Wear Resistance of Packable Resin Composites after Simulated Toothbrushing Test

Effect of brushing simulation on the wear behavior of repaired CAD-CAM restorations

OBJECTIVE

The aim of the present study was to evaluate the influence of multidirectional brushing on the surface roughness, morphology, and bonding interface of resin-repaired CAD-CAM ceramic and composite restorations.

MATERIALS AND METHODS

Twelve (N = 12) blocks (4 mm × 4 mm × 2 mm for parallel axis; 5 mm × 4 mm × 2 mm for perpendicular axis) of lithium disilicate glass-ceramic (IPS e.max CAD, Ivoclar AG) and CAD-CAM resin composite (Tetric CAD, Ivoclar AG) were obtained and repaired with direct resin composite (Clearfil AP-X, Kuraray). An abrasive slurry was prepared and the brushing was performed according to each restorative material and axis of brushing (n = 6; perpendicular to repair interface and parallel to repair interface) during 3,650 cycles (240 strokes per minute) to simulate 3 years of brushing. The surface roughness (Ra) and the profile variation for each material (restoration and direct repair resin composite) were measured at the baseline condition and after brushing, and the mean roughness and presence of steps at the repair interface were evaluated through factorial analysis of Variance (ANOVA). Scanning Electron Microscopy (SEM) images were taken to evaluate the surface topography of the repaired materials after brushing.

RESULTS

The mean roughness of the repaired CAD-CAM restorations was affected by the brushing (P < .05), mainly when evaluating the repair material and the interface (P < .05), while the restorative CAD-CAM materials presented more stable values. The profile evaluation showed higher steps at the interface when repairing lithium disilicate than for CAD-CAM resin composite.

CONCLUSION

Repaired CAD-CAM restorations were susceptible to wear after brushing simulation. The surface roughness of the direct resin composite was the most affected leading to step development at the interface, particularly in the repaired lithium disilicate samples. Cinical maintenance recalls and polishing protocols must be considered to enhance the longevity of such restorations.

Mechanical Performance of Extensive Restorations Made with Short Fiber-Reinforced Composites without Coverage: A Systematic Review of In Vitro Studies

In recent years, composite resin materials have been the most frequently used materials for direct restorations of posterior teeth. These materials have some clinically relevant limitations due to their lack of fracture toughness, especially when used in larger cavities with high volume factors or when utilized as direct or indirect overlays or crown restorations. Recently, short-fiber-reinforced composite materials have been used in bi-structure restorations as a dentine substituting material due to their superior mechanical properties; however, there is no scientific consensus as to whether they can be used as full restorations. The aim of our review was to examine the available literature and gather scientific evidence on this matter. Two independent authors performed a thorough literature search using PubMed and ScienceDirect up until December 2023. This study followed the PRISMA guidelines, and the risk of bias was assessed using the QUIN tool. The authors selected in vitro studies that used short-fiber-reinforced composite materials as complete restorations, with a conventional composite material as a comparison group. Out of 2079 potentially relevant articles, 16 met our inclusion criteria. All of the included studies reported that the usage of short-fiber-reinforced composites improved the restoration's load-bearing capacity. Fifteen of the included publications examined the fracture pattern, and thirteen of them reported a more favorable fracture outcome for the short-fiber-reinforced group. Only one article reported a more favorable fracture pattern for the control group; however, the difference between groups was not significant. Within the limitations of this review, the evidence suggests that short-fiber-reinforced composites can be used effectively as complete restorations to reinforce structurally compromised teeth.

Influence of abrasive dentifrices on polymeric reconstructive material properties after simulated toothbrushing

To assess the influence of dentifrices with different abrasiveness levels on the properties of dental reconstructive materials. Forty-eight cylinders were obtained from four polymeric materials, being two CAD/CAM acrylic resins (Ivotion-Dent and Ivotion-Base), one injected acrylic resin (IvoBase-Hydrid) and one light-cured resin composite (Empress Direct). Specimens were allocated to four subgroups for toothbrushing simulation according to the dentifrice relative dentin abrasivity (RDA) and silica content: (i) RDA 0 = 0%; (ii) RDA 50 = 3%; (iii) RDA 100 = 10%; and (iv) RDA 120 = 25%. Specimens were then subjected to toothbrushing. Surface analyses [surface roughness Ra (SR) and scanning electron microscopy (SEM)] along with hardness and optical properties [translucency parameter (TP) and contrast ratio (CR)] were evaluated before and after toothbrushing. Statistical analyses were performed using ANOVA and Tukey test. A significant increase in SR was observed after toothbrushing with higher RDA toothpastes for Ivotion-Dent (100 and 120) and IvoBase-Hybrid (120). Ivotion-Base and Empress Direct presented no significant differences in SR when analyzed as a function of timepoint and RDA levels. Hardness was not influenced by toothbrushing with different RDA dentifrices, except for Empress Direct with RDA 0 toothpaste, where a decrease in the hardness was observed. TP of Ivotion-Dent and Empress Direct significantly decreased after toothbrushing with higher RDA dentifrices and CR of Ivotion-Dent, Empress Direct and IvoBase-Hybrid significantly increased with higher RDA dentifrices. The levels of dentifrice abrasiveness affected differently the SR, hardness and optical properties of polymeric reconstructive materials after toothbrushing.

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.

Evaluation of Surface Roughness of Different Esthetic Restorative Materials after Immersion in Different Acidic Media

Abstract: Background: Dental erosion that resulted from increasing the acidity of oral conditions not only affects tooth substrates but also the performance of some esthetic restorations. Objective: The aim of the current study was to measure and evaluate the surface roughness of different tooth colored restorative materials (resin composites) after immersion for certain time in different acidic food and drinks. Material and method: Three types of composite restoration have been used in this study. The three types were of three main groups. Each group of twenty specimens (n= 20) were divided according to type of acidic media they were immersed in into five sub-groups (n=4). Different acidic beverages and drinks were used in this study include Coke Cola soft drink, orange juice, Pepsi soft drink, sports drink, and lemon juice. Immersion of specimens’ in previously mentioned acidic drinks were for 5 minutes then they have been immersed in distilled water to simulate to great extent what happened in oral cavity. These procedures repeated daily for 14 days. Surface roughness for specimens have been measured by a profilo-meter (Talysurf CLI 1000, Leicester, England) device before and after immersion. Data were collected, tabulated and analyzed using one-way ANOVA. Results: The assessment of surface roughness by one-way ANOVA and Tukey's post hoc tests showed significant differences for composite material types as well as an interaction between these parameters for each composite after immersion in different acidic beverages (P<.05). Conclusion: Within the limitation of this study, results revealed that composition of both resin composite and different acidic beverages and drinks play an important role in initiation and conduction of surface roughness at the outer surface of resin composite restoration.

Evaluation of the Surface Roughness of Resin Composites before and after Applying Different Bleaching Materials

Abstract: Background: Bleaching is a conservative treatment and has been shown to be both efficient and safe but the effects of bleaching on teeth and dental materials have been studied in several studies. Objective: The aim of the current study was to evaluate the surface roughness of resin composites before and after applying different bleaching materials. Material and method: Three types of resin composites were used in this in vitro study. Two types of bleaching techniques were used: in office and at home bleach. Sixteen specimens of each resin composite type were fabricated and used in this study. Surface roughness of the samples was measured using a profilometer (Talysurf CLI 1000, Leicester, England). The surface roughness measurements and data were statistically analyzed using the one-way ANOVA and Tukey's tests through SPSS version 21 (SPSS Inc. Chicago, IL, USA). The assessment of surface roughness was done using one-way ANOVA and Tukey's post hoc tests. P < 0.05 was considered statistically significant. Results: The assessment of surface roughness by one-way ANOVA and Tukey's post hoc tests showed significant differences for composite material types as well as an interaction between these parameters for each tested bleaching gels (P<.05). Conclusion: The composition of both resin composite and bleaching material play an important role in initiation and conduction of surface roughness at the outer surface of resin composite restoration.

Evaluation of the marginal adaptation of class II restorations carried out in a Faculty in the State of Espírito Santo

Abstract Introduction composite resins are materials widely used for Class II restorations, to restore the anatomization of the dental element. However, there are several factors that can interfere with the quality of a good restoration. Objective the objective of the present study is to carry out a retrospective evaluation of the clinical performance of Class II restorations performed by undergraduate students of Dentistry at the Escola São Francisco de Assis (ESFA), and to identify the main errors. Material and method we selected the medical records of patients treated in the disciplines of Dentistry II, Integrated I and II in the Dentistry clinic at ESFA, which presented detailed information on the Class II procedure, as well as initial radiographic examinations, using the FDI method. The sample consisted of 33 medical records that included 72 teeth. Result it was observed that more than 80% of the restorations were classified as acceptable. And, only 19.44% of the restorations were unacceptable, failing due to functional and biological properties. Conclusion it was found that undergraduate students in Dentistry at ESFA, who are guided by professors to perform treatments following pre-established clinical protocols, are capable of carrying out quality restorative procedures.

Evaluation of Wear Properties of Four Bulk-Fill Composites: Attrition, Erosion, and Abrasion

Purpose

Wear and increased surface roughness are among the reasons for failure of posterior composite restorations. Considering the widespread use of bulk-fill composites in the posterior region, information about their wear resistance is imperative. The aim of this study was to compare the wear and surface roughness of four bulk-fill composite resins with a conventional composite.

Methods

Thirty composite discs (4 mm × 10 mm) were fabricated from EverX Posterior (GC), X-tra fil (Voco), Filtek Bulk-Fill Posterior (3M, USA), SonicFill 2 (Kerr), and Z250 (3M) composites. The baseline weight and surface roughness of specimens were measured. For the assessment of the attrition wear, the specimens were placed in a chewing simulator (Mechatronik). pH cycling was performed to erode the composite discs. They were then placed in a tooth brushing simulator machine (Dorsa) for abrasion wear. Finally, the weight and surface roughness of the specimens were measured. Data were compared using one-way ANOVA (alpha ≤ 0.05).

Results

One-way ANOVA showed that the mean weight changes were significant after attrition, abrasion, and erosion (P = 0.019), but changes in surface roughness were not significant (P ≥ 0.05). The results of Tukey's test showed no significant difference between the bulk-fill composites and Z250 regarding weight loss (P ≥ 0.05), but the weight loss of X-tra fil was significantly greater than that of EverX (P = 0.007) and Filtek Bulk-Fill (P = 0.005).

Conclusions

Considering the limitations of this study, it appears that the wear and surface roughness of bulk-fill composites are within the acceptable range and are not different from those of a conventional composite.

Silane content influences physicochemical properties in nanostructured model composites

OBJECTIVE

To determine the effect of organosilane content on the physicochemical properties of model composites formulated with nano-sized fillers.

METHODS

Model composites were formulated with dimethacrylate-based monomers, a photoinitiator/co-initiator system and silicon dioxide nano-sized fillers treated with different amounts of 3-methacryloxypropyltrimethoxysilane (MPTS): 1.0 (G_1%), 2.0 (G_2%), 5.0 (G_5%), 7.5 (G_7.5%) and 10 (G_10%) wt.% relative to SiO₂. Non-silanized fillers (G_0%) were used in the control group. Degree of conversion (DC) was assessed by Fourier-transformed infrared spectroscopy (ATR-FTIR). Knoop hardness (KHN) and elastic modulus were determined before and after water storage for 4 months. Water sorption (Wsp) and solubility (Wsl) were calculated by successive mass determinations in analytical balance. Surface gloss and roughness were characterized before and after toothbrushing simulation.

RESULTS

With the exception of those fillers treated with 1% MPTS, DC was not dependent on the silane content. Within the silanized groups, G_1% showed the lowest initial and final KHN, without statistical difference from G_0%. The elastic modulus was not affected by the silane content, regardless of the storage condition, but those groups formulated with at least 5% silane presented improved values after storage. Silane content did not affect the WSl, but affected Wsp, in which those groups formulated with at least 2 wt.% of MPTS produced a more resistant material than G_0%. The use of treated particles with at least 2 wt.% of silane was able to produce materials that did not change their gloss after the brushing process. Additionally, these materials presented lower surface roughness than G_0% after the brushing process (p < 0.05).

SIGNIFICANCE

The concentration of MPTS affected the physicochemical properties of nano-filled composites. Therefore, 2 wt.% of silane was the optimized quantity to produce materials resistant to degradation, both in bulk and surface properties.

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.

Properties of manual toothbrush that influence on plaque removal of interproximal surface in vitro

Background/purpose

Few papers were available on the interproximal cleaning efficiency by manual toothbrushes when used alone. The aim was to investigate the efficiency of commercially available toothbrushes on interproximal cleaning and determine the key properties that would make the differences.

Materials and methods

Artificial-teeth were coated with manicure type experimental dental plaque covering mainly the interproximal surface and fixed in the jaw model of a dental simulator. A modified scrubbing technique was employed to brush out the plaque conducted by one trained dentist using 26 different toothbrushes from the equal number of separate interproximal conditions. The rate of the plaque removal (%) was calculated by measuring the plaque free areas on the post-brush images.

Results

The data analysis using mixed effect modelling showed that stiffness, number of tufts and total length have effect on the rate of the plaque removable from the interproximal surfaces.

Conclusion

This study indicated consideration should be given to toothbrush properties to enhance plaque removal from the interproximal surfaces.

In Vitro Evaluation of Surface Properties and Wear Resistance of Conventional and Bulk-fill Resin-based Composites After Brushing With a Dentifrice

Objectives:

This study evaluated the effect of toothbrushing with a dentifrice on gloss, roughness profile, surface roughness, and wear of conventional and bulk-fill resin-based composites.

Methods and Materials:

Gloss and surface roughness of resin-based composites (RBCs; Admira Fusion X-tra, Aura Bulk Fill, Filtek Bulk Fill Flowable, Filtek Bulk Fill Posterior Restorative, Filtek Supreme Ultra, Herculite Ultra, Mosaic Enamel, SDR flow+, Sonic Fill 2, Tetric EvoFlow Bulk Fill and Tetric EvoCeram Bulk Fill) were analyzed before and after brushing; the roughness profile and wear were also determined after toothbrushing. Representative three-dimensional images of the surface loss and images comparing the unbrushed and brushed surfaces were also compared. Analysis of variance and Tukey post hoc tests were applied (α=0.05) to the gloss, surface roughness, roughness profile, and surface loss data. Pearson's correlation test was used to determine the correlation between gloss and surface roughness, surface loss and percentage of gloss decrease after brushing, and surface loss and surface roughness after brushing.

Results:

For all RBCs tested after 20,000 brushing cycles, the gloss was reduced and the surface roughness increased (p&lt;0.05). However, the roughness profile and the amount of surface loss were dependent on the RBC brand. Admira Fusion X-tra, Aura, Tetric EvoCeram Bulk Fill, and Tetric EvoFlow Bulk Fill showed the deepest areas of wear (p&lt;0.05). A significant negative correlation was found between gloss and surface roughness, and a weak correlation was found between the decrease in gloss and the extent of surface loss, and any increase in surface roughness and the surface loss.

Conclusions:

Toothbrushing with a dentifrice reduced the gloss, increased the surface roughness, and caused loss at the surface of all the RBCs tested. Considering all the properties tested, Mosaic Enamel exhibited excellent gloss retention and a low roughness profile and wear, while Admira Fusion X-tra exhibited the greatest decrease in gloss, the highest roughness profile, and the most wear.

Surface roughness and filler particles characterization of resin-based composites

The purpose of this study was to evaluate the surface roughness (Ra), and the morphology and composition of filler particles of different composites submitted to toothbrushing and water storage. Disc-shaped specimens (15 mm × 2 mm) were made from five composites: two conventional (Z100™, and Filtek™ Supreme Ultra Universal, 3M), one "quick-cure" (Estelite ∑ Quick, Tokuyama), one fluoride-releasing (Beautiful II, Shofu), and one self-adhering (Vertise Flow, Kerr) composite. Samples were finished/polished using aluminum oxide discs (Sof-Lex, 3M), and their surfaces were analyzed by profilometry (n = 5) and scanning electron microscopy (SEM; n = 3) at 1 week and after 30,000 toothbrushing cycles and 6-month water storage. Ra data were analyzed by two-way analysis of variance and Tukey's test (α = 0.05). Filler particles morphology and composition were analyzed by SEM and X-ray dispersive energy spectroscopy, respectively. Finishing/polishing resulted in similar Ra for all the composites, while toothbrushing and water storage increased the Ra of all the tested materials, also changing their surface morphology. Beautifil II and Vertise Flow presented the highest Ra after toothbrushing and water storage. Filler particles were mainly composed of silicon, zirconium, aluminum, barium, and ytterbium. Size and morphology of fillers, and composition of the tested composites influenced their Ra when samples were submitted to toothbrushing and water storage.

Effect of Polymerization Time and Home Bleaching Agent on the Microhardness and Surface Roughness of Bulk-Fill Composites: A Scanning Electron Microscopy Study

OBJECTIVE

The aim of this study is to evaluate the microhardness and surface roughness of two different bulk-fill composites polymerized with light-curing unit (LCU) with different polymerization times before and after the application of a home bleaching agent.

MATERIALS-METHODS

For both microhardness and surface roughness tests, 6 groups were prepared with bulk-fill materials (SonicFill, Filtek Bulk Fill) according to different polymerization times (10, 20, and 30 s). 102 specimens were prepared using Teflon molds (4 mm depth and 5 mm diameter) and polymerized with LCU. 30 specimens (n = 5) were assessed for microhardness. Before home bleaching agent application, the bottom/top (B/T) microhardness ratio was evaluated. After bleaching agent application, the microhardness measurements were performed on top surfaces. Roughness measurements were performed in 72 specimens (n = 12) before and after bleaching application. Additionally, for SEM analyses, two specimens from all tested groups were prepared before and after bleaching agent application. The data B/T microhardness ratio before bleaching was analyzed by two-way ANOVA and Tukey's HSD test. The data from the top surface of specimens' microhardness before and after bleaching were analyzed using Wilcoxon signed-rank test, Kruskal-Wallis, Mann-Whitney U tests. The data from surface roughness tests were statistically analyzed by multivariate analysis of variance and Bonferroni test (p < 0.05).

RESULTS

The B/T microhardness ratio results revealed no significant differences between groups (p > 0.05). Comparing the microhardness values of the composites' top surfaces before and after bleaching, a significant decrease was observed exclusively in FB30s (p < 0.05). No significant differences in surface roughness values were observed when the groups were compared based on bulk-fill materials (p > 0.05) while the polymerization time affected the surface roughness of the SF20s and SF30s groups (p < 0.05). After bleaching, surface roughness values were significantly increased in the SF20s and SF30s groups (p < 0.05).

CONCLUSION

The clinicians should adhere to the polymerization time recommended by the manufacturer to ensure the durability of the composite material in the oral environment.

Wear of dental materials: Clinical significance and laboratory wear simulation methods -A review

This review focusses on tribological aspects of teeth during function, the clinical significance of wear, wear of natural teeth and restorative materials and laboratory methods to simulate wear of restorative materials. Ceramic, metal alloy and amalgam show low material wear, whereas resin-based materials demonstrate substantial wear in the long term. The clinical wear shows a high variability with the patient factor accounts for about 50% of the variability. Wear as such seldomly compromises the function of the stomatognath system or individual teeth and is in most cases an esthetic problem. Particles that are ingested due to attrition and abrasion wear may pose a health risk to the patient, especially those from composite resin materials. However, systematic clinical studies on that issue are not available. For laboratory research many wear simulation devices and methods have been developed but only few are validated and have a moderate correlation with clinical wear.

Characterization of a new fiber-reinforced flowable composite

This study aimed to evaluate certain physical properties including surface wear of a new experimental short fiber-reinforced flowable resin composite (SFRC) in comparison with different commercial flowable bulk fill resin composites (SDR, Tetric EvoFlow Bulk Fill, Filtek Bulk Fill Flowable and Estelite Bulk Fill Flow). The following properties were examined according to ISO standard: flexural strength, flexural modulus, fracture toughness, water sorption, volumetric shrinkage, and depth of cure. Degree of conversion (DC%) was determined by FTIR spectrometry. A wear test was conducted with 15000 chewing cycles using a dual-axis chewing simulator. Wear depth was measured by a three-dimensional (3D) noncontact optical profilometer. Scanning electron microscopy was used to evaluate the microstructure of SFRC. Data were statistically analyzed with analysis of variance ANOVA (p = 0.05). SFRC exhibited the highest fracture toughness (2.8 MPa m^1/2) and flexural strength (146.5 MPa) values (p < 0.05) and the greatest depth of cure (5 mm) and lowest wear depth (18.2 µm) among the flowable bulk fill materials tested. SDR showed the lowest volumetric shrinkage percentage (2.9%), while the other resin composites had comparable volumetric shrinkage values (p > 0.05). The new short fiber-reinforced flowable resin composite differed significantly in its measured fracture toughness compared to the tested flowable bulk fill resin composites.

The Effect of Desensitizing Toothpastes and Coffee Staining on the Optical Properties of Natural Teeth and Microhybrid Resin Composites: An In-Vitro Study

Objective

To evaluate the effect of different desensitizing toothpastes and coffee staining on the discoloration rate of natural human tooth and composite materials.

Materials and Methods

A total of 56 human teeth and 56 composite specimens were used. After initial color measurements were taken, specimens and teeth were exposed to simulated toothbrushing with six desensitizing toothpastes containing different active ingredients: stannous fluoride, strontium acetate, potassium citrate and hydroxyapatite, cetylpyridinium chloride, arginine, and novamin. Specimens were then exposed to coffee staining. Throughout the staining procedure, the storing solution was refreshed every day and the specimens were brushed with the tested toothpastes. Color measurements and changes were recorded at each stage and analyzed with one-way ANOVA, Dunnett tests, and paired sample t-test (p<0.05).

Results

The largest color change was obtained with the stannous fluoride toothpaste after coffee staining for natural teeth (2.6 ΔE ₀₀ ^⁎) and composite specimens (3.1 ΔE ₀₀ ^⁎). Coffee staining resulted in significant changes for ΔE ₀₀ ^⁎ values of all groups, except for natural teeth brushed with a novamin-based (p= 0.06) toothpaste. For composite specimens, only the stannous fluoride and cetylpyridinium chloride-based toothpastes resulted in significant color changes relative to the control group. ΔL^⁎ and Δb^⁎ values were also increased after staining for all groups (p<0.05).

Conclusions

Desensitizing toothpastes alone did not cause perceptible color changes; however, in combination with coffee staining, it tended to increased discoloration for both composites and natural teeth.

Academy of Dental Materials guidance-Resin composites: Part I-Mechanical properties

OBJECTIVE

The objective of this project, which was initiated from the Academy of Dental Materials, was to review and critically appraise methods to determine fracture, deformation and wear resistance of dental resin composites, in an attempt to provide guidance for investigators endeavoring to study these properties for these materials.

METHODS

Test methods have been ranked in the priority of the specific property being tested, as well as of the specific test methods for evaluating that property. Focus was placed on the tests that are considered to be of the highest priority in terms of being the most useful, applicable, supported by the literature, and which show a correlation with clinical findings. Others are mentioned briefly for the purpose of being inclusive. When a standard test method exists, including those used in other fields, these have been identified in the beginning of each section. Also, some examples from the resin composite literature are included for each test method.

RESULTS

The properties for evaluating resin composites were ranked in the priority of measurement as following: (1) Strength, Elastic Modulus, Fracture toughness, Fatigue, Indentation Hardness, Wear-abrasion (third body) and Wear-attrition (contact/two body), (2) Toughness, Edge strength (chipping) and (3) Wear determined by toothbrush.

SIGNIFICANCE

The following guidance is meant to aid the researcher in choosing the proper method to assess key properties of dental resin composites with regard to their fracture, deformation and wear resistance.

Effect of Brushing Time and Dentifrice Abrasiveness on Color Change and Surface Roughness of Resin Composites

Abstract: Dentifrice abrasiveness and brushing time may increase color change (∆E) and surface roughness (∆Ra) of resin composites. This study aimed to evaluate the effect of mechanical brushing time of dentifrices with different abrasiveness on ∆E and ∆Ra of nanofilled (Z350, 3M ESPE) and nanohybrid (Tetric N-Ceram, Ivoclar Vivadent) resin composites. Sixteen specimens (12 mm diameter x 2 mm thick) were fabricated using a white Teflon matrix of each resin composite and a ceramic (IPS e.max Ceram, Ivoclar Vivadent), used as control. After initial color readouts on white backgrounds (Spectrophotometer PCB 6807, Byk Gardner), with D65 standard illuminant, and surface roughness (Rugosimeter Surfcorder SE 1700, Kosalab) with cut-off=0.8 mm and speed=0.25 mm/s, specimens were assigned (n=8) according to the abrasiveness of the dentifrices: RDA* 68 (Colgate) and RDA* 180 (Colgate Total Plus Whitening). Specimens were submitted to mechanical brushing (58,400 cycles) and after every 14,600 cycles (1 year of brushing by a healthy individual), new color and surface roughness readouts were taken. Color stability was calculated by CIEDE2000. Data were analyzed by 3-way repeated measures ANOVA and Bonferroni test (p<0.05), and demonstrated that the dentifrice abrasiveness (p=0.02) and brushing time (p<0.0001) affected the ∆E of nanofilled resin composite. There was no difference on surface roughness of materials (p=0.6752) or brushing time (p=0.7997). In conclusion, the longer the brushing time and dentifrice abrasiveness, the greater the color change of the nanofilled resin composite. The surface roughness was not influenced by dentifrice abrasiveness.

Micro-sized erosions in a nanofilled composite after repeated acidic beverage exposures: consequences of clusters dislodgments

Objective

To evaluate the hardness (KHN), color stability (DE), and superficial micromorphology of two categories of composites after immersion in either distilled water or grape juice for up to 45 days.

Material and Methods

Cylindrical specimens (6 mm diameter x 2 mm thick) were obtained according to the factors: composite [Opallis (FGM) and Filtek Z350XT (3M ESPE)]; immersion solution (distilled water and grape juice); and evaluation time: 24 h and 7, 14, 21, 28, and 45 days. After photoactivation, the specimens were stored at 37ºC for 24 h. KHN (50 g/15 s) and ΔE were then repeatedly assessed according to the immersion solutions. Data were analyzed (three-way ANOVA/Tukey's test). Scanning electron microscopy (SEM) topographic analysis was also performed.

Results

In general, KHN of both composites reduced after 24 h, irrespective of the immersion solution and time. A significantly lower KHN was noted for Opallis compared with Filtek Z350XT in all parameters. An increase in ΔE over time was noted for both composites, irrespective of the immersion solution. Significantly higher ΔE was noted for Filtek Z350XT immersed in grape juice compared with Opallis, regardless of the evaluation time. The grape juice caused significantly higher DE compared with water in all periods. SEM analysis showed eroded areas for Filtek Z350XT but not for Opallis.

Conclusions

The compositions and immersion solutions influence the composite hardness and the color stability. In spite of the higher hardness, the nanofilled composite is more susceptible to color change than the microhybrid when immersed in an acidic dyed solution.

Resistance of dentin coating materials against abrasion by toothbrush

Thin-film coating of root dentin surface by all-in-one adhesives has been shown to be an effective option to prevent root surface caries. The purpose of this study was to investigate the wear resistance against toothbrush abrasion of two all-in-one coating materials; Shield Force (SF) and Hybrid Coat (HC). Bovine dentin surfaces were covered with one of the coating materials; SF or HC. After storage in water for 24 h, the testing surface was subjected to the toothbrush abrasion test up to 50,000 cycles either in water or toothpaste slurry. The remaining thickness of the coating material was measured using SEM. Toothpaste slurry significantly increased rate of tooth brush abrasion of the coating materials. While SF and HC wore at a similar pace under toothbrush abrasion, SF had a thicker coat and could protect dentin longer, up to 50,000 cycles.

Effects of toothbrush hardness on in vitro wear and roughness of composite resins

AIM

To investigate and compare the effects of toothbrushes with different hardness on abrasion and surface roughness of composite resins.

MATERIALS AND METHODS

Toothbrushes (DENT. EX Slimhead II 33, Lion Dental Products Co. Ltd., Tokyo, Japan) marked as soft, medium and hard, were used to brush 10 beam-shaped specimens of each of three composites resins (Venus [VEN], Venus Diamond [VED] and Venus Pearl [VEP]; HeraeusKulzer) with standardized calcium carbonate slurry in a multistation testing machine (2N load, 60 Hz). After each of five cycles with 10k brushing strokes the wear depth and surface roughness of the specimens were determined. After completion of 50k strokes representative samples were inspected by SEM. Data were treated with ANOVA and regression analyses (p < 0.05).

RESULTS

Abrasion of the composite resins increased linearly with increasing number of brushing cycles (r² > 0.9). Highest wear was recorded for VEN, lowest for VED. Hard brushes produced significantly higher wear on VEN and VEP, whereas no difference in wear by toothbrush type was detected for VED. Significantly highest surface roughness was found on VED specimens (Ra > 1.5 µm), the lowest one on VEN (Ra < 0.3 µm). VEN specimens showed increased numbers of pinhole defects when brushed with hard toothbrushes, surfaces of VEP were uniformly abraded without level differences between the prepolymerized fillers and the glass filler-loaded matrix, VED showed large glass fillers protruding over the main filler-loaded matrix portion under each condition.

CONCLUSION

Abrasion and surface roughness of composite resins produced by toothbrushing with dentifrice depend mainly on the type of restorative resin. Hardness grades of toothbrushes have minor effects only on abrasion and surface roughness of composite resins. No relationship was found between abrasion and surface roughness.

CLINICAL SIGNIFICANCE

The grade of the toothbrush used has minor effect on wear, texture and roughness of the composite resin.

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

Objectives

Nanofilled composite resins are claimed to provide superior mechanical properties compared with microhybrid resins. Thus, the aim of this study was to compare nanofilled with microhybrid composite resins. The null hypothesis was that the size and the distribution of fillers do not influence the mechanical properties of surface roughness and wear after simulated toothbrushing test.

Material and methods

Ten rectangular specimens (15 mm x 5 mm x 4 mm) of Filtek Z250 (FZ2), Admira (A), TPH3 (T),Esthet-X (EX), Estelite Sigma (ES), Concept Advanced (C), Grandio (G) and Filtek Z350 (F) were prepared according to manufacturer's instructions. Half of each top surface was protected with nail polish as control surface (not brushed) while the other half was assessed with five random readings using a roughness tester (Ra). Following, the specimens were abraded by simulated toothbrushing with soft toothbrushes and slurry comprised of 2:1 water and dentifrice (w/w). 100,000 strokes were performed and the brushed surfaces were re-analyzed. Nail polish layers were removed from the specimens so that the roughness (Ra) and the wear could be assessed with three random readings (µm). Data were analyzed by ANOVA and Tukey's multiple-comparison test (α=0.05).

Results

Overall outcomes indicated that composite resins showed a significant increase in roughness after simulated toothbrushing, except for Grandio, which presented a smoother surface. Generally, wear of nanofilled resins was significantly lower compared with microhybrid resins.

Conclusions

As restorative materials suffer alterations under mechanical challenges, such as toothbrushing, the use of nanofilled materials seem to be more resistant than microhybrid composite resins, being less prone to be rougher and worn.

The influence of "C-factor" and light activation technique on polymerization contraction forces of resin composite

Objectives

This study evaluated the influence of the cavity configuration factor ("C-Factor") and light activation technique on polymerization contraction forces of a Bis-GMA-based composite resin (Charisma, Heraeus Kulzer).

Material and Methods

Three different pairs of steel moving bases were connected to a universal testing machine (emic DL 500): groups A and B - 2x2 mm (CF=0.33), groups C and D - 3x2 mm (CF=0.66), groups e and F - 6x2 mm (CF=1.5). After adjustment of the height between the pair of bases so that the resin had a volume of 12 mm³ in all groups, the material was inserted and polymerized by two different methods: pulse delay (100 mW/cm² for 5 s, 40 s interval, 600 mW/cm² for 20 s) and continuous pulse (600 mW/cm² for 20 s). Each configuration was light cured with both techniques. Tensions generated during polymerization were recorded by 120 s. The values were expressed in curves (Force(N) x Time(s)) and averages compared by statistical analysis (ANOVA and Tukey's test, p<0.05).

Results:

For the 2x2 and 3x2 bases, with a reduced C-Factor, significant differences were found between the light curing methods. For 6x2 base, with high C-Factor, the light curing method did not influence the contraction forces of the composite resin.

Conclusions

Pulse delay technique can determine less stress on tooth/restoration interface of adhesive restorations only when a reduced C-Factor is present.

56-month clinical performance of Class I and II resin composite restorations

OBJECTIVE

This study evaluated the 56-month clinical performance of Class I and II resin composite restorations. Filtek P60 was compared with Filtek Z250, which are both indicated for posterior restorations but differ in terms of handling characteristics. The null hypothesis tested was that there is no difference in the clinical performance of the two resin composites in posterior teeth.

MATERIAL AND METHODS

Thirty-three patients were treated by the same operator, who prepared 48 Class I and 42 Class II cavities, which were restored with Single Bond/Filtek Z250 or Single Bond/Filtek P60 restorative systems. Restorations were evaluated by two independent examiners at baseline and after 56 months, using the modified USPHS criteria. Data were analyzed statistically using Chi-square and Fisher's Exact tests (a=0.05).

RESULTS

After 56 months, 25 patients (31 Class I and 36 Class II) were analyzed. A 3% failure rate occurred due to secondary caries and excessive loss of anatomic form for P60. For both restorative systems, there were no significant differences in secondary caries and postoperative sensitivity. However, significant changes were observed with respect to anatomic form, marginal discoloration, and marginal adaptation. Significant decreases in surface texture were observed exclusively for the Z250 restorations.

CONCLUSIONS

Both restorative systems can be used for posterior restorations and can be expected to perform well in the oral environment.

Effect of different surface penetrating sealants on the roughness of a nanofiller composite resin

This study evaluated the effectiveness of different sealants applied to a nanofiller composite resin. Forty specimens of Filtek Z-350 were obtained after inserting the material in a 6x3 mm stainless steel mold followed by light activation for 20 s. The groups were divided (n=10) according to the surface treatment applied: Control group (no surface treatment), Fortify, Fortify Plus and Biscover LV. The specimens were subjected to simulated toothbrushing using a 200 g load and 250 strokes/min to simulate 1 week, 1, 3 and 6 months and 1 and 3 years in the mouth, considering 10,000 cycles equivalent to 1 year of toothbrushing. Oral-B soft-bristle-tip toothbrush heads and Colgate Total dentifrice at a 1:2 water-dilution were used. After each simulated time, surface roughness was assessed in random triplicate readings. The data were submitted to two-way ANOVA and Tukey's test at a 95% confidence level. The specimens were observed under scanning electron microscopy (SEM) after each toothbrushing cycle. The control group was not significantly different (p>0.05) from the other groups, except for Fortify Plus (p<0.05), which was rougher. No significant differences (p>0.05) were observed at the 1-month assessment between the experimental and control groups. Fortify and Fortify Plus presented a rougher surface over time, differing from the baseline (p<0.05). Biscover LV did not differ (p>0.05) from the baseline at any time. None of the experimental groups showed a significantly better performance (p>0.05) than the control group at any time. SEM confirmed the differences found during the roughness testing. Surface penetrating sealants did not improve the roughness of nanofiller composite resin.

Toothbrush Abrasion of Resin Composites with Different Filler Concepts

Purpose

To investigate the effect of tooth brushing wear with and without calcium carbonate slurry on four commercial resin composites based on different filler concepts.

Materials and methods

One nanofiller composite MI FIL (MFI, GC), one conventional hybrid type Venus (VEN) and two nanohybrid composites Venus Diamond (VED) and Venus Pearl (VEP) all from Heraeus Kulzer were examined. Forty beam-shaped specimens (12 × 3 × 3 mm) from each product were prepared and subdivided in two equal groups for pregrinding on SiC paper #600 and #4000 respectively. Ten specimens of each pre-ground group were subjected to toothbrush abrasion with calcium carbonate slurry, and 10 to toothbrushing with water only. The samples were submitted to five subsequent runs of 10,000 brushing strokes. Depth of wear and surface roughness (Ra) were measured with a profilometer after each 10 k strokes. Specimens after 50 k strokes were assessed by SEM. Additionally, the KHN (0.25 N/15 s) and the degree of conversion (DC) were determined. Data analysis was done by linear regression and ANOVA followed by Tukey's post-hoc test (p ≤ 0.05).

Results

Toothbrushing with abrasive slurry produced significantly different wear depths: VEN > MIF > VEP > VED. Linear relationships between depth of wear and number of cycles (r2 ≥ 0.94) were established for each material. Pregrinding with SiC #4000 resulted in less wear than pregrinding with #600. Ra figures were much higher for VED than for the other materials tested. MIF and VEN were uniformly abraded, whereas the largest glass fillers in VED protruded from the surroundings and the prepolymer particles in VEP were deeper abraded than the bulk of the material. Toothbrushing with water only revealed not measurable wear. Roughness Ra was practically unchanged when compared with the preground samples before challenging with toothbrushes. Ranking by KHN was: MIF < VEN, VEP < VED, by DC: MIF < VEN < VEP < VED.

Conclusion

Filler concepts and monomer compositions affect wear and roughness of resin composites when tooth brushed with abrasive slurry. Toothbrushing without abrasive medium produced neither wear nor roughness. Careful polishing of resin composite restorations is an important determinant of wear and surface roughness.

How to cite this article

Suzuki T, Kyoizumi H, Araki Y, Finger WJ, Kanehira M. Toothbrush Abrasion of Resin Composites with Different Filler Concepts. World J Dent 2012;3(2):184-193.

Fracture resistance of weakened teeth restored with condensable resin with and without cusp coverage

Objectives:

This in vitro study evaluated the fracture resistance of weakened human premolars (MOD cavity preparation and pulp chamber roof removal) restored with condensable resin composite with and without cusp coverage.

Material and Methods:

Thirty human maxillary premolars were divided into three groups: Group A (control), sound teeth; Group B, wide MOD cavities prepared and the pulp chamber roof removed and restored with resin composite without cusp coverage; Group C, same as Group B with 2.0 mm of buccal and palatal cusps reduced and restored with the same resin. The teeth were included in metal rings with self-curing acrylic resin, stored in water for 24 h and thereafter subjected to a compressive axial load in a universal testing machine at 0.5 mm/min.

Results:

The mean fracture resistance values ± standart deviation (kgf) were: group A: 151.40 ± 55.32, group B: 60.54 ± 12.61, group C: 141.90 ± 30.82. Statistically significant differences were found only between Group B and the other groups (p<0.05). The condensable resin restoration of weakened human premolars with cusp coverage significantly increased the fracture resistance of the teeth as compared to teeth restored without cusp coverage.

Conclusion:

The results showed that cusp coverage with condensable resin might be a safe option for restoring weakened endodontically treated teeth.

The role of surface sealants in the roughness of composites after a simulated toothbrushing test

OBJECTIVES

To evaluate the influence of two surface sealants (BisCover/Single Bond) and three application techniques (unsealed/conventional/co-polymerization) on the roughness of two composites (Filtek Z250/Z350) after the toothbrushing test.

METHODS

Seventy-two rectangular specimens (5 mm x10 mm x 3 mm) were fabricated and assigned into 12 groups (n=6). Each sample was subjected to three random roughness readings at baseline, after 100,000 (intermediate), and 200,000 (final) toothbrushing strokes. Roughness (R) at each stage was obtained by the arithmetic mean of the reading of each specimen. Sealant removal was qualitatively examined (optical microscope) and classified into scores (0-3). Data were analyzed by Student's paired t-test, two-way ANOVA/Tukey's test, and by Wilcoxon, Kruskal-Wallis and Miller's test (alpha=0.05).

RESULTS

Z250 groups at baseline did not differ statistically from each other. Unsealed Z350 at baseline had lower R values. All the unsealed groups presented gradual decrease in R from baseline to final brushing. From baseline to the intermediate stage, Z250 co-polymerized groups presented a significant reduction in R (score 3). Conventionally sealed groups had no significant changes in R (scores 2-0.8). From baseline to the intermediate stage, the conventionally sealed Z350 Single Bond group had an increase in R (score 1.5). In the final stage, all the conventionally sealed groups presented a reduction in R (scores 0.7-0). Co-polymerized Single Bond groups had a significant reduction in R (scores 2.5-2.7), and co-polymerized BisCover groups an increase in R (scores 2.8-3).

CONCLUSIONS

At any brushing stage, sealed composites presented superior performance when compared with unsealed composites.

Evaluation of weight loss and surface roughness of compomers after simulated toothbrushing abrasion test

This study aimed at analyzing the compomers wear by an "in vitro" toothbrushing abrasion test. The null hypotheses tested were that there would be no differences in weight loss and no significant changes in surface roughness of the compomers after this test. The utilized commercial brands were Dyract (Dentsply), Dyract AP (Dentsply), Compoglass F (Vivadent), Freedom (SDI), F2000 (3M ESPE), which were compared to the two resin composites Z100 (3M ESPE) and Silux Plus (3M ESPE). Ten cylindrical specimens for each commercial brand were prepared with 5mm diameter and 3mm thickness. An appropriate machine with soft bristle tips containing dentifrice solution and deionized water was used. A total of 100,000 brushing cycles were performed. The amount of weight loss was measured by the percentage alteration between the initial (before toothbrushing) and final weight (after toothbrushing), measured by a Sartorius analytical balance. The surface roughness change was determined by the percentage difference between initial and final means after 5 tracings by a T 1000 Hommel Tester roughness meter on the specimen's surfaces before and after toothbrushing abrasion test. The statistical analysis (Students paired t-test, ANOVA and Tukey, á=0.05) showed that all materials presented statistically significant weight loss and roughness increase after abrasion test. All compomers presented higher weight loss than resin composites. Freedom and Dyract AP presented the lowest weight loss among compomers. F2000 presented the worst abrasion resistance, without statistical differences with Dyract. For roughness changes, Dyract, Dyract AP, Z100, Compoglass F and Silux Plus showed the lowest surface roughness alteration, in increasing order, without statistical differences between them. Freedom was the statistically roughest material of the study.