Effect of Effervescent Denture Cleansers on 3D Surface Roughness of Conventional Heat Polymerized, Subtractively, and Additively Manufactured Denture Base Resins: An In Vitro Study.

Aim:The purpose of this study was to evaluate the effect of different denture cleansers on the color stability, surface hardness, and roughness of different denture base resins.Materials and Methods:Three denture base resin materials (conventional heat cure resin, high impact resin, and polyamide denture base resin) were immersed for 180 days in commercially available two denture cleansers (sodium perborate and sodium hypochlorite). Color, surface roughness, and hardness were measured for each sample before and after immersion procedure.Statistical Analysis:One-way analysis of variance and Tukey's post hoc honestly significant difference test were used to evaluate color, surface roughness, and hardness data before and after immersion in denture cleanser (α =0.05).Results:All denture base resins tested exhibited a change in color, surface roughness, and hardness to some degree in both denture cleansers. Polyamides resin immersed in sodium perborate showed a maximum change in color after immersion for 180 days. Conventional heat cure resin immersed in sodium hypochlorite showed a maximum change in surface roughness and conventional heat cure immersed in sodium perborate showed a maximum change in hardness.Conclusion:Color changes of all denture base resins were within the clinically accepted range for color difference. Surface roughness change of conventional heat cure resin was not within the clinically accepted range of surface roughness. The choice of denture cleanser for different denture base resins should be based on the chemistry of resin and cleanser, denture cleanser concentration, and duration of immersion.

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

Different denture cleansers have an effect on color and different surface properties of polyamide denture base material. Thus, selecting a denture cleanser solution for polyamide denture base materials should be based on the properties of the denture cleanser itself. The present in vitro study is aimed to evaluate and compare the effect of different denture base cleansers on color, surface roughness and hardness of polyamide denture base material. Thirty specimens of commercially available polyamide denture base material were fabricated and divided into three groups of 10 each. Specimens from each group were immersed in different denture cleansers (sodium perborate, thyme oil and ozonated water) for 10 mins per day for 180 days. Initial and final color, surface roughness and surface hardness of each specimen were measured and the difference was calculated. Data was tabulated and subjected to statistical analysis using One way ANOVA for pair wise comparison. Polyamide denture base resin exhibited some degree of change in color, surface roughness, and surface hardness in all denture cleansers but was not statistically significant. The choice of denture cleanser for different denture base resins should be based on the chemistry of resin and the cleanser, denture cleanser concentration and duration of immersion.

To compare the impact of three different chemical denture cleansers (CDCs) (Corega, chlorhexidine, and hydrogen peroxide) on the surface roughness, microhardness, and color stability of 3D-printed, computer-aided design and computer-aided manufacturing (CAD-CAM) milled, and heat-polymerized denture base material (DBM). A total of 420 disc-shaped specimens (10 ±0.1 × 2 ±0.1mm) were fabricated using three different construction techniques: three-dimensional (3D) printing (n = 140), CAD-CAM milling (n = 140), and heat-polymerization (n = 140). Sixty specimens (20 of each DBM) were used for baseline (pre-immersion) measurements (T1) for the tested surface properties (hardness [n = 10/material] and roughness [n = 10/material]). The remaining 360 specimens (n = 120/material) were investigated for surface roughness, microhardness, and color change after immersion for 1 year (T2) in distilled water or CDCs (n = 30/solution and n = 10/test). The data were analyzed using two-way ANOVA, one-way ANOVA followed by post-hoc Tukey's test at a significance level of less than 0.05. Significant differences were observed in the effects of the tested CDCs on the surface roughness, micro-hardness, and color stability of varying DBM specimens (p<0.05). Corega showed the highest surface roughness and color change in all DBMs while H2O2 resulted in the lowest microhardness for all DBMs. The lowest changes in all tested properties were seen with distilled water followed by chlorhexidine. A significant effect of type of cleanser, denture base material, and the interaction between the two was seen on all measured properties (p<0.05). The tested CDCs significantly affected the surface properties of all DBMs but at varying degrees. Corega produced the highest negative effect on roughness and color change while H2O2 dramatically affected the microhardness. Prolonged use of CDCs should be cautiously followed.

ABSTRACTObjective:This study aimed to evaluate the effect of various sugary drinks and a denture cleanser on the color stability and surface roughness of two tested denture teeth materials (3D printed and CAD/CAM milled).Materials and Methods:CAD/CAM additive and subtractive techniques were used to fabricate 160 custom disc-shaped specimens from two commercially available denture teeth resins. Specimens were randomly divided into 16 groups (n = 10) based on the immersion media used: a control group (artificial salivary substitute), sugary drinks groups (Pepsi, Gatorade, and ice tea), and denture cleanser groups after exposure to sugary drinks. These immersion cycles were repeated for 180 days, and the changes in color and surface roughness measurements were recorded. The data related to change in color and surface roughness was tabulated, and the statistical analysis was performed.Results:When exposed to sugary drinks, the change in color for both milled and 3D-printed materials was maximum when tested specimens were exposed to ice tea (ΔE = 3.548 and 4.055), followed by a carbonated drink (Pepsi) (ΔE = 2.334 and 3.503) and sports drink (Gatorade) (ΔE = 1.272 and 1.443), respectively. Whereas the change in surface roughness was highest after exposure to carbonated drink (ΔRa = 0.052 μm and 0.074 μm), followed by ice tea (ΔRa = 0.043 μm and 0.061 μm) and sports drink (ΔRa = 0.039 μm and 0.049 μm) for milled and 3D-printed materials, respectively.Conclusion:The 3D-printed denture tooth resins have poor color stability and are prone to more changes in surface roughness when exposed to different sugary drinks as compared to CAD/CAM milled denture teeth.

Tobacco consumption in its different forms can affect the optical and surface properties of dental materials that are used in the oral cavity. Thus, the present study was conducted to evaluate the effects of two commercially available smokeless tobacco products on the color stability and surface roughness of denture base resins that were fabricated using three different techniques (CAD/CAM milling, 3D printing, and conventional heat polymerization). A total of 126 denture base resin specimens were fabricated using the three different manufacturing techniques (n = 42 each). Specimens from each group were further subdivided into three subgroups (n = 14 each) and immersed in three different immersion media (a khaini suspension, a tabbaq suspension, and artificial saliva). The differences in color and surface roughness were assessed according to data that were collected and statistically analyzed using SPSS version 24.0. The tabbaq smokeless tobacco was found to cause greatest changes in color and surface roughness; the effect was observed to be highest in the 3D-printed specimens followed by the conventional heat-polymerized and CAD/CAM milled specimens. The mean changes in color and surface roughness were the highest for the tabbaq smokeless tobacco followed by the khaini smokeless tobacco and the artificial saliva. Statistically significant (p-value < 0.05) differences were observed among all techniques and suspensions. We concluded that the mean changes in color and surface roughness were significantly higher for the 3D-printed dentures compared to the conventional heat-polymerized and CAD/CAM-milled dentures. Thus, the results of the present study strengthened the concept that tobacco in any form can lead to changes in the color and surface roughness of denture base materials.

Longevity of extrinsic stains on monolithic zirconia restorations: An in vitro study

Objectives: This study aimed to evaluate the changes of surface roughness and hardness of conventional heat-cured (CHC) and CAD/CAM PMMA after immersion in alkaline peroxide chemical denture cleansers (DC), simulating one -year of use. Materials and Methods: 30 specimens of CHC, and another 30 specimens of CAD/CAM PMMA were divided into three groups (n= 10), each were immersed in two commercially available alkaline peroxide DC (Corega tablets and Polident tablets) as well as distilled water (control group). The mean surface roughness (Ra) of the specimens was recorded using contact stylus surface analyzer device. The surface hardness (VHN) was recorded using Vickers micro-hardness tester. T‑test for paired observation and independent samples T-test were used to indicate and compare any changes in Ra and hardness between the baseline and after simulated daily immersion in DC for one-year. Results: The tested DC had no significant effect on the Ra and hardness of CAD/CAM PMMA specimens. But both types of DC produced significant increase in Ra and significant decrease in VHN of the CHC PMMA specimens (P < 0.05). The Ra of the CAD/CAM PMMA specimens was significantly lower and the VHN was significantly higher than that of the CHC PMMA after treatment with DC. Conclusions: Alkaline peroxide DC appears not to affect the Ra and hardness of CAD/CAM PMMA. Alkaline peroxide DC produced negative effect on the Ra and hardness of CHC PMMA. CAD/CAM denture base resins might be considered the material of choice to produce more durable dentures.

Caries management by risk assessment (CAMBRA) and its effect on the surface roughness of various restorative materials

Denture cleansing is essential for maintaining the prosthesis and oral health, so choosing an appropriate cleanser which is not only efficient but also not adversely affects the properties of denture base resin itself with prolonged use is important. Hence, the present study was undertaken. To evaluate the effect of different chemical cleansers on surface roughness and flexural strength of heat cure denture base resin when used daily for three months. A total of 40 rectangular specimens (65 mm x 10 mm x 2.5 mm) and 32 disc shaped specimens (10 mm x 2 mm) were fabricated from heat cure denture base resin (DPI Heat Cure) for evaluation of flexural strength and surface roughness respectively. The specimens not subjected to cleansing served as control whereas other specimens were subjected to daily cleansing with one of the three cleansers (1% sodium hypochlorite, fittydent tablets, 100% vinegar) daily and stored in distilled water for three months. Surface analyser (Surftest SJ-210, Mitutoyo, USA) was used to evaluate change in surface roughness of the specimens (ΔRa) before and after cleansing. Also, flexural strength (S) of specimens after cleansing was evaluated by subjecting the specimens to load of 50 kgf at a crosshead speed of 5 mm/min in universal testing machine (INSTRON). Data obtained by testing was compiled and analysed using statistical software SPSS version 17.5. ANOVA and Post-hoc Tukey's tests were used and p-value <0.05 was considered significant in all tests. Results showed that the surface roughness of the specimens was significantly increased and flexural strength significantly decreased after immersion in 1% sodium hypochlorite solution for three months (p<0.05). No statistically significant difference were observed in flexural strength and surface roughness of the specimens cleaned with fittydent and 100% vinegar for three months (p>0.05). Within the limitations of this in vitro study, it was concluded that immersion in 1% sodium hypochlorite solutions for three months influences the surface roughness and flexural strength of heat cure denture base resin; hence it should be used with caution when used for long period. Fittydent and 100% vinegar can be recommended as a routine chemical cleansing agent for long term use.

Background:Candida albicans adhesion to denture base materials is a primary contributor to denture stomatitis. To address this issue, numerous studies have explored the incorporation of various additives into denture base resins to enhance their antifungal properties. Titanium tetrafluoride (TiF4) is an inorganic fluoride compound that has proven antimicrobial properties but has not yet been tested with denture materials. This study aimed to evaluate the effect of TiF4 addition into different denture base materials on antifungal activity, surface roughness, hardness, and color properties. Methodology: A total of 200 disc-shaped specimens were prepared-100 heat-polymerized acrylic resins and 100 3D-printed NextDent resins. Four different concentrations of TiF4 were incorporated: 1 wt%, 2 wt%, 3 wt%, and 4 wt% for both resins, while one group of each resin remained unmodified as a control. All specimens were subjected to thermal cycling for 5000 cycles, and four tests were conducted: Candida albicans adherence, surface roughness, hardness, and color change. A scanning electron microscope (SEM) was used to prove Candida albicans colonies' adhesion on the specimens' surfaces, and Fourier-transformed infrared (FTIR) analysis was performed to show the presence of TiF4 in the resin material; data were analyzed using one-way ANOVA followed by a post hoc test (α = 0.05). Results: TiF4 significantly reduced the Candida albicans adhesion to heat-polymerized specimens (p < 0.001). Compared to the control group, the incorporation of TiF4 resulted in a substantial reduction in C. albicans colony counts, with reductions of approximately 97.6% in 1HP, 97.2% in 2HP, 97.4% in 3HP, and complete inhibition (100%) in 4HP. However, there was no significant difference between the 3D-printed ones (p = 0.913). Surface roughness, hardness, and color change of heat-polymerized groups were not significantly affected by TiF4 (p > 0.05) except the color of the group treated with 4% (p < 0.05). For the 3D-printed groups, no significant differences were detected between the groups regarding candida count, hardness was significantly increased at 2% TiF4 compared to the control (p = 0.002), and roughness was least with 4% TiF4, while the color varied significantly between the groups (p < 0.001). Conclusions: TiF4 addition decreased Candida albicans adhesion to heat-polymerized denture base materials but showed no antifungal effect on the 3D-printed resin. While roughness remained low in 3D-printed groups at higher concentrations. Hardness was not significantly altered in the heat-polymerized resin, whereas it increased significantly in the modified 3D-printed resin. Color stability was compromised at higher TiF4 concentrations, particularly in the 3D-printed groups. The type of denture base material and TiF4 concentration both influenced antifungal activity and denture surface properties.

During the implantation process, an expandable balloon stent undergoes a change in mesh shape with a high strain rate. Permanent mesh shape changes to the stents indicate plastic deformation has occurred. On a micro-scale, plastic deformation has significant influence when interacting with the soft tissue of human blood vessels. This experimental study aims to investigate the effect of surface treatment and cutting orientation on the changes in surface roughness that definitely occurs when a stent deployed. To study the effect of surface treatment, two types of surface treatment were applied after surface polishing, i.e. etching and electropolishing. Surface polishing is carried out to enable microscopic observation. As for examining the effect of cutting orientation, the plate is cut in lateral and longitudinal orientation against the predicted-rolling direction of 316L sheet-type of stainless steel. An intermittent tensile test is conducted to obtain information about the changes in surface roughness. The surface observation is carried out three times on a similar surface of testpiece after reaching plastic deformation. The experimental study shows that the orientation of raw material has an insignificant effect on the changes in stent surface roughness. As for the surface treatments, electropolishing tended to decrease the tensile property of material.

Objective:To evaluate the effect of four commercially available denture adhesives (DAs) on surface roughness of two chemically different denture base materials.Materials and Methods:Fifty specimens of heat-cured polymethyl methacrylate, and another fifty specimens of light-cured urethane dimethacrylate were divided into five groups (n = 10), each was immersed in four prepared DAs (Corega Super Cream, Corega Ultra Powder, Olivafix Cream, Protefix Cream) as well as distilled water (control group). The mean surface roughness (Ra) of the polished and unpolished surfaces of the specimens was recorded using profilometer device. T-test for paired observation was used to indicate any changes in surface roughness between the baseline and after 30 days of immersion in the DA.Results:Almost all the tested DAs had no significant effect on the roughness of polished and unpolished surfaces of both denture base materials. The Corega super cream DA produced significant increase in the roughness of the polished surfaces of both types of acrylic specimens (P < 0.05).Conclusion:The majority of the investigated DAs appears not to affect the surface roughness of denture base materials. Only Corega super cream DA produced detectable increase in the roughness of polished surfaces of denture base specimens.

The response of turbulent boundary layers to sudden changes in surface roughness under adverse-pressure-gradient conditions has been studied experimentally. The roughness used was in the ‘d’ type array of Perry, Schofield &amp; Joubert (1969). Two cases of a rough-to-smooth change in surface roughness were considered in the same arbitrary adverse pressure gradient. The two cases differed in the distance of the surface discontinuity from the leading edge and gave two sets of flow conditions for the establishment and growth of the internal layer which develops downstream from a change in surface roughness. These conditions were in turn different from those in the zero-pressure-gradient experiments of Antonia &amp; Luxton. The results suggest that the growth of the new internal layer depends solely on the new conditions at the wall and scales with the local roughness length of that wall. Mean velocity profiles in the region after the step change in roughness were accurately described by Coles’ law of the wall-law of the wake combination, which contrasts with the zero-pressure-gradient results of Antonia &amp; Luxton. The skin-friction coefficient after the step change in roughness did not overshoot the equilibrium distribution but made a slow adjustment downstream of the step. Comparisons of mean profiles indicate that similar defect profile shapes are produced in layers with arbitrary adverse pressure gradients at positions where the values of Clauser's equilibrium parameter β (= δ*τ−10dp/dx) are similar, provided that the pressure-gradient history and local values of the pressure gradient are also similar.

Soft denture lining materials were immersed into solutions of denture cleansers for 8 h at room temperature, and immersed into distilled water for the remainder of the 24-h period at 37 degrees C. Surface roughness of the soft denture lining materials was measured by contact type surface roughness instrument. For the colour stability test, soft denture lining materials were immersed in the denture cleansers as described above for 180 days. Finally, the colour changes of each material were quantitatively measured by a photometrical instrument to obtain the colour differences between newly processed specimen and immersed specimens (P < 0.01). An autopolymerizing silicone material, Evatouch, exhibited severe changes in surface roughness by all denture cleanser, and the generic material GC Denture Relining showed the minimal changes. Severe colour changes were also observed with some liner and cleanser combinations (P < 0.01). Except for Evatouth, the four silicone soft liners were more stable in surface roughness and in colour change than the two acrylic soft liners. One autopolymerizing silicone (GC denture relining) and one heat curing silicone (Molloplast B) demonstrated the best stability.