Effect of self-etch adhesives on the internal adaptation of composite restoration: a CP-OCT Study

Abstract

Despite improvements in dental adhesive materials, internal adaptation remains a challenge in bonded restorations. The aim of this study was to compare microgaps and internal floor adaptation between two different self-etch adhesives in class-V cavities using cross-polarization optical coherence tomography (CP-OCT). In this in vitro study, standardized round class-V cavities were prepared in 20 non-carious human upper central incisor teeth. They were randomly divided into two groups, TN and SE, with each group receiving a different dental adhesive. In TN group, the adhesive used was all-in-one Tetric N-Bond Self-Etch (TN; Ivoclar/Vivadent, Liechtenstein), while SE group was bonded with two-step self-etch Clearfil SE Bond 2 adhesive (SE; Kuraray Noritake Dental Inc, Japan). The prepared cavities were restored with flowable composite and then stored in distilled water for 24 h. Next, they were immersed in silver nitrate, followed by immersion in a photo-developing solution. Optical comparison was carried out by CP-OCT to assess microgaps and composite adaptation at the cavity floor. A Mann-Whitney test was applied to the data, which showed a statistically significant difference in composite adaptation among the two groups (p < 0.001) with the SE group showing superior adaptation. CP-OCT is a reliable tool for non-invasive imaging that gives an insight into composite performance. Better adaptation was found with the two-step self-adhesive for the composite used in this study.

Tomographic Evaluation of the Internal Adaptation for Recent Calcium Silicate-Based Pulp Capping Materials in Primary Teeth

“…The CP-OCT system was fitted with an adjustable probe that projects a high scanning rate diode laser (30 kHz) and a continuous wavelength centered about 1310 nm, with a wavelength range of 100 nm. The lateral resolution for axial resolution was about 30 μ m and 12 μ m, while the sensitivity of the device was 95 dB, and the output power of the probe was within the safety limits established by the American National Standard Institute [ 35 , 40 ].…”

Interfacial Gap Assessment of Two Dental Adhesives and Polymer-Based Resin Composites Using Cross-Polarization Optical Coherence Tomography

“…Although many reports presented the superior performance of two-step self-etch adhesives over one-step [24,36,37], the obtained results showed no significant difference between SE-ESA and PL-ESA groups. It seems that the co-polymers compatibility between the bonded resins in PL-ESA had played a significant role in improving PL performance and gap reduction under the restoration.…”

“…Upon CP-OCT imaging, areas with heavy accumulation of silver scattered the light into different direction reflection and produced diffuse reflections (bright pixels). While the areas that devoid of silver particles were not showing any considerable reflection in a form of bright pixels [24].…”

“…Hence, to broaden the application of CP-OCT, immersion in metallic contrasting agent to intensify the gap appearance was necessary to improve the gap reflection under the composite restoration [24].…”

“…Although, these adhesives have a direct influence on composite adaptation during cavity restoration, they are undetectable by conventional invasive imaging techniques. Recent studies showed the usefulness of cross-polarization OCT (CP-OCT) in measuring gaps under composite restorations [22][23][24].…”