introduction

Dental practice has been significantly revolutionized by the development of composite filling materials [1]. These materials satisfy the esthetic demands of the patients, and allow for easy manipulation and contouring of the material to replace or fill the lost or damaged tooth. A resin-based composite filling material can be used routinely in the clinic to restore caries and worn structures, close diastemas, and remodel malformed or fractured teeth [2]. It is essential that a durable bond is formed between the adhesive and the dental tissue during direct composite restoration. Adhesive resin monomers should properly integrate and polymerize with the demineralized dental tissue

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