In vitro analysis of riboflavin-modified, experimental, two-step etch-and-rinse dentin adhesive: Fourier transform infrared spectroscopy and micro-Raman studies

Abstract

To modify two-step experimental etch-and-rinse dentin adhesive with different concentrations of riboflavin and to study its effect on the bond strength, degree of conversion, along with resin infiltration within the demineralized dentin substrate, an experimental adhesive-system was modified with different concentrations of riboflavin (m/m, 0, 1%, 3%, 5% and 10%). Dentin surfaces were etched with 37% phosphoric acid, bonded with respective adhesives, restored with restorative composite–resin, and sectioned into resin–dentin slabs and beams to be stored for 24 h or 9 months in artificial saliva. Micro-tensile bond testing was performed with scanning electron microscopy to analyse the failure of debonded beams. The degree of conversion was evaluated with Fourier transform infrared spectroscopy (FTIR) at different time points along with micro-Raman spectroscopy analysis. Data was analyzed with one-way and two-way analysis of variance followed by Tukey's for pair-wise comparison. Modification with 1% and 3% riboflavin increased the micro-tensile bond strength compared to the control at 24 h and 9-month storage with no significant differences in degree of conversion (P<0.05). The most predominant failure mode was the mixed fracture among all specimens except 10% riboflavin-modified adhesive specimens where cohesive failure was predominant. Raman analysis revealed that 1% and 3% riboflavin adhesives specimens showed relatively higher resin infiltration. The incorporation of riboflavin in the experimental two-step etch-and-rinse adhesive at 3% (m/m) improved the immediate bond strengths and bond durability after 9-month storage in artificial saliva without adversely affecting the degree of conversion of the adhesive monomers and resin infiltration.

The effect of dentin pre-treatment with activated riboflavin on the bond strength of a two-step self-etch adhesive system

“…21 In contrast to our findings, some studies have reported that dentin surface pretreatment with UVA-activated RF increased μTBS immediately and after storage in comparison with a control group. 9,16,21,32 The difference between our results and those of previous studies may be attributed to the duration of exposure and the source of light used for activation, as well as the storage conditions.…”

“…[13][14][15] Increasing the cross-linking of collagen fibrils before applying an adhesive agent may increase bonding durability. 2,16 Despite the promising results of the application of cross-linkers, there are still some problems which need to be solved before they can be extensively used in clinical situations. For instance, glutaraldehyde is effective 13 as a collagen cross-linker, but is also toxic.…”

“…19 When RF is photoactivated with ultraviolet A light (UVA), it produces free radicals and reactive oxygen species (ROS) such as superoxide anion (O 2 − ) and hydroxyl radical (˙OH). 20 Some studies have shown that in E&R adhesive systems, cross-linking dentin collagen with the use of RF/UVA increases the immediate bond strength, decreases nanole-akage, 9,16,21 stabilizes the adhesive interface, and inhibits the activity of dentin MMPs. 9,22 Furthermore, using RF to change the dentin collagen matrix stabilizes the fibrillar collagen network, promotes resin infiltration and hybrid layer formation 23 and improves the mechanical properties and mechanical stability of a demineralized dentin substrate against hydrolytic or collagenolytic degradation.…”

Graphene oxide nano-filler based experimental dentine adhesive. A SEM / EDX, Micro-Raman and microtensile bond strength analysis

“…Currently, Raman spectrum is considered as the tool to evaluate the structural information of hybrid layer, minute biochemical alteration and depth of resin infiltration in the hybrid layer. 17 Nevertheless, limited correlative studies were performed through microtensile bond strength, Energy Dispersive X-Ray Spectroscopy (EDX) and Micro-Raman spectroscopy. In addition, the interaction between GO and hybrid layer is still unknown despite the reported significance of GO.…”

Polymerization capability of simplified dental adhesives with camphorquinone, phenyl-propanedione and bis-alkyl phosphine photoinitiators

“…Bisphenol A glycidyl dimethacrylate (BisGMA) and hydroxyethyl methacrylate (HEMA) (60:40 wt%) (Sigma-Aldrich, St. Louis, MO, USA) were mixed with ethanol (30 wt%) 17 . Then, five different materials were generated with the addition of these various photoinitiators: CQ (1 mol%), CQ/PPD (0.5/0.5 mol%), CQ/BAPO (0.5/0.5 mol%), PPD (1 mol%), and BAPO (1 mol%).…”