Fluoride release/recharging ability and bond strength of glass ionomer cements to sound and caries‑affected dentin

Objectives: The aim of this in vitro study was to evaluate the microtensile bond strength (μTBS) of different glass ionomer cements (GICs) on sound/caries-affected dentin and to assess the fluoride release/recharging ability.Methods: After creating artificial caries lesions, teeth with sound and caries-affected dentin were assigned to be restored with one of the GICs: Ketac N100; GC Equia; GCP Glass Fill, and tested using a microtensile test. Ten of each material were prepared, and fluoride ion-release was measured at 10 different intervals. After 1.23% acidulated phosphate fluoride-gel immersion, fluoride re-release was then measured at the same intervals.Results: In sound dentin, GC Equia exhibited significantly higher μTBS value (P < 0.05). The mean μTBS of Ketac N100 to caries-affected dentin was significantly lower than the other materials (P < 0.05). All materials showed maximal fluoride release at 24 h, GC Equia released the most fluoride.Conclusion: The bond strength of GICs is affected by tooth substrate. High-viscosity GICs show higher initial fluoride release as well as greater fluoride recharge capacity.Key words: Bond strength, caries‑affected dentin, fluoride release, glass ionomer cement

Effect of Different Modes of Erbium:yttrium Aluminum Garnet Laser on Shear Bond Strength to Dentin

Objectives: The aim of this study was to evaluate the effect of different surface treatments on the shear bond strength (SBS) of resin composites to dentin using total etch dentin bonding adhesives. Materials and Methods: Sixty extracted human molars were flattened to obtain dentin surfaces. The samples were divided into three groups (n = 20): Group I: 37% phosphoric acid + optibond FL + resin composite; Group II: Erbium:yttrium aluminum garnet (Er:YAG) laser (medium short pulse [MSP] mode, 120 mJ/10 Hz) + optibond FL + resin composite; Group III: Er:YAG laser (quantum square pulse [QSP] mode, 120 mJ/10 Hz) + optibond FL + resin composite. After the specimens were prepared, the SBS test was performed at a crosshead speed of 0.5 mm/min. The fractured specimens were examined under a stereomicroscope to evaluate the fracture pattern. Statistical analyses were performed with one‑way ANOVA and Tukey’s honestly significant difference tests. One sample of treated dentin surface from each group was sputter‑coated with gold, and scanning electron microscope (SEM) images were captured. Results: Acid etching showed significantly higher SBS than the other groups (P < 0.05). However, the difference between Er:YAG MSP and QSP mode groups was not statistically significant (P > 0.05). SEM images of the acid‑etched dentin surface showed opened dentinal tubule with a regular surface, but Er:YAG MSP mode treated surface was irregular. The surface treated with Er:YAG QSP mode represented wide dentinal tubules with a clean and flat surface. Conclusion: Using different modes (MSP and QSP) of Er:YAG laser for dentin surface treatment before application of total etch adhesives is still not an sufficient alternative compared to acid etching.Keywords: Acid etching, dentin conditioning, erbium:yttrium aluminum garnetlaser, quantum square pulse mod

Fluoride release/recharging ability and bond strength of glass ionomer cements to sound and caries-affected dentin

Objectives: The aim of this in vitro study was to evaluate the microtensile bond strength (mu TBS) of different glass ionomer cements (GICs) on sound/caries-affected dentin and to assess the fluoride release/recharging ability. Methods: After creating artificial caries lesions, teeth with sound and caries-affected dentin were assigned to be restored with one of the GICs: Ketac N100; GC Equia; GCP Glass Fill, and tested using a microtensile test. Ten of each material were prepared, and fluoride ion-release was measured at 10 different intervals. After 1.23% acidulated phosphate fluoride-gel immersion, fluoride re-release was then measured at the same intervals. Results: In sound dentin, GC Equia exhibited significantly higher mu TBS value (P < 0.05). The mean mu TBS of Ketac N100 to caries-affected dentin was significantly lower than the other materials (P < 0.05). All materials showed maximal fluoride release at 24 h, GC Equia released the most fluoride. Conclusion: The bond strength of GICs is affected by tooth substrate. High-viscosity GICs show higher initial fluoride release as well as greater fluoride recharge capacity

Effect of different modes of erbium:yttrium aluminum garnet laser on shear bond strength to dentin

Objectives: The aim of this study was to evaluate the effect of different surface treatments on the shear bond strength (SBS) of resin composites to dentin using total etch dentin bonding adhesives. Materials and Methods: Sixty extracted human molars were flattened to obtain dentin surfaces. The samples were divided into three groups (n = 20): Group I: 37% phosphoric acid + optibond FL + resin composite; Group II: Erbium: yttrium aluminum garnet (Er: YAG) laser (medium short pulse [MSP] mode, 120 mJ/10 Hz) + optibond FL + resin composite; Group III: Er: YAG laser (quantum square pulse [QSP] mode, 120 mJ/10 Hz) + optibond FL + resin composite. After the specimens were prepared, the SBS test was performed at a crosshead speed of 0.5 mm/min. The fractured specimens were examined under a stereomicroscope to evaluate the fracture pattern. Statistical analyses were performed with one-way ANOVA and Tukey's honestly significant difference tests. One sample of treated dentin surface from each group was sputter-coated with gold, and scanning electron microscope (SEM) images were captured. Results: Acid etching showed significantly higher SBS than the other groups (P 0.05). SEM images of the acid-etched dentin surface showed opened dentinal tubule with a regular surface, but Er: YAG MSP mode treated surface was irregular. The surface treated with Er: YAG QSP mode represented wide dentinal tubules with a clean and flat surface. Conclusion: Using different modes (MSP and QSP) of Er: YAG laser for dentin surface treatment before application of total etch adhesives is still not an sufficient alternative compared to acid etching