Effects of Finishing and Polishing Methods on the Surface Roughness and Surface Free Energy of Bulk-fill Resin Composites

Effect of polishing systems on the roughness, color, and staining of conventional and bulk-fill resin composites with and without S-PRG filler

OBJECTIVE

To evaluate the effect of polishing systems on the color and roughness of conventional and bulk-fill nanofilled resins, compared to conventional and bulk-fill nano-hybrid resins with S-PRG fillers.

MATERIALS AND METHODS

Discs (n = 12) were fabricated from the following resin composites: conventional nanofilled resin (Filtek Z350 XT, 3 M), bulk-fill nanofilled resin (Filtek One Bulk-Fill, 3 M), conventional nano-hybrid resin with S-PRG fillers (Beautifil II LS, Shofu), and bulk-fill nano-hybrid resin with S-PRG filler (Beautifil Bulk Restorative, Shofu). Polishing was conducted using multi-grit aluminum oxide abrasive discs (Sof-Lex Pop On, 3 M) or a single-grit aluminum oxide tip (OneGloss, Shofu). Roughness (Ra) and color (CIEL*a*b*, ΔEab and ΔE00) were assessed at baseline, post-polishing, and post-coffee staining. Surface micromorphology was analyzed using scanning electron microscopy (SEM).

RESULTS

Roughness increased after polishing with the aluminum oxide tip for all materials (p < 0.0001; Mann-Whitney). Bulk-fill nanofilled resin showed increased roughness, while conventional nano-hybrid resin with S-PRG filler showed decreased roughness after multi-grit disc polishing (p < 0.0001; Mann-Whitney). Coffee staining significantly increased the roughness in resin composites with S-PRG filler (p < 0.0001; Mann-Whitney). All resin composites exhibited reduced L* and b* (p < 0.05; generalized linear mixed models for repeated measures) and increased a* (p < 0.05; Friedman and Nemenyi) values after coffee staining. ΔEab and ΔE00 were significantly higher for bulk-fill nano-hybrid containing S-PRG filler, irrespective of polishing type (p < 0.0001; Friedman and Nemenyi). SEM analysis revealed surface degradation and/or particle loss in resin composites with S-PRG filler (conventional and bulk-fill) post-polishing. Single-grit polishing resulted in greater surface irregularities across all resins.

CONCLUSION

Polishing systems significantly influence resin composite roughness based on their composition, with single-grit polishing causing the highest roughness. Bulk-fill nano-hybrid resin composite with S-PRG filler exhibited the greatest color and roughness changes post-staining.

CLINICAL RELEVANCE

Bulk-fill resin composite with S-PRG filler demonstrated lower color and surface stability. Importantly, these changes were significantly mitigated when polished using a multi-stage polishing system.

Experimental study of polishing systems on surface roughness and color stability of novel bulk-fill composite resins

OBJECTIVE

This in vitro study aimed to investigate the effect of five polishing systems on the surface roughness (SR) and color change (CC) of novel bulk-fill composite resins.

METHODS

Fifty composite resin samples were prepared for each of the five groups: Stark Bulk Fill, SDR Plus, SonicFill 3, Charisma Bulk Flow One, and Filtek Z250. Each group of composite resins was further subdivided into five subgroups based on the polishing method applied: OptraGloss (OG), OptraGloss combined with Diapolisher paste (OGD), OptiDisc (OD), OptiDisc combined with Diapolisher paste (ODD), and Occlubrush (OCC) (n = 10). Surface roughness was measured using a profilometer following the polishing procedures, while surface morphology was assessed through atomic force microscopy and scanning electron microscopy. Subsequently, the samples were divided into two further subgroups for aging in distilled water and coffee (n = 5). The initial color parameters and those measured after 7 days were recorded to evaluate color change. Statistical analysis was performed using two-way ANOVA, followed by Tukey's post-hoc tests (α = 0.05).

RESULTS

SR significantly varied based on the composite resin and polishing system (p < 0.001). OCC polishing yielded the smoothest surface for STARK and SDR composites, while Charisma exhibited the lowest roughness in the ODD group (p < 0.05). OGD group consistently produced lower SR across multiple composites compared to the OG group (p < 0.001). Significant color changes (ΔE00) were found, with SonicFill and Filtek showing the greatest color stability when polished with OGD and OCC. For all polishing systems, except ODD, the SDR composite showed the greatest CC in coffee storage (p < 0.003).

CONCLUSION

This study demonstrated that both the polishing technique and composite resin type significantly influenced SR. SR was notably affected by the interaction between the polishing method and resin type, with the OCC system consistently producing the lowest SR values. Additionally, Charisma exhibited surface properties similar to Filtek. Variations in color change were also observed based on both the polishing method and resin type, highlighting the critical role these factors play in determining the color stability of restorative materials.

Coating Agents for Resin Composites: Effect on Color Stability, Roughness, and Surface Micromorphology Subjected to Brushing Wear

This study evaluated the influence of six resin composite coating agents on color stability and surface roughness after toothbrushing abrasion. Discs (Ø6 mm x 2 mm) of nanofilled resin composite (Filtek Z350XT) were prepared for application of coating agents (n=10): control (absence), two surface sealants (PermaSeal and BisCover LV), two adhesive systems (Scotchbond Multi-Purpose Adhesive/3M Oral Care and Single Bond Universal), and two modeling liquids (Modeling Resin and Composite Wetting Resin). CIELab*, WID, and color change (ΔEab, ΔE00, and ΔWID) were analyzed at baseline, after finishing and polishing, after application of coating agents, after coffee staining (simulating 30 days and one year of staining), and after toothbrushing abrasion. Roughness evaluations (Ra) were performed at the initial time point, after finishing and polishing, after application of coating agents, and after toothbrushing abrasion. Surface micromorphology was evaluated (2,000×) before and after toothbrushing abrasion. Generalized linear mixed models or Kruskal-Wallis and Dunn tests (α=0.05) showed that L* decreased significantly (p<0.0001) and a* increased significantly in all the groups after staining (p<0.0001). After toothbrushing, Modeling Resin showed higher ΔEab and ΔE00 than the control, Scotchbond Multi-Purpose Adhesive, Composite Wetting Resin, PermaSeal, or BisCover LV (p<0.0001). There was a significant increase in roughness for Composite Wetting Resin, Modeling Resin, and PermaSeal after application of the agents (p<0.05), but a significant decrease for BisCover LV (p<0.05), which achieved high surface smoothness. After abrasive wear, BisCover LV showed the lowest roughness values among all agents. Composite Wetting Resin and Modeling Resin showed higher roughness than the other groups (p<0.05), and surface irregularities. In conclusion, the coating agents did not prevent coffee staining, and they also led to increased surface roughness, with only BisCover LV providing greater surface smoothness after toothbrush abrasion.

Beverage-Induced Surface Changes in Biomimetic Dental Resin Composite: AFM and Bacterial Analysis

OBJECTIVE

 Continuous advancements in composite resin materials have revolutionized and expanded its clinical use, improving its physical and mechanical properties. Attaining and retaining surface texture and gloss are crucial for the long-term durability of the composite resin material. This study investigated the supra-nanospherical filler composite material compared with different composite resin materials immersed in different beverages. The study evaluated their surface roughness and subsequent adhesion of bacteria.

MATERIALS AND METHODS

 A total of 144 specimens were made, using Teflon mold from different composite materials. Eighty-four specimens were used for surface roughness testing, using four different resin composite materials, Tetric N-Ceram (Ivoclar Vivadent, Schaan, Liechtenstein), Multichrome (Harvard Dental, Germany), Filtek Z350 XT (3M ESPE, Minnesota, United States), and Palfique LX5 (Tokuyama Dental Corporation, Taitō-Ku, Tokyo, Japan; n = 21). They were further subdivided into three subgroups according to the immersion solution (n = 7) for Monster, Gatorade, and deionized water, which served as the control group. Surface roughness values were tested via atomic force microscopy (AFM). Then, for biofilm testing the bacterial count was performed on the remaining 60 composite specimens from the four tested composite materials (n = 15), that were subdivided randomly based on the immersion solutions into three subgroups (n = 5).

STATISTICAL ANALYSIS

 Data were collected and statistically analyzed using the Kruskal-Wallis test followed by Dunn's post hoc test with Bonferroni's correction (p ≤ 0.05). The intergroup comparison showed a significant difference among different composite materials (p < 0.05), with the Multichrome showing the highest roughness values. Also, there was a significant difference between all composite materials with different beverages, with Palfique LX5 showing the lowest average roughness (Ra) values. All studied materials' average surface roughness, however, remained below the crucial Ra value of 0.2 μm. For the bacterial count, there was a significant difference between different materials in different beverages (p < 0.05), with Z350 XT and Palfique LX5 showing the lowest bacterial count.

CONCLUSION

 Supra-nanospherical composite (Palfique LX5) exhibited better resistance to different beverage challenges regarding surface roughness, while nanohybrid composite (Z350) showed the least bacterial adherence.

Roughness profile and surface roughness after toothbrushing and degree of conversion of bulk-fill resins

The aim of this study was to assess roughness profile and surface roughness after simulated toothbrushing cycles, as well as the degree of conversion (DC) of bulk-fill resin composites at different depths. Forty nine composite discs were made from three low-viscosity bulk-fill resins (Filtek Bulk-Fill Flowable/3M Oral Care - FBF, Beautifil-Bulk Flowable/Shofu Inc. - BBF and Surefill SDR Flow/Dentsply Caulk - SDR), three high-viscosity bulk-fill resin composites (Filtek Bulk-Fill Restorative/3M Oral Care - FBR, Beautifil-Bulk Restorative/Shofu Inc. - BBR and Tetric EvoCeram Bulk Fill/Ivoclar Vivadent - TEB) and one conventional composite (Filtek Supreme Ultra/3M Oral Care - FSU) (n=7), using addition silicon molds (2 mm thick x 10 mm diameter). The roughness profile (Rv) and surface roughness (Sa) were analyzed after 30,000 brushing cycles using confocal laser scanning microscopy. Five samples (4 mm thick x 2 mm diameter) were produced per resin composite and light-cured for 20 seconds using a LED-curing unit. After 24 hours at 37oC, DC of samples was evaluated at four depths, using a confocal Raman microscope. The data were analyzed by ANOVA and Tukey post hoc multiple-comparison tests (α = 0.05). The Rv values of FSU were lower than those obtained for BBR and BBF. The toothbrushing significantly decreased the Sa for all composites. The DC was significantly reduced at 4 mm depth. Toothbrushing changed composite surface of all materials, especially for BBR and BBF. Composites were not able to maintain the DC values shown at the top compared with those at the bottom (4 mm depth).

Effect of different polishing systems on surface roughness and gloss values of single-shade resin composites

BACKGROUND

The aim of this study was to evaluate variations in the surface roughness and gloss of different single-shade resin composites after polishing with a range of systems.

METHODS

In total, 120 specimens were prepared from three different types of single-shade resin composites (supra-nanospherical-Omnichroma, nanohybrid-Charisma Diamond One, and microhybrid- Essentia Universal). The specimens were placed in distilled water and stored at 37 °C for 24 h. Each resin composite (n = 40) was divided into four groups (n = 10) according to the finishing/polishing (F/P) system: Mylar strip (control), Sof-Lex (multi-step), Twist Dia (two-step), and OneGloss (one-step). Surface roughness and gloss were measured. Surface characteristics were evaluated by atomic force microscopy (AFM) and a scanning electron microscope (SEM). A two-way analysis of variance (ANOVA) and Tukey's honestly significant difference test were used for statistical analysis (p < 0.05).

RESULTS

Among all the composites, both the highest surface roughness and lowest gloss values were obtained in the groups treated with the OneGloss polishing system (p < 0.05). Compared with all the composites, Omnichroma had the lowest surface roughness and highest gloss values (except Twist Dia) both unpolished and after polishing with all the F/P systems (p < 0.05). All composites treated with the Twist Dia F/P system had similar gloss values. The results of the AFM and SEM analyses were consistent with the surface roughness measurements.

CONCLUSIONS

The gloss values of both the microhybrid and nanohybrid composites after F/P using the two-step system was superior to that of the traditional multistep system. The surface of the supra-nanofilled resin-based composite was smoother than that of both the microhybrid and nanohybrid composites.

Enhancing Esthetics in Direct Dental Resin Composite: Investigating Surface Roughness and Color Stability

Dental restorations must replicate the natural appearance of teeth while ensuring biocompatibility and durability. This study evaluated the surface characteristics and color stability of three dental composites-Herculite Ultra XRV, G-ænial A'CHORD, and Omnichroma-exposed to acidic beverages (red wine, black coffee, and Coca-Cola). Sixty disk-shaped specimens were prepared, polished, and immersed in these beverages. Surface roughness was assessed using profilometry and SEM analysis, hydrophobicity via contact angle analysis, and surface charge through streaming potential measurements. Color stability was evaluated using a spectrophotometer, and the pH levels of the solutions were recorded. Results showed that Herculite Ultra XRV had the highest mean contact angle (79.46° ± 6.52), indicating superior hydrophobicity, while Omnichroma had the lowest (64.94° ± 3.08), indicating more hydrophilicity. Significant color changes were observed, especially in black coffee, with ∆E values indicating notable discoloration. The acidic pH of the solutions increased surface roughness and color changes. Statistical analyses confirmed significant increases in surface roughness and color change for all composites, with the nanohybrid resin composite showing the greatest variability. These findings highlight the need for dental restorative materials with enhanced resistance to acidic environments to improve the longevity and esthetics of dental treatments.

Effect of Polishing Systems on the Surface Roughness and Color Stability of Aged and Stained Bulk-Fill Resin Composites

The aim of this study is to investigate how two different polishing techniques affect the color stability, surface roughness, and changes in surface morphology of aged and coffee-stained bulk-fill resin composites. A total of 112 disc-shaped samples were prepared using Omnichroma Flow Bulk (OB), Charisma Bulk Flow One (CB), Estelite Bulk Fill Flow (EB), and Estelite Sigma Quick (control). Samples were divided into two subgroups (n = 16) and aged using thermocycling. A profilometer was used to measure the surface roughness (Ra) and a spectrophotometer was used for color stability (ΔE00). The EB group had the highest Ra values both before aging (disc: 0.23 ± 0.05, twist: 0.42 ± 0.05) and after aging (discs: 0.28 ± 0.04, twist: 0.46 ± 0.05). The OB group had the highest ΔE00 values before and after aging (discs: 3.06 ± 0.54, twist 3.05 ± 0.41) and the highest after coffee-staining (discs: 3.75 ± 0.70, twist: 3.91 ± 0.57). Re-polishing reduced the ΔE00 values in all materials but did not restore all to clinically acceptable levels. According to the results of this study, it can be concluded that the surface roughness and color stability of resin composites are notably influenced by the polishing technique, aging process, and coffee staining. Specimens that were polished using the multi-stage Super-Snap discs consistently exhibited smoother surfaces across all bulk-fill resin composites compared to those polished with the two-stage Diacomp plus Twist.

Clinical evaluation of subgingival open sandwich restorations: 3-year results of a randomized double-blind trial

OBJECTIVES

To provide a 3-year follow-up of previously treated patients to assess and compare the periodontal responses and clinical performance of proximal subgingival open sandwich restorations.

MATERIALS AND METHODS

Ninety-five adults participated in the study, with a combined total of 120 compound Class II cavities. These cavities had gingival margins located below the CEJ. Four different restorative materials were used to elevate the dentin/cementum gingival margins of the cavities: resin-modified glass ionomer, glass hybrid, flowable bulk-fill composite, or ion-releasing material, which were then completed with the same overlaying composite. Different periodontal and clinical evaluations, based on the criteria set by the World Dental Federation (FDI) criteria, were performed at different time intervals, including baseline, 6 months, 1, 2, and 3 years.

RESULTS

The type of base material did not affect the periodontal evaluations. There were no statistically significant differences between different time intervals or base material groups in any of the evaluated FDI parameters. However, the ion-releasing material scored significantly worse in the radiographic evaluation than any of the other groups.

CONCLUSIONS

All tested materials are suitable for proximal subgingival open sandwich restorations, as long as the restoration/tooth margin is at least 2-mm away from the bone crest.

CLINICAL SIGNIFICANCE

Clinicians can confidently choose any of the tested materials for proximal subgingival open sandwich restorations, as they have shown good outcomes from both periodontal and clinical perspectives.

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.

Performance of bulk-fill versus conventional nanocomposite resin restorations supporting the occlusal rests of removable partial dentures: An in vitro investigation

STATEMENT OF PROBLEM

Placing removable partial denture (RPD) rests on composite resin restorations has long been a debatable issue. Despite developments in composite resins such as nanotechnology and bulk-filling techniques, studies investigating the performance of composite resin restorations when used to support occlusal rests remain scarce.

PURPOSE

The purpose of this in vitro study was to investigate the performance of bulk-fill versus incremental (conventional) nanocomposite resin restorations when they are used to support RPD rests under functional loading.

MATERIAL AND METHODS

Thirty-five caries-free intact maxillary molars of similar coronal size were collected and divided into 5 equal groups (n=7): Enamel (Control) group: rest seats prepared entirely in enamel; Class I Incremental group: Class I cavities restored with incrementally placed nanohybrid resin composite resin (Tetric N-Ceram); Class II Incremental group: Mesio-occlusal (MO) Class II cavities restored with Tetric N-Ceram; Class I Bulk-fill group: Class I cavities restored with high-viscosity bulk-fill hybrid resin composite (Tetric N-Ceram Bulk-Fill); and Class II Bulk-fill group: MO Class II cavities restored with Tetric N-Ceram Bulk-Fill. Occlusal rest seats were prepared mesially in all groups, and clasp assemblies were fabricated and cast in cobalt-chromium alloy. Specimens with their clasp assemblies were subjected to thermomechanical cycling using a mechanical cycling machine (250 000 masticatory cycles) and 5000 thermal cycles (5 °C to 50 °C). Surface roughness (Ra) was measured with a contact profilometer before and after cycling. Fracture analysis was done using stereomicroscopy, and margin analysis was done with a scanning electron microscope (SEM) before and after cycling. Statistical analysis of Ra was conducted using ANOVA followed by the Scheffé test for between-group comparison and paired t test for within-group comparison. The Fisher exact probability test was used for fracture analysis. The Mann-Whitney test was used for between-group comparison and Wilcoxon signed rank test for within-group comparison for the SEM images (α=.05).

RESULTS

Mean Ra increased significantly after cycling in all groups. Significant differences in Ra were found between enamel and all 4 resin groups (P<.001), with no significant differences between incremental and bulk-fill resin groups for both Class I and II specimens (P>.05). No significant differences were found between the 2 resin groups with regard to fracture and margin analysis (P>.05).

CONCLUSIONS

The surface roughness of enamel was significantly lower than that of both incremental and bulk-fill nanocomposite resins before and after functional loading. Incremental and bulk-fill nanocomposite resins showed comparable performance in terms of surface roughness, fracture behavior, and marginal adaptation.

Effect of 16% Carbamide Peroxide and Activated-Charcoal-Based Whitening Toothpaste on Enamel Surface Roughness in Bovine Teeth: An In Vitro Study

Background: Activated charcoal is a nanocrystalline form of carbon with a large specific surface area and high porosity in the nanometer range, having consequently the capacity to absorb pigments, chromophores, and stains responsible for tooth color change, while carbamide peroxide is unstable and breaks down immediately upon contact with tissue and saliva, first dissociating into hydrogen peroxide and urea and subsequently into oxygen, water, and carbon dioxide. Therefore, the aim of the present study was to assess the effect of 16% carbamide peroxide and activated-charcoal-based whitening toothpaste on enamel surface roughness in bovine teeth. Materials and Methods: The present experimental in vitro, longitudinal, and prospective study consisted of 60 teeth randomly distributed in six groups: A: artificial saliva, B: conventional toothpaste (Colgate Maximum Protection), C: whitening toothpaste with activated charcoal (Oral-B 3D White Mineral Clear), D: 16% carbamide peroxide (Whiteness Perfect 16%), E: 16% carbamide peroxide plus conventional toothpaste (Whiteness Perfect 16% plus Colgate Maximum Protection), and F: 16% carbamide peroxide plus whitening toothpaste with activated charcoal (Whiteness Perfect 16% plus Oral-B 3D White Mineral Clear). Surface roughness was assessed with a digital roughness meter before and after each treatment. For the statistical analysis, Student’s t test for related samples was used, in addition to the ANOVA test for one intergroup factor, considering a significance level of p < 0.05. Results: The surface roughness variation of bovine tooth enamel, before and after application of bleaching agent, was higher in groups of whitening toothpaste with activated charcoal (0.200 µm, Confidence Interval (CI): 0.105; 0.296 µm) and 16% carbamide peroxide plus whitening toothpaste with activated charcoal (0.201 µm, (CI): 0.092; 0.309 µm). In addition, bovine teeth treated with conventional toothpaste (p = 0.041), whitening toothpaste with activated charcoal (p = 0.001), and 16% carbamide peroxide plus whitening toothpaste with activated charcoal (p = 0.002) significantly increased their surface roughness values. On the other hand, significant differences were observed when comparing the variation in surface roughness between the application of artificial saliva (control) and the whitening toothpaste with activated charcoal (p = 0.031), and the 16% carbamide peroxide plus whitening toothpaste with activated charcoal (p = 0.030). Conclusion: The use of whitening toothpaste with activated charcoal and in combination with 16% carbamide peroxide significantly increased enamel surface roughness in bovine teeth.

Surface roughness and oxygen inhibited layer control in bulk-fill and conventional nanohybrid resin composites with and without polishing: in vitro study

Background

It has been demonstrated that dental restorations with rough surfaces can have several disadvantages such as pigment retention or plaque accumulation, which can facilitate caries formation, color variation, loss of brightness, degradation of restoration, among others. The present study aimed to assess surface roughness in bulk fill and conventional nanohybrid resins with and without polishing, controlling the oxygen inhibited layer.

Methods

This in vitro and longitudinal experimental study consisted of 120 resin blocks of 6 mm diameter and 4 mm depth, divided into two groups: Bulk Fill (Tetric^® N-Ceram Bulk-fill, Opus Bulk Fill APS, Filtek™ Bulk Fill) and conventional nanohybrid (Tetric^® N-Ceram, Opallis EA2, Filtek™ Z250 XT). Each resin group was divided into two equal parts, placing glycerin only on one of them, in order to control the oxygen inhibited layer. Subsequently, the surface roughness was measured before and after the polishing procedure with Sof-Lex discs. The data were analyzed with the T-test for related measures, and for comparison between groups before and after polishing, the non-parametric Kruskal Wallis test with the Bonferroni post hoc was used, considering a significance level of p < 0.05.

Results

Before polishing, the resin composites with the lowest surface roughness were Opus Bulk Fill APS (0.383 ± 0.186 µm) and Opallis EA2 (0.430 ± 0. 177 µm) with and without oxygen inhibited layer control, respectively; while after polishing, those with the lowest surface roughness were Opus Bulk Fill APS (0.213 ± 0.214 µm) and Tetric N-Ceram (0.097 ± 0.099 µm), with and without oxygen inhibited layer control, respectively. Furthermore, before and after polishing, all resins significantly decreased their surface roughness (p < 0.05) except Opus Bulk Fill APS resin with oxygen inhibited layer control (p = 0.125). However, when comparing this decrease among all groups, no significant differences were observed (p < 0.05).

Conclusion

The Opus Bulk Fill APS resin with oxygen inhibited layer control presented lower surface roughness both before and after polishing, being these values similar at both times. However, after polishing the other bulk fill and conventional nanohybrid resins with and without oxygen inhibited layer control, the surface roughness decreased significantly in all groups, being this decrease similar in all of them.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-022-02297-w.

Evaluation of different composite resin finishing and polishing protocols by confocal laser scan microscopy

Aim: This study aimed to analyze the influence of finishing and polishing (F/P) protocols on resin surface through roughness (Ra) values and laser scan microscopy observations. Methods: Forty-eight (n=48) resin specimens were sorted into four groups (n=12), according to the type of resin used: Filtek Z250 (Z250), Filtek Z350 (Z350), Filtek One Bulk Fill (BF), Filtek P60 (P60). The specimens were sorted into six groups according to the type of F/P system used (n=2/group): Control group, Diamond bur (KG Sorensen), Soflex Pop-On Discs (3M ESPE), Soflex Spiral (3M ESPE), Dura Gloss (American Burs), and Praxis (TDV). Results: The highest roughness values (Ra) were attributed to BF group for all F/P systems, except for the Soft-Lex PopOn discs. The Soft-Lex PopOn, Spiral, and Praxis discs presented a better performance for the surface treatment of the tested composite resins. Regardless of the restorative material, the use of diamond bur or single-step abrasive rubber (Dura Gloss) were associated with the highest Ra values. Conclusion: The effect of F/P systems on Ra is material-dependent and instrument or system-dependent.

Flexural Properties and Polished Surface Characteristics of a Structural Colored Resin Composite

OBJECTIVE

The aim of this study was to determine the flexural properties and surface characteristics of a structural colored resin composite after different finishing and polishing methods, in comparison to those of conventional resin composites.

METHODS AND MATERIALS

A structural color resin composite, Omnichroma (OM, Tokuyama Corp, Chiyoda City, Tokyo, Japan), and two comparison resin composites, Filtek Supreme Ultra (FS, 3M, St Paul, MN, USA) and Tetric EvoCeram (TE, Ivoclar Vivadent, Schaan, Liechtenstein), were used. The flexural properties of the resin composites were determined in accordance with the ISO 4049 specifications. For surface properties, 70 polymerized specimens of each resin composite were prepared and divided into seven groups of 10. Surface roughness (Sa), gloss (GU), and surface free energy (SFE) were investigated after the following finishing and polishing methods. Three groups of specimens were finished with a superfine-grit diamond bur (SFD), and three with a tungsten carbide bur (TCB). After finishing, one of the two remaining groups was polished with a one-step silicone point (CMP), and the other with an aluminum oxide flexible disk (SSD). A group ground with SiC 320-grit was set as a baseline.

RESULTS

The average flexural strength ranged from 116.6 to 142.3 MPa in the following order with significant differences between each value: FS > TE > OM. The average E ranged from 6.8 to 13.2 GPa in the following order with significant differences between each value: FS > TE > OM. The average R ranged from 0.77 to 1.01 MJ/mm3 in the following order: OM > FS > TE. The Sa values of the OM groups polished with CMP and SSD were found to be significantly lower than those of the other resin composites, regardless of the finishing method. The GU values appeared to be dependent on the material and the finishing method used. The OM specimens polished with SSD showed significantly higher GU values than those polished with CMP. Most of the resin composites polished with SSD demonstrated significantly higher γS values compared to the other groups. Extremely strong negative correlations between Sa and GU in the combined data from the three resin composites and each resin composite and between Sa and γS in the OM specimens were observed; GU showed a strong positive correlation with γS in the same material.

CONCLUSION

These findings indicate that both flexural and surface properties are material dependent. Furthermore, the different finishing and polishing methods used in this study were observed to affect the Sa, GU, and SFE of the resin composites.

Handling properties and surface characteristics of universal resin composites

OBJECTIVE

This study investigated the handling and surface characteristics of universal resin composites and determined the interrelations among the composites' handling, mechanical, and physical properties.

METHODS

Five recently introduced universal resin composites were tested. Twelve specimens per material were used to measure the stiffness and stickiness (handling properties) of the resin composite pastes. Additionally, surface properties (Knoop hardness number [KHN], surface roughness [Sa], surface gloss [SG], water contact angle [CA], and surface free energy [SFE]) of cured resin composites were determined in 12 specimens per material immediately after preparation (baseline) and after subjection to thermal cycles (TCs).

RESULTS

Handling and surface properties of the resin composites were material dependent. All the resin composites showed significantly lower KHN in the post-TC subgroups than that in the baseline subgroups. However, the influence of TC on the other surface properties was dependent on the material used. Some resin composites did not indicate any significant differences in Sa, SG, or CA between the baseline and post-TC groups.

SIGNIFICANCE

Although the resin composites in the baseline groups presented with different handling and surface properties, the surface properties of most of the composites were significantly affected by TC. Extremely strong positive or negative correlations were observed between stiffness and stickiness, KHN and Sa, KHN and SG, Sa and SG, and CA and SFE. Most correlations between the handling and surface properties were weak. Therefore, the selection of resin composites in clinical situations should be based on comprehensive consideration of their properties.

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 Finishing and Polishing on The Surface Roughness of Bulk Fill Composites

Objective:

The aim of this in vitro study was to compare the effect of three finishing/polishing systems on the surface roughness (Ra) of conventional and Bulk-fill composite resins.

Materials and methods:

The Ra values of three different brands of Bulk-fill composites (Filtek Bulk-fill®, 3M ESPE; SonicFill Bulk-fill®, Kerr; SDR Bulk-fill®, Dentsply) were tested and compared with the Ra of a conventional composite (Filtek XT Z350®, 3M ESPE). A total of 30 discs (10 mm × 2 mm) were fabricated from four test materials and divided into three groups (n = 10/group) depending on the three finishing/polishing systems used (Astropol®, Ivoclar Vivadent; PoGo®, Dentsply; Sof-LexTM®, 3M ESPE). The Ra of each specimen was recorded with an optical profilometer (Contour-GT-X®, USA). ANOVA and Tukey’s tests were used for statistical analysis.

Results:

Statistically significant differences (P < 0.05) were observed between the Ra values of all composite materials tested with three finishing/polishing systems. Among composite materials, only Group-III showed a significant difference (P = 0.003) in Ra obtained using all three finishing/polishing systems. SDR Bulk-fill® and Filtek XT Z350® showed the highest (0.810 ± 0.373 µm) and lowest (0.365 ± 0.119 µm) Ra values, respectively. Individually, the highest Ra was recorded for SDR Bulk-fill® when it was finished/polished with the Astropol® system. SonicFill Bulk-fill® and SDR Bulk-fill® composites exhibited the lowest Ra values when they were finished with the PoGo® system.

Conclusion:

Finishing and polishing techniques greatly affect the surface roughness of different Bulk-fill composites because variations in the surface roughness were observed for all tested composite materials. Filtek XT Z350® exhibited the lowest surface roughness, while SDR Bulk-fill® exhibited the highest surface roughness among the tested composite materials.

Effect of Fluoride Gels on the Surface Roughness of Different Composite Resins

Background:

The pH of fluoride gels influences the roughness of composite resins, which affects their clinical durability.

Objective:

To evaluate the effect of fluoride gels (1.23% acidified phosphate fluoride and neutral fluoride) on the morphology of different composite resins after finishing and polishing.

Methods:

We prepared sixty specimens with a diameter of 5 mm and a height of 2 mm. The specimens were then divided into six groups (n = 10), according to the type of composite resin (Z250 micro-hybrid (Z), Filtek Z350 XT nanoparticles (XT), and Tetric N-Ceram nano-hybrid (TC)) and fluoride gel treatment (1.23% acidified phosphate (APF) or neutral fluoride (NF)) to measure surface roughness (Ra). The material was light-cured using an LED-curing unit (Elipar Freelight Deep Cure-3M/ESPE) for 20 s with a light intensity of 1.200 mW/cm2. Ra measurements were performed before and after treatment with different fluoride gels using a rugosimeter (Mitutoyo SJ210). After Ra, we selected two samples from each group for evaluation using scanning electron microscopy. Data were analyzed using the Shapiro-Wilk, ANOVA, and Tukey tests, with a significance of 5%.

Results:

The average Ra before and after NF did not differ statistically. The average Ra values of the groups treated with APF showed statistically significant differences. The photomicrographs of the groups treated with NF were similar to those of the groups without fluoride treatment. The APF-treated groups showed significant morphological changes.

Conclusion:

NF did not promote changes in the morphology of the evaluated composite resins, in contrast to APF, which caused significant changes.

Surface Geometry of Four Conventional Nanohybrid Resin-Based Composites and Four Regular Viscosity Bulk Fill Resin-Based Composites after Two-Step Polishing Procedure

Objectives. The aim of the study was to determine the quantitative and qualitative surface structure of contemporary RBCs in posterior teeth reconstructions: regular viscosity bulk fill and conventional composites, obtained after two-stage polishing procedure. Materials and Methods. Four conventional nanohybrid composites (Tetric EvoCeram, GrandioSO, Filtek Z550, and Ceram·X Mono) and four regular viscosity bulk fill composites (Tetric EvoCeram Bulk Fill, X-tra fil, Filtek Bulk Fill Posterior, and QuixFil) were tested. Samples of each RBC were prepared using PMMA cylindrical mold. After two-step polishing procedure, a surface geometry was evaluated under profilometry (Turbowave v. 7.36, Hommel-Etamic) and SEM (VEGA 3, Tescan Analytics). To evaluate differences between values, the following nonparametric tests were used: Friedman’s ANOVA, Wilcoxon’s matched-pair test, ANOVA Kruskal-Wallis, and Mann-Whitney U. Results. All conventional RBCs showed Ra values in the range of 0.20-0.26 μm. Bulk fill showed higher values in range of 0.49-1.36 μm except for Filtek Bulk Fill Posterior, which achieved 0.23 μm Ra value. SEM images of conventional RBCs were described as smooth surfaces with slight damage except for TEC, which presented smooth surface with no damage. Bulk fill composites showed rough surface, except for TBF, which presented smooth surface with slight damage. Conclusions. Regular viscosity bulk fill composites do not constitute a homogeneous group regarding surface roughness after polishing. They obtain, for the most part, poorer smoothness values after polishing than conventional RBCs.

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.