Impact of filler size and distribution on roughness and wear of composite resin after simulated toothbrushing

Comparison of volumetric loss and surface roughness of composite dental restorations obtained by additive and subtractive manufacturing methods

Statement of problem

Permanent crown materials produced with new generation additive manufacturing and traditional subtractive manufacturing materials have not been compared in terms of wear resistance.

Purpose

This study aims to compare the volumetric loss related to wear and resulting surface roughness after aging in a chewing simulator between resin nano ceramics produced with milling technique and permanent crown materials produced with three dimensional (3D) printing.

Materials and methods

Three different hybrid composite-ceramic (HCC) (The three materials are GC: Cerasmart, VE: Vita Enamic, and GV: Grandio Voco.) and one 3D printed definitive crown resin (FormLabs Permanent Crown Resin) were investigated before aging (n:8), the surface roughness of all samples was measured with a profilometer, and 1 randomly selected sample from each subgroup was imaged with scanning electron microscope (SEM). 3D scans of each sample were obtained with a desktop scanner. Thermomechanical aging was performed using a chewing simulator. Four hundred thousand cycles were completed under a vertical occlusal force of 49 ± 0.7 N with a thermal cycle of 1.7 Hz 5-55° and with a dwell time of 120 s, mimicking 2 years of aging. The imaging procedures were repeated, and the change in surface roughness was evaluated. 3D images were also overlapped, and the volumetric loss was calculated with the relevant inspector software. The data obtained were analyzed by two-way ANOVA (p < 0.05).

Result

The results showed significant statistical differences for both parameters (p > 0.05). The highest volumetric loss was found in the GV group while the lowest volumetric loss was in the VE group. The highest surface roughness values were observed in the GV group, while the lowest values belonged to the VE one.

Conclusion

Of the restorative materials evaluated, the VE group is suitable for long-term restorations, whereas the GV one is suitable for medium-term restorations. It is promising in terms of 3D printing technologies that the 3D material gives comparable results with the GV group.

Clinical i̇mplication

Additive manufacturing techniques are a successful method that accelerates the manufacturing process. Permanent crown resins are promising alternatives to conventional production.

Analysis of color stability and degree of conversion of different types of resin composites

Resin composites containing surface pre-reacted glass (S-PRG) have been introduced to reduce demineralization and improve remineralization of the tooth structure. However, water diffusion within the material is necessary for its action, which can impair its overall physicomechanical properties over time, including color stability. This study aimed to evaluate the color stability and related degree of conversion (DC) of four resin composites. Discs (6 x 4 mm, n = 5/group) of microhybrid (MH), nanofilled (NF), nanohybrid (NH), and S-PRG-based nanohybrid (S-PRG-NH) composites with two opacities (A2/A2E and A2O/A2D) were prepared. Color (CIELab and CIEDE2000) was evaluated with a spectrophotometer after aging in grape juice (2 x 10 min/10mL/7days). The DC was analyzed by using Fourier transform infrared spectroscopy before and after light-curing. Data were statistically analyzed by using two-way analysis of variance and post-hoc least significant difference tests (p<0.05). In the color stability analysis, the interaction between filler type and opacity was significant (CIELab, p = 0.0015; CIEDE2000, p = 0.0026). NH presented the highest color stability, which did not differ from that of MH. The greatest color alteration was observed for S-PRG-NH. S-PRG fillers also influenced DC (p < 0.05). The nanohybrid resin composite presented favorable overall performance, which is likely related to its more stable organic content. Notwithstanding the benefits of using S-PRG-based nanohybrid resins, mostly in aesthetic procedures, professionals should consider the susceptibility of such resins to color alteration, probably due to the water-based bioactive mechanism of action.

Effect of thickness and shade of CAD/CAM composite on the light transmission from different light-curing units

The thickness and shade of a restoration will affect the transmission of light from the light-curing unit (LCU). This study determined the power (mW), spectral radiant power (mW/nm), and beam profile of different LCUs through various thicknesses and shades of a CAD-CAM resin composite (BRAVA Block, FGM). Five thicknesses: 0.5; 0.75; 1.0; 1.5, and 2.0 mm, in three shades: Bleach; A2 and A3.5 of a CAD-CAM resin (n = 5). Two single-peak LCUs: EL, Elipar DeepCure-S (3M Oral Care); and OP, Optilight Max (Gnatus), and one multiple-peak LCU: VL, VALO Grand (Ultradent), were used. The LCUs were positioned touching the surface of the BRAVA Block. The power and emission spectrum were measured using a fiberoptic spectrometer attached to an integrating sphere, and the beam profiles using a laser beam profiler. The effect of the material thickness on the light attenuation coefficients was determined. VL and EL delivered more homogeneous beam profiles than OP. The type of the BRAVA Block had a significant effect on the transmitted power, and wavelengths of transmitted light (p < 0.001). There was an exponential reduction in the power and emission spectrum as the thickness of the BRAVA Block increased (p < 0.001). The light transmission through the A2 shade was least affected by the thickness (p < 0.001). The attenuation coefficient was higher for the violet light and higher for A3.5 than the A2 or Bleach shades. No violet light from the VL could be detected at the bottom of 2.0 mm of the BRAVA Block.

An In Vitro Study regarding the Wear of Composite Materials Following the Use of Dental Bleaching Protocols

Composite materials used in dental restorations are considered resistant, long-lasting and aesthetic. As the wear of restorations is an important element in long-term use, the aim of this study was to evaluate the surface condition of nanohybrid and microfilled composite resins, after being subjected to the erosive action of dental bleaching protocols. This paper reflects a comparative study between one nanofilled composite and three microfilled composites used in restorations. For each composite, three sets of samples (under the form of composite discs) were created: a control group, an "office bleach" group with discs bleached with 40% hydrogen peroxide gel, and a "home bleach" group with discs bleached with 16% carbamide peroxide gel. Wear was numerically determined as the trace and the coefficients of friction obtained using a tribometer, the ball-on-disk test method, and two balls: alumina and sapphire. For all composite groups, there were statistically significant differences between the wear corresponding to the control and bleaching groups, for both testing balls. Regarding the composite type, the largest traces were recorded for GC Gradia direct anterior, for all groups, using the alumina ball. In contrast, for the sapphire ball, 3M ESPE Filtek Z550 was characterized by the largest traces. With respect to the friction coefficients, the "office bleach" group recorded the largest values, no matter the composite or the ball type used. The 3M ESPE Valux Plus composite recorded the largest friction coefficients for the alumina ball, and 3M ESPE Filtek Z550 for the sapphire ball. Overall, the "office bleach" group was characterized by higher composite wear, compared to the "home bleach" protocol or control group. Nanofilled composite resins showed superior wear resistance to microfilled resins after undergoing a bleaching protocol.

Surface profile characterization of prefabricated resin composite veneers following simulated abrasion. An in vitro study

Background

The surface of resin composite veneers is susceptible to the effect of the oral environment and surface profile characterization of different veneer systems is of importance to the longevity and clinical performance of the materials. The aim of the present study was to evaluate surface profile properties, as defined by gloss and roughness parameters, of prefabricated resin composite veneers (PCV) and compare with a laboratory resin composite (LRC) system, following simulated abrasion.

Material and Methods

Twenty eight composite veneers equally divided to a prefabricated composite veneer (PCV) system and a laboratory resin composite (LRC) (control group) were tested following abrasion under a toothbrush simulator. Alterations in gloss (ΔGloss) and roughness (ΔSa, ΔSz, ΔSci, ΔSdr) parameters were examined (after- before abrasion) using a glossmeter and a 3D-optical profilometer, respectively. Correlation matrices between ΔGloss and ΔRoughness parameters were sought across the two resin composite veneer groups.

Results

Τhere was weak evidence that the PCV group exhibited less change in surface gloss after experimental abrasion (PCV vs LRC: mean difference ΔGloss in GU, (MD: -1.7; 95% CI: -3.3, -0.1; p=0.04). For the roughness parameters, ΔSci in nm3/nm2 (MD : 0.2; 95% CI: 0.1, 0.3; p=0.002) and ΔSdr in percentage (MD: 10.6; 95% CI: 3.7, 17.5; p=0.004), exhibited the most pronounced differences between the groups with strong evidence demonstrating greater changes for the PCV group compared to the LRC. No strong correlation pattern could be identified between changes in gloss and roughness parameters across the groups.

Conclusions

After abrasion, both PCV and LCR showed an increase in surface gloss, while the PCV group demonstrated a rougher core surface profile than LRC. Key words:Prefabricated, resin composite, veneers, gloss, roughness.

Effect of tooth brushing simulation on the surface properties of various resin-matrix computer-aided design/computer-aided manufacturing ceramics

PURPOSE

The purpose was to investigate the alterations in surface properties of different resin-matrix CAD/CAM ceramics following tooth brushing simulation (TBS) and compare them with a direct resin composite and a glass ceramic CAD/CAM material.

MATERIALS AND METHODS

Four resin-based CAD/CAM restoratives (Brilliant Crios-BR, Lava™ Ultimate-LV, Grandio Blocs-GR and Shofu Block HC-SH), a leucite-reinforced glass ceramic (IPS Empress® CAD-EC) and a resin composite (Filtek™ Z250-FZ) for direct restorations were tested. In particular, surface loss, hardness, roughness and morphology were investigated utilizing confocal microscopy, scanning electron microscopy and nanoindentation tester. TBS was conducted for 4 × 15 min on the surface of the samples and then the changes in their surface properties were evaluated.

RESULTS

After TBS, all the experimental groups exhibited surface loss to different extent. FZ and BR presented the highest surface loss, while EC and GR the lowest (p < 0.05). Regarding surface roughness, all the tested materials exhibited increase after TBS (p < 0.05), except LV (p = 0.099). EC presented the lowest Sa values, while FZ and BR the highest (p < 0.05). Changes in surface morphology were in compliance with the results of surface roughness and also surface hardness was correlated with surface loss.

CONCLUSIONS

The tested resin-matrix CAD/CAM ceramic restorative materials showed a competent behavior against abrasive forces applied during TBS. Surface loss and roughness changes were material dependent and superior compared to a resin composite for direct restorations, while in comparison with a leucite-reinforced glass ceramic exhibited inferior properties.

CLINICAL SIGNIFICANCE

Tooth brushing affected differently the surface of the tested restorative materials. However, the abrasive wear that was induced was negligible. Clinical studies are necessary to ascertain if there is clinical significance of these surface alterations that may demand repair of such restorations.

Surface Properties of Resin Composites and CAD/CAM Blocks After Simulated Toothbrushing

OBJECTIVES

This study aimed to evaluate the surface gloss, surface roughness, and color change of restorative materials after a three-body wear abrasion.

METHODS AND MATERIALS

Four resin composites with different filler particle size (Gracefil Flo [GFF, 0.7 μm], Gracefil LoFlo [GFL, 0.25 μm], Gracefil ZeroFlo [GFZ, 0.15 μm], and Gracefil Putty [GFP, 0.3 μm]), two CAD/CAM resin composite blocks with different filler particle size (Cerasmart 300 [CS3, 0.7 μm] and Cerasmart Prime [CSP, 0.3 μm], GC), and one CAD/CAM lithium disilicate glass-ceramic block (Initial LiSi Block [ILS], GC) as a control were evaluated. Twenty slab-shaped specimens were obtained from each material. Ten specimens were subjected to 80,000 toothbrushing strokes and measured for surface gloss (Gloss Unit, GU), surface roughness (Ra, μm), and color (L*, a*, and b* values) before toothbrushing and at every 20,000 strokes. Color differences (ΔL*, Δa*, Δb*, and ΔE00) before and after toothbrushing were calculated. After 80,000 strokes, abraded surfaces were observed using scanning electron microscopy. The other 10 specimens were measured for Vickers microhardness (VHN).

RESULTS

After 80,000 toothbrushing strokes, the mean GU ranged from 60.43 to 16.12 (the highest for ILS and lowest for GFL), and the mean Ra ranged from 0.079 to 4.085 (the lowest for ILS and highest for GFL). At all measuring stages, the calculated ΔE00 values ranged from 0.31 to 0.92 for all materials. The mean VHN ranged from 632.34 to 39.08 (the highest for ILS and lowest for GFZ). The resin composite containing the largest filler particle (GFF) showed significantly lower Ra and higher VHN than other resin composites (GFL, GFZ, and GFP). The CAD/CAM resin composite block containing a smaller filler particle (CSP) retained significantly higher GU than that containing a larger filler particle (CS3). A negative correlation between GU and Ra was detected.

CONCLUSIONS

Based on the findings, toothbrush abrasion induced a decrease in GU and an increase in Ra for all resin-based materials tested. Resin-based materials with larger filler size tended to show lower Ra, while resin-based materials with smaller filler size tended to show a smaller reduction in GU. These were more pronounced for light-cure resin composites than for resin composite blocks for CAD/CAM.

In Vitro evaluation of the effects of whitening toothpastes on the color and surface roughness of different composite resin materials

BACKGROUND

The aim of this study was to evaluate the effects of traditional and whitening toothpastes on the color and surface roughness of different composite resin materials.

METHODS

Eighty disc-shaped samples were prepared for each of the following composite resins: nano-hybrid (Filtek Ultimate Universal; 3 M/ESPE, Saint Paul, USA), micro-hybrid (Charisma Smart; Kulzer, Hanau, Germany) and supra-nano-filled (Omnichroma; Tokuyama, Tokyo, Japan). Each composite-resin sample was randomly divided into the following four subgroups (n = 20 per group): Group 1, control; Group 2, traditional toothpaste (Colgate Total 12; Colgate Palmolive, New York, USA); Group 3, peroxide-based toothpaste (Colgate Optic White; Colgate-Palmolive, New York, USA); and Group 4, blue covarine-based toothpaste (Meridol Gentle White; CP-GABA, Hamburg, Germany). The samples for the toothpaste subgroups were immersed in a coffee solution for 10 min and washed twice a day before each brushing cycle. The specimens were brushed for 30 days. Color analyses were performed using a spectrophotometer (SpectroShade Micro, MHT, Italy). Surface roughness analyses were conducted using a profilometer (Surftest SJ-210 Mitutoyo, Tokyo, Japon). The color and surface roughness analyses were performed at baseline and 1, 7 and 30 days after each treatment. Furthermore, surface topography analysis was performed using Scanning Electron Microscopy (FEG 250-FeiQuanta, the Netherlands). The data were analysed with a three-way robust ANOVA and Bonferroni post-hoc correction (p < 0.05).

RESULTS

The smallest color change was observed for the micro-hybrid composite resin, and the greatest color change was observed for the nano-hybrid composite resin. Based on the tested composite resin samples, the greatest color change was obtained after using blue covarine-based toothpaste, while the smallest color change was observed after using peroxide-based toothpaste. Moreover, the supra-nano-filled composite resin samples exhibited the lowest roughness values (robust ANOVA test, p < 0.001). There was no statistically significant difference between the mean values of roughness for the composite, group and time interaction (p = 0.937).

CONCLUSION

Charisma Smart composite resin exhibited significantly lower staining than all the other composite resins tested after using all toothpastes included in the study. Further laboratory and clinical studies are needed to fully understand the long-term effectiveness of whitening toothpaste on composite resin materials.

Impact of combined at-home bleaching and whitening toothpaste use on the surface and color of a composite resin

Objective

This in vitro study aimed to evaluate the effects of different whitening toothpastes on a composite resin during at-home bleaching with 10% carbamide peroxide.

Materials and Methods

Sixty samples (7 mm × 2 mm) were used for color and roughness analyses, while another 60 samples (3 mm × 2 mm) were utilized to assess microhardness. The factors analyzed included toothpaste, for which 5 options with varying active agents were tested (distilled water; conventional toothpaste; whitening toothpaste with abrasive agents; whitening toothpaste with abrasive and chemical agents; and whitening toothpaste with abrasive, chemical, and bleaching agents). Brushing and application of whitening gel were performed for 14 days. Surface microhardness (SMH), surface roughness (Ra), and color (∆L*, ∆a*, ∆b, ∆E*ab, and ∆E00) were analyzed. The Ra and SMH data were analyzed using mixed generalized linear models for repeated measures, while the color results were assessed using the Kruskal-Wallis and Dunn tests.

Results

Between the initial and final time points, all groups demonstrated significant increases in Ra and reductions in SMH. No significant differences were found between groups for SMH at the final time point, at which all groups differed from the distilled water group. Conventional toothpaste exhibited the lowest Ra, while whitening toothpaste with abrasive agent had the highest value. No significant differences were observed in ∆L*, ∆a*, and ∆b.

Conclusions

While toothpaste composition did not affect the color stability and microhardness of resin composite, combining toothbrushing with whitening toothpaste and at-home bleaching enhanced the change in Ra.

Surface Analysis of a Universal Resin Composite and Effect of Preheating on its Physicochemical Properties

This study was aimed at analyzing the surface properties of a universal resin composite and evaluating the effect of preheating on its physicochemical properties. Two commercial resin composites were used under two conditions: Filtek Universal Restorative (UR); UR preheated (URH); Filtek Supreme (FS) and FS preheated (FSH). The film thickness (FT) test (n = 10) was done using two glass slabs under compression. Flexural strength (FLS) and modulus (FLM) were evaluated using a three-point flexion test (n = 10). Polymerization shrinkage stress (PSS) was evaluated in a universal testing machine (n = 5). Gap width (GW) between composite and mold was measured in internally polished metallic molds (n = 10). The degree of conversion (DC) was evaluated by Fourier Transform Infrared spectroscopy (n = 3). The morphology of the filler particles was checked by scanning electron microscope (SEM) and EDX analysis. Surface gloss (SG) and surface roughness (SR) were evaluated before and after mechanical brushing (n = 10). The outcomes were submitted to 2-way ANOVA and Tukey's test (α = 0.05). Lower mean values of FT were observed for the preheated groups when compared to the non-preheated groups. URH and FSH showed higher mean values of FLS and FLM when compared with UR and FS. No differences were observed between groups in the PSS test. The GW was higher for the UR and FS groups when compared with URH and FSH. The DC was higher for preheated resin composites when compared to the non-preheated groups. The SR of the UR composite was higher than the FS after mechanical brushing, while the SG was higher for the FS groups. In conclusion, the universal resin composite tested generally presented similar physicochemical properties compared with the nanofilled resin composite and either similar or slightly inferior surface properties. The preheating improved or maintained all properties evaluated.

Comparative study on the impact-sliding wear behaviour of CAD/CAM resin-ceramic materials and tooth enamel

OBJECTIVES

To compare the impact-sliding wear of different CAD/CAM resin-ceramic materials and tooth enamel, and explore the corresponding wear damage mechanism.

METHODS

Human tooth enamel (EN), Vita ENAMIC (Vita, VE), Lava Ultimate (3 M, LU), and GC CERASMART (GC, CS) were used in this study. The hardness, elastic modulus, and roughness values of the samples were measured. Further, impact-sliding wear tests were performed in a ball-on-flat configuration with spherical zirconia antagonists and the coefficients of friction (CoF) were recorded simultaneously. Additionally, a white light interferometer was used to determine the volume losses and scanning electron microscopy was used to observe the wear morphology of the wear scars and the damage feature in the vertical sections to clarify the damage mechanism during the impact-sliding wear test.

RESULTS

EN exhibited the highest elastic modulus and CoF, followed by VE, LU, and CS. The hardness and roughness of EN and VE were similar and were higher than those of LU and CS. Throughout the wear tests, VE exhibited the highest volume loss, whereas CS exhibited the lowest. The wear damage characteristics of VE were similar to those of EN, displaying brittle fractures of inorganic substances and plastic deformation of organic substances in the impact part, exhibiting plough marks in the sliding parts. In the case of LU and CS, the entire wear areas displayed plastic deformation of the resin matrix, exfoliation of the filler particles, and plough marks.

SIGNIFICANCE

Enamel and polymer-infiltrated ceramic network materials exhibit similar wear damage modes. Additionally, the high-density nanocomposite resin material is the most resistant to impact-sliding wear from a tribological perspective.

Influence of filler types on wear and surface hardness of composite resin restorations

OBJECTIVE

Wear and surface hardness of resin composites are of relevance from the clinical standpoint. With the incorporation of novel filler system, more studies need to be performed to investigate newly marketed resin composites. The objective of this study was to investigate the abrasive wear and surface hardness of dental restorative with different filler types.

METHODS

Nanohybrid filled Harmonize (HM) and Tetric N-Ceram (TNC), microhybrid filled Filtek Z250 (Z250), nanofilled Filtek Z350 (Z350) were included in the study. Twelve cylindrical resin composites specimens with 10 mm in diameter and 6 mm in thickness were prepared for abrasive wear test. Eight hundred cycles under 17 kg load were conducted for final wear by CW3-1 wear machine. The specimen was cleaned with an ultrasonic unit for 3 min followed with drying procedure. After measurement of weight loss and the density of specimens, the specimens were kept for measurement of surface hardness. Surface hardness was measured using a micro-hardness tester with a Vickers diamond indenter after polishing. Three specimens of each material were observed by scanning electron microscopy (SEM) after the abrasion to evaluate the morphology of the surface. Data were analyzed using one-way analysis of variance (ANOVA), followed by Tukey HSD test (α = .05).

RESULTS

Z250 performed the least volume wear loss (41.1 ± 2.1 mm3), as well as the hardest value (102.7 ± 2.9 HV). There was no significant difference with the volume wear loss (p = 1.000) and surface hardness (p = 0.874) of HM and TNC. SEM images of nanohybrid filled HM and TNC represented smoother surface compared with other types of resin composites.

CONCLUSIONS

Microhybrid Z250 showed the highest wear resistance and surface hardness, nanofilled and nanohybrid resin composites may still face the insufficient of wear and surface hardness quality.

Effect of Water Storage and Bleaching on Light Transmission Properties and Translucency of Nanofilled Flowable Composite

This study investigated the effect of water sorption and bleaching on light transmission properties (Straight-light transmission (G0), Light diffusion (DF) and Amount of transmitted light (AV)) and translucency parameters (TP) of nano-filled flowable composites. A total of 35 composite disks (0.5 mm thickness) were prepared using A2 shade of 5 nanofiller composites (n = 7/each); Beautifil Flow Plus X F03 (SHOFU INC), Clearfil Majesty ES Flow (Kuraray Noritake Dental), Estelite Universal Flow (EUF, Tokuyama Dental), Estelite Flow Quick (Tokuyama Dental) and Filtek Supreme Ultra Flowable Restorative (FSU, 3M ESPE). Then, they were cured by LEDs (VALO, Ultradent) on standard mood (1000 mW/cm2) for 20 s. Samples were tested for straight-line transmission (G0), diffusion (DF), the amount of transmitted light (AV) and (TP) immediately after 24 h (dry storage), after 1-week water storage and after each of the three cycles of in-office bleaching (HiLite, SHOFU INC). Result: G0, DF, AV and TP were significantly affected by different materials (p < 0.001). The AV of FSU increased significantly after the 1-week water storage, then after the second bleaching cycle (p < 0.001). The TP for EUF slightly decreased (p = 0.019) after 1-week water storage, then increased throughout bleaching. Conclusion: Ageing/bleaching conditions do not affect G0, DF, AV and TP. The compositional variation between nano-filler composites resulted in a significant difference between materials.

Optimal Surface Pre-Reacted Glass Filler Ratio in a Dental Varnish Effective for Inhibition of Biofilm-Induced Root Dentin Demineralization

A unique type of dental varnish (DV) containing surface pre-reacted glass (S-PRG) fillers of different concentrations was evaluated to determine the unpresented optimal ratio for inhibiting root dentin bio-demineralization. S-PRG DVs (10% to 40%)—10%-S, 20%-S, 30%-S, and 40%-S—were applied to bovine root dentin blocks and compared with controls—0%-f (no S-PRG) and 5%-NaF (5%-NaF). The Streptococcus mutans biofilm challenge was executed inside and outside an oral biofilm reactor for 7 days. The specimens were examined using a confocal laser scanning microscope and swept-source optical coherence tomography. Furthermore, they were observed using a scanning electron microscope and analyzed using energy-dispersive X-ray spectroscopy. The roughness (SzJIS) due to leaching of DV materials and demineralization depth were significantly less in the S-PRG groups than the control groups (p < 0.05). Complete or partially plugged dentinal tubules (DTs) were observed in 20%-S, 30%-S, and 40%-S, while wide-open DTs were observed more in controls. Cylindrical tags were present in groups containing more than 20% S-PRG. F, Na, Al, and Sr were detected in a higher percentile ratio in the 20%-S, 30%-S, and 40%-S groups compared to 0%-f and 10%-S. Nonetheless, it is suggested that incorporating 20% to 30% S-PRG fillers in DVs would be effective enough as an anti-demineralization coating, together with supplementing minerals; further evaluation is required to validate these findings.

In Vitro Evaluation of Gastric Acid and Toothbrushing Effect on the Surface State of Different Types of Composite Resins

Background and Objectives: The aim of this in vitro study was to evaluate the effect of gastric acid associated with the effect of toothbrushing on the surface roughness of different types of composite resin used for direct restorations. Materials and Methods: The materials used in this study were two microhybrid (Filtek Z250, Herculite XRV) and two nanohybrid (Filtek Z550, Herculite XRV Ultra) composite resins. Two hundred and forty cylindrical samples with a height of 2 mm and a diameter of 6 mm were divided into four groups (groups A, B, C and D) corresponding to each tested material (n = 60). Each group was divided in two subgroups: subgroup I—the samples were submersed in hydrochloric acid and immediately submitted to toothbrushing; subgroup II—the samples were submitted only to toothbrushing. The simulation of the acid attack was performed by immersing the samples in a 0.01 M hydrochloric acid solution for 90 min. This procedure was followed immediately by toothbrushing simulation with 10,000 cycles. The acid attack and toothbrushing simulation were performed for two times. The surface roughness evaluation was performed with a Proscan 2100 profilometer. Repeated Measures ANOVA and Bonferroni post-hoc tests were used to perform the statistical analysis. Results: Simulation of one year of toothbrushing associated or not to hydrochloric acid exposure increases the surface roughness of microhybrid and nanohybrid composite resins. Six months of toothbrushing associated to six months of hydrochloric acid exposure increase the surface roughness of nanohybrid composite resins. Conclusions: Microhybrid composite resins surface becomes rougher after toothbrush and acid submersion when comparing to nanohybrid composite resins.

Digital Volumetric Analysis of CAD/CAM Polymeric Materials after Tooth Brushing

The objective of the study was to evaluate the volumetric wear of four composite materials for CAD/CAM (computer-aided design/computer-aided manufacturing) systems. The materials evaluated were: Cerasmart (CER), Shofu Block HC (SBH), Tetric CAD (TEC) and Brava (BRA). All the samples (n = 40) were subjected to simulated brushing (100,000 cycles). Wear was evaluated by superimposing pre-and post-brushing scans obtained with an intraoral optical scanner (CEREC Primescan; Dentsply Sirona, Germany), which were subsequently imported into the OraCheck software 5.0 (Dentsply Sirona, Germany). The data were analyzed by ANOVA test and Tukey’s HSD test was used for multiple comparisons. Cerasmart showed the least wear after brushing. All the tested materials exhibited mass loss.

The Effect of Dentifrice on Micro-Hardness, Surface Gloss, and Micro-Roughness of Nano Filled Conventional and Bulk-Fill Polymer Composite-A Micro Indentation and Profilometric Study

The aim of the present study was to evaluate the effect of brushing with two whitening dentifrices (Colgate Optic White (COW) and Colgate Optic White Charcoal (COC)) on surface gloss, micro-roughness, and micro-hardness of nanostructured hybrid conventional (Z350) and bulk-fill (Tetric N Ceram bulk-fill) polymer composite. In total, 96 disk samples using two nano-hybrid composite polymers (Z350 and Tetric N Ceram Bulk-fill) were prepared. All specimens were exposed to two different dentifrices (COW and COC), resulting in four main subgroups in the study. Specimens were assessed for surface gloss, micro-roughness (Ra), and micro-hardness using standardized methodology. Means and standard deviations of properties compared using paired t-test, one-way and two-way ANOVA, and post hoc test. The presence of dentifrices did not show any significant difference in micro-hardness values of Z350 (p > 0.05), whereas micro-hardness of bulk-fill composite significantly reduced on dentifrices exposure (p ≤ 0.05). Bulk-fill polymer composite showed significant reduction in gloss after dentifrice exposure (p < 0.05), however, Z350 showed no significant loss of gloss due to dentifrices (p > 0.05). A significant increase in Ra was observed for both resin materials after exposure to dentifrices (COC and COW). Conventional resin composite (Z350) showed comparable surface hardness and gloss before and after dentifrice exposure, however, micro-roughness increased significantly due to dentifrice exposure. Bulk-fill resin (Tetric N Ceram) showed significant loss of micro-hardness and gloss and increase in micro-roughness on dentifrice exposure. Conventional nano-hybrid composite polymer showed better durability in resisting loss of surface properties compared to bulk-fill resin polymer in the present experiment.

Effect of simulated brushing on surface roughness and wear of bis-acryl-based materials submitted to different polishing protocols

BACKGROUND

Provisional materials must have enough strength to withstand masticatory loads without suffering deformation or fracture, and their surfaces must have good finishing and polishing characteristics to reduce biofilm accumulation. Thus, the purpose of this study was to investigate the best polishing protocol for different bis-acryl composite resins in comparison with a conventional resin composite and a self-curing acrylic resin aiming to obtain a smooth restoration surface and resistance to wear.

MATERIAL AND METHODS

One hundred and four samples (15 mm length x 5 mm width x 4 mm depth) were prepared and divided into four groups according to the material tested: Protemp 4 and Structur 3 bis-acryl composite resins, Dencor self-curing acrylic resin, Filtek Z350XT conventional composite resin. The polishing procedures were performed with Sof-Lex Pop-On discs or Sof-Lex spirals and abrasion procedures were performed on a brushing machine. The surface roughness was analyzed at three periods (initial, post-polishing and post-brushing) and the wear was evaluated after simulated brushing. The results were submitted to ANOVA followed by the Tukey (α = 0.05).

RESULTS

Filtek Z350XT groups showed the lowest values of initial surface roughness followed by Structur 3, Protemp 4 and Dencor groups. After polishing and simulated brushing, Filtek Z350XT groups also presented the lowest roughness values, followed by bis-acryl groups (Structur 3 and Protemp 4) and Dencor groups demonstrated the highest surface roughness. Sof-Lex Pop-On discs system exhibited lower roughness values for all groups.

CONCLUSIONS

Sof-Lex Pop-On discs system promoted the best polishing for all groups. Overall, Filtek Z350XT groups presented lower results for both roughness and wear for all periods evaluated, followed by Protemp 4 and Structur 3, meanwhile Dencor groups presented the highest roughness and wear values for all periods. Key words:Acrylic resin, bis-acryl, brushing, composite resin, polishing, roughness, wear.

The Influence of Abrasive and Acidic Aggressions on the Surface Condition of Flowable Composite Resin

The aim of this in vitro study was to evaluate the effect of hydrochloric acid associated with the abrasive effect of toothbrushing on the surface condition of three flowable composite resins used for direct restoration. Seventy samples of each composite resin: Grandio Flow (VOCO, Germany)—group A, Filtek Ultimate Flow (3M-ESPE, MN, USA)—group B, G-aenial Flo X (GC Europe)—group C were prepared, submersed in hydrochloric acid 30% for 60 min and then submitted to simulated toothbrushing procedure using 5000 cycles with toothbrushes with medium and hard bristles, immediately after the chemical attack, after 30 min or without any chemical attack. The sample’s surface roughness was analyzed using a noncontact profilometer (Dektak XT, Bruker, USA). ANOVA and post hoc Bonferroni tests, with a p < 0.05, were used to analyze the values. Hydrochloric acid action for 60 min and six months of toothbrushing using toothbrushes having medium hardness or firm bristles affects the surface roughness of tested flowable composite resins. Toothbrushing with firm bristles immediately after acidic challenge determines increased surface roughness for two of the three flowable composite resins (Grandio Flow and Filtek Ultimate Flow). Toothbrushing with medium or firm bristles thirty minutes after the acidic aggression determine no effect on surface condition of flowable composite resins.

Wear behavior of a microhybrid composite vs. a nanocomposite in the treatment of severe tooth wear patients: A 5-year clinical study

OBJECTIVE

This study aimed to compare the wear behavior of a microhybrid composite vs. a nanocomposite in patients suffering from severe tooth wear.

METHODS

A convenience sample of 16 severe tooth wear patients from the Radboud Tooth Wear Project was included. Eight of them were treated with a microhybrid composite (Clearfil APX, Kuraray) and the other eight with a nanocomposite (Filtek Supreme XTE, 3M). The Direct Shaping by Occlusion (DSO) technique was used for all patients. Clinical records were collected after 1 month (baseline) as well as 1, 3 and 5 years post-treatment. The maximum height loss at specific areas per tooth was measured with Geomagic Qualify software. Intra-observer reliability was tested with paired t-tests, while multilevel logistic regression analyses were used to compare odds ratios (OR) of "large amount of wear".

RESULTS

Intra-observer reliability tests confirmed that two repeated measurements agreed well (p > 0.136). For anterior mandibular teeth, Filtek Supreme showed significantly less wear than Clearfil APX; in maxillary anterior teeth, Clearfil APX showed significantly less wear (OR _material = 0.28, OR _{jaw position} = 0.079, p < 0.001). For premolar and molar teeth, Filtek Supreme showed less wear in bearing cusps, whereas Clearfil APX showed less wear in non-bearing cusps (premolar: OR _material = 0.42, OR _{bearing condition} = 0.18, p = 0.001; molar: OR _material = 0.50, OR _{bearing condition} = 0.14, p < 0.001).

SIGNIFICANCE

Nanocomposite restorations showed significantly less wear at bearing cusps, whereas microhybrid composite restorations showed less wear at non-bearing cusps and anterior maxillary teeth.

Predicting transmitted irradiance through CAD/CAM resin composite crowns in a simulated clinical model

OBJECTIVE

To predict the clinically relevant transmitted irradiance that is available for luting when a CAD/CAM restoration is inserted. The influence of irradiance, exposure distance, light curing unit (LCU) angulation and direction of polymerization is analyzed when curing through crowns of different thicknesses.

METHODS

Three modern CAD/CAM resin-based composites (RBCs) were used to produce 45 crown-shaped specimens. The distance between fissure and crown base was set at 1.0, 1.5 and 2.0 mm (n = 5). Transmitted irradiance, while using a violet-blue LCU, was measured with a photo-spectrometer. 180 exposure conditions per specimen were investigated by variation in LCU curing mode, angulation, exposure distance and direction. Data was analyzed using univariate ANOVA followed by Tukey HSD (α = 0.05) and comparison of 95% confidence intervals.

RESULTS

The CAD/CAM-RBC's decadic absorption coefficient ranges from 0.317 mm^-1 to 0.387 mm^-1 and the reflection correcting factor for crowns ranges from 0.305 to 0.337. Transmitted irradiance decreases significantly with increasing exposure distance and decreasing incident irradiance. For tilt angles greater than 10°, transmitted irradiances are significantly reduced (-11% for 20°, -23% for 30°). Significantly lowest transmitted irradiances were measured for vestibular curing direction (up to -15%).

SIGNIFICANCE

A calculation model can predict the transmitted irradiance through a CAD/CAM restoration in dependence of restoration thickness and radiant emittance. The practitioner can be supported by this model to adapt material choice of dental restoration and adhesive system to the individual situation. Variation in exposure conditions shows negative effect on the transmission of light and should be limited.

Wear of contemporary dental composite resin restorations: a literature review

Composite resins are the most commonly used dental restorative materials after minimally invasive dental procedures, and they offer an aesthetically pleasing appearance. An ideal composite restorative material should have wear properties similar to those of tooth tissues. Wear refers to the damaging, gradual loss or deformation of a material at solid surfaces. Depending on the mechanism of action, wear can be categorized as abrasive, adhesive, fatigue, or corrosive. Currently used composite resins cover a wide range of materials with diverse properties, offering dental clinicians multiple choices for anterior and posterior teeth. In order to improve the mechanical properties and the resistance to wear of composite materials, many types of monomers, silane coupling agents, and reinforcing fillers have been developed. Since resistance to wear is an important factor in determining the clinical success of composite resins, the purpose of this literature review was to define what constitutes wear. The discussion focuses on factors that contribute to the extent of wear as well as to the prevention of wear. Finally, the behavior of various types of existing composite materials such as nanohybrid, flowable, and computer-assisted design/computer-assisted manufacturing materials, was investigated, along with the factors that may cause or contribute to their wear.

In Vitro Effects of Fluoride, Hydroxyapatite, and Bromelain-Containing Toothpaste Types on Surface Roughness of Different Restorative Materials

Aim:

To examine the effects of fluoride, hydroxyapatite, and bromelain-containing toothpaste types on the surface roughness of nanohybrid, nanofilled, flowable, and bulk-fill composites; conventional, light-curing, and low-viscosity glass ionomers; and compomers.

Materials and Methods:

A total of 160 specimens were fabricated using nanohybrid, nanofilled, flowable, and bulk-fill composites; conventional, light-curing, and low-viscosity glass ionomers; and compomers. Each material group was divided into four subgroups ( n = 5) as follows: Control (C), fluoride toothpaste (FT), bromelain toothpaste (BT), and hydroxyapatite toothpaste (HT). Surface roughness values of all specimens were examined using an optical profilometer and a scanning electron microscope at 500, 1,000, and 3,500 magnifications.

Results:

The highest average roughness value (Ra; µm) was obtained from the conventional glass ionomer material ( P < .001). While the mean Ra value was 0.155±0.116 µm at baseline, it was 0.262±0.203 µm in the fluoride group, 0.237±0.192 µm in the hydroxyapatite group, 0.260±0.293 µm in the bromelain group, and 0.198± 0.187 µm in the control group ( P < .001).

Conclusion:

We have found that brushing with various types of toothpaste containing fluoride, bromelain, and hydroxyapatite may not result in obtaining different surface roughness values from different types of restorative materials. Differences in surface roughness values of restorative materials may be found at different magnifications under scanning electron microscope.

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.

Characterization of low-cost Brazilian resin composites submitted to tooth brushing

This in vitro study aimed to evaluate surface microhardness, roughness, color, gloss and topography of low-cost Brazilian resin composites, compared with an international one. All 120 samples (8mm ø x 2mm height) were prepared and divided into 5 groups: Ultrafill (Biodinâmica), Llis (FGM), Fill Magic (Coltene), Applic (Makira), and Filtek Z250XT (3M Oral Care). Surface microhardness (KHN) (n=10) was analyzed at two time periods: before and after simulated tooth brushing (STB). Other standardized samples of each group (n=10) were analyzed for surface roughness (Ra), color (ΔL, Δa, Δb, ΔE, ΔE00) and gloss unit (GU) at the same two periods. The topography of non-brushed and brushed samples of each group (n=4) was evaluated by scanning electron microscopy. Data were analyzed statistically by two-way repeated measures ANOVA with Bonferroni post-hoc test (KHN, Ra, GU), and one-way ANOVA with Tukey post-hoc test (ΔL, Δa, Δb, ΔE, ΔE00) (α=0.05). Topographic images were submitted to descriptive analysis. The low-cost Brazilian resin composites investigated were compared with the international one and revealed: lower KHN, regardless of before or after STB; statistically similar Ra before STB, except Ultrafill, which presented higher values; lower Ra after STB, except Ultrafill, which presented statistically similar values; statistically similar color change in ΔL, Δa, Δb parameters; statistically similar color change in ΔE, ΔE00 parameters, except Fill Magic, which presented lower values; lower gloss before STB; lower gloss after STB, except Ultrafill, which presented statistically similar values. In a situation of scarce resources, low-cost Brazilian composites might be an acceptable cost-effective restorative alternative.

Mechanical and optical properties of indirect veneering resin composites after different aging regimes

This study tested and compared properties of six modern indirect veneering resin composites (VRC), namely Ceramage (Shofu), dialog Vario (Schütz Dental), Gradia Plus (GC Europe), in:joy (Dentsply), Signum composite (Heraeus Kulzer), and SR Nexco (Ivoclar Vivadent). Specimens were fabricated from dentin and enamel pastes and following properties were analyzed: (1) two-body wear (TB), (2) surface roughness (SR), (3) Martens hardness parameters (HM and E_IT), and (4) translucency (T). The highest impact on HM and E_IT was exerted by VRC brand (HM: η_P²=0.960/ E_IT: η_P²=0.968; p<0.001), followed by VRC paste material (HM: η_P²=0.502/ E_IT: η_P²=0.580; p<0.001), and aging duration (HM: η_P²=0.157/ E_IT: η_P²=0.112; p<0.001). Lowest and highest TB were measured for Signum composite and dialog Vario, respectively (p<0.001). Highest T was showed Signum composite and Ceramage (p<0.001). VRCs should be individually selected with respect to the indication area, due to different surface properties.

Experimental synthesis of size-controlled TiO2 nanofillers and their possible use as composites in restorative dentistry

The aim of this work was to obtain an efficient protocol with a green, fast and facile way to synthesize TiO2 NPs and its application as fillers for enhancement of desired dental properties of light curing dental composites. A comparative study comprised the fabrication of light curing restorative composite materials with incorporating different fillers with varying wt%, varying resin material composition, to determine optimal dental restoration by focusing on the physical properties of dental materials. It was observed that the as-prepared green synthesized TiO2 nanohybrid particles contributed to the improvement in physical properties, thus promoting the green and rapid synthesis of nanohybrid fillers. In addition, mechanical values for experimental cured resin materials with bare and surface modified fillers were obtained. The experimental light curing nanocomposites with 5 wt% (wt%) nanohybrid surface modified filler particles with BisGMA (60 wt%), TEGDMA (20 wt%) and UDMA (20 wt%) resin composition provided increased physical strength and durability with higher compressive stress 195.56 MPa and flexural stress 83.30 MPa. Furthermore, the dental property, such as polymerization shrinkage (PS) obtained from volumetric method was decreased up to 3.4% by the addition of nano-hybrid fillers. In addition to this, the biocompatible and antimicrobial nature of TiO2 and its aesthetics properties such as tooth-like color makes TiO2 favorable to use as fillers. This study presents a green and facile method for the synthesis of TiO2 nanohybrid particles that can be successfully used as fillers in an experimental light curing resin matrix for enhancing its dental properties. This describes the potential of the green synthesized TiO2 nanohybrid particles to use as fillers in restorative dentistry.

Influence of Thermal Stress on Simulated Localized and Generalized Wear of Nanofilled Resin Composites

Objective:

This study investigated the influence of thermal stress on the simulated localized and generalized wear of nanofilled resin composites.

Methods:

Six nanofilled resin composites were evaluated and then subjected to a wear challenge of 400,000 cycles in a Leinfelder-Suzuki (Alabama) wear simulation device after 24 hours of water storage (24-hour group) and 24 hours of water storage and 10,000 thermal cycles (TC group). Simulated localized wear was generated using a stainless-steel ball bearing, and simulated generalized wear was generated using a flat-ended stainless-steel cylinder. Wear testing was accomplished in a water slurry of polymethyl methacrylate beads. Simulated localized and generalized wear was determined using a noncontact profilometer (Proscan 2100) in conjunction with Proscan and AnSur 3D software.

Results:

Wear was significantly different (p&lt;0.05) among the resin composites for both simulated localized and generalized wear of either the 24-hour group or the TC group. The simulated localized wear of the TC group was significantly greater than that of the 24-hour group; however, the simulated generalized wear of most of the resin composites of the TC group was not significantly different from that of the 24-hour group.

Conclusion:

The simulated localized and generalized wear of nanofilled resin composites is material dependent. The simulated localized wear of nanofilled resin composites appears to be influenced by thermal stress, whereas this effect is not as apparent in simulated generalized wear testing.

Polishing effects and wear performance of chairside CAD/CAM materials

OBJECTIVES

To investigate the surface roughness of CAD/CAM materials immediately after milling and after different chairside and labside polishing procedures. A two-body wear test was performed to compare the different wear characteristics of the materials and the corresponding antagonists.

MATERIALS AND METHODS

Specimens (n = 12 per series) from different CAD/CAM materials (three composites: Lava Ultimate, Cerasmart, BRILLIANT Crios; one hybrid ceramic: VITA Enamic; three ceramics: Celtra Duo, VITA Suprinity, IPS Emax.CAD) were polished according to the manufacturer's instructions. The effect of different polishing procedures was investigated by comparing surface roughness (R_a, R_max) after labside polishing and after chairside polishing. Wear behavior (mean, volume, and maximum wear) of specimens and antagonists as well as changes in surface roughness were determined in a pin-on-block wear test. Statistical analysis was performed with a one-way analysis of variance (ANOVA)/Bonferroni multiple-comparison post hoc test and a multifactorial ANOVA/Tukey's significant difference post hoc test (α = 0.05). SEM micrographs were used for the qualitative evaluation of surfaces and wear traces.

RESULTS

After chairside high-gloss polishing, ceramics and composites exhibited R_a values between 0.08 and 0.10 μm and between 0.11 and 0.13 μm, respectively. After labside high-gloss polishing, values varied between 0.02 and 0.09 μm for ceramics and between 0.06 and 0.16 μm for resin composites. No significant differences were found between labside and chairside pre- and high-gloss polishing. For the ceramics, lower mean wear depths (between - 132.2 ± 19.9 and - 137.0 ± 19.0 μm) were identified compared to the resin composites (which exhibited wear depths between - 159.1 ± 19.4 and - 176.3 ± 23.9 μm). For maximum wear depth and volume, a different ranking of the materials was found. Antagonistic wear varied between 12.0 ± 6.4% and 30.6 ± 9.9% and was higher for the ceramic materials and Lava Ultimate. For all materials, a smoothing between 0.20 and 2.70 μm (R_a) was identified after wear simulation.

CONCLUSIONS

Chairside polishing is as effective as labside polishing, although surfaces were directly adjusted (roughened) only before the chairside polishing. Wear was lowest for ceramics, followed by the resin-infiltrated material and the resin composites.

CLINICAL RELEVANCE

Polishing after milling or adjustment is essential to guaranteeing optimal clinical performance. Chairside polishing after adjustment leads to comparably smooth surfaces as labside polishing after milling and grinding. Ceramics are expected to exhibit lower wear than resin composites under clinical conditions.

Wear of resin composites: Current insights into underlying mechanisms, evaluation methods and influential factors

The application of resin composites in dentistry has become increasingly widespread due to the increased aesthetic demands of patients, improvements in the formulation of resin composites, and the ability of these materials to bond to tooth structures, together with concerns about dental amalgam fillings. As resistance to wear is an important factor in determining the clinical success of resin composite restoratives, this review article defines what constitutes wear and describes the major underlying phenomena involved in this process. Insights are further included on both in vivo and in vitro tests used to determine the wear resistance of resin composite and the relationships between these tests. The discussion focuses on factors that contribute to the wear of resin composite. Finally, future perspectives are included on both clinical and laboratory tests and on the development of resin composite restorations.

Macro- and microtopographical examination and quantification of CAD-CAM composite resin 2- and 3-body wear

STATEMENT OF PROBLEM

The selection of an appropriate restorative material based on wear behavior is important for the long-term success of a dental restoration. For computer-aided design and computer-aided manufacturing (CAD-CAM) composite resins, information about their wear resistance and wear mechanism is scarce.

PURPOSE

The purpose of this in vitro study was to compare the 2- and 3-body wear of CAD-CAM composite resins with that of lithium disilicate ceramic and to develop analysis software.

MATERIAL AND METHODS

Flat specimens were prepared from the following CAD-CAM composite resins: Cerasmart (CS), SHOFU Block HC (SH), Katana Avencia (KA), Brilliant Crios (BC), an experimental composite resin (EXP), and lithium disilicate ceramic IPS e.max CAD (REF). The specimens underwent 2-body wear (50 N, 5/55°C, 400 000 cycles) opposed by human enamel antagonists. Specimen wheels were prepared with each material on each wheel for 3-body wear with a millet slurry (15 N, 15% slip, 200 000 cycles). All specimens were digitized by using a dedicated laser scanner. Analysis software was developed to calculate macrotopographical examination of volume loss. The microtopography of the surfaces was examined by using scanning electron microscopy. For data analysis, the Kruskal-Wallis test with the Tukey-Kramer post hoc test and the 1-sample Wilcoxon test were used (α=.05).

RESULTS

After 2-body wear simulation, SH and KA presented higher volume loss than the other CAD-CAM materials. For 3-body wear, REF had lower volume loss than CS, SH, or BC. In addition, BC led to higher volume loss than EXP. The patterns of 2- and 3-body wear were different.

CONCLUSIONS

The ceramic showed good global wear resistance. The volume loss of the CAD-CAM composite resins differed and depended on the material. The 2- and 3-body wear test methods tended to differ with regard to volume loss. Examination of the worn surfaces revealed different mechanisms acting in 2- and 3-body wear test.

Simulated localized wear of resin luting cements for universal adhesive systems with different curing mode

This study evaluated the simulated localized wear of resin luting cements for universal adhesive systems using different curing modes. Five resin luting cements for universal adhesive systems were evaluated and subsequently subjected to wear challenge in a Leinfelder-Suzuki wear simulation device. Overall, 20 specimens from each resin luting cement were photo-cured for 40 s (dual-cure group), and 20 specimens of each material were not photo-cured (chemical-cure group). Simulated localized wear was generated using a stainless steel ball-bearing antagonist in water slurry of polymethylmethacrylate beads. In addition, scanning electron microscopy (SEM) observations of resin luting cements and wear facets were conducted. Significant differences in simulated wear and SEM observations of wear facets were evident among the materials in the dual- and chemical-cure groups. The simulated wear and SEM observations of wear facets of G-CEM LinkForce and Panavia V5 were not influenced by the curing mode. SEM observations of resin luting cements were material dependent. In most cases, dual curing appears to ensure greater wear resistance of resin luting cements than chemical curing alone. The wear resistance of some resin luting cements appears to be material dependent and is not influenced by the curing mode.

Comparative abrasive wear resistance and surface analysis of dental resin-based materials

OBJECTIVE

The objective of this study was to assess the surface properties (microhardness and wear resistance) of various composites and compomer materials. In addition, the methodologies used for assessing wear resistance were compared.

MATERIALS AND METHODS

This study was conducted using restorative material (Filtek Z250, Filtek Z350, QuiXfil, SureFil SDR, and Dyract XP) to assess wear resistance. A custom-made toothbrush simulator was employed for wear testing. Before and after wear resistance, structural, surface, and physical properties were assessed using various techniques.

RESULTS

Structural changes and mass loss were observed after treatment, whereas no significant difference in terms of microhardness was observed. The correlation between atomic force microscopy (AFM) and profilometer and between wear resistance and filler volume was highly significant. The correlation between wear resistance and microhardness were insignificant.

CONCLUSIONS

The AFM presented higher precision compared to optical profilometers at a nanoscale level, but both methods can be used in tandem for a more detailed and precise roughness analysis.

Avaliação ex vivoda obliteração de túbulos dentinários humanos pelo uso comparativo de agentes dessensibilizantes convencionais e dessensibilizantes contendo biovidro

O objetivo do presente estudo foi avaliar a eficácia ex vivo de um dentifrício dessensibilizante contendo biovidro (Sensodyne®Repair&Protect, GlaxoSmithKline Brasil Ltd., Rio de Janeiro, Brasil), quanto ao potencial de obliteração dos túbulos dentinários e compará-lo com os dentifrícios convencionais (Colgate® Sensitive Pro-Alívio™, Colgate-Palmolive, São Paulo, SP, Brasil eSensodyne® Rápido Alívio, GlaxoSmithKline Brasil Ltd., Rio de Janeiro, Brasil). Foram utilizados 12 pré-molares humanos divididos em: G1 (n=4) - escovação com Colgate®Sensitive Pró-Alívio; G2 (n=4) - escovação com Sensodyne® Rápido Alívio; e G3 (n=4) - escovação com Sensodyne®Repair&Protect. As amostras foram submetidas à simulação de escovação de um período de oito semanas, com duas escovações diárias e analisadas em microscopia eletrônica de varredura (MEV), quanto à presença e características dos túbulos dentinários; a espectroscopia de raios-X por dispersão em energia (EDS), a fim de avaliar os elementos químicos presentes nos túbulos dentinários. A análise qualitativa da obliteração dos túbulos dentinários foi avaliada por meio das fotomicrografias. Para verificar a distribuição normal dos dados da EDS, utilizou-se o teste de Shapiro-Wilk (p<0,05). De acordo com a normalidade apresentada, foram executados teste t-Studentde amostras pareadas e teste de Wilcoxon. No grupo G1 foi verificada diminuição na luz dos túbulos dentinários, enquanto no G2, além da diminuição dos túbulos, nítida deposição de partículas obliteradoras foi observada. No G3, foi detectada não só a obliteração dos túbulos, mas também a diminuição na quantidade dos mesmos; além da formação de uma camada de hidroxidocarbonato de apatita (HCA)sobre a dentina. A análise conjunta dos dados permitiu concluir que os dentifrícios testados foram capazes de ocluir os túbulos dentinários e que o dentifrício Sensodyne®Repair&Protect apresentou melhor eficácia na obliteração dos túbulos dentinários, seguido respectivamente dos dentifrícios Sensodyne® Rápido Alívioe Colgate®Sensitive Pró-Alívio.

Evaluation of ex vivo effectiveness of commercial desensitizing dentifrices

BACKGROUND

Dentin hypersensitivity is a short, severe pain with fast onset. Therapy aims to either prevent or decrease neural transmission or physically occlude the dentinal tubules. This study aimed to evaluate the effectiveness of commercial desensitizing dentifrice by means of an ex vivo method.

MATERIAL AND METHODS

Samples (n=8 lower human premolars for each group) were randomly allocated into: G1- brushing with Colgate®Sensitive Pro-Relief; G2- brushing with Sensodyne®Rapid Relief; G3- brushing with Sensodyne®Repair & Protect; and G4- brushing with Colgate®Maximum Cavity Protection. The test bodies were submitted to simulated toothbrushing and dentifrices were analyzed regarding their hydrodynamic size, polydispersity index (PI) and zeta potential. Specimens were evaluated using: scanning electron microscopy (SEM); spectroscopy energy dispersive X-ray (EDS); and profilometry. A qualitative analysis of the photomicrographs and topographies was performed.

RESULTS

The dentifrices showed statistical similar physical and chemical characteristics. They also demonstrated obliteration of dentinal tubules when micrographs were observed. Regarding the chemical elements present in the dentin samples, there was a statistically significant difference between the control and experimental surfaces in the four groups.

CONCLUSIONS

Joint data analysis shows that the desensitizing dentifrice showed better results with regards to the obliteration of dentinal tubules compared to positive and negative controls. Key words:Dentin hypersensitivity, dentin desensitizing agents, toothpastes.

Surface roughness of composite resins subjected to hydrochloric acid

The purpose of this study was to determine the influence of hydrochloric acid on surface roughness of composite resins subjected to brushing. Sixty samples measuring 2 mm thick x 6 mm diameter were prepared and used as experimental units. The study presented a 3x2 factorial design, in which the factors were composite resin (n=20), at 3 levels: microhybrid composite (Z100), nanofilled composite (FiltekTM Supreme), nanohybrid composite (Ice), and acid challenge (n=10) at 2 levels: absence and presence. Acid challenge was performed by immersion of specimens in hydrochloric acid (pH 1.2) for 1 min, 4 times per day for 7 days. The specimens not subjected to acid challenge were stored in 15 mL of artificial saliva at 37 oC. Afterwards, all specimens were submitted to abrasive challenge by a brushing cycle performed with a 200 g weight at a speed of 356 rpm, totaling 17.8 cycles. Surface roughness measurements (Ra) were performed and analyzed by ANOVA and Tukey test (p≤0.05). Surface roughness values were higher in the presence (1.07±0.24) as compared with the absence of hydrochloric acid (0.72±0.04). Surface roughness values were higher for microhybrid (1.01±0.27) compared with nanofilled (0.68 ±0.09) and nanohybrid (0.48±0.15) composites when the specimens were not subjects to acid challenge. In the presence of hydrochloric acid, microhybrid (1.26±0.28) and nanofilled (1.18±0,30) composites presents higher surface roughness values compared with nanohybrid (0.77±0.15). The hydrochloric acid affected the surface roughness of composite resin subjected to brushing.

Influence of Thermal Cycling on Flexural Properties and Simulated Wear of Computer-aided Design/Computer-aided Manufacturing Resin Composites

OBJECTIVE

The purpose of this study was to evaluate the influence of thermal cycling on the flexural properties and simulated wear of computer-aided design/computer-aided manufacturing (CAD/CAM) resin composites.

METHODS

The six CAD/CAM resin composites used in this study were 1) Lava Ultimate CAD/CAM Restorative (LU); 2) Paradigm MZ100 (PM); 3) CERASMART (CS); 4) Shofu Block HC (SB); 5) KATANA AVENCIA Block (KA); and 6) VITA ENAMIC (VE). Specimens were divided randomly into two groups, one of which was stored in distilled water for 24 hours, and the other of which was subjected to 10,000 thermal cycles. For each material, 15 specimens from each group were used to determine the flexural strength and modulus according to ISO 6872, and 20 specimens from each group were used to examine wear using a localized wear simulation model. The test materials were subjected to a wear challenge of 400,000 cycles in a Leinfelder-Suzuki device (Alabama machine). The materials were placed in custom-cylinder stainless steel fixtures, and simulated localized wear was generated using a stainless steel ball bearing (r=2.387 mm) antagonist in a water slurry of polymethyl methacrylate beads. Simulated wear was determined using a noncontact profilometer (Proscan 2100) with Proscan and AnSur 3D software.

RESULTS

The two-way analysis of variance of flexural properties and simulated wear of CAD/CAM resin composites revealed that material type and thermal cycling had a significant influence (p<0.05), but there was no significant interaction (p>0.05) between the two factors. The flexural properties and maximum depth of wear facets of CAD/CAM resin composite were different (p<0.05) depending on the material, and their values were influenced (p>0.05) by thermal cycling, except in the case of VE. The volume losses in wear facets on LU, PM, and SB after 10,000 thermal cycles were significantly higher (p<0.05) than those after 24 hours of water storage, unlike CS, KA, and VE.

CONCLUSION

The results of this study indicate that the flexural properties and simulated wear of CAD/CAM resin composites are different depending on the material. In addition, the flexural properties and simulated wear of CAD/CAM resin composites are influenced by thermal cycling.

Effect of whitening dentifrices on the surface roughness of a nanohybrid composite resin

Objectives:

The present study verified the influence of whitening dentifrices on the surface roughness of a nanohybrid composite resin.

Materials and Methods:

Thirty-two specimens were prepared with Filtek™ Z350 XT (3M/ESPE) and randomly divided into four groups (n = 08) that were subjected to brushing simulation equivalent to the period of 1 month. The groups assessed were a control group with distilled water (G1), Colgate Total 12 Professional Clean (G2), Sensodyne Extra Whitener Extra Fresh (G3), and Colgate Luminous White (G4). A sequence of 90 cycles was performed for all the samples. The initial roughness of each group was analyzed by the Surface Roughness Tester (TR 200-TIME Group Inc., CA, USA). After the brushing period, the final roughness was measured, and the results were statistically analyzed using nonparametric Kruskal–Wallis and Dunn tests for intergroup roughness comparison in the time factor. For intragroup and “Δ Final − Initial” comparisons, the Wilcoxon test and (one-way) ANOVA were, respectively, performed (α = 0.05).

Results:

The roughness mean values before and after brushing showed no statistically significant difference when the different dentifrices were used. None of the dentifrices analyzed increased significantly the nanohybrid composite resin surface roughness in a 1 month of tooth brushing simulation.

Conclusions:

These results suggest that no hazardous effect on the roughness of nanohybrid composite resin can be expected when whitening dentifrices are used for a short period. Similar studies should be conducted to analyze other esthetic composite materials.

Evaluation of the surface roughness of a nanofilled composite resin submitted to different smoothing and finishing techniques

Abstract Introduction: Controlling the surface smoothness characteristics of the composite resin when performing a direct restorative technique is one of the factors involved in achieving restorative success. Objective: The purpose of this study was to evaluate the surface roughness of a nanofilled composite resin submitted to different smoothing and finishing techniques. Material and method: Fifty test specimens were made with the Z350 XT composite resin (3M ESPE) and then divided into five study groups according to the smoothing and finishing method applied, as follows: G1 (control), polyester strip; G2, composite spatula; G3, brush cleaned with absolute alcohol and dried; G4, brush cleaned with absolute alcohol, dried and moistened with Single Bond (3M ESPE); and G5, brush cleaned with absolute alcohol, dried and moistened with Natural Glaze surface sealant (DFL). After fabrication, the specimens were stored for 24 h in deionized water. The surface roughness of the specimens was measured using a profilometer. Surface roughness means were compared by analysis of variance followed by Tukey’s test at a level of significance of 5%. Result: The lowest surface roughness was observed in G1 (control group) and the highest, in G3. G5 had lower surface roughness values compared to the other test groups, and presented values similar to those of the control group. Conclusion: The smoothing and finishing techniques influenced the surface roughness of the composite resin. Application of the surface sealant by the copolymerization technique resulted in lower roughness values. The use of a clean, dry brush promoted roughness values beyond the acceptable limit, and is therefore liable to compromise the performance of composite resin restorations.

Comparative Study of the Effect of Acid Etching on Enamel Surface Roughness between Pumiced and Non-pumiced Teeth

BACKGROUND

The objective was to perform a comparative analysis of the effect of acid etching on enamel roughness between pumiced and non-pumiced teeth.

MATERIALS AND METHODS

The sample was composed of 32 dental surfaces divided into two groups: Group 1-16 surfaces having received pumice prophylaxis; and Group 2-16 surfaces not having received pumice prophylaxis. The teeth were kept in saline until the first record of surface roughness prior to etching. For each surface, a roughness graph was obtained through trials using a surface roughness tester. This procedure was repeated two more times at different locations for a total of three readings which, later, were converted in a mean value. The teeth were then acid etched with a 37% phosphoric acid for 60 s, rinsed with water, air dried, and tested with the roughness tester again using the same protocol described for baseline. The Quantikov image analysis program was used to measure the length of the graphs. The average value of the lengths was recorded for each surface before and after etching. The increase in roughness caused by acid etching was calculated and compared between groups.

RESULTS

The mean increase in roughness caused by the etching was 301 µm (11.37%) in Group 1 and 214 µm (8.33%) in Group 2. No statistically significant difference was found between samples with and without pumice prophylaxis (P = 0.283).

CONCLUSION

The present study showed that the effect of acid etching on enamel roughness was not significantly affected by prior pumice prophylaxis.

The effect of three polishing systems on surface roughness of flowable, microhybrid, and packable resin composites

Objectives:

The aim of this study was to evaluate the effects of three different polishing systems on the surface roughness of three types of resin composite materials.

Materials and Methods:

Three types of resin composites (Heliomolar flow, TPH spectrum, and Tetric Ceram HB) and three polishing systems (Astropol, Enhance, and Soflex) were used. A total number of 40 samples were prepared from each one of the restorative materials and divided randomly into four groups (n = 10) according to the polishing procedure. The first group underwent no treatment and was used as a control group. Each one of the remaining groups was polished with one of the tested polishing systems. After completion of sample preparation, the mean surface roughness (Ra) value was measured using a surface profilometer. Data were analyzed using one-way analysis of variance (ANOVA).

Results:

The control group of each material recorded the lowest Ra value. Among the tested polishing systems, the groups finished with Soflex system exhibited the lowest Ra value. Among the resin composites, Heliomolar flow exhibited the lowest Ra value, regardless of the polishing system used.

Conclusions:

The smoothest surface of all types of resin composite was achieved under Mylar strip.

Localized and Generalized Simulated Wear of Resin Composites

A laboratory study was conducted to examine the wear of resin composite materials using both a localized and generalized wear simulation model. Twenty specimens each of seven resin composites (Esthet•X HD [HD], Filtek Supreme Ultra [SU], Herculite Ultra [HU], SonicFill [SF], Tetric EvoCeram Bulk Fill [TB], Venus Diamond [VD], and Z100 Restorative [Z]) were subjected to a wear challenge of 400,000 cycles for both localized and generalized wear in a Leinfelder-Suzuki wear simulator (Alabama machine). The materials were placed in custom cylinder-shaped stainless steel fixtures. A stainless steel ball bearing (r=2.387 mm) was used as the antagonist for localized wear, and a stainless steel, cylindrical antagonist with a flat tip was used for generalized wear. A water slurry of polymethylmethacrylate (PMMA) beads was used as the abrasive media. A noncontact profilometer (Proscan 2100) with Proscan software was used to digitize the surface contours of the pretest and posttest specimens. AnSur 3D software was used for wear assessment. For localized testing, maximum facet depth (μm) and volume loss (mm3) were used to compare the materials. The mean depth of the facet surface (μm) and volume loss (mm3) were used for comparison of the generalized wear specimens. A one-way analysis of variance (ANOVA) and Tukey post hoc test were used for data analysis of volume loss for both localized and generalized wear, maximum facet depth for localized wear, and mean depth of the facet for generalized wear. The results for localized wear simulation were as follows [mean (standard deviation)]: maximum facet depth (μm)—Z, 59.5 (14.7); HU, 99.3 (16.3); SU, 102.8 (13.8); HD, 110.2 (13.3); VD, 114.0 (10.3); TB, 125.5 (12.1); SF, 195.9 (16.9); volume loss (mm3)— Z, 0.013 (0.002); SU, 0.026 (0.006); HU, 0.043 (0.008); VD, 0.057 (0.009); HD, 0.058 (0.014); TB, 0.061 (0.010); SF, 0.135 (0.024). Generalized wear simulation results were as follows: mean depth of facet (μm)—Z, 9.3 (3.4); SU, 12.8 (3.1); HU, 15.6 (3.2); TB, 19.2 (4.8); HD, 26.8 (6.5); VD, 29.1 (5.5); SF, 35.6 (8.4); volume loss (mm3)—Z, 0.132 (0.049); SU, 0.0179 (0.042); HU, 0.224 (0.044); TB, 0.274 (0.065); HD, 0.386 (0.101); VD, 0.417 (0.076); SF, 0.505 (0.105). The ANOVA showed a significant difference among materials (p&lt;0.001) for facet depth and volume loss for both localized and generalized wear. The post hoc test revealed differences (p&lt;0.05) in localized and generalized wear values among the seven resin composites examined in this study. The findings provide valuable information regarding the relative wear characteristics of the materials in this study.

Effect of Toothbrushing-mouthrinse-cycling on Surface Roughness and Topography of Nanofilled, Microfilled, and Microhybrid Resin Composites

The purpose of this study was to evaluate the influence of toothbrushing-mouthrinse-cycling (TMC) on the surface roughness and topography of three resin composites with different filler particle systems (Z350, nanofilled [Nf]; Durafill, microfilled [Mf], and Empress Direct, microhybrid [Mh]). Twenty specimens of each resin composite (8.0 mm diameter and 2 mm height) were randomly divided into four groups (n=5) according to the mouthrinses: alcohol-free (Plax – P) and alcohol-containing (Listerine – L and Plax Fresh Mint – PM) and artificial saliva (control – AS). The specimens were submitted to TMC for nine weeks. A surface roughness tester and a three-dimensional profilometer were used to measure the roughness (Ra) and the topography (Sa) before and after TMC. The data were analyzed by multifactor analysis of variance and Tukey post hoc test (α=0.05). In all media, Mh presented greater roughness than Mf (p&lt;0.05). The highest value of roughness was presented by Mh immersed in L (p&lt;0.05). The lowest values of roughness were presented by Mf (p&lt;0.05). The three resin composites presented the highest roughness after immersion in mouthrinses containing alcohol (PM and L) (p&lt;0.05). For the three resin composites, the increase in roughness was noticeable after the fifth week. Topographic analysis showed that the smoothest surfaces were present after immersion in AS.