Color Stability of Heat-cure Acrylic Resin Subjected to Simulated Short-term Immersion in Fast-acting Denture Cleansers

Nanoparticle-Modified 3D-Printed Denture Base Resins: Influence of Denture Cleansers on the Color Stability and Surface Roughness In Vitro

This study aimed to evaluate the influence of denture cleansers on the color, stability, and surface roughness of three-dimensional (3D)-printed denture base resins modified with zirconium dioxide nanoparticles (nano-ZrO2). A total of 440 specimens were fabricated using one heat-polymerized resin, and two 3D-printed resins (NextDent and ASIGA). According to the nano-ZrO2 content, the specimens for each resin were divided into five groups (0%, 0.5%wt, 1%wt, 3%wt, and 5%wt). Each concentration was divided into four subgroups (n = 10) based on the immersion solution (distilled water, sodium hypochlorite, Corega, and Fittydent) and immersion duration (360 and 720 days). The color changes (∆E00) and surface roughness (Ra, µm) of each specimen were measured at different time intervals (base line, 360 days, 720 days) using a spectrophotometer and a non-contact profilometer, respectively. The results were statistically analyzed using ANOVA and a post hoc Tukey's test (α = 0.05). Sodium hypochlorite showed the highest significant color change of all the denture base resins (p < 0.001). The average value of ΔE00 for sodium hypochlorite was significantly higher than the values for the other solutions (Fittydent, Corega, and water) (p < 0.001). Color stability was significantly affected by immersion time for all types of solutions except Corega (p < 0.001). All of the tested immersion solutions (distilled water, sodium hypochlorite, Corega, and Fittydent) showed a significant increase in the surface roughness of all the denture base resins (p < 0.05). Surface roughness was substantially increased by immersion time for all types of solution except Fittydent (p < 0.001). Denture cleansers can result in substantial color change and affect the surface roughness of unmodified and nanoparticle-modified denture base resins. Therefore, the selection of denture cleanser and appropriate types of material is critical for denture longevity.

Effect of denture cleansers on the surface properties and color stability of 3D Printed denture base materials

OBJECTIVES

To evaluate the effect of denture cleansers on surface roughness, hardness and color stability of 3D-printed resins compared to heat-polymerized resins.

METHODS

Acrylic specimens (N=160) were prepared using one heat-polymerized (HP) and three 3D-printed denture base resins. Specimens per material were randomly divided into four groups (n = 10) according to immersion solutions as follows: distilled water (DW), sodium hypochlorite (NaOCl), effervescent tablet 1 or effervescent tablet 2. Color changes (∆E) were measured using a spectrophotometer. Surface roughness (Ra, µm) and microhardness were evaluated. The results were analyzed using one- and three-way ANOVA with Tukey's post hoc test (α = 0.05).

RESULTS

After 360 days of cleaning protocols, we observed a significant increase in the surface roughness of tested materials (P<0.001). Hardness values significantly decreased in all groups (P<0.001), except HP and ND specimens, cleaned with effervescent tablet 1 (P>0.05) and AS specimens with effervescent tablet 2 (P=0.051). According to the National Bureau of Standards (NBS) score, all denture base specimens had 'perceivable' to 'extremely marked' color change after immersion in NaOCl, while immersion in effervescent tablets 1 and 2 resulted in a 'slight' to 'marked' color change.

CONCLUSION

3D-printed denture bases exhibited changes in surface roughness, hardness and color of 3D-printed dentures similar to HP denture base material. The use of denture cleansers resulted in a time-dependent increase in surface roughness and a decrease in hardness. The color change was significant with NaOCl, while effervescent denture cleansers produced a minimal color difference.

CLINICAL SIGNIFICANCE

Denture cleansers seem to influence surface properties over time. The degree of impact is mainly dependent on the type of cleanser selected, regardless of the type of denture base material.

Color Stability and Surface Properties of PMMA/ZrO2 Nanocomposite Denture Base Material after Using Denture Cleanser

Objectives

This study aimed to evaluate denture cleanser effects on color stability, surface roughness, and hardness of PMMA denture base resin reinforced with nano-ZrO₂.

Materials and Methods

A total of 420 specimens were fabricated of unreinforced and nano-ZrO₂ reinforced acrylic resin at 2.5% and 5%, resulting in 3 main groups. These groups were further subdivided (n = 10) according to immersion solution (distilled water, Corega, sodium hypochlorite, and Renew) and immersion duration. Surface roughness, hardness, and color were measured at baseline (2 days-T₀) in distilled water and then after 180 and 365 days of immersion (T₁ & T₂) in water or denture cleansing solutions. Data was collected and analyzed using two-way ANOVA followed by Bonferroni post hoc test (α = 0.05).

Results

Surface roughness increased significantly after denture cleanser immersion of unmodified and nano-ZrO₂-modified PMMA materials while hardness decreased (P < 0.001). The denture cleansers significantly affected the color of both PMMA denture bases (P < 0.001). The immersion time in denture cleansers significantly affected all tested properties (P < 0.001). Within denture cleansers, NaOCl showed the highest adverse effects (P < 0.05) while Renew showed the least adverse effects.

Conclusion

Denture cleansers can significantly result in color change and alter the surface roughness and hardness of denture base resin even with ZrO₂ nanoparticles addition. Therefore, they should be carefully used.

Composition's effect of Origanum Syriacum essential oils in the antimicrobial activities for the treatment of denture stomatitis

This research has several purposes: First to assess the bacterial and fungal minimum inhibitory concentration of Origanum Syriacum essential oil. Second to quantify its bactericidal and fungicidal minimal concentration against S. aureus, S. mutans, and C. albicans found in denture stomatitis. The third purpose is to look at the influence of three different soils (Annaya, Bhanin and Michrif) on the essential oils composition. Three essential oils were extracted by hydro-distillation from three different Origanum Syriacum plant origins. Bioassays were conducted using a broth microdilution methods. Gas Chromatography analysis was used to calculate the abundance of most components in each essential oil. Post hoc tests assessed antimicrobial effects between ecotypes while Pearson's test correlated the different components and their antimicrobial efficiency (α < 0.05). All tested essential oils were efficient against all microorganisms. Origanum Syriacum essential oils derived from Annaya and Bhanin soils showed a superior antimicrobial activity compared to the Michrif one. The most abundant component and most efficient among all essential oils constituents was carvacrol. It can be concluded that Origanum Syriacum essential oils have an antimicrobial activity, which depends on the ecotype, its origin and its composition. They might be used to start a clinical trial for the treatment of denture stomatitis.