Color stability, roughness, and water sorption/solubility of glass ionomer-Based restorative materials.

OBJECTIVES: The aim of this study was to investigate the effects of various drinks on color stability and roughness of glass ionomer cement-based/-containing restorative materials and water sorption/solubility behavior of them. MATERIALS AND METHODS: A total of 130 specimens for each material (GC Equia, GCP Glass Fill, Ketac N100, Glasiosite; a total of 520) were prepared using a Tefl on ring (7 × 2 mm). After specimen preparations, baseline color and surface roughness measurements were performed using a spectrophotometer and surface profi lometer, respectively. Specimens were immersed in four different solutions (n = 15; distilled water, cola, orange juice, and chocolate milk) during the 28-day test period. The immersion media were renewed daily. Color and surface roughness measurements were repeated at 1st, 7th, and 28th days. For water sorption, specimens (n = 15) were immersed in 10 mL of distilled water in individual containers and weighed at 1st week, 14th, and 28th days. After a total immersion time of 28 days, the specimens were dried to a constant mass, in a desiccator for 28 days. Each specimen was measured using a digital electronic caliper. Data were statistically analyzed (P < 0.05). RESULTS: After 28 days, the highest ΔE* value was calculated in GCP Glass Fill immersed in chocolate milk (10.54 ± 0.69). All the tested materials showed signifi cantly higher Ra values compared with baseline scores after immersion in various beverages regardless of the immersion solutions used (P < 0.05). Glasiosite showed the smallest water sorption (16.75 µg/mm3) among the tested materials, whereas Ketac N100 (155.41 µg/mm3) and GCP Glass Fill (161.01 µg/mm3) had the highest. CONCLUSIONS: The compositions of restorative materials play key roles in their color stability, surface roughness, and water sorption/solubility.

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.

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.

Influence of blood contamination during multimode adhesive application on the microtensile bond strength to dentin.

OBJECTIVES: The present study evaluated the effects of blood contamination performed at different steps of bonding on the microtensile bond strength (µTBS) of multimode adhesives to dentin when using the self-etch approach. MATERIALS AND METHODS: Seventy-five molars were randomly assigned to three adhesive groups comprising 25 specimens each: two multimode adhesives [Single Bond Universal (SBU) and All-Bond Universal (ABU)] and a conventional one-step self-etch adhesive [Clearfil S3 Bond Plus (CSBP)]. Each group was subdivided as follows: (1) uncontaminated (control): bonding application/light curing as a positive control; (2) contamination-1 (cont-1): bonding application/light curing/blood contamination/dry as a negative control; (3) contamination-2 (cont-2): bonding application/light curing/blood contamination/rinse/dry; (4) contamination-3 (cont-3): bonding application/blood contamination/dry/bonding re-application/light curing; and (5) contamination-4 (cont-4): bonding application/blood contamination/rinse/dry/bonding re-application/light curing. Dentin specimens were prepared for µTBS testing after the composite resin application. Data were analyzed with two-way ANOVA and post-hoc tests (α = 0.05). RESULTS: µTBS values were similar in cont-3 groups, and ABU/cont-4 and corresponding control groups, but were significantly lower in the other groups than in their control groups (P < 0.05). Cont-1 groups showed the lowest µTBS values (P < 0.05). CONCLUSIONS: Neither decontamination method prevented the decrease in µTBS when contamination occurred after light curing. Drying the blood contaminants and reapplying the adhesive may regain the dentin adhesion when contamination occurs before light curing. Alternatively, rinsing and drying contaminants followed by adhesive re-application may be effective depending on adhesive type.

Evaluation of shear bond strength, penetration ability, microleakage and remineralisation capacity of glass ionomer-based fissure sealants.

AIM: The aim of this study was to evaluate the bond strength, penetration ability, microleakage, and remineralisation capacity of glass ionomer-based fissure sealant materials. MATERIALS AND METHODS: In this study, three glass ionomer-based fissure sealants were evaluated (Fuji Triage, Fuji VII EP, and GCP Glass Seal). A dye-penetration test was performed to evaluate microleakage under a stereomicroscope. The materials were applied to occlusal tooth surfaces, and bucco-lingual sections (1 mm width) were assessed to evaluate the penetration ability. Shear bond strength of tested materials was assessed using a universal testing machine. Finally, the remineralisation capacities of the materials were evaluated with EDS. RESULTS: The Fuji Triage exhibited the lowest microleakage and unfilled area proportion (p<0.05). The highest shear bond strength was calculated with Fuji VII EP (p<0.05). The fluoride content for all treatment groups was significantly different when remineralisation values were compared to demineralisation (p<0.05). CONCLUSION: Both the Fuji Triage and Fuji VII EP yielded compatible and satisfactory results and all fissure sealants used in this study are sufficient as anti-caries agents.

Effect of different surface pre-treatment methods on the microleakage of two different self-adhesive composites in Class V cavities.

AIM: To evaluate the effect of different surface pre-treatment methods on the microleakage of self-adhesive flowable composites (SAFCs) in comparison with a conventional flowable composite applied with an etch-and-rinse adhesive system. MATERIALS AND METHODS: One hundred and thirty-five standardised Class V cavities were randomly divided into nine groups: (1) three-step etch-and-rinse adhesive (Optibond FL - Kerr, Orange, USA)/flowable composite (Clearfil Majesty Flow - Kuraray, Tokyo, Japan) (E&Ra/flowC); (2) Fusio Liquid Dentin (Pentron Clinical, Orange, USA); (3) Er:YAG Laser/Fusio Liquid Dentin (Er&Las/Fusio Liquid Dentin); (4) Phosphoric Acid/Fusio Liquid Dentin (PhosA/Fusio Liquid Dentin); (5) Polyacrylic Acid/Fusio Liquid Dentin (PolyA/Fusio Liquid Dentin); (6) Vertise Flow (Kerr, Orange, USA); (7) Er:YAG Laser/Vertise Flow (Er&Las/Vertise Flow); (8) Phosphoric Acid/Vertise Flow (PhosA/Vertise Flow); (9) Polyacrylic Acid/Vertise Flow (PolyA/Vertise Flow). After thermocycling and immersion in a 0.5% basic fuchsin, the restorations were evaluated under a stereomicroscope (n = 30). The data were statistically analysed (α = 0.05). RESULTS: Both SAFCs showed higher leakage scores than E&Ra/flowC in enamel and dentin (p < 0.05). Vertise Flow showed lower leakage than Fusio Liquid Dentin in dentin (p < 0.05). Pre-phosphoric acid etching reduced the microleakage scores of Fusio Liquid Dentin in both enamel and dentin (p < 0.05), while all surface pre-treatment methods led to a significant reduction in the microleakage scores of Vertise Flow at the enamel margin (p < 0.05). CONCLUSION: Pre-etching of enamel and dentin by phosphoric acid may be satisfactory in improving the sealing ability of Fusio Liquid Dentin, while phosphoric acid or polyacrylic acid etching or laser irradiation may be used to improve the adhesion of Vertise Flow to enamel.

Shear bond strength of a self-adhering flowable composite when used for lingual retainer bonding.

OBJECTIVE: The goal of this work was to assess the shear bond strength (SBS) and fracture mode of a self-adhering flowable composite when used after thermocycling for lingual retainer bonding. MATERIALS AND METHODS: A total of 80 human mandibular incisor teeth were categorized into four equal groups: group 1: Vertise™ Flow (VF) without acid etching; group 2: VF with acid etching; group 3: VF with a self-etching bonding agent accompanied by an additional acid etching; group 4: Transbond LR control. Either VF or Transbond LR was applied to the lingual surface of the teeth by packing the material into cylindrical plastic matrices to simulate the lingual retainer bonding area. After all teeth were thermocycled (5000 cycles, 5 and 55 °C), fracture modes were examined under × 20 magnification. The SBS data were assessed via analysis of variance (ANOVA) and Tukey's tests. Fracture modes were analyzed by the χ(2) test at a significance level of 0.05. RESULTS: Statistically significant differences in SBS values between groups (p < 0.001) were observed. Group 4 exhibited the highest (14.63 ± 1.36 MPa) and group 1 the lowest SBS (2.67 ± 1.35 MPa) values. Statistically significant differences were noted in fracture modes between groups 1, 3, and 4 (p < 0.001). In all the self-adhering flowable composite groups, the adhesive type (tooth-composite interface) fracture occurred more frequently than cohesive and mixed-type fractures. CONCLUSION: When applied to bond lingual retainers to unetched enamel or with self-etching bonding agent accompanied by an additional acid etching, Vertise™ Flow resulted in a significant decrease in bond strength.