This study was conducted to evaluate the effect of biphasic calcium phosphate (BCP) coated with reduced graphene oxide (rGO) as bone graft materials on bone regeneration. The rGO-coated BCP bone graft material was fabricatied by mixing rGO and BCP at various concentrations. The surface charge of rGO-coated BCP was measured to be −14.43 mV, which formed a static electrostatic interaction. Cell viabilities were significantly diminished at higher concentrations of ≥100 μg/mL. The calvarial defects of 48 rats were implanted rGO-coated BCPs at a weight ratio of 2:1000 (rGO2), 4:1000 (rGO4), and 10:1000 (rGO10), repectively. BCP was used as a control group. The micro-CT and histological analysis were performed to evaluate new bone formation at 2 and 8 weeks after surgery. The results showed that the new bone volume (mm³) was significantly higher in the experimental groups than in the control group. Histological analysis showed that new bone areas (%) were significantly higher in the rGO2 and rGO10 than in the control, and significantly higher in rGO4 than in the rGO2 and rGO10. Conclusively, the rGO-coated BCP was found to be effective on osteogenesis and the concentration of the composite was an important factor.

The aim of this in-vitro research was to evaluate the microtensile bond strength in the newly introduced PEKK tooth post with various surface treatments and resin cements. A fiberglass tooth post was included in order to compare it with PEKK as a possible post material. The microtensile bond strengths of the fiberglass post (FRC Postec Plus) and the PEKK post (Pekkton^®) were tested using three kinds of self-adhesive resin cements (G-CEM LinkAce, Multilink Speed, and RelyX U200) and one self-etching resin cement (PANAVIA F2.0). The surface treatments of the fiberglass posts were processed according to the manufacturer’s recommendations (F1, application of 37% phosphoric acid etching gel and silanization). For the PEKK post groups, various surface treatments were performed like no surface treatment (P1), sandblasting (P2), silica-coating and silanization (P3), and sandblasting with a composite primer (P4). In the surface treatment, PEKK posts with silica coating and silane treatment (P3) showed a significantly higher microtensile bond strength (mean MPa: 18.09, p < 0.05). The highest microtensile bond strength was shown when the PEKK posts were treated with a silica coating and silane treatment and cemented with RelyX U200 (mean MPa: 22.22). The PEKK posts with surface treatments of silica-coating and silanization or sandblasting displayed superior microtensile bond strengths (mean MPa: 18.09 and 16.25, respectively) compared to the conventional fiberglass posts (mean MPa: 14.93, p < 0.05).

Seo YH, et al. J Adv Prosthodont. 2016 Aug;8(4):313-320. https://doi.org/10.4047/jap.2016.8.4.313

This study compared shear bond strength (SBS) of six self-adhesive resin cements (SARC) and one resin-modified glass ionomer cement (RMGIC) to zirconia before and after thermocycling. The cylinder shape (Φ 2.35 mm × 3 mm) of six SARCs (G-CEM LinkAce (GLA), Maxcem Elite (MAX), Clearfil SA Luting (CSL), PermaCem 2.0 (PM2), Rely-X U200 (RXU), Smartcem 2 (SC2)) were bonded to the top surface of the zirconia specimens with light-curing. RMGIC (Fujicem (FJC)) was bonded to the specimens with self-curing. The shear bond strength of all cemented specimens was measured with universal testing machine. Half of the specimens were thermocycled 5000 times before shear bonding strength testing. Fractured surfaces were examined with a field-emission SEM (10,000×) and analyzed by energy dispersive x-ray analysis. MAX, PM2, SC2 group without thermocycling and GLA, MAX, PM2 group with thermocycling showed adhesive failure, but GLA, CSL, RXU, FJC group without thermocycling and SLC, RXU, SC2, FJC group with thermocycling indicated cohesive failure. Within the limitation of this study, All of SARCs except MAX demonstrated higher bond strength than that of RMGIC regardless of thermocycling. Also, SARC containing MDP monomers (CSL) retained better bonds than other cements.

Yun MJ, et al. J Adv Prosthodont. 2017 Feb;9(1):1-13. https://doi.org/10.4047/jap.2017.9.1.1

The aim of this study was to evaluate the wear properties of resin teeth with different opposing dental restorative materials. One type of resin tooth (Trubyte Biotone) was tested against six types of restorative materials including type III gold alloy (GO), monolithic zirconia (MZ), lithium disilicate glass ceramic (LD), nickel–chromium alloy (NC), feldspathic ceramic (FC), and steatite (ST). Two-body wear tests were performed under a vertical load of 5 kgf and thermo-cycling at 5/55 °C with a total of 120,000 cycles. The wear amount was quantified by measuring the volume loss of the resin teeth and the vertical substance loss of the opposing materials using three-dimensional images. The FC group showed a significantly greater amount of wear of the resin teeth, followed by the ST, NC, LD, MZ, and GO groups. The GO group showed significantly less wear of resin teeth than the other groups. There were no statistically significant differences in the wear of opposing restorative materials between groups. Within the limits of this study, it is recommended that zirconia, rather than feldspathic ceramic, should be used for restorations in the esthetic zone, and gold alloy should be used for areas with little or no esthetic demand.