Dentin Bond Integrity of Hydroxyapatite Containing Resin Adhesive Enhanced with Graphene Oxide Nano-Particles—An SEM, EDX, Micro-Raman, and Microtensile Bond Strength Study

Abstract

The aim was to synthesize and characterize an adhesive incorporating HA and GO nanoparticles. Techniques including scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX), micro-tensile bond strength (μTBS), and micro-Raman spectroscopy were employed to investigate bond durability, presence of nanoparticles inside adhesive, and dentin interaction. Control experimental adhesive (CEA) was synthesized with 5 wt% HA. GO particles were fabricated and added to CEA at 0.5 wt% (HA-GO-0.5%) and 2 wt% GO (HA-GO-2%). Teeth were prepared to produce bonded specimens using the three adhesive bonding agents for assessment of μTBS, with and without thermocycling (TC). The adhesives were applied twice on the dentin with a micro-brush followed by air thinning and photo-polymerization. The HA and GO nanoparticles demonstrated uniform dispersion inside adhesive. Resin tags with varying depths were observed on SEM micrographs. The EDX mapping revealed the presence of carbon (C), calcium (Ca), and phosphorus (P) in the two GO adhesives. For both TC and NTC samples, HA-GO-2% had higher μTBS and durability, followed by HA-GO-0.5%. The representative micro-Raman spectra demonstrated D and G bands for nano-GO particles containing adhesives. HA-GO-2% group demonstrated uniform diffusion in adhesive, higher μTBS, adequate durability, and comparable resin tag development to controls.

Influence of Different Conditioning Treatments on the Bond Integrity of Root Dentin to rGO Infiltrated Dentin Adhesive. SEM, EDX, FTIR and MicroRaman Study

“…The rGO nanoparticles, when observed on the SEM, revealed flake-shaped morphology, and this finding is consistent with several previous studies [ 25 , 32 ]. In general, the reduction process to yield GO nanoparticles produces flake-shaped sharp-edged sheets due to the presence of oxygen groups in the oxide sheets [ 33 ].…”

“…In general, the reduction process to yield GO nanoparticles produces flake-shaped sharp-edged sheets due to the presence of oxygen groups in the oxide sheets [ 33 ]. The Micro-Raman representative spectra of rGO-5% adhesive demonstrated two vibrational bands; the D band was seen at 1341 cm −1 whereas the G band was perceived at 1584 cm −1 , and this particular finding was similar to a previous study [ 25 ]. For the materials having graphite, the observation of two bands is common as they are created due to the shift in energy caused by the laser excitation [ 34 ].…”

“…Previously, the addition of various nano-inorganic fillers in the adhesive has yielded very positive outcomes [ 29 , 30 ]. Notably, the incorporation of GO and rGO filler nanoparticles inside the composite resin and adhesive has been shown to improve the adhesive’s mechanical properties in the past [ 22 , 25 ]. Considering the advantageous properties of rGO filler nanoparticles, we also wanted to explore the effect of their addition on various properties of the adhesive.…”

“…The EA was synthesized following the prior recommendations of Ye et al [ 24 ], and the steps of the preparation of EA mentioned in our previous study [ 25 ] were precisely replicated.…”

“…To protect the notion that precise quantity of rGO nanoparticles were incorporated in the EA, these particles were first weighed up (in milligrams), and their volume was then computed (in milliliters). The subsequent formula was used to calculate weight/volume % ( w/v %) for the EA group, as suggested formerly by AlFawaz et al [ 25 ]: w / v % = weight of solute/volume of solution × 100 …”