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.

The force required to fracture endodontically roots restored with various materials as intra-orifice barriers.

OBJECTIVE: To evaluate the effect of various materials as intra-orifice barriers on the force required fracture roots. MATERIALS AND METHODS: One hundred-thirty five mandibular premolars were decoronated and prepared up to size #40. The root canals were filled and randomly divided into two control and seven experimental groups (n = 15), as follows: Positive control group (the intra-orifice barrier cavity was not prepared), negative control group (the intra-orifice barrier cavity was prepared, but not filled), filling using glass ionomer cement, nano-hybrid composite resin, short fiber-reinforced composite, bulk-fill flowable composite, MTA Angelus, Micro Mega MTA or Biodentine. A fracture strength test was performed, and the data were analyzed using one-way ANOVA and Tukey's post hoc tests. RESULTS: Nano-hybrid composite, short fiber-reinforced composite, bulk-fill flow able composite, and glass ionomer cement increased the force required fracture the roots compared to the positive and negative control groups (P < 0.05). While MTA groups did not increase the force required fracture the roots compared to the control groups, Biodentine increased significantly. CONCLUSIONS: Within the limitations of the present study, the use of nano-hybrid composite, short fiber-reinforced composite, bulk-fill flowable composite, and glass ionomer cement as an intra-orifice barrier may be useful in reinforcing roots. MTA placement (MTA Angelus or Micro Mega MTA) did not significantly increase the fracture resistance of endodontically treated roots compared to the control groups, however Biodentine did.

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 the Radiopacities of Bulk-fill Restoratives Using Two Digital Radiography Systems.

This study investigated the radiopacity values of bulk-fill restoratives by using two digital radiography systems. Nine bulk-fill restoratives and a conventional composite were used in the study. Six disc-shaped specimens were prepared from each of these materials, three each at thicknesses of 1 mm and 2 mm, and tooth slices with these same thicknesses were obtained. As a control, an aluminum step wedge varying in thickness from 0.5 to 10 mm in was used. Three specimens of each of the materials, together with the tooth slice and the aluminum step wedge, were placed over a complementary metal oxide semiconductor (CMOS) sensor and a storage photostimulable phosphor (PPS) plate system and exposed using a dental x-ray unit. The images were analyzed using a software program to measure the mean gray values (MGVs). Five measurements were obtained from each of the restorative materials, the enamel, the dentin, and the stepwedge. The MGVs were converted to the equivalent aluminum thicknesses. Three-way analysis of variance (ANOVA) was used to determine the significance of the differences among the groups. A Tukey test was applied for pairwise comparisons (p<0.05). All composite-based restoratives were found to have greater radiopacities than enamel or dentin. Equia Fil had the lowest radiopacity value. Radiopacity increased as the thicknesses of the restorative material increased. The CMOS system showed significantly higher radiopacity values than the PSP system. In conclusion, all investigated bulk-fill restoratives passed the International Organization for Standardization and American National Standard Institute/American Dental Association requirements for radiopacity values when evaluated with the two digital radiography systems.

The bond strength of endodontic sealers to root dentine exposed to different gutta-percha solvents.

AIM: To evaluate the effects of various gutta-percha solvents on the push-out bond strength of several root canal sealers on root dentine. METHODOLOGY: The root canals of 210 single-rooted human teeth were prepared with the ProTaper System (Dentsply Maillefer, Ballaigues, Switzerland) up to a master apical file size of F4, and the following variables evaluated for bond strength: solvent type (chloroform, eucalyptol and orange oil), time (2 and 5 min), sealer type (AH Plus, MTA Fillapex and Sealapex) and root thirds (coronal, middle and apical). After canal filling, three 1-mm-thick slices were obtained from each root sample, and the bond strength of the test materials was measured using a push-out test set-up at a cross-head speed of 1 mm min(-1) . The data were analysed using four-way factorial anova (P = 0.05). RESULTS: Bond strength was significantly affected by solvent type and time (P < 0.001). The use of chloroform for 5 min in the root canal decreased bond strength of all sealers (P < 0.001). Eucalyptol and orange oil did not affect the bond strength of the sealers (P > 0.05). In all conditions, the push-out bond strength was highest for AH Plus and lowest for MTA Fillapex (P < 0.001). Bond strength values decreased in a corono-apical direction in all groups (P < 0.001). CONCLUSIONS: Chloroform used for 5 min during retreatment decreased the bond strength of AH Plus, Sealapex and MTA Fillapex to root dentine.