Aluminum Oxide Discs Research Articles

Comparative Evaluation of Biofilm Formation on Temporization Crown Materials Used in the Rehabilitation of Primary Dentition With Different Polishing Materials: An In Vitro Study.

Introduction Advancements in dental materials have enhanced aesthetic treatments for managing dental caries and injuries in primary dentition. Bis-acryl composite-based temporization materials are now preferred for restoring primary crowns due to their superior properties. However, prolonged exposure to dietary and hygienic factors can lead to discoloration and roughness, making efficient polishing essential to prevent plaque buildup. Objective This study aims to evaluate Streptococcus mutans biofilm formation on temporization material polished with different polishing systems. Methods This study tested bis-acryl methacrylate temporization material. Thirty disk-shaped specimens were prepared and divided into three groups according to the polishing system used (n = 10 per group): Shofu Super Snap mini kit (Shofu, San Marcos, CA), aluminum oxide polishing paste, and propol polishing paste. Each group's specimens were polished according to the manufacturer's instructions. Surface roughness (SR), scanning electron microscopy (SEM) morphological analysis, and Streptococcus mutans biofilm formation were assessed for each group. Results The results showed significant differences in roughness average (Ra) values among the polishing materials, with the Shofu Super Snap mini kit having the highest roughness (Ra = 2.04), followed by propol polishing paste (Ra = 1.30)and aluminum oxide paste (Ra = 0.75). Additionally, polishing methods significantly affected mean colony-forming unit (CFU) levels, with the first group having the highest mean CFU value (0.24), with SEM images showing substantial biofilm formation by Streptococcus mutans. Conclusion Bacterial biofilm formation on the aluminum oxide paste group's surface differed from that on the propol polishing paste and aluminum oxide disc groups. The polishing techniques that we tested significantly influenced surface properties and biofilm formation. These findings suggest that selecting an appropriate polishing system can reduce the risk of gingival inflammation associated with temporization materials.

Effect of finishing and polishing systems on surface roughness and color stability of aesthetic restorations exposed to staining solution.

The color and the surface roughness of aesthetic restorations are related to the clinical sucess and longevity of these treatments. Aim: This study evaluated the influence of finishing and polishing systems, and storage media on the surface roughness and color stability of aesthetic restorative composites. Materials and Method: Cylindrical specimens (n=10) were prepared and treated according to: 1. Type of composite resin (nanofilled- Filtek Z350XT, suprananofilled- Estelite Omega, nanohybrid- Empress Direct); 2. Type of finishing and polishing systems (no polishing, aluminum oxide discs or abrasive rubber polishers); and 3. Type of immersion medium (water or coffee, 3 h/day/30 days). Surface roughness (Ra - μm) and color stability (L, ∆Eab, and ∆E00) were evaluated at baseline (after polishing) and final time (after immersion). Data were subjected to Kruskal-Wallis, Mann-Whitney, Wilcoxon, and Student- Newman-Keuls tests (α=0.05). Results: Nanohybrid (p<0.001) and suprananofilled composite resins (p=0.004) showed an increase in Ra after polishing, regardless the finishing and polishing system. After immersion in coffee, the nanofilled composite had the highest roughness values (p=0.032). L values increased for all resins after polishing (p<0.05). Suprananofilled composites had the greatest color stability with the lowest values of ∆Eab and ∆E00. Conclusions: Finishing and polishing systems had an impact on the surface roughness and color stability of all aesthetic resins, and their effectiveness depended on the type of composite resin.

In vitro study on the impact of various polishing systems and coffee staining on the color stability of bleach-shaded resin composite

ObjectiveTo evaluate the effects of different polishing techniques and coffee staining on the color stability of four commercially available bleach-shade composite resins, namely microhybrid, nanohybrid, nanofilled, and injectable nanohybrids.Material and methodsA total of 224 discs (8 mm diameter and 2 mm thickness) were fabricated from four different bleach-shade composite resins, namely microhybrid (Gradia Direct Anterior), nanohybrid (Palfique LX5), nanofilled (Filtek Universal), and injectable nanohybrid (flowable G-aenial universal injectable). The composite resin groups were polished via four techniques: no polishing, 4-step polishing using aluminum oxide discs, 3-step polishing using silicon rubber diamond discs, and one-step polishing. Half of each group was immersed in water, while the other half was immersed in coffee for 12 days (n = 7). Colors were measured using a clinical spectrophotometer, and color differences were calculated (ΔE). The results were analyzed statistically.ResultsThe alterations in color were significantly influenced by the techniques employed for finishing and polishing techniques, composite resin type, and degree of coffee staining. Regardless of the polishing technique and storage medium, different material types showed a significant color change (ΔE) at P < 0.001. Filtek exhibited the most significant color change, followed by Gradia and Palfique, with no significant differences between them. In addition, Different polishing techniques resulted in significant color changes (P < 0.001). The highest degree of color change was seen in the no-polishing group, followed by the 4-step and 1-step polishing groups, with negligible differences between each other. Also, Storage media had a significant effect on ΔE values.ConclusionAppropriate finishing and polishing procedures can improve the color stability of bleach-shaded composite resins. Coffee has a deleterious effect on color; however, injectable flowable nanohybrid composites are more resistant to staining.

Finishing and polishing systems influence the roughness and color stability of acrylic and bis-acryl composite resins.

To evaluate the effect of different finishing and polishing systems on the surface roughness and color changes of bis-acryl (Protemp 4 - 3M ESPE- St. Paul, USA; Structur 3 - Voco, Cuxhaven, Germany) and chemically activated acrylic materials (Duralay - Reliance, SP, Brazil). Specimens (10 x 2 mm) thick were prepared for each material. The specimens were subjected to polishing and finishing procedures with aluminum oxide discs (Diamond Master - FGM, Joinville, Santa Catarina, Brazil) and spiral rubber disks (Sof-Lex - 3M ESPE, Germany). The control did not receive any polishing and finishing procedures. Surface roughness and color measurement values were obtained after the finishing and polishing procedures and immediately after 30 days of storage in water, coffee, and red wine. Data for each material were analyzed by One-Way ANOVA (p<0.05). The polishing with aluminum oxide discs was able to affect the initial surface roughness values of chemically activated acrylic material (p<0.05). After immersion in staining solutions, lower ∆E values were only observed for the bis-acryl composite resins compared to the control group (p<0.05). The finishing and polishing systems influenced the surface roughness and color stability of the materials tested. The chemically activated acrylic resin showed lower surface roughness and higher color stability than the bis-acryl materials. Key words:Acrylic resin, bis-acryl resin, provisional restoration.

Unilateral peg-shaped mandibular central incisor and direct composite resin treatment: A case report

Aim: This case report describes the restorative treatment process of a non-syndromic unilateral peg-shaped left mandibular central incisor. Case presentation: A 23-year-old female patient was admitted for aesthetic concerns related to the appearance of the anterior mandible and a peg-shaped incisor. The color selection was done on clean, hydrated teeth. The teeth were roughened with a minimal red belt bur, a 37% phosphoric acid gel was applied to the enamel for 30 seconds, and the teeth were washed with water for 30 seconds to remove the acid agent. Following the application of a universal adhesive to the surface according to the manufacturer’s instructions, the palatal and proximal walls were formed using a mylar strip and an A2B-colored resin composite. Then, polymerization of the restoration was completed using an incremental layering technique. After the removal of any excess restoration, low-speed finishing and polishing were done using aluminum oxide and flexible rubber polishing disks containing diamond particles. After the resin application, the treatment was completed. Conclusion: To achieve optimal results in the treatment of patients, restorative treatment can be recommended, considering the position and condition of the tooth. When choosing the most appropriate treatment for a patient, the advantages and limitations of each technique should be carefully explained, and the most conservative treatment should be recommended. How to cite this article: Fidan M. Unilateral peg-shaped mandibular central incisor and direct composite resin treatment: A case report. Int Dent Res 2023;13(1):44-47. https://doi.org/10.5577/idr.2023.vol13.no1.7 Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.

Quantitative and Qualitative Assessment of Enamel Surface following Two Composite Removal Methods after Bracket Debonding

Aims: To evaluate and compare morphology and roughness of the enamel surface after debonding and polishing by two methods: aluminum oxide disks (Shofu, Super-Snap) and 30-fluted tungsten carbide bur (Strauss and Co.) using a surface roughness tester and a scanning electron microscope (SEM), respectively. Subjects and Methods: For this study, we selected 15 orthodontic patients with bonded metal brackets. After the completion of fixed orthodontic treatment, metal brackets for the maxillary central incisors were removed with a debonding plier. For every patient, teeth were chosen on a random basis to be finished and polished with Super-Snap aluminum oxide disks on one side (n = 15) and with 30-fluted tungsten carbide bur (n = 15) on the other side. Epoxy resin was used to obtain the replicas of maxillary anterior teeth (before and after tooth polishing). SEM analysis was done for five samples from each group. Results: The average roughness after resin removal in the 30-fluted tungsten carbide bur group (0.328 mm ± 0.099) was found to be significantly higher when compared to the Super-Snap aluminum oxide disks (0.299 mm ± 0.109). Conclusions: The Super-Snap aluminum oxide disks resulted in superior finishing and polishing than 30-fluted tungsten carbide bur.

Fast‐current‐driven synthesis of ultrathin ZIF‐8 membrane on ceramic tube for propene/propane separation

AbstractMOF membranes are very promising in molecular separation, but it is still a challenge for industrial applications due to the complex and time‐consuming synthesis. We use the fast current‐driven synthesis (FCDS) method to achieve controlled growth of ZIF‐8 membranes on porous graphite‐coated ceramic tubes by controlling the growth time and current density. Grown for 30 min at a current density of 0.74 mA/cm2, the ZIF‐8 membrane exhibits selectivity for C3H6/C3H8 up to 63 with C3H6 permeance of 6 × 10−9 mol/(m2 s Pa). Furthermore, the ZIF‐8 membrane exhibits a pressure resistance of up to 3 bar and good stability of ~96 h. This work realizes the breakthrough of the MOF membrane synthesis via FCDS method from the frequently‐used expensive and fragile anodic aluminum oxide (AAO) disc substrate to the tough ceramic tubular substrate, which broadens the road for the industrialization of MOF membranes in gas separation fields.

Evaluation of the Effect of Different Polishing Systems on the Color Change of the New Alkasite Restorative Material

Amaç: Bu çalışmanın amacı, farklı sistemlerle polisajlanmış diş dolgularında kullanılan alkasitin bir renklendirici ajana maruz kalmasının ardından 24. saat ve yedinci gününde oluşan renk değişimlerinin incelenmesidir. Yöntem: 8 mm çapında ve 2 mm yüksekliğinde teflon kalıplar içerisine yerleştirilen alkasit materyali mylar strip uygulaması altında polimerize edildi ve toplam 30 adet örnek elde edildi (n=10). Materyaller rastgele 3 gruba ayrıldı; Grup 1: Elmas grenli polisaj lastikleri (Twist Dia; Kuraray, Japan), Grup 2: Alüminyum oksit diskleri (Sof-Lex; 3M ESPE, MN, USA) uygulanarak polisaj işlemi tamamlandı. Grup 3’te polisaj sistemi uygulanmadı. İlk renk ölçümü bir spektrofotometre kullanılarak gerçekleştirildi. Kahve içerisine daldırıldıktan 24. saat ve 7. gün sonra ikinci ve üçüncü renk ölçümleri aynı cihaz ile tamamlandı. CIEDE2000 renk formülü kullanılarak renk değişimleri (ΔE00) belirlendi. Bulgular tek yönlü ANOVA ve Tukey testi kullanılarak %95 güven aralığında analiz edildi. Bulgular: ΔE00 değerleri 24 saat ile 7. gün arasında alınan ölçümlerde tüm gruplar için istatistiksel olarak anlamlı bir artış gözlenmiştir. 24 saat sonunda en düşük ortalama renk değişimi değerleri Grup 2’de gözlenirken (p0,05). Kontrol grubu ise en yüksek renk değişim değerlerini göstermiştir (p

Effect of Different Repolishing Procedures on The Color Change of Alkasite

Objectives: An esthetic restoration with an unacceptable color is the main cause for replacement of anterior tooth restorations. The aim of this study is to evaluate the effect of repolishing on the color change of the new material group of alkasite after exposure to coffee solution. Materials and Methods: Alkasite material placed in Teflon molds with a diameter of 8 mm and a height of 2 mm was polymerized under the application of mylar strip and a total of 32 samples were obtained. The samples were randomly immersion into groups. Group R: Diamond grained polishing rubbers, Group D: Aluminum oxide discs are applied and the polishing process is completed. After the first color measurement was made, it was immersed in coffee and the measurement was repeated 1 week later. L was divided into two groups (n=8) and repolished with rubber (RR) and discs (RD). In the D group, re-polishing was done with rubber (DR) and disc (DD) and color measurements were repeated. Results were analyzed by using one-way ANOVA and Tukey test at 95% confidence interval. Results: The greatest color change (ΔE00) was in group R. At the end of seven days, similar color change values were found between the groups of R and D (p &amp;gt; 0.05). There is no difference between the RR and RD groups. Significantly less color change was observed in the DD group than in the RR and RD groups (p = .003, p = .042, respectively). Similarly, the DR group showed less color change than the RR group (p = .015). Conclusions: The color stability of the alkasite was affected by the polishing procedure. The repolishing process reduced the color change, but not at a clinically acceptable level.

The effect of aluminum oxide sandblasting and discs on shear bond strength of metal brackets rebonded in eroded enamel

This research aimed to assess the effect of aluminum oxide sandblasting and discs on the bond strength of metal brackets rebonded on artificially eroded enamel. Fifty-four bovine incisors were divided into groups: Control (Artificial Saliva), AlOx (Aluminum oxide sandblasting), and SL (Aluminum oxide discs). They had their enamel surface flattened with Al2O3 discs and a metallographic polisher, then Knoop microhardness was assessed. AlOx and SL specimens were eroded with Coca-Cola™ for 1 minute, 3 times a day for 7 days. Metal brackets were bonded to the tooth. Shear strength was measured by an EMIC universal testing machine (0.5 mm/min). The Adhesive Remnant Index (ARI) was performed after shearing through magnifying glass (10X). Kolmogorov-Smirnov, Levene, homoscedasticity and ANOVA tests were applied to assess microhardness and shear strength (p=0.163). All groups presented shear bond strength with no significant differences. The ARI showed statistically significant difference between the groups. The prevalence for the control group was ARI 3. However for AlOx and SL, ARI 1 and 2 prevailed. The aluminum oxide sandblasting and aluminum oxide discs did not positively increase the bond strength of brackets when bonded to artificially eroded enamel. The ARI indicated that eroded teeth present higher resin adhesion to enamel.

Evaluation of enamel roughness after the removal of brackets bonded with different materials: In vivo study

The aims of this in vivo study were to evaluate the effect of bonding with resin-modified glass ionomer cement (RMGIC) and to assess enamel surface roughness before and after the removal of brackets bonded with composite or RMGIC from the maxillary central incisors. Fifteen orthodontic patients were selected for the study. For each patient, the teeth were rinsed and dried, and brackets were bonded with composite (Transbond XT) and RMGIC (Vitremer Core Buildup/Restorative). At the conclusion of orthodontic treatment, their brackets were removed. Dental replicas were made of epoxy resin in initial conditions (before bonded) and after polishing with an aluminum oxide disc system. Adhesive remnant index (ARI) and surface roughness was measured on the dental replicas and data were evaluated statistically by Mann-Whitney and paired t-test, respectively. No bracket debonding occurred during patients' treatment periods. It was verified that the ARI values of the two maxillary central incisors were similar (p = 0.665). For both bonding materials, the ARI value of 3 was predominant. After polishing, surface roughness was similar in the composite and RMGIC groups (0.245 μm and 0.248 μm, respectively; p = 0.07). In both groups, enamel surface roughness values were significantly lower after polishing compared with the initial condition (p < 0.001). RMGIC promoted efficiency in cementing brackets without fail during treatment; the choice of composite or RMGIC materials was not a factor that influenced the roughness of the enamel surface, however, polishing led to smoother surfaces than those found at the beginning of the treatment.

Effect of Additional Light Curing on Colour Stability of Composite Resins

AimThe objective of this study was to evaluate the effect of additional light curing on the colour stability of composite resins. Materials and methods: Four different composite resins—a nanofill, a nanohybrid, a microhybrid, and a bulk-fill composite resin—were tested. Eighty disc-shaped specimens were prepared from each material using either a quartz tungsten halogen or a light-emitting diode light source and were randomly divided into 2 groups according to the surface treatment: no polishing (nonpolished) or polishing with aluminum oxide discs (polished). Then additional light curing was applied to half of the specimens in each group. All specimens were immersed in coffee solution for 1 week. Colour was measured with a spectrophotometer at baseline and after 1 week of storage in coffee solution. Results: Statistically significant differences in colour stability were observed in the restorative materials according to the composition of composite resin, the polishing protocol, and additional light curing, whilst there were no significant differences according to the light source. Additional light curing reduced discolouration in all groups tested. Conclusions: Additional light curing may be beneficial after finishing and polishing in order to maintain aesthetics and increase the resistance of composite resins to discolouration.

Numerical Analysis of Wear Characteristics of Zirconia Coated Aluminum 6061 Alloy

Any mechanical systems with moving parts encounter the problem of wear and industriesacross the world are trying to reduce its detrimental effects. In this paper, Finite Element Method (FEM) is used for analysis of wear characteristics of Yttrium stabilized Zirconia coating on Al6061 Aluminum alloy. Aluminum alloy 6061, having high strength to weight ratio, is used as the substrate material upon which Thermal Barrier Coating (TBC) is applied. Friction and wear coefficient obtained from Continuous Sliding Motion (CSM) of Yttrium stabilized Zirconia coating over Aluminum oxide disc material is used for the numerical analysis inputs. Tribological characteristics such as contact pressure, frictional stress and wear thickness are evaluated numerically using ANSYS Mechanical based on Archard wear model.

New Experimental Zirconia-Reinforced Rice Husk Nanohybrid Composite and the Outcome of Its Surface Roughness and Microhardness in Comparison with Commercialized Nanofilled and Microhybrid Composite Resins

Background:An ideal composite resin should demonstrate smooth surface after polishing and high hardness value to provide long-term success. Thus, this study aimed to compare the surface roughness and microhardness of new experimental zirconia-reinforced rice husk nanohybrid composite (Zr-Hybrid) with commercialized nanofilled (Filtek-Z350-XT) and microhybrid composite (Zmack-Comp) resins before and after artificial ageing.Methods:One hundred and eighty standardized disc samples were prepared, of which ninety samples each were used for surface roughness and microhardness test, respectively. They were divided equally into: Group 1 (Filtek-Z350-XT), Group 2 (Zmack-Comp), and Group 3 (Zr-Hybrid). For surface roughness test, all samples were polished with aluminium oxide discs and further subdivided into aged and unaged subgroups, in which composite samples in aged subgroups were subjected to 2500 thermal cycles. Next, all the samples were subjected to surface roughness test using a contact stylus profilometer. As for microhardness test, all the aged and unaged samples were tested using a Vickers hardness machine with a load of 300 kgf for 10 s and viewed under a digital microscope to obtain microhardness value. Data were analyzed using two-way ANOVA followed by post hoc Tukey's honestly significant difference and paired sample t-test with significance level set at P = 0.05.Results:In both the aged and unaged groups, Zr-Hybrid showed statistically significantly lower surface roughness (P < 0.05) than Filtek-Z350-XT and Zmack-Comp, but no statistically significant difference was noted between Filtek-Z350-XT and Zmack-Comp (P > 0.05). A similar pattern was noted in microhardness test, whereby Zr-Hybrid showed the highest value (P < 0.05) followed by Filtek-Z350-XT and lastly Zmack-Comp. Besides, significant differences in surface roughness and microhardness were noted between the aged and unaged groups.Conclusion:Zr-Hybrid seems to demonstrate better surface roughness and microhardness value before and after artificial ageing.

The Effect of Finishing and Polishing Sequences on The Surface Roughness of Three Different Nanocomposites and Composite/Enamel and Composite/Cementum Interfaces

The purpose of this study was to investigate the effect of final surface treatment and dental composite type on the roughness of the composite surface, composite/enamel interface, and composite/cementum interface, as well as on the polishing time. Class V cavities prepared in extracted teeth (n = 126) were restored using one of the three nanohybrid composites with different filler sizes. The specimens were randomly assigned to three different finishing and polishing sequences. The roughness (Ra) of the investigated surfaces was measured using the contact profilometer. The time required to achieve visible gloss was documented. The data were analyzed using ANOVA with Tukey’s post hoc test (p < 0.05). There was no significant influence of the composite type on the restoration surface roughness (p = 0.088), while the polishing method had a significant impact (p < 0.001). The Ra of the composites ranged between 0.08 µm and 0.29 µm, with the lowest values (0.09 µm ± 0.05 µm) found in the aluminum oxide disc group (p < 0.001). The time to achieve a visible composite gloss was influenced by the polishing method, composite type, and interactions between these factors (p < 0.001). The interface roughness was significantly greater than that of the composite surface (p < 0.001), and depended on the composite type and polishing system employed.

Mechanical and thermal effects of abrasive cut-off applied in low and medium carbon steels using aluminum oxide cutting disc

Abrasive cutting is broadly applied to obtain structural and electromechanical parts for the industry, as well as metallographic specimens for research laboratories. However, the literature about this process is still scarce, making further studies necessary. Usually, the final quality of the obtained products plays a minor role in comparison to the costs associated with tool wear. In this context, an experimental investigation of the abrasive cut-off operation of low and medium carbon steels, using aluminum oxide discs with different feed rates (2.0, 3.4, and 4.6 mm/s), is reported. The cutting power, disc wear, and process temperature were monitored and comprehensively evaluated. Besides, a computational simulation was developed for temperature prediction and the results were compared with the experimental data. The disc surface was assessed through confocal and scanning electron microscopies, and the chips were analyzed with scanning electron microscopy and energy dispersive spectroscopy. Contrary to what was expected, an increase of 130% in feed rate led to a decrease of approximately 57% in maximum temperature, and 84% in diametrical wheel wear, improving process efficiency. On the other hand, the consumed cutting power increased by up to 127%. The proposed simulation model presented a high correlation with the experimental data and can be applied to predict and prevent thermal damages to the parts.

Discoloration of Resin Composites Induced by Coffee and Tomato Sauce and Subjected to Surface Polishing: An In Vitro Study

BackgroundThe purpose of this study is to evaluate and compare color stability of 3 resin based restorative materials when immersed into staining media at 0, 3, 30, 45, 60, and 75 days, and to assess the efficacy of surface polishing in reducing possible discoloration.Material/MethodsNinety composite discs were prepared in a custom-made mold (5 mm diameter and 2 mm thick) from 3 different light cured composites (Filtek™ Z250, Harmonize™, and G-aenial). Color differences of all specimens were measured by a spectrophotometer according to the CIE L*a*b* system. After baseline color measurements, 30 discs from each composite group were randomly divided into 3 subgroups of 10 specimens each. Subgroups (n=10) were immersed for 75 days into different staining solutions: coffee, tomato sauce, and distilled water (control). Solutions were changed every week and color measurements were repeated every 15 days. At day 75, color measurements of the specimens were performed before and after surface polishing with aluminum oxide discs. The experimental data were statistically evaluated using repeated measures one-way ANOVA test followed by Tukey’s multiple pairwise comparison with a significance level of 5%.ResultsOf the 3 composites, G-aenial reported the highest color change deviation when immersed into coffee (ΔE=8.674), and tomato sauce (ΔE=7.737) at day 75, followed by Harmonize that also exhibited a significant difference for coffee (ΔE=4.7) and tomato sauce (ΔE=3.8) when compared to distilled water. While Filtek™ Z250 did not show any significant difference between the 3 storage solutions (P>0.05).Only G-aenial had significant color change (P<0.05) after polishing with aluminum oxide discs for all tested samples, whereas Filtek™ Z250 and Harmonize presented no significant difference after surface polishing (P>0.05).ConclusionsUnder the tested experimental conditions, Filtek™ Z250, among the 3 resin-based composites, exhibited the highest color stability when subjected to coffee and tomato sauce as well. Whereas, G-aenial presented the highest color deviation when immersed in both staining media.Surface polishing effectively reduced coffee and tomato sauce discolorations for G-aenial’s specimens and had no significant effect regarding Filtek™ Z250 and Harmonize.

An evaluation of surface roughness after staining of different composite resins using atomic force microscopy and a profilometer.

The aim of this study was to compare the surface roughness of different composite resins using atomic force microscope (AFM) and a profilometer after storage in different solutions. Eight different composite resins were used in this study. Twenty specimens of each composite resin material were prepared using a 2-mm thick and 8-mm diameter stainless steel mold. After the composites had been placed in the mold, they were polymerized with a LED curing unit. The surfaces of all specimens were polished using aluminum oxide discs, and the specimens were then divided into four groups. The specimens in the experimental groups were stored in cola, coffee, or red wine, while the control group was stored in distilled water. Specimen surface roughness was examined after 30 days using an AFM and a profilometer, and the data obtained were subjected to analysis. Evaluation of the surface roughness of composite resins using a profilometer revealed no statistically significant difference between the groups, but significant differences were found using the AFM. The mean surface roughness of nanohybrid composites was lower than that of microhybrid composites. The surface roughness of the composite resins varies with storage in different solutions, depending on the organic matrix structure and inorganic fillers of the resin.

Roughness and stability of compound resin color exposed to bleaching strips after surface treatment

ABSTRACT Objective to analyze the surface roughness and color stability of the composite resin after surface treatment with the aluminum oxide discs and subsequent exposure to the Advanced Teeth Whitening Strips. Methods 20 specimens of the Filtek Z350XT restorer (3M®) were prepared and daily subjected to home bleaching for 30 minutes during 14 days. A precision rugosimeter was used in order to verify the roughness by means of 3 random readings in the same direction in each sample. For color stability the CIELAB system (L*, a*, b* values) was used through the spectrophotometer (MINOLTA CR -321, Japan). The means of the test specimens as well as the mean of each group were calculated using the random readings. Data statistical analysis were performed by ANOVA- analysis of variance. The level of significance was set at 5% (p ≤ 0.05). Results Roughness did not present great numerical variations. No statistically significant difference between the means obtained concerning the surface roughness of the composite resin with p = 0.44 was observed. However, it was found that there was a statistically significant difference between the means obtained in relation to the color stability of the composite resin, p=0. 007. Conclusion It was concluded that pre-contoured strips containing 6% hydrogen peroxide do not have a significant adverse effect on the roughness of Z350XT (3M®) resin. However, it was also concluded that according to the color stability analysis performed, there may be an indication of the restoration replacement after the bleaching treatment, due to their color change.

Effect of different polishing techniques for composite resin materials on surface properties and bacterial biofilm formation

ObjectivesBoth direct and indirect techniques are used for composite resin material (CRM) restorations. Polishing processes are needed in both techniques after intraoral adjustment. However, it is unclear as to which polishing technique should be preferred with respect to decreasing biofilm. The purpose of thisin vitro study was to evaluate the surface properties and Streptococcus mutans biofilm formation on direct and indirect CRMs after using different polishing techniques. MethodsTwo CRMs (direct and indirect) and four polishing techniques (aluminium oxide discs, diamond polishing paste, aluminium oxide polishing paste, and silicon carbide brush) were evaluated. The specimens were prepared for taking scanning electron microscopy images (n = 2) and determining surface roughness, surface free energy, and bacterial biofilm formation (BBF) with colony-forming unit counting and confocal laser scanning microscopy assays (n = 7). The data were analysed using two-way analysis of variance with Bonferroni as a post hoc test and Pearson’s correlation (p < .05). ResultsThe surface roughness values in the control group were higher than those in the diamond polishing paste group (p = 0.025), but the values in the aluminium oxide polishing paste and silicon carbide brush groups were comparable with those in the control group (p = 0.156 and p = 1.000, respectively). The highest surface free energy values were recorded in the silicon carbide brush group (p < 0.001), whereas there were no differences found among the other groups (p > 0.05). The highest BBF was seen in the silicon carbide brush (p < 0.001) and direct CRM (p < 0.001) groups. ConclusionBBF on the surface of direct CRMs differed from that on indirect CRMs after polishing the surface. The tested polishing techniques significantly influenced surface properties and BBF. Clinical significanceIn situations that require the intraoral adjustment of CRMs, polishing with a diamond polishing paste seems to be a good option to polish the surface of both direct and indirect CRMs because the diamond polishing paste results better in terms of decreasing biofilm formation and improving surface properties.