Significant Difference In Surface Roughness Research Articles

The Impact of Surface Roughness on Conformal Cooling Channels for Injection Molding

Injection molding technology is widely utilized across various industries for its ability to fabricate complex-shaped components with exceptional dimensional accuracy. However, challenges related to injection quality often arise, necessitating innovative approaches for improvement. This study investigates the influence of surface roughness on the efficiency of conformal cooling channels produced using additive manufacturing technologies, specifically Direct Metal Laser Sintering (DMLS) and Atomic Diffusion Additive Manufacturing (ADAM). Through a combination of experimental measurements, including surface roughness analysis, scanning electron microscopy, and cooling system flow analysis, this study elucidates the impact of surface roughness on coolant flow dynamics and pressure distribution within the cooling channels. The results reveal significant differences in surface roughness between DMLS and ADAM technologies, with corresponding effects on coolant flow behavior. Following that fact, this study shows that when cooling channels’ surface roughness is lowered up to 90%, the reduction in coolant media pressure is lowered by 0.033 MPa. Regression models are developed to quantitatively describe the relationship between surface roughness and key parameters, such as coolant pressure, Reynolds number, and flow velocity. Practical implications for the optimization of injection molding cooling systems are discussed, highlighting the importance of informed decision making in technology selection and post-processing techniques. Overall, this research contributes to a deeper understanding of the role of surface roughness in injection molding processes and provides valuable insights for enhancing cooling system efficiency and product quality.

Enhancing bonding of zirconia lithium silicate ceramics to dentin: The effect of surface treatment and resin cement

This laboratory study evaluated the influence of surface treatments on surface topography, and the bonding of CAD/CAM (computer-aided design computer-aided manufacturing) zirconia-containing lithium silicate (ZLS) surfaces to human dentin using various contemporary resin cements. Specimens from ZLS CAD/CAM blocks (Celtra™ Duo and Vita™ Suprinity) underwent three surface pretreatments: grinding only; 5 % hydrofluoric acid etching followed by application of a silane coupling agent, and a self-etching ceramic primer. The specimens were bonded to a flat exposed dentin surface using two etch-and-rinse and two self-adhesive resin cements, and then sectioned into microspecimens for microtensile bond strength (μTBS) testing. Failure modes of bonded surfaces, and ceramic surface roughness and topography were assessed. Results indicated that surface treatment was essential for ZLS-dentin bonding. Hydrofluoric acid and silane, along with the self-etching primer resulted in comparable strengths and outperformed the control group. Etch-and-rinse cements yielded significantly higher μTBS than self-adhesive cements. Significant differences in surface roughness and topography were observed among the treatment groups. Hydrofluoric acid exhibited the highest roughness parameters and most prominent surface changes. These findings highlight the importance of surface treatment for enhancing zirconia-containing lithium silicate bonding to dentin, and emphasize the critical role of the resin cement choice in optimizing dental restorative outcomes.

Comparison of Enamel Surface Roughness after Orthodontic Brackets Debonding and Surface Polishing with Restorative and Orthodontic Composites

Introduction: Emergence of superficial enamel roughness following orthodontic bracket debonding leads to the accumulation of microbial plaque, resulting in the development of dental caries and compromising the aesthetics and health of the tooth enamel. The objective of this current study is to investigate the Enamel Surface Roughness after Orthodontic Brackets Debonding and Surface Polishing with Restorative and Orthodontic Composites. Materials and Methods: In the present study, three types of composites were used for bonding metal orthodontic brackets. The samples were randomly divided into three cure groups: XT, GC, and SHOFU. Subsequently, the brackets were debonded, and the target surfaces were treated using a carbide bur for one minute by an operator to remove adhesive remnants and be prepared for bonding. The superficial enamel roughness was then examined. Furthermore, the samples were evaluated for the Adhesive Remnant Index before and after adhesive removal and enamel surface preparation. The data were analyzed using ANOVA test and SPSS software version 22. Results: The results indicated that there was no significant difference in surface roughness among the tested groups. However, a significant difference was observed between the surface roughness of the experimental groups and the healthy enamel surface (P<0.05). Moreover, among the different experimental groups, there were statistically significant differences in the Adhesive Remnant Index (ARI) after bracket debonding, before and after enamel surface cleaning. These differences were primarily due to distinctions between the XT and SHOFU groups, as well as between the GC and SHOFU groups. However, there was no significant difference in ARI before and after enamel surface cleaning between the XT and GC groups (P>0.05). Conclusion: The results of the present study indicate a desirable and acceptable performance of the composite material. It is suggested that future studies focus on a comparative investigation of several cleaning and surface preparation systems.

Evaluating color stability and enamel surface roughness following resin infiltration treatment.

To assess the impact of resin infiltration treatment on enamel color stability and surface roughness after simulating daily exposure to coffee stains and regular toothbrushing with standard toothpaste. In this in vitro study, we utilized 47 caries-free human enamel specimens, which were divided into two distinct groups. The teeth in the study group underwent artificial demineralization, Icon resin infiltration, and polishing, while the control group received only polishing. Following this, all teeth from both groups were regularly immersed in freshly brewed coffee for 15 min, twice daily, over a span of 30 days. After each staining session, the teeth underwent 10 heavy circular strokes using a soft toothbrush and standard toothpaste. Color changes were measured on Days 1 and 30 using a spectrophotometer. The L*, a*, b* color system defined by the International Commission on Illumination was used to assess the changes. Surface roughness was evaluated at baseline and after 30 days using a 3D surface Metrology Microscope. After 30 days of immersion in coffee, both the study and control groups showed significant changes in color. However, differences were statistically significant between groups for "L" and "a" parameter but not for "b." The overall color change in the study group was higher than the control group. There were no significant differences in surface roughness within or between the groups before and after staining and brushing. Resin infiltration leads to a significant increase in staining compared to untreated enamel. These staining properties should be taken into account when making clinical decisions regarding the treatment of white spot lesions.

Effect of Heat Treatment Duration and Cooling Conditions on Flexural Strength and Surface Roughness of Cobalt-Chromium Alloys produced by Selective-Laser-Melting

Post-heat treatment may enhance mechanical properties of selective laser melting (SLM) Cobalt chromium (Co-Cr) alloys, however it is unknown what duration the heat treatment needs to last and how the rate of cooling impacts the alloy's flexural strength and surface roughness. In this study, SLM Co-Cr alloy specimens were heated at 1150 C for 1 or 6 hours and subsequently cooled by air cooling (AC), furnace cooling (FC), or water quenching (WC). Flexural strength and surface roughness were then tested. Aim of this study: Investigate the effect of heat treatment and different cooling conditions on the flexural strength and surface roughness of SLM Co-Cr alloy specimens. The heat treatment will be conducted at 1150 C for two different durations (1-hour and 6-hours) and under three cooling conditions (AC, FC, and WC). Materials and methods: A total of forty-two rectangular specimens, measuring (34×13×1.5 mm) were manufactured through SLM and divided into seven groups, six specimens for each group as follows: The first group denoted as control with no heat treatment and no cooling applied, second and third groups heated for 1 or 6 hours then cooled in the air (AH-1 and AH-6), fourth and fifth groups heated for 1 or 6 hours and left inside the furnace until they cooled (FH-1 and FH-6), sixth and seventh groups heated for 1 or 6 hours and cooled by water quenching (WH-1 and WH-6). Flexural strength and surface roughness tests were performed on the specimens. A flexural strength value of (2147.33 MPa) was indicated that the control group exhibited the highest flexural strength, whereas the FH-6 group exhibited the lowest flexural strength value (1282.66 MPa). The control group showed the worst surface roughness (1.63 μm) while all other groups demonstrated no significant differences in surface roughness ranging from (0.32 to 0.49 μm) with a slight increase in the 6-hours heated groups. Conclusions: Slow cooling rate inside the furnace affects flexural strength negatively. Therefore, a high cooling rate is recommended to get a better flexural strength. On the other hand, surface roughness results suggests that 1-hour is better than 6-hours in terms of heat treatment duration and time saving

Mechanical and microbiological properties of orthodontic resin modified with nanostructured silver vanadate decorated with silver nanoparticles (βAgVO3)

ObjectiveTo investigate the impact of incorporating the antimicrobial nanomaterial β-AgVO3 into orthodontic resin, focusing on degree of conversion, surface characteristics, microhardness, adhesion properties, and antimicrobial activity. MethodsThe 3 M Transbond XT resin underwent modification, resulting in three groups (Control, 2.5% addition, 5% addition) with 20 specimens each. Fourier transform infrared spectroscopy assessed monomer conversion. Laser confocal microscopy examined surface roughness, and microhardness was evaluated using Knoop protocols. Shear strength was measured before and after artificial aging on 36 premolar teeth. Microbiological analysis against S. mutans and S. sanguinis was conducted using the agar diffusion method. ResultsDegree of conversion remained unaffected by time (P = 0.797), concentration (P = 0.438), or their interaction (P = 0.187). The 5% group exhibited the lowest surface roughness, differing significantly from the control group (P = 0.045). Microhardness showed no significant differences between concentrations (P = 0.740). Shear strength was highest in the control group (P < 0.001). No significant differences were observed in the samples with or without thermocycling (P = 0.759). Microbial analysis revealed concentration-dependent variations, with the 5% group exhibiting the largest inhibition halo (P < 0.001). ConclusionsIncorporating β-AgVO3 at 2.5% and 5% concentrations led to significant differences in surface roughness, adhesion, and antimicrobial activity. Overall, resin modification positively impacted degree of conversion, surface characteristics, microhardness, and antimicrobial activity. Further research is warranted to determine clinically optimal concentrations that maximize antimicrobial benefits while minimizing adverse effects on adhesion properties. Clinical SignificanceIncorporating β-AgVO3 into orthodontic resin could improve patient quality of life by prolonging intervention durability and reducing the impact of cariogenic microorganisms. The study's findings also hold promise for the industry, paving the way for the development of new materials with antimicrobial properties for potential applications in the health sector.

Evaluating the Translucency, Surface Roughness, and Cytotoxicity of a PMMA Acrylic Denture Base Reinforced with Bioactive Glasses.

The colonisation of the surface of removable acrylic dentures by various types of microorganisms can lead to the development of various diseases. Therefore, the creation of a bioactive material is highly desirable. This study aimed to develop a denture base material designed to release bioactive ions into the oral environment during use. Four types of bioactive glasses (BAG)-S53P4, Biomin F, 45S5, and Biomin C-were incorporated into the PMMA acrylic resin, with each type constituting 20 wt.% (10 wt.% non-silanised and 10% silanised) of the mixture, while PMMA acrylic resin served as the control group. The specimens were subsequently immersed in distilled water, and pH measurements of the aqueous solutions were taken every seven days for a total of 38 days. Additionally, surface roughness and translucency measurements were recorded both after preparation and following seven days of immersion in distilled water. The cytotoxicity of these materials on human fibroblast cells was evaluated after 24 and 48 h using Direct Contact and MTT assays. Ultimately, the elemental composition of the specimens was determined through energy-dispersive X-ray (EDX) spectroscopy. In general, the pH levels of water solutions containing BAG-containing acrylics gradually increased over the storage period, reaching peak values after 10 days. Notably, S53P4 glass exhibited the most significant increase, with pH levels rising from 5.5 to 7.54. Surface roughness exhibited minimal changes upon immersion in distilled water, while a slight decrease in material translucency was observed, except for Biomin C. However, significant differences in surface roughness and translucency were observed among some of the BAG-embedded specimens under both dry and wet conditions. The composition of elements declared by the glass manufacturer was confirmed by EDX analysis. Importantly, cytotoxicity analysis revealed that specimens containing BAGs, when released into the environment, did not adversely affect the growth of human gingival fibroblast cells after 48 h of exposure. This suggests that PMMA acrylics fabricated with BAGs have the potential to release ions into the environment and can be considered biocompatible materials. Further clinical trials are warranted to explore the practical applications of these materials as denture base materials.

Evaluation of the physical properties and antibacterial effects on Candida albicans of denture base resin containing silver sulfadiazine

Objectives: The purpose of this study was to evaluate the physical properties and antibacterial activity of denture base resin with added silver sulfadiazine. Methods: Specimens were made from self-curing denture base resin and silver sulfadiazine as an inorganic antibacterial agent. For physical evaluation of the specimens, surface roughness, surface hardness, and contact angle were measured. Bacterial growth was assessed by optical densityat 600 nm (OD600) and colony forming units (CFU) measurements to confirm antibacterial activity. Results: There was no significant difference in surface roughness, surface hardness, and contact angle in the experimental group containing silver sulfadiazine compared to the control group. In contrast, the experimental group showed a significant decrease in antibacterial activity compared to the control group in terms of OD value. Analysis of CFU confirmed a significant decrease in colonies in the experimental group compared to the control group. Conclusions: Denture base resin containing silver sulfadiazine, an inorganic antibacterial agent, exhibited enhanced antibacterial activity without physical changes. In conclusion, the use of denture base resin containing inorganic antibacterial agents may be expected in the future.

Effect of Milling Strategy on the Surface Quality of AISI P20 Mold Steel

This paper explores the impact of various milling strategies, including up-milling, down-milling, and hybrid approaches, on the surface roughness of AISI P20 mold steel. The study is methodically divided into three stages to comprehensively understand the effects of these strategies. The first stage involves milling single slots with varying cutting parameters to establish baseline effects. The second stage examines the effects of consistent milling strategies (up-up and down-down) on surface quality. The third stage probes into hybrid strategies (up-down and down-up) to assess their effectiveness. Central to this investigation is not only the type of milling strategy but also how cutting speed and feed rate influence the resultant surface roughness. Our findings indicate that up-milling generally leads to a 22% increase in surface roughness compared to down-milling. This trend is visually verified by surface texture analyses. When comparing consistent strategies, up-up milling tends to produce rougher surfaces than down-down milling by approximately 25%, characterized by distinctive scratches and feed mark overlays. Remarkably, while the hybrid milling strategies do not exhibit significant differences in surface roughness, variations in cutting speed and feed rate play a crucial role. Specifically, at lower speeds, hybrid milling achieves smoother surfaces than the identical double milling mode, while at a cutting speed of 100 m/min, the double mode demonstrates a notable decrease in roughness. Additionally, this study introduces a color mapping simulation for machined pockets, validated by experimental results, to predict surface roughness based on the strategic history of milling, thereby offering valuable insights for optimizing milling processes.

An In Vivo Investigation of Non-Metallic vs. Metallic Hand Scalers on Zirconia Implant-Supported Crowns: A Year-Long Analysis of Peri-Implant Maintenance.

This study examined whether the degree of abutment surface modification that may occur with regular periodontal instrumentation has a clinical impact in terms of increased plaque accumulation and increased peri-implant tissue inflammation on zirconia implant abutments. Thirteen patients who had zirconia implant crowns were recruited in this randomized clinical trial. Each patient acted as their control and had either the buccal or lingual surface of their screw-retained implant restoration scaled with a metallic scaler and the other surface with a non-metallic scaler at 3, 6, 9, and 12 months. Cytokine testing of the peri-implant crevicular fluid was completed at 0, 3, and 12 months for IL-2, IL-4, IL-6, IL-8, IL-10, TNF-α, or IFNγ. Implant crowns were removed at 12 months and evaluated under an atomic force microscope for the average roughness (Ra). The implant crowns were polished and re-inserted. The results were analyzed using the Kruskal-Wallis test, and post hoc tests were conducted with a significance level of α = 0.05. Significant differences in surface roughness (Ra) were observed between the metallic and non-metallic scalers. The median Ra values were 274.0 nm for metallic scalers and 147.1 nm for non-metallic scalers. However, there were no significant differences between the type of scaler used and the amount of clinical inflammation or cytokine production. Metallic scalers produced deeper, more aggressive surface alterations to the abutment/crown zirconia surface, but there was no statistically significant difference between the degree of surface alterations, amount of BOP, and the amplitude of cytokine inflammation produced.

Effect of denture cleansers on color stability and surface properties of denture base material containing titanium dioxide nanoparticles.

To investigate the effect of different denture cleansers on color stability, surface roughness, and hardness of polymethylmethacrylate (PMMA) infused with titanium dioxide nanoparticles (TiO2 NPs) at concentrations of 1% and 2% by weight on each. In this in vitro study, 90 disc-shaped specimens (10×10×2mm) were divided into 3 main groups: the non-containing nanoparticle group (0wt% concentration), 1wt% concentration, and 2wt% concentration TiO2 NPs groups. Each group was further assorted into 3 subgroups (n = 10): immersed in distilled water, oxygenating tablet (Corega), and 0.5% sodium hypochlorite. Color change, surface roughness, and hardness values were assessed after 90 and 180 days of storage. Color changes (∆E) were measured with a spectrophotometer (VITA, Easy Shade V, Germany) and assessed using the CIE L*a*b* colorimetric system and the American National Bureau of Standards (NBS = 0.92×∆E). The surface roughness and surface hardness values were measured using a profilometer device and Vickers hardness tester, respectively. First, ANOVA-repeated measurements were performed, followed by the Tukey test. The significance level in this study was considered 0.05. At all concentrations, there were significant differences in the mean color changes of samples immersed in cleansers compared to distilled water (p < 0.01). Moreover, hypochlorite caused a significant increase compared to Corega at 0wt% concentration after 90 days and at 1wt% concentration after 90 and 180 days. Evaluations also showed that the mean NBS values in all cleanser groups were in the range of appreciable change, except the water group. In addition, only hypochlorite changed the color higher than the clinically acceptable range (∆E >3.7). The mean roughness of samples immersed in hypochlorite at 0wt% concentration was significantly higher than the samples containing TiO2 NPs (p = 0.006). No significant difference was observed in surface roughness of samples containing different concentrations of TiO2 NPs immersed in different cleansers; however, hypochlorite increased the surface roughness of samples without TiO2 NPs compared to samples containing TiO2 NPs after 180 days. The immersion time in cleansers had a significant influence on the surface roughness and hardness while having no effect on the color. In general, the cleansers had a significant effect on color change in all groups compared to distilled water. The adverse effect of hypochlorite was more than Corega. The cleansers in the samples containing TiO2 NPs did not make a significant difference in surface roughness in comparison with the distilled water groups. Surface hardness of the samples was not affected in a steady pattern by the cleansers.

Effect of whitening toothpastes on the surface roughness and microhardness of human teeth—an in vitro study

ObjectiveTo determine the effect of whitening toothpastes on the surface roughness and microhardness of human teeth.MethodologySurface roughness was estimated using the Talysurf instrument, and microhardness was estimated using the Vickers hardness tester before and after the application of whitening toothpastes on mounted extracted human teeth.ResultsIn the activated charcoal group, there was a reduction in the surface roughness from 1.21 at baseline to 1.09 at 1 month and a further reduction to 1.02 at 3 months, which was found to be statistically significant. However, no statistically significant difference in surface roughness was found in the other toothpaste groups. With respect to microhardness, all 4 whitening toothpastes showed a statistically significant reduction in microhardness after 3 months of brushing. However, the reduction was significantly higher in group 2 and in group 4 compared to the others.ConclusionThis study showed that whitening toothpaste containing activated charcoal significantly reduced the surface roughness, whereas toothpastes with blue covarine and toothpastes containing activated charcoal significantly reduced the microhardness of the tooth.Clinical relevanceThis study emphasizes the need for healthcare professionals to be aware of the potential disadvantages of whitening toothpastes and make evidence-based decisions when recommending the product to patients.

Comparison of the Effect of the Same Polishing Method on the Surface Roughness of Conventional, CAD/CAM Milling and 3D Printing Denture Base Materials

Objective: The aim of this study was to evaluate the effect of both the same polishing method and those with and without thermal aging on the surface roughness of conventional, CAD/CAM milling and 3D printing denture base materials.&#x0D; Materials and Methods: A total of 30 round shaped specimens were obtained by 3 different methods (n=10): Conventional, CAD/CAM milling and 3D-Printing. After applying the same polishing technique to all groups, surface roughness values were measured. Profilometer device was used for surface roughness measurement. Then, after the thermal aging of all samples, surface roughness values were measured and the roughness values between no-thermocycling and thermocycling were compared. Tukey, Mann Whitney U and Kruskal Wallis tests were used statistically. P values of ≤ 0.05 were considered significant. &#x0D; Results: As a result of the same polishing process, there was a difference in surface roughness in all groups. While the highest surface roughness values were seen in 3D-printing, the lowest roughness value was seen in the CAD/CAM milling and was statistically significant (p&amp;lt;0.05). Thermocycling did not show a statistically significant difference in surface roughness (p&amp;gt;0.05).&#x0D; Conclusions: The same polishing process caused different surface roughness values in the denture base materials obtained with different methods, and the lowest surface roughness value was seen in the CAD/CAM milling.

Evaluation of surface roughness of differently manufactured denture base materials

The popularity of computer-aided design and computer-aided manufacturing (CAD-CAM) dentures has led to the introduction of new denture materials and resins. However, studies on the surface characteristics of these materials and how they compare to dentures fabricated by more traditional methods are lacking. The purpose of this cross-sectional study was to determine whether the surface roughness (Ra) of denture base materials differed based on manufacturing technique. Disks of Ø10×2-mm (n=10) were fabricated using 6 different manufacturing techniques, including compression molding (Lucitone 199), injection molding (Ivocap High Impact), Computer Numerical Control (CNC) milling (Ivotion Base), and additive manufacturing on the Carbon M2 (Lucitone Digital Print), the SprintRay Pro55 S (Dentca Denture Base II), and the Envision One (Flexcera Base) systems. An automatic, noncontact laser confocal microscope (VK-X1000 Series; KEYENCE) was used to analyze the Ra surface roughness of each specimen at ×5 magnification. The images were imported into a multifile analyzer, horizontal and vertical roughness profiles were inserted into each scan, and Ra values were calculated and averaged by following the International Organization for Standardization (ISO) 4287 standard. A 1-way analysis of variance (ANOVA) was performed to compare the effect of manufacturing technique on surface roughness, followed by the Tukey multiple comparisons test (α=.05). The additively manufactured Dentca Denture Base II (AM-DB) exhibited a statistically significantly higher Ra when compared with the other test groups (P<.001). The additively manufactured Flexcera Base (AM-FB) showed a higher Ra mean value when compared with injection molding (IM) (P=.036). No statistically significant difference in surface roughness was found among the other tested materials representing the different processing methods (P>.05). The manufacturing method influences the Ra of denture base materials with varying results. The injection molding method resulted in the smoothest surface compared with additively manufactured and CNC-milled denture base materials.

The Influence of Various Adhesive Systems and Polishing Methods on Enamel Surface Roughness after Debonding of Orthodontic Brackets: A Three-Dimensional In Vitro Evaluation.

A slight alteration of the enamel surface is inevitable upon debonding of orthodontic brackets, adhesive removal, and finishing/polishing. The aim of this in vitro study was to compare two adhesives and three polishing methods by measuring enamel surface roughness using confocal laser scanning microscopy (CLSM). Brackets were bonded on 42 extracted human premolars using Transbond XT (Transbond group) or Fuji Ortho (Fuji group). After debracketing, adhesives were removed with a tungsten carbide bur, and surfaces were polished using Sof-Lex discs, a rotary brush with a prophylactic paste (Depural), or a prophylactic cup with two polishing pastes (n = 7 in each subgroup). Surface roughness (Sa, Sku, Sq, and Sz) was measured using CLSM and compared before treatment (T1), after debracketing and adhesive removal (T2), and after polishing (T3). The data were statistically analyzed using the Mann-Whitney U and Kruskal-Wallis tests with Bonferroni correction. The time required for adhesive removal was measured and compared using a two-sample t-test. Surface roughness at T2 increased compared to T1, but the difference was significant only for the Fuji group (p < 0.01). The time required to remove Transbond XT (94.1 ± 6.8 s) was significantly higher compared to Fuji (72.1 ± 5.9 s, p < 0.0001). Polishing with Sof-Lex discs resulted in lower surface roughness compared to T1 (p = 0.018). Using Depural and polishing pastes showed no significant difference in surface roughness compared to T1, except for a significant decrease in Sa and Sq for Transbond (p = 0.043) and in Sku for Fuji (p = 0.018) after polishing with Depural. In conclusion, the removal of Transbond took significantly longer, but there were fewer residues of composite resin on the enamel surface. Sof-Lex discs decreased enamel roughness, whereas enamel morphology and roughness were similar to the pre-treatment state after polishing with polishing pastes.

Effect of Potassium Carbonate Additives on the Properties of Copper Foils Electroplated at High Current Density

The amount and kind of additives in electrolytes play a very important role on the electroplating of Cu foil, which is used as a cathode materials for secondary batteries. As the use of Cu foil increased, various studies on the electroplated Cu foil are urgently needed. We studied surface characteristics and changes in structural properties due to the addition of inhibitors under electroplating conditions with high current density. The surface layer was observed, to analyze the effect of the amount of potassium carbonate as an inhibitor. When the potassium carbonate was added at 5~25 ppm without any other additives, the initial plating voltage was observed to decrease. To uniformly distribute crystals without agglomeration at the initial stage of electroplating, it is reasonable to add potassium carbonate within the range of 20~25 ppm. There was no significant difference in surface roughness and specific resistance due to the amount of potassium carbonate, when the additives were added complexly. There was an increase in the relative strength of the preferred growth orientation of (220) in a group with 20 ppm potassium carbonate, compared to the group with 10 ppm potassium carbonate. The grain size decreased with the amount of potassium carbonate added with other additives. However, there was no significant difference in tensile strength and elongation (p-value: 0.000). To ensure uniform properties with a combination of 4 kinds of additives it is reasonable to add potassium carbonate in the range of 10~20 ppm.

Effect of effervescent C vitamins on the surface roughness and color stability of composite resins: A SEM study

Objective: To investigate the effect of effervescent vitamins C on the color change and surface roughness of resin composites. Methods: 30 specimens (8 mm*2 mm) were prepared for each restorative material (G-ænial Posterior, Solidex). The specimens were polymerized with LED device for 20 seconds and were incubated in distilled water for 24 hours for post-polymerization. Initial color values were measured using a spectrophotometer (Vita Easyshade V, Vita Zahnfabrik, Bad Säckingen, Germany), and initial surface roughness was measured with roughness tester (Mitutoyo SJ-410 Surftest Analyzer). The specimens were randomly divided into 3 groups according to their immersion solution (Redoxon, Ocean efervit, and distilled water). During the 28-day test period, the specimens were immersed in the solutions 2 times a day. Color changes and surface roughness measurement procedures were repeated. Data were subjected to One-way ANOVA, Tukey test, and t-test (p=0.05). Results: When the color change (ΔE00) results are examined statistically; the highest ∆E values were observed in the Redoxon group, regardless of the restorative material. G-ænial Posterior specimens from both study groups and Solidex specimens incubated in Redoxon showed clinically unacceptable discoloration. When the average roughness values (Ra) are analyzed statistically, roughness values above the threshold surface roughness (Ra=0.2 µm) was detected in all groups. However, no statistically significant difference between groups (p&amp;gt;0.05). Conclusion: Despite the fact that effervescent C vitamins significantly increased the discoloration of the tested composite resins, not cause a statistically significant difference in surface roughness.

Biofilm Formation on the Surfaces of CAD/CAM Dental Polymers.

Dental polymers are now available as monolithic materials which can be readily used in computer-aided design and computer-aided manufacturing (CAD/CAM) systems. Despite possessing numerous advantages over conventionally produced polymers, the polymers produced by either of these systems fail to exhibit immunity to surface microbial adhesion when introduced into the oral environment, leading to the development of oral diseases. The aim of this study was to analyze the biofilm formation of six microorganisms from the oral cavity and its correlation to the surface characteristics of CAD/CAM dental polymers. A total of ninety specimens were divided into three groups: resin-based composite, polymethyl methacrylate, and polyether ether ketone. The experimental procedure included surface roughness and water contact angle measurements, colony forming unit counting, and scanning electron microscopy analysis of biofilm formed on the surface of the tested materials. The data were analyzed using the Kruskal-Wallis test, with a Dunn's post hoc analysis, and one way analysis of variance, with a Tukey's post hoc test; the correlation between the measurements was tested using Spearman's correlation coefficient, and descriptive statistics were used to present the data. Despite using the same manufacturing procedure, as well as the identical manufacturer's finishing and polishing protocols, CAD/CAM dental polymers revealed significant differences in surface roughness and water contact angle, and the increased values of both parameters led to an increase in biofilm formation on the surface of the materials. The CAD/CAM resin-based composite showed the lowest number of adhered microorganisms compared to CAD/CAM polymethyl methacrylate and CAD/CAM polyether ether ketone.

Assessing the Surface Modifications of Contaminated Sandblasted and Acid-Etched Implants Through Diode Lasers of Different Wavelengths: An In Vitro Study.

Objective: The present study was conducted to compare the effects of 810 nm, 980 nm, and dual (810: 50%-980: 50%) diode lasers on the surface modifications of implants contaminated by a standard strain of Escherichia coli. Methods: Based on the operation on their surface, the implants were divided into six groups: "Group 1" was the positive control group undergoing no specific procedures. "Groups 2, 3, 4, 5, and 6" were contaminated by a standard strain of E. coli; "Group 2" was also set as the negative control group. "Groups 3, 4, and 5" were irradiated by 810 nm, 980 nm, and dual lasers (810: 50%-980: 50%; 1.5W, 320 μm fiber) for 30 sec, respectively. "Group 6" was treated using standard titanium brushes. All groups were examined to evaluate the surface modifications by the X-ray diffraction analysis, scanning electron microscope, and atomic force microscopy. Results: The values of carbon, oxygen, aluminum, titanium, and vanadium were significantly different in the surface composition of the contaminated implants from the control groups (p = 0.010, 0.033, 0.044, 0.016, and 0.037, respectively). In all target areas, there were significant differences in surface roughness (p < 0.0001); the same was also true about the pairwise comparison of the study groups (p < 0.0001). "Group 5" demonstrated lower morphological surface changes and roughness degrees. Conclusions: Overall, laser irradiation could alter the surfaces of the contaminated implants. Titanium brushes and 810/980 nm lasers resulted in similar morphological alterations. Dual lasers enjoyed the least degree of morphological alterations and surface roughness.

Effect of cleaning solutions on surface roughness and flexural strength of removable orthodontic appliances

Purpose: Compare the roughness of self-curing acrylic resin and the flexural strength of nickel-chrome (Ni-Cr) wires of orthodontic appliances submitted to different cleaning processes. Materials and methods: Samples were made with NiCr orthodontic wires bent into a “T” loop and embedded in self-curing acrylic resin and submitted to four different cleaning procedures (n = 21): Group 1 – immersion for 15 minutes in deionized water and active oxygen-based tablet; Group 2 - immersion for 15 minutes in chlorhexidine 0.12%; Group 3 – spray with chlorhexidine 0.12% solution; and Group 4 – immersion in deionized water (control) por 15 minutes twice a day. Flexural strength of the orthodontic wire and roughness of the acrylic resin surface were determined at baseline as well as 90 and 120 days using an optical microscope. Normality of the data was determined using the Shapiro-Wilk test. The Kruskal-Wallis and Mann-Whitney tests were used for comparisons of surface roughness. ANOVA followed by Duncan’s post hoc test was used for the comparison of flexural strength (α = 0.05). Results: No significant difference in surface roughness was found, except in Group 4, in which the last reading (2.25 ± 0.89) was significantly higher than the baseline reading (1.15 ± 0.27) (p = 0.013). Significant reductions in the flexural strength of the wires occurred in all groups (p = 0.002). Conclusions: Immersion in the cleaning solutions did not alter the surface roughness of the acrylic resin but promoted a reduction in the flexural strength of the wires.