Evaluation of the surface hardness, roughness, gloss and color of composites after different finishing/polishing treatments and thermocycling using a multitechnique approach

In vitro comparison of one-step, two-step, and three-step polishing systems on the surface roughness and gloss of different resin composites

OBJECTIVES

This laboratory study evaluated the effect of three polishing systems on the surface roughness and gloss of resin composites.

MATERIALS AND METHODS

Thirty specimens (6 mm Ø × 8 mm) were fabricated from each of three resin composites: Z 350 XT (nanofill), Harmonize (nanohybrid), and Estelite Omega (supranonofill). All specimens were photopolymerized using a multi-peak LED curing unit (VALO-Standard mode), having a exitance irradiance of approximately 1000 mW/cm2 against a polyester strip (PS). 2 mm was then removed from the irradiated end (finished) using #320 abrasive paper (F). Specimens were then randomly polished (P) using a one-step (1S) (OneGloss), two-step (2S) (EVE Diacomp Twist Basic CA), or 3-step (3S) (Astropol P) system (n = 10). For PS, F, and P groups, surface roughness (Ra) was measured using a surface roughness tester, and surface gloss was measured with a glossmeter. For each specimen, the percent recovery to the PS value (%R) of surface roughness and surface gloss were calculated. Data were analyzed using two-way ANOVA, followed by Tukey's test. Surface roughness and gloss values were submitted to Pearson's correlation test (α = 0.05). All statistical testing was performed using a pre-set alpha of 0.05.

RESULTS

The interaction term [resin composite × polishing system] was significant for both surface roughness (p = 0.001) and gloss (p = 0.0001). For all resin composites, the 2S and 3S systems provided a higher %R of surface roughness and gloss compared to those of the 1S system. There was a negative correlation between surface roughness and gloss, but only a few combinations showed strong correlations.

CONCLUSIONS

The 2S and 3S polishing systems provided surfaces having greater smoothness and gloss compared to the 1S system. The ability to recover surface roughness and gloss was dependent on type of resin composite filler classification.

CLINICAL SIGNIFICANCE

The 3S and 2S polishing systems were more effective in achieving PS values than was the 1S system for all tested resin composites. However, individual polishing systems performed differently depending on type of resin composite.

Effect of aging and fiber-reinforcement on color stability, translucency, and microhardness of single-shade resin composites versus multi-shade resin composite

OBJECTIVE

The purpose of this study was to evaluate the effect of aging and fiber-reinforcement on the color stability, translucency, and microhardness of single-shade resin composites versus multi-shade resin composite.

MATERIALS AND METHODS

Four resin composites (Filtek Z250, Omnichroma, Vittra APS Unique, Zenchroma) were tested. Three subgroups of specimens were prepared for each of the composites: control, polyethylene fiber-reinforcement, and glass fiber-reinforcement- groups (n = 10/per group). The samples were subjected to aging for 10,000 thermal cycles. Color differences (ΔE00 ) were calculated after aging. Relative translucency parameter (RTP00 ) and microhardness values were calculated before and after aging. A two-way analysis of variance and the generalized linear model was used (p < 0.05).

RESULTS

The lowest and highest ΔE00 values were found for Filtek Z250 (0.6 ± 0.2) and Omnichroma resin composites (1.6 ± 0.4), respectively. The ΔE00 value of the polyethylene fiber-reinforcement group (1.2 ± 0.6) was significantly higher than the ΔE00 value of the glass fiber-reinforcement group (1.0 ± 0.4, p < 0.001). The RTP00 value of the glass fiber-reinforcement group (1.92 ± 0.78) was significantly higher than the RTP00 value of the polyethylene fiber-reinforcement group (1.72 ± 0.77, p < 0.001). The highest microhardness values were found in glass fiber-reinforcement group (76.48 ± 17.07, p < 0.001).

CONCLUSION

Single-shade resin composites were more translucent, had higher color change, and lower hardness than multi-shade resin composite. For relative translucency and microhardness, statistical significance was found in the material and fiber type interaction. The glass fiber-reinforcement provided higher translucency, lower color change and higher microhardness values than polyethylene fiber-reinforcement group after aging. Thermocycling had a significant impact on the color stability, translucency parameter, and microhardness of the tested resin composite materials.

CLINICAL SIGNIFICANCE

Single-shade resin composite materials have greater color-changing potential. The glass fiber-reinforcement optimize resin material mechanical properties and color stability more than polyethylene fiber-reinforcement.

A comparison of the effects of incremental and snowplow techniques on the mechanical properties of composite restorations

BACKGROUND

Glass fibre-reinforced composite (GFRC) has the potential to enhance the mechanical properties of resin-based restorations. Nevertheless, the application technique can influence the cervical margin porosity, potentially reducing the mechanical strength of restorations.

METHODS

In an in vitro setup, mould specimens underwent six different treatments to assess the effects of snowplow and incremental curing techniques on the properties of GFRC (EverX) and universal resin composite (Filtek). Mechanical properties, namely flexural strength (FS), compressive strength (CS) and Vickers hardness (VH), were evaluated following ISO 4049 standards. Data interpretation utilized the Kruskal-Wallis tests.

RESULTS

No significant difference emerged across groups for FS. CS in the snowplow method with lesser EverX thickness (SnPl_1) was comparable with only EverX and Filtek (P > 0.05). The CS was reduced in the snowplow technique with greater EverX thickness (SnPl_2) (P < 0.05) and further decreased with the incremental method (P < 0.001). VH results showed that EverX Posterior was consistently softer than Filtek, with specific patterns of hardness variations among different application methods.

CONCLUSIONS

Applying EverX and Filtek using the snowplow technique delivers superior CS and VH for restorations in contrast to the incremental method. Utilizing the snowplow approach in high-stress areas can make restorations more fracture-resistant.

Effect of different finishing and polishing systems on surface properties of universal single shade resin-based composites

BACKGROUND

Recently, universal single-shade resin composites have become increasingly available in the dental market. The modification of their composition can have an inadvertent effect on their physical and surface properties, and subsequently determinantal effect on their clinical function and longevity. Therefore, this study aimed to evaluate the effect of different finishing and polishing (F/P) systems on surface roughness (Ra), surface gloss (GU), and Vickers microhardness (VMH) of universal single-shade RBCs.

MATERIALS AND METHODS

Four commercial RBCs were used; the universal single-shade RBCs were Omnichroma, Charisma® Diamond ONE, and Vittra APS Unique, and a conventional nanocomposite Filtek™ Z250 XT was used as a control. The 3 F/P systems were Sof-Lex™ XT, Enhance®/PoGo®, and Diacomp® Plus Twist. A total of 160 discs were used for the 3 F/P system groups for all RBCs (n = 10). After F/P, the Ra, GU, and VMH were assessed. The data were analyzed using 2-way ANOVA at p-value < 0.05.

RESULTS

Significant differences were found among the four RBCs and the 3 F/P systems (p < .000). Omnichroma showed the lowest Ra and acceptable GU, but the lowest VMH. Charisma showed the highest Ra, acceptable GU, and VMH. Vittra showed acceptable Ra, GU, and VMH and Filtek showed the highest GU, VMH, and acceptable Ra.

CONCLUSION

Although conventional nanohybrid RBC (Filtek Z250 XT) showed better GU and VMH values, the universal single-shade RBCs demonstrated comparable surface properties. The highest GU & VMH and lowest Ra were achieved by Diacomp followed by Enhance and Soflex.

Effect of a demineralization model on the microhardness, surface roughness and topography of giomers: An in vitro study

The purpose of this study is to compare the effect of a demineralization model on the microhardness, surface roughness, and topography of giomers.Seventy-two discs of six different dental materials in three different presentations (pit and fissure sealant (PFS), flowable and restorative materials) were divided into six groups (n = 12 p/g). Three experimental groups (giomers) consisted of BeautiSealant, Beautifil Flow Plus, and Beautifil II, and three control groups (resin-based materials) were formed using ClinproTM, FiltekTM Z350 XT Flow, and Filtek™ Bulk Fill materials. Vickers microhardness, surface roughness, and topographic analysis with atomic force microscopy were measured at the beginning (0) after four (1) and 7 days (2) of immersion in a demineralizing model. Statistical analysis was performed using One-way and Repeated Measures ANOVA and Pearson's correlation coefficient (p ≤ .05). The microhardness values showed significant variations, except for the G_RM group. All the groups presented significant increases in roughness through the experiment stages, except for RB_PFS in the Ra parameter. The topographic analysis showed variations in the micromorphology, especially in the experimental group at the end of the demineralization model. Finally, there was no correlation between microhardness and surface roughness. The demineralization model decreased the microhardness, with the lowest reductions in the giomers groups. The effect of the demineralizing model on the surface roughness and topography showed an increase in specific patterns for the experimental and control groups. Therefore, their clinical use is recommended. RESEARCH HIGHLIGHTS: The demineralization model decreased the microhardness property of the evaluated materials, with better performance for the giomer groups. The effect of the demineralizing model on surface roughness showed an increase with specific patterns for the experimental and control groups. Although the materials presented changes in their microhardness, roughness, and topography, their clinical use is recommended.

Effect of different finishing and polishing procedures on surface roughness and microbial adhesion on highly-filled composites for injectable mold technique

OBJECTIVE

To evaluate the effect of different finishing and polishing procedures on surface roughness and microbial adhesion and viability of Streptococcus mutans on novel highly-filled composites for injectable mold technique.

MATERIALS AND METHODS

One hundred sixty specimens were divided into four material groups: FSF (Filtek Supreme Flowable Restorative), TE (Tetric EvoFlow), GUI (G-aenial Universal Injectable) and GUF (G-aenial Universal Flo). Within each group, specimens were split regarding finishing and polishing (F/P) procedures into: SLD (Sof-Lex Discs), SLS (Sof-Lex Spirals), OG (OneGloss) and PG (PoGo). Surface roughness was analyzed using profilometer (Ra and Rz) and scanning electron microscopy (SEM) and Strep. mutans biofilm formation was analyzed using colony forming unit (CFU) and cell viability assay. Two-way analysis of variance (ANOVA) followed by Tukey's post hoc test were used for comparison among groups, Pearson's coefficient was applied for the correlation between Ra and CFU/ml and all data were presented as mean ± SD.

RESULTS

Both materials and F/P procedures affect Ra, Rz and Strep. mutans CFU/ml values (p ≤ 0.05). Considering the Ra and Rz, GUI and GUF revealed lower values, compared to FSF and TE and SLD and SLS revealed lower values, compared to OG and PG. Considering the Strep. mutans CFU/ml and viability, GUI and TE presented lower values, compared to GUF and FSF and SLD and SLS presented lower values, compared to OG and PG. Moderate positive correlation was found between Ra and CFU/ml (r = 0.552).

CONCLUSIONS

The smoothest surfaces possess GUI and GUF, among materials and SLD and SLS, among F/P procedures. GUI adhered the lowest amount of Strep. mutans, due to the smoothest surfaces. FSF and GUF revealed the highest amount of Strep. mutans, due to bis-GMA, bis-MEPP and TEGDMA in their composition.

CLINICAL SIGNIFICANCE

The findings of the present study may be beneficial for the proper selection of highly-filled composites and an adequate finishing and polishing procedure when performing the injectable mold composite resin veneer technique.

The Effect of Different Finishing and Polishing Systems on Surface Properties of New Flowable Bulk-fill Resin Composite

AIM

The purpose of this research was to explore how various finishing and polishing techniques affect the surface roughness (Ra) and gloss of flowable bulk-fill injectable resin composite utilized for posterior teeth restoration, following exposure to a range of food-simulating liquids (FSLs) over three months.

MATERIALS AND METHODS

This study comprised fifty-six disk specimens of G-aenial™ Bulk Injectable flowable resin composite which were created using a Teflon mold (10 × 4 mm). Two techniques of finishing and polishing (F/P) were employed: The two-step 3M™ Sof-Lex™ F/P spiral wheels system and the multiple-step 3M™ Sof-Lex™ XT finishing disks supplemented by the Ultradent Jiffy HiShine polisher cup system. The Ra and gloss of the prepared specimens were measured using an interference microscope system and Horiba gloss checker respectively, immediately post-finishing and polishing and then reassessed after three months in artificial saliva and Coca-Cola.

RESULTS

The two-step system showed a statistically significant difference, exhibiting greater "surface roughness (Ra)" and lower "surface gloss (GU)" mean values compared to the multiple-step system under different storage conditions, particularly after 3 months of storage (p = 0.001).

CONCLUSION

The multiple-step polishing system improved the "Ra" and "GU" of resin composite, suggesting their suitability for posterior resin composite restorations. Acidic media had a deleterious impact on the "Ra" and "GU" of resin composite restoration.

CLINICAL SIGNIFICANCE

The quality of resin composite restorations can be significantly improved with the correct use of finishing and polishing systems, particularly in complex areas of posterior teeth restorations, leading to successful dental procedures.

Does Sterilization Affect the Performance of Single-Step Resin Composite Polishers?

(1) Background: Single-step polishers are used extensively for resin-composite polishing. The purpose of this study was to evaluate the effect of sterilization on their performance. (2) Methods: Optrapol Next Generation/Ivoclar-Vivadent, Jazz Supreme/SS White, Optishine Brush/Kerr and Jiffy Polishing Brush/Ultradent were used for polishing a nanohybrid resin composite (IPS Empress Direct/Ivoclar-Vivadent). Polishers (n = 40) were microscopically inspected before use. After polishing, surface roughness (Sa, Sz, Sdr, Sci) and gloss were determined. Polishers were subsequently sterilized and microscopically re-examined. The process was repeated four times on new samples (n = 200). Data were analyzed using the Friedman test and Wilcoxon post hoc test, at α = 0.05. (3) Results: Optrapol's performance improved after the first sterilization for Sa and gloss, whereas it declined after the fourth sterilization for Sa. Jazz's, improved after the second sterilization for Sa and gloss and after the third sterilization for Sdr. An improvement trend was observed for Optishine after the first sterilization, but not statistically significant. Sa, Sz, and gloss declined after the fourth sterilization. Jiffy's performance was inconsistent, with a trend of performance loss after the fourth sterilization. (4) Conclusions: Performance of all polishing systems improved after the initial sterilization, but deteriorated after the fourth sterilization cycle. However, their performance can be considered clinically acceptable for a longer period of use.

Surface smoothness of resin composites after polishing-A systematic review and network meta-analysis of in vitro studies

A systematic review and network meta-analysis was performed to provide evidence for the best polishing protocol for different types of resin composites to minimize surface roughness. A search was performed in PubMed, Scopus, Web of Science, LILACS, BBO, EMBASE, and Cochrane Library on July 2, 2019 (updated in December, 2020). In vitro studies that included at least two systems for polishing resin composites and analyzed surface roughness were included. The risk of bias was evaluated. A random-effects Bayesian-mixed treatment comparison model was used to compare surface roughness in resin composites with the different types of polishers. Surface under the cumulative ranking curve (SUCRA) analysis was performed to rank the probability for the best polishing system. After removal of duplicates, title and abstract screening yielded 34 studies. Network meta-analysis was not possible for hybrid and microhybrid composites. SUCRA analysis showed that abrasive paper discs allowed greater surface smoothness for nanohybrid and nanofill composites to a probability of between 83% and 91.6%. Silicon carbide brush had a 78.2% probability of being the best system for microfill composites. The use of abrasive paper disc polishers showed a favorable result in nanofill and nanohybrid resin composites. Silicon carbide brush has a greater chance of promoting a smoother surface for microfill resin composites.

Effect of Hydrothermal Factors on the Microhardness of Bulk-Fill and Nanohybrid Composites

This study evaluates the effect of aging in artificial saliva and thermal shocks on the microhardness of the bulk-fill composite compared to the nanohybrid composite. Two commercial composites, Filtek Z550 (3M ESPE) (Z550) and Filtek Bulk-Fill (3M ESPE) (B-F), were tested. The samples were exposed to artificial saliva (AS) for one month (control group). Then, 50% of the samples from each composite were subjected to thermal cycling (temperature range: 5-55 °C, cycle time: 30 s, number of cycles: 10,000) and another 50% were put back into the laboratory incubator for another 25 months of aging in artificial saliva. The samples' microhardness was measured using the Knoop method after each stage of conditioning (after 1 month, after 10,000 thermocycles, after another 25 months of aging). The two composites in the control group differed considerably in hardness (HK = 89 for Z550, HK = 61 for B-F). After thermocycling, the microhardness decrease was for Z550 approximately 22-24% and for B-F approximately 12-15%. Hardness after 26 months of aging decreased for Z550 (approximately 3-5%) and B-F (15-17%). B-F had a significantly lower initial hardness than Z550, but it showed an approximately 10% lower relative reduction in hardness.

Effect of different polishing systems and speeds on the surface roughness of resin composites

Aims and Objectives

The objective of this study was to compare surface roughness of a nano-spherical resin composite using four different multi-step polishing disc systems at five different speeds.

Materials and Methods

In total, 154 discs samples were prepared using a supra-nano spherical resin composite. The samples were divided into negative and positive control groups and the following four finishing and polishing disc systems: Sof-Lex, Bisco Finishing Discs, OptiDisc, and Super-Snap. Each polishing disc system was applied at five different speeds (2000, 5000, 10,000, 15,000, and 20,000 revolutions per minute [RPM]) (n = 7). The surface roughness of samples was measured using a profilometer. One sample from each group was evaluated by scanning electron microscopy and atomic force microscopy. Two-way analysis of variance was used to evaluate the average roughness (Ra) data from the profilometric experiments using statistical software (GraphPad Prism4-GraphPad Software; La Jolla, CA, USA). The mean values were compared using the Bonferroni test (P = 0.05).

Results

The mean roughness ranged from 0.07 μm to 0.41 μm. The smoothest surfaces were obtained with OptiDisc at 20,000 RPM and Super-Snap at 20,000 RPM. The Bisco Finishing Discs group at 2,000 RPM showed the highest surface roughness values. For all polishing systems, the roughness at 20,000 RPM was lower than that at other speeds.

Conclusion

Within the limitations of the present in vitro study, it can be concluded that the polishing performance was in the following order: Super-Snap > OptiDisc > Sof-Lex > Bisco Finishing Discs. In addition, the surface roughness decreased as the polishing speed increased.

Accelerated Aging Effects on Color Change, Translucency Parameter, and Surface Hardness of Resin Composites

Background

The aging process can induce a change in the surface microstructure of materials, the chemical compositions of matrices, and the filler particles of resin composites. This study is aimed at evaluating the effects of accelerated artificial aging (AAA) on the color change, translucency parameter (TP), and surface hardness of resin composites.

Methods

Five resin composite materials (Tetric N-Ceram, Filtek Z250, Charisma Smart, Herculite Classic, and Escom100) were evaluated. A spectrophotometer was used for color measurements (L∗, a∗, and b∗). TP and color changes (ΔE₀₀) were calculated using the CIEDE2000 formula. The resin materials were subjected to aging for 300 hours. The hardness and TP values were measured before and after AAA. One- and two-way ANOVA and the Tukey test were used. The significance level was accepted as p < 0.05.

Results

Escom100 had significantly higher ΔE₀₀ values than the other resin composites, and Charisma Smart had significantly lower ΔE₀₀ values than the other tested materials (p < 0.05). Before and after AAA, Charisma Smart had the lowest TP values, and Filtek Z250 exhibited the highest hardness values (p < 0.05). For TP and surface hardness, the effect size value of the composite material was found to be higher than that of AAA.

Conclusions

After AAA, the investigated resin composites had ΔE₀₀ values that were above clinically acceptable thresholds. After aging, the tested materials generally exhibited decreases in L∗ values and a∗ values, while increases in b∗ values were observed. The ΔTP values of the resin composites were similar. AAA significantly increased the surface hardness of the tested materials.

ANTİ-HALİTOSİS GARGARALARININ REZİN BAZLI RESTORATİF DENTAL MATERYALLERİN YÜZEY ÖZELLİKLERİ ÜZERİNE ETKİSİ

Amaç: Bu in-vitro çalışmanın amacı anti-halitosis etkili beş farklı ağız gargarasının iki farklı restoratif materyalin renk stabilitesi ve yüzey pürüzlülüğü üzerine olan etkisinin araştırılmasıdır. Gereç ve Yöntemler: Çalışmada nano-hibrit (Filtek Z550, 3M ESPE) ve giomer (Beautifill II, Shofu Dental) yapıda olan iki çeşit reçine bazlı restoratif materyal kullanılmıştır. Her iki materyalden test edilmek üzere toplam 120 adet kompozit disk üretici talimatları doğrultusunda 10x2mm ebatlarında silindir kalıplar kullanılarak hazırlanmıştır. Rastgele seçilen örnekler, 5 farklı ağız gargarası (Listerine Fresh Burst, Listerine Total Care, Colgate Plax, Oderol, Halitosil) ve 1 kontrol grubunda (distile su) bekletilmek üzere toplam 6 farklı gruba ayrılmıştır. Başlangıç renk koordinatları CIELAB renk sistemine göre spektrofotometre (Easyshade Compact) ile yüzey pürüzlülük değerleri (Ra) ise kontakt profilometre (Surtronic 25) ile ölçülmüştür. Tüm örnekler 37°C'de ağız gargaralarında 12boyunca bekletilmiş ardından renk ve pürüzlülük ölçüm prosedürleri aynı şekilde gerçekleştirilmiştir. Elde edilen veriler SPSS 24.0 programı ile Kruskal-Wallis H ve Bonferroni Post Hoc testleri kullanılarak 0.05 anlamlılık düzeyinde analiz edilmiştir. Bulgular: Bu çalışmanın sonuçları, yüzey pürüzlülük değerlerinde istatistiksel olarak anlamlı bir artış olmadığını göstermiştir. Ağız gargaralarında bekletilen Beautifil II materyallerinin tamamında CIELAB değerlerinde önemli bir değişiklik olmuştur (P

The effect of erosive beverages and polishing systems on the surface properties of nanohybrid composite resin

Aims and Background

The aim of this study is to evaluate the surface microhardness and roughness of composites treated with three different polishing systems exposed to two different corrosive beverages.

Material and Methods

Ninety-six composite resin disks were randomly divided into four groups, one of which was the control group. The surface roughness and microhardness values were measured after 24 h in the polishing process. The samples were divided into three subgroups and kept in distilled water, cola, and ice tea for 20 min a day for 14 days. Then, the roughness and microhardness measurements of the samples were taken again. Two samples randomly selected from each group were examined using a scanning electron microscope (SEM) and analyzed statistically using the two way anova (ANOVA) and Duncan tests.

Results

A statistically significant difference was found between the roughness and hardness values at the end of 24 h and 14 days. Onegloss (OG), Dentoflex (DF), and Super-snap (SNP) polish systems showed the highest roughness in the cola group, respectively. Microhardness values: The unpolished group had the lowest significant microhardness in the coke group (P < 0.05).

Conclusion

In this study, it was seen that the lowest success rate was the OG polishing system.

Effects of Immediate Coating on Unset Composite with Different Bonding Agents to Surface Hardness

OBJECTIVES

 This study evaluated the surface microhardness of composite, affected by surface coating with different dental adhesive systems.

MATERIALS AND METHODS

 A total of 100 composite discs were divided into five groups. Group 1 was uncoated (control group C), and groups 2 to 5 were coated with different adhesive systems (OptiBond FL: FL, OptiBond SOLO Plus: SOLO, OptiBond XTR: XTR, and OptiBond All in one: AIO, respectively). The Vickers microhardness (VHN) was measured without and with 500 thermocycles.

STATISTICAL ANALYSIS

 The data were analyzed using two-way ANOVA and Tukey's posthoc test at the 95% confidence level.

RESULTS

 At 24 hours, the VHN of C (59.96 ± 3.68) and FL (59.83 ± 4.54) were significantly higher than SOLO (51.73 ± 4.63) and AIO (51.45 ± 4.11). The VHN of XTR (54.96 ± 3.68) was not significant compared with that of C and all other groups. After thermocycling, VHN were significantly decreased in all groups. However, there were no significant differences among all groups.

CONCLUSIONS

 At 24 hours, composite coated with different adhesive systems have different effects to VHN. Thermocycling all adhesive resin systems coated on composite surface significantly decreased the VHN.

Effects of storage and toothbrush simulation on color, gloss, and roughness of CAD/CAM, hand-cast, thermoforming, and 3D-printed splint materials

Objectives

The aim was to investigate color, gloss, or roughness of splint materials after storage in liquids and toothbrush simulation.

Materials and methods

A total of 58 × 8 (n = 10 per material and group) specimens were fabricated (hand-cast, thermoforming, CAD/CAM-milled, 3D-printed materials); stored in air, water, coffee, red wine, and cleaning tablets; and investigated after fabrication, 24 h, two-, and four-week storage or toothbrushing. Color values (L*, a*, b*; ISO 11664–4:2008; CM–3500d, Konica-Minolta), gloss (ISO 2813:2014), and roughness values were determined (3D laser-scanning-microscope, KJ 3D, Keyence) before and after simulation or storage. Statistics: Levene-test, one-way ANOVA, Bonferroni post hoc test, between-subjects effects, Pearson correlation (α = 0.05).

Results

Color, gloss, and roughness altered due to contact with staining solutions/toothbrush simulation. Highest impact on color, gloss, and roughness presented the material followed by storage time (ΔE material (η2 = 0.239/p < 0.001), storage time (η2 = 0.179/p < 0.001); gloss (η2 = 0.751/p < 0.001) (η2 = 0.401/p < 0.001); Ra/Rz (η2 ≥ 0.801/p < 0.001) (η2 ≥ 0.416/p < 0.001)). Correlations were found between Rz and Ra (Pearson 0.887/p ≤ 0.001) or Rz and ΔE (0.517/p ≤ 0.001) or Ra and ΔE (0.460/p ≤ 0.001).

Conclusions

Storage and toothbrushing were accompanied by a change in color, gloss, and roughness. Almost all materials showed visible discoloration after 4 weeks of storage. Gloss values decreased as storage time increased. The initial roughness and polishability were better with harder materials.

Clinical relevance.

Milled and 3D printed splints show good color, gloss, and roughness resistance after 4-week storage or toothbrush application.

Development and maintenance of surface gloss of dental composites after polishing and brushing: Review of the literature

OBJECTIVE

To describe the effect of the composites' composition to produce high surface smoothness/gloss using finishers/polishers, and to assess maintained smoothness/gloss under toothbrush abrasion.

MATERIALS AND METHODS

PubMed papers published from January 01, 2000 to September 01, 2021 were included, and keywords used were: filler particle size, shape, amount of dental composites; finishing/polishing, gloss/roughness, and toothbrush abrasion of composites. Seventy-five in-vitro studies were included in this literature review. Forty-six articles assessed filler particle size/composition/shape and distribution to obtain high gloss/smoothness on different formulations; and the finishers/polishers effect on these materials. Twenty-nine papers assessed toothbrush abrasion of composites.

RESULTS

Suprananofill/nanofill/microfills typically showed the smoothest and glossiest surfaces compared to nanohybrid, microhybrid and hybrid composites. Microfill (0.04-0.07 μm, 71-88 GU); suprananofill (0.001-0.8 μm, 52-92 GU), microhybrids (0.05-0.35 μm, 35-95 GU) and nanohybrids (0.05-0.21 μm, 66-97 GU). Composites with small, spherical particles tend to show smoother, glossier surfaces and more wear resistant compared to resin composites with larger or irregular particles. Several studies showed higher roughness and reduced gloss after toothbrush abrasion.

CONCLUSIONS

Within the limitations of this study, suprananofill/nanofill/microfill composites tended to show the smoothest/glossiest surfaces due to smaller particle size. Composites with small, spherical particles tended to show smoother/glossier surfaces. Overall, toothbrush abrasion showed higher surface roughness and reduced gloss.

CLINICAL SIGNIFICANCE

Suprananofills/nanofills/microfills had good polishability and polish retention due to their smaller particle size. The effectiveness of a polishing system is material-dependent. In general, Enhance-PoGo, Sof-Lex discs, and Sof-Lex Spiral wheels showed similar level of smoothness.

Influence of Toothbrush Abrasion and Surface Treatments on Roughness and Gloss of Polymer-Infiltrated Ceramics

The aim of this study was to compare the surface roughness and gloss of polymer-infiltrated ceramics after simulated in vitro toothbrushing in different storage mediums. Four polymer- infiltrated ceramics were evaluated, Lava ultimate (LU), Vita enamic (EN), Shofu (SH), and Crystal ultra (CU). The control group was a feldspathic ceramic, Vita Mark II (VM). One hundred and twenty specimens (12 × 14 × 2.5 mm) were prepared using a precision saw. For each material (n = 24), the specimens were allocated into two groups, polished and stained. The specimens of each group were stored (for 7 days) in either citric acid (0.2N) or distilled water. Data for surface gloss (ΔE*_SCE-SCI) and roughness (Ra) were evaluated before (baseline) and after simulated toothbrushing. For toothbrushing simulation, a toothpaste slurry containing a toothpaste of 100 relative dentin abrasion (RDA) and 0.3 ml distilled water was used for 3650 cycles (7300 strokes) for each specimen. Data were analyzed using t-test and ANOVA. A p-value of ≤ to 0.05 was considered significant. The highest mean value of surface gloss was identified in CU (stained—water) (4.3 (0.47)) (ΔE*) and EN (stained—acid) (4.3 (1.00)) (ΔE*) specimens, whereas the lowest mean value was shown by SH (stained—acid) (2.04 (0.42)) (ΔE*) samples. The highest mean value of surface roughness was observed in SH (0.40 (0.99)) Ra (stained—acid) whereas the lowest in VM (0.13 (0.039)) Ra (polished— water). A significant difference (p < 0.05) was observed in surface roughness and gloss between the materials with simulated toothbrushing, except in VM and LU, respectively. Therefore, it can be concluded that simulated toothbrushing impacts on surface roughness and gloss, irrespective of the storage medium.

Reduced-step composite polishing systems - a new gold standard?

OBJECTIVES

To compare the surface gloss and surface roughness of three contemporary composites when polished with reduced-step polishing systems or a conventional multiple-step technique.

METHODS

Fifty Discs (8 mm ø x 2 mm) were each fabricated from three composites; Essentia (ES), BRILLIANT EverGlow (EG), and Filtek Universal, (FU). 5 different polishing systems were randomly assigned 10 specimens from each composite group. The 'gold standard' multiple-step system consisted of Sof-Lex XT discs followed by DiaPolisher diamond paste (GC) (P1). The two-step systems were Polishettes (P2) and DIATECH ShapeGuard (P3) and the one-step systems used were; Opti1Step (P4) and OneGloss (P5). Surface gloss was measured using a glossmeter and surface roughness was measured by a profilometer. Statistical analysis was conducted using one-way ANOVA and Pearson correlation tests. Samples were also imaged across different length scales using scanning electron microscopy and macro-lens photography.

RESULTS

The highest gloss was obtained when P2 and P3 were used in all composite groups (p < 0.05). EG composite showed the lowest Sa (0.08 µm) when polished with P3 and highest gloss when polished with P2 (96.7 GU). Polishing with P5 resulted in highest Sa and lowest surface gloss in all composite groups (p < 0.05). A high correlation was found between Sa and gloss, r = 0.73 (p < 0.05). Both SEM and macro-lens photography supported quantitative data.

CONCLUSION

Both two-step composite polishing systems produced superior gloss compared to the traditional multiple-step polishing system. Mean surface roughness (Sa) and surface gloss are highly correlated with each other.

CLINICAL SIGNIFICANCE

Some reduced step composite polishing systems tested in this study produced superior gloss outcomes compared to the traditional gold-standard multi-step polishing system. This may enable significant clinical chair-time reduction and faster polishing protocols.

Comparison of enamel surface roughness and color alteration after bracket debonding and polishing with 2 systems: A split-mouth clinical trial

INTRODUCTION

This split-mouth randomized clinical trial aimed to compare the enamel surface roughness (SR) and color alteration after bracket debonding and polishing using 2 systems.

METHODS

After removal of excess adhesive using a 12-blade tungsten carbide bur on a low-speed handpiece, a randomized polishing procedure using Sof-Lex discs was applied on 1 side (n = 36) and Sof-Lex Spiral Wheels on the contralateral side (n = 36). Dental replicas were obtained with epoxy resin before bracket bonding and after tooth polishing. The SR was evaluated using a profilometer. The color was assessed using an Easyshade spectrophotometer before bracket bonding, immediately after tooth polishing, and 30 days after polishing. Two-way analysis of variance and t tests were applied for statistical analysis.

RESULTS

The SR of enamel showed similar results between the polishing systems (P = 0.309) and between moments (before bracket bonding and after tooth polishing) (P = 0.317). The color change was also similar between the polishing systems (P >0.05).

CONCLUSIONS

The Sof-Lex discs and Sof-Lex Spiral Wheel polishing systems used after removal of excess adhesive using a 12-blade tungsten carbide bur on a low-speed handpiece did not appear to significantly damage the enamel surface, and the color change was similar between them.

Surface evaluations of a nanocomposite after different finishing and polishing systems for anterior and posterior restorations

This study aims to evaluate the effects of different finishing and polishing (F/P) systems on gloss and surface morphology of a new nanocomposite. Thirty discs of Filtek Universal Restorative material (3 M, ESPE) were prepared and divided into six groups (n = 5). Group A and B followed F/P protocols for anterior restorations, whereas Group C and D for posterior ones. Group E represented the control (covered by Mylar strip) and Group F represented the nanocomposite placement by means of clinical hand instruments; Groups E and F did not undergo F/P procedures. Among the polished groups, Group B showed the highest values (68.54 ± 7.54 GU), followed by Group A and D (46.87 ± 5.52 GU; 53.76 ± 2.65 GU). Finally, Group C (37.38 ± 4.93 GU) displayed the lowest results. Overall, Group E showed the highest gloss values (93.45 ± 8.27 GU), while Group F presented the lowest ones (1.74 ± 0.64 GU). Surface analysis revealed that Group A, C, and D displayed a smooth surface. Group B showed the lowest irregularities. Group E exhibited the most uniform superficial morphology. On the other hand, Group F displayed the most irregular one. In conclusion, using the tested material, only two protocols achieved appropriate gloss values. Then, clinicians might use the protocols of Group B and Group D, for anterior and posterior restorations, respectively.

Visually acceptable gloss threshold for resin composite and polishing systems

BACKGROUND

The objective of this study was to compare dentists' perceptions of gloss values of composite specimens with increased levels and to identify the gloss value considered to be clinically acceptable.

METHODS

Disk-shaped composite specimens were finished and polished 3 ways: metallurgically using silicon carbide papers and alumina paste, manually using Enhance finisher and PoGo polisher (EP) (Dentsply Sirona), and manually using Sof-Lex (SLex) disks (3M). Specimens were produced with surface gloss ranging from 0 through 100 gloss units (GU) in increments of approximately 10 GU as measured with a glossmeter. A GU of 0 was nonglossy, and a GU of 100 was perfectly glossy. Ten dentists evaluated the specimens, ranking them in order from low to high gloss and in 4 groups: low (dull or rough), medium (moderate gloss, clinically unacceptable), high (glossy, clinically acceptable), and superior gloss. The authors performed Spearman correlation analysis (α = 0.05).

RESULTS

For each finish and polish method, there was an excellent correlation between the machine-measured (actual) gloss ranks and the clinician-evaluated gloss ranks (r2 ≥ 0.95). There was no difference in perception of surface gloss of the composite when metallurgically polished (with silicon carbide papers and alumina paste) or polished with EP to the same GU. There was a slight difference in gloss perception when comparing the 2 different commercial polishing systems.

CONCLUSIONS

Ten dentists consistently perceived gloss of 40 through 50 GU as clinically acceptable. However, the composite was considered clinically acceptable at a lower gloss (40 GU) when polished with SLex disks than when polished with EP or metallurgically (50 GU).

PRACTICAL IMPLICATIONS

Gloss values of 40 through 50 GU are considered to be clinically acceptable for resin composites.

Effect of different polishing systems on the surface roughness of various bulk-fill and nano-filled resin-based composites: An atomic force microscopy and scanning electron microscopy study

The aim of the study was to evaluate the effects of different polishing systems on the surface roughness of various bulk-fill and nano-filled resin-based composites using different methods. For the study, a total of 192 disc-shaped samples (10-mm wide and 2-mm thick) were prepared from four different bulk-fill composites (Filtek Bulk Fill, X-tra fil, Beautifil-Bulk Restorative and Fill Up) and two nano-filled resin-based composites (Ceram.x SphereTEC and Filtek Z550). The samples in each composite group were divided into four subgroups according to the polishing system to be used (n = 8). Four different polishing systems (Sof-Lex Diamond, Clearfil Twist Dia, HiLuster Plus, OptiDisc) were applied. Then, surface roughness measurements were carried out using a contact-type profilometer. One sample from each group was subjected to atomic force microscopy (AFM) and scanning electron microscope (SEM) examinations. Surface roughness (Ra) values were statistically analyzed in terms of composites and polishing systems using the two-way analysis of variance (ANOVA) and comparisons among groups were performed using the Tukey test (α = .05). Surface roughness values differed significantly in relation to the composite and polishing system used (p < .05). Among all composites, the lowest surface roughness values were obtained in the groups treated with the OptiDisc polishing system (except Beautifil-Bulk Restorative), whereas the highest roughness values were observed in the group polished with Clearfil Twist Dia (except Filtek Z550). X-tra fil showed the highest roughness value with all polishing systems tested. The findings of AFM analyses were consistent with profilometric measurements. The nano-filled resin-based composites showed smoother surface than bulk-fill composites and the type of the polishing systems was found to affect surface roughness.

Effect of water storage and thermocycling on light transmission properties, translucency and refractive index of nanofilled flowable composites

The effect of 1-week water storage and subsequent 10,000 thermal cycles on light transmission properties (straight-line transmission (G0), diffusion (DF), the amount of transmitted light (AV)), translucency parameter (TP) and refractive index (RI) of four nanofilled flowable composites was examined. The composites included Filtek Supreme Ultra Flowable Restorative (FSU), Estelite Flow Quick (EFQ), Estelite Universal Flow, (EUF), and Clearfil Majesty ES Flow (ESF), all of A3 shade. For composites with lower filler load (FSU, EFQ), water storage increased G0, AV and TP, but subsequent thermocycling decreased them. An opposite tendency was found for DF. Materials with higher filler load (EUF, ESF) were not significantly affected by aging conditions. RI of EFQ and EUF containing bisphenol A polyethoxy methacrylate (Bis-MPEPP) increased significantly after thermocycling. Additionally, morphological changes were observed using scanning electron microscopy which revealed cracks within nanocluster fillers and dislocation of particles in FSU and EFQ after thermocycling.

Effect of polishing technique and immersion in beverages on color stability of nanoceramic composites

Background

Polishing of dental composite restorations to achieve a highly smooth and reflective surface not only enhances esthetics but also their color stability and improves resistance to staining. The objective of this study was to evaluate the effect of beverages on the color stability of nanoceramic composites polished using different techniques.

Methods

80 samples of ceram. X SphereTEC one were prepared by condensing the material into a stainless-steel split mold and divided randomly into two groups. Group I was subjected to polishing using Sof-Lex system™ disks, and Group II was kept unpolished. Each group was subdivided into four sub-groups of 10 samples each. Each subgroup samples were immersed into designated beverages (Tropicana orange juice, Coco-cola, Nescafe coffee, and distilled water) for a duration of 15mins/day for 15 days. The color of all specimens before immersion, one day, and 15 days after immersion was measured using a Spectrophotometer.

Results

Significant staining of the material was found with cola drinks and coffee compared to orange juice and distilled water. Polished material showed better resistance to staining by various beverages compared to control group.

Conclusion

Nanoceramic composites exhibited superior color stability after polishing with Sof-Lex system™. Among the beverages, coco-cola significantly altered the color of the composite.

The Effects of Irradiance on Translucency and Surface Gloss of Different Bulk-Fill Composite Resins: An in vitro Study

Purpose

The influence of different light-emitting diode (LED) curing light intensities on the translucency and surface gloss of bulk-fill resin-based composite (RBC) restorative materials was evaluated.

Materials and Methods

Forty specimens of each RBC (Filtek One bulk-fill posterior, Reveal HD bulk, Tetric N-Ceram, and Filtek Z350) were prepared. The RBCs were shaped into molds and cured using an LED curing light unit at high intensity (1,200 mW/cm²) for 20 s and low intensity (650 mW/cm²) for 40 s. A spectrophotometer was used to determine the translucency, and a gloss meter was used to evaluate surface gloss. Data were analyzed using one- and two-way analysis of variance (ANOVA), independent t-test, and Tukey's and Scheffe's post hoc multiple comparison tests.

Results

The highest translucency value was observed for Reveal HD (7.688 ± 0.861) with a high curing intensity, while Filtek One showed the lowest value (1.750 ± 0.376) with a low curing intensity. The materials showed no significant difference in surface gloss with a high curing intensity. With low-intensity light curing, Filtek One showed the highest gloss value (55.270 ± 10.106), while Tetric N-Ceram and Reveal HD showed the lowest gloss values (35.560 ± 6.533 and 35.680 ± 6.648, respectively).

Conclusion

Curing light intensity had no effect on both the gloss and translucency for all the materials tested, although for Tetric N-Ceram, higher intensity corresponded to higher gloss values while for Filtek One, higher intensity corresponded to a higher translucency value.

Effect of Shortened Light-Curing Modes on Bulk-Fill Resin Composites

CLINICAL RELEVANCE

Shortened light curing does not affect volumetric polymerization shrinkage or cohesive tensile strength but negatively affects the shear bond strength of some bulk-fill resin composites. When performing shortened light curing, clinicians should be aware of the light output of their light-curing units.

SUMMARY

Purpose: To evaluate volumetric polymerization shrinkage (VPS), shear bond strength (SBS) to dentin, and cohesive tensile strength (CTS) of bulk-fill resin composites (BFRCs) light activated by different modes.Methods and Materials: Six groups were evaluated: Tetric EvoCeram bulk fill + high mode (10 seconds; TEC H10), Tetric EvoFlow bulk fill + high mode (TEF H10), experimental bulk fill + high mode (TEE H10), Tetric EvoCeram bulk fill + turbo mode (five seconds; TEC T5), Tetric EvoFlow bulk fill + turbo mode (TEF T5), and experimental bulk fill + turbo mode (TEE T5). Bluephase Style 20i and Adhese Universal Vivapen were used for all groups. All BFRC samples were built up on human molar bur-prepared occlusal cavities. VPS% and location were evaluated through micro-computed tomography. SBS and CTS tests were performed 24 hours after storage or after 5000 thermal cycles; fracture mode was analyzed for SBS.Results: Both TEC H10 and TEE H10 presented lower VPS% than TEF H10. However, no significant differences were observed with the turbo-curing mode. No differences were observed for the same BFRC within curing modes. Occlusal shrinkage was mostly observed. Regarding SBS, thermal cycling (TC) affected all groups. Without TC, all groups showed higher SBS values for high mode than turbo mode, while with TC, only TEC showed decreased SBS from high mode to turbo modes; modes of fracture were predominantly adhesive. For CTS, TC affected all groups except TEE H10. In general, no differences were observed between groups when comparing the curing modes.Conclusions: Increased light output with a shortened curing time did not jeopardize the VPS and SBS properties of the BFRCs, although a decreased SBS was observed in some groups. TEE generally showed similar or improved values for the tested properties in a shortened light-curing time. The VPS was mostly affected by the materials tested, whereas the SBS was affected by the materials, curing modes, and TC. The CTS was not affected by the curing modes.

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.

Evaluation of Surface Roughness, Hardness, and Gloss of Composites After Three Different Finishing and Polishing Techniques: An In Vitro Study

Introduction The purpose of this in vitro study was to evaluate the effect of three different polishing systems on the microhardness, surface roughness, and gloss of resin composites. Materials and Methods The materials evaluated were 3M™ ESPE™ Filtek™ Z-350 XT (3M™, St. Paul, MN, USA), Grandio (Voco, Cuxhaven, Germany), 3M™ ESPE™ Filtek™ Z250 (3M™, St. Paul, MN, USA), Shofu-Beautifil Flow (Shofu, Kyoto, Japan), and RestoFill HV N-FLO (Anabond Stedman, Chennai, India). A total of 450 samples were fabricated. Three finishing and polishing systems: PoGo® (Dentsply Caulk, Milford, DE, USA), Sof-Lex Spiral, and Sof-Lex Pop-On (3M™, St Paul, MN, USA) were evaluated. Hardness, roughness, and gloss were evaluated after finishing and polishing. The surface roughness was measured with a surface profilometer, microhardness was measured with the Struers Duramin-5 microhardness tester (Struers A/S, Ballerup, Denmark) and gloss was measured using a gloss meter. The measurement values were analysed by Kolmogorov-Smirnov, Shapiro-Wilks test, and two-way ANOVA. Results The Sof-Lex Spiral group exhibited higher mean microhardness (p < 0.001), less surface roughness (p < 0.001), and higher gloss (p < 0.001). Filtek Z-250 exhibited higher mean microhardness (p < 0.001) than Grandio (p < 0.001) and Shofu Beautifil Flow (p < 0.001), and Filtek Z-350 XT exhibited more microhardness than Shofu Beautifil Flow (p < 0.001). Filtek Z-350 XT exhibited lower mean surface roughness than Filtek Z-250 (p < 0.05). Filtek Z-250 polished with Sof-Lex Spiral proved to have higher gloss (34.89 gloss units (GU)) than Grandio and RestoFill HV N-FLO (p < 0.05). Conclusions Hardest, smoothest, and glossiest surfaces were obtained with the Sof-Lex Spiral finishing/polishing system. The mean microhardness of Filtek Z-250 and Filtek Z-350 XT was found to be higher than other composites used in this study. Filtek Z-350 showed a lower mean surface roughness and Filtek Z-250 exhibited a higher mean gloss.

Effect of polishing protocols on the surface roughness of polyetheretherketone

The purpose of this study was to evaluate the influence of various polishing protocols on the surface roughness of polyetheretherketone (PEEK) and identify an effective polishing method of dental prostheses at the chairside. The PEEK specimens were assigned to seven groups with different protocols: no additional polishing (NT); polishing using a rubber point (C); polishing using "silky shine" (S); polishing using "aqua blue paste" (A); protocol C followed by protocol S (CS); protocol C followed by protocol A (CA); and protocol C followed by protocols S and A (CSA). The surface roughness (Sa and Ra) of the polished surfaces was measured. The surface roughness decreased in the following order of groups: NT, C, S, CS, CSA, CA, and A. In Groups C and S, wide deep pits formed by abrasive grains of SiC paper were observed, whereas only fine linear structures were observed on the surface in other groups. With respect to the polishing protocol of PEEK, clinically acceptable surface roughness was obtained using a soft polishing brush and agent for more than 3 min.

Effect of air-polishing on surface roughness of composite dental restorative material - comparison of three different air-polishing powders

Background

Increased composite roughness enhances bacterial adhesion and discoloration, thus increasing the risk of gingival inflammation and secondary caries. Concerns about detrimental effects of sodium bicarbonate on surface roughness influenced the development of less abrasive powders: a glycine-based powder and an erythritol-based powder, additionally - sodium bicarbonate-based powder of reduced grain size. However, there is limited evidence on effects of these materials on the surface of dental fillings. The aim of the present study was to compare the effects of three air-polishing powders (of a reduced abrasiveness) on surface roughness of microhybrid restorative composite material.

Material and methods

Microhybrid light-cure resin composite samples were placed on 64 plaster cubes and light-cured through polyester strips. Surface roughness was measured using laser confocal microscope (magnification 2160x). The specimens were randomly divided into three groups (n = 20, 20 and 24) and air-polished with: sodium bicarbonate (40 μm), glycine (25 μm) and erythritol (14 μm), respectively. Then surface roughness was remeasured, keeping the same field of observation. Specialized 3D analysis software was used for data processing. Parameters according to ISO 25178: Sa, Sq, Sku, Sp, Sv, Sz, Ssk were used to describe surface roughness.

Results

Sa, Sq, Sp, Sv, Sz increased significantly following air polishing. Ssk was significantly higher, whereas Sku was significantly lower in sodium bicarbonate and erythritol groups than before air polishing. Comparison between the three powders revealed that Sa was significantly higher in sodium bicarbonate group than in glycine group. Sku was significantly higher in glycine and erythritol groups than in sodium bicarbonate group.

Conclusions

Sodium bicarbonate has a stronger detrimental effect on composite surface than glycine or erythritol. No advantage of erythritol comparing to glycine could be found.

The effect of polishing protocol on surface gloss of different restorative resin composites

Aim

The purpose of this in vitro study was to determine the effects of different polishing protocols on the surface gloss (SG) of different commercial dental resin composites (RCs).

Material and methods

A total of 147 block-shaped specimens (40 mm length × 10 mm width × 2 mm thick) were made from conventional RCs (G-aenial Ant. and Flo X), bulk-fill RC (Filtek Bulk Fill), fluoride-releasing RCs (BEAUTIFIL II, ACTIVA-Restorative) and discontinuous microfiber-reinforced RCs (Alert and everX Flow). Each group was subdivided into seven subgroups (n = 3), according to polishing protocol: Laboratory-machine polishing with different siliconcarbide paper grits (G1: 320) → (G2: 800) → (G3: 1200) → (G4: 2000) → (G5: 4000). Chairside-hand polishing using a series of Sof-Lex spiral (G6) and abrasive polishing points (G7). Glossmeter was used to determine the SG at 60° incidence angle. SG was measured before and after polishing. Three-dimensional (3 D) noncontact optical profilometer and scanning electron microscopy (SEM) analysis were performed. Data were analyzed using ANOVA (p = .05).

Results

Significant differences in SG (ranged 3–93 GU) were found according to the type of polishing protocol and RC (p < .05). Specimens polished with 4000 grit paper showed the highest SG (93 GU) values among all the groups tested.

Conclusions

The tested chairside-hand polishing protocols presented lower SG values than laboratory-machine polishing (4000 silicon paper grit) and unpolished surfaces.

Spectrophotometric Evaluation of Colour Stability of Nano Hybrid Composite Resin in Commonly Used Food Colourants in Asian Countries

INTRODUCTION

There is growing interest in colour stability of aesthetic restorations. So far few studies have been reported.

AIM

This study was designed to investigate the effects of different common food colourants i.e., Turmeric and Carmoisine (orange red dye) consumed by patients in Asian countries on a recent nano hybrid composite resin.

MATERIALS AND METHODS

A total of sixty disk shaped specimens measuring 10 mm in diameter and 2 mm in thickness were prepared. The samples were divided into two groups {Z 100 (Dental restorative composite) Filtek Z 250 XT (Nano hybrid universal restorative)}. Baseline colour measurement of all specimens were made using reflectance spectrophotometer with CIE L*a*b* system. Specimens were immersed in artificial saliva and different experimental solutions containing food colourants (carmoisine solution and turmeric solution) for three hours per day at 37°C. Colour measurements were made after 15 days. Colour difference (ΔE*) was calculated. Mean values were compared by one-way analysis of variance (ANOVA). Multiple range test by Tukey Post-hoc test procedure was employed to identify the significant groups at 5% level.

RESULTS

Z 100 showed minimum staining capacity when compared to Z 250 XT in both the colourant solutions.

CONCLUSION

The nanohybrid composite resin containing TEGDMA showed significant colour change when compared to that of microhybrid composite resin as a result of staining in turmeric and carmoisine solution.

Flexural strength and microhardness of anterior composites after accelerated aging

BACKGROUND

This study aimed to evaluate the flexural strength and microhardness of three different anterior composites after 10 000 thermocycles.

MATERIAL AND METHODS

The mechanical properties of a nano-fill composite (Filtek Ultimate Universal Restorative (FUR) (Enamel)), a nano-hybrid composite (Clearfil Majesty ES2 (ES2) (Enamel)), and a micro-hybrid composite (G Aenial Anterior (GAA)) were investigated in this study. For the microhardness test, 8-mm diameter and 2-mm thickness composite discs were used (n = 10), and for the flexural strength test, 25x2x2 mm bar-shaped specimens were prepared (n = 13). The specimens were tested at 24 h and after 10 000 thermocycles. Data were analyzed using two-way analysis of variance and the post-hoc Tukey test (p < .05). Correlations between hardness and flexural strength were calculated using Pearson's correlation analysis.

RESULTS

There was a significant difference in the microhardness values of the materials (p < .05). FUR exhibited significantly higher microhardness than ES2 and GAA. However, the flexural strength of three composites was statistically similar at 24 h (p > .05). Pearson correlation analysis revealed that there was a negative relationship between the mean hardness and flexural strength values (correlation coefficient = -0.367, p = .043). After 10 000 thermocycles, microhardness values of each material and flexural strength of ES2 and GAA decreased significantly according to 24 h.

CONCLUSIONS

The nano-fill composite FUR displayed significantly higher microhardness values. However, each resin composite was statistically similar for flexural strength values. Ten thousand thermocycles significantly affected microhardness and flexural strength. Key words:Flexural strength, microhardness, anterior composites.