Influence of filler loading on the two-body wear of a dental composite

An evaluation of dental paste-like bulk-fill composite wear using intra-oral scanner

This study evaluates the wear resistance of dental paste-like bulk-fill composites compared to conventional paste-like composite resins using an intraoral scanner and 3-D analyzing software. Six different dental composite materials, including five bulk-fill composites and one conventional composite, were tested alongside natural human enamel as a control group. A computer-controlled chewing simulator for wear testing. A one-way ANOVA test was used to identify any significant differences between the means of the tested dental composite materials α=0.05. The results showed variability among bulk-fill composites, with some demonstrating wear resistance similar to conventional composites (p<0.05). Human enamel displayed the lowest wear values, but some bulk-fill composites matched this resistance(p>0.05). Significant variability was observed among bulk-fill composites but the results were comparable to those of conventional composites. The enamel control group demonstrated the lowest wear values, with some bulk-fill composites showing similar wear resistance. This study provides valuable information about the wear resistance of contemporary bulk-fill composite materials, commonly used in current clinical practice, contributing to enhancing clinical procedures.

Evaluation of the effects of whitening toothpaste containing nanohydroxyapatite on surface roughness and color change in restorative materials

Background

The effects of whitening toothpastes containing nanohydroxyapatite on the surfaces of restorative materials are not well known. This study evaluated the changes in surface roughness and color of coffee-stained restorative materials after brushing with nanohydroxyapatite and other whitening toothpastes.

Methods

Disc-shaped specimens were formed using microhybrid, nanohybrid, and supra-nano-filled composite (n = 30) and stained with a coffee solution. A brushing simulation was applied with toothpastes containing nanohydroxyapatite (Dentiste Plus White), perlite (Signal White System) and hydrogen peroxide (Colgate Optic White) for 7, 15, and 30 days. Color and surface roughness measurements were taken before and after brushing. Color change (∆E₀₀) was calculated using the CIEDE2000 system.

Results

Supra-nano-filled composite-Dentiste Plus White, supra-nano-filled composite-Colgate Optic White, and nanohybrid composite-Signal White System were the groups with the greatest color change observed on the 7th, 15th, and 30th days, respectively. The smallest color change was seen in the microhybrid composite-Signal White System, microhybrid composite-Dentiste Plus White, and nanohybrid composite-Dentiste Plus White groups on the 7th, 15th, and 30th days, respectively. No significant surface roughness changes were observed in the nanohybrid composite-Dentiste Plus White, supra-nano-filled composite-Colgate Optic White, supra-nano-filled composite-Dentiste Plus White, or supra-nano-filled composite-Signal White System groups.

Conclusions

Whitening toothpaste containing nanohydroxyapatite provided a high degree of color change in the short term and did not create significant surface roughness in nanohybrid or supra-nano-filled composites.

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.

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

OBJECTIVE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

CLINICAL SIGNIFICANCE

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

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.

A study on the characteristics of resin composites for provisional restorations

In this study, we evaluated the characteristics of five commercial resin composites used for provisional restorations. The inorganic filler contents of the resins were measured, and three-point bending, wear, surface hardness, water absorption, and staining tests were performed. The specimens underwent additional three-point bending tests after water storage and undergoing thermal stresses at 5°C and 55°C (10,000 cycles). Data were analyzed using one- or two-way analysis of variance and Bonferroni post-hoc tests. Pearson's correlation coefficient was used for pairwise comparisons. Each resin composite presented with different mechanical properties, based on variations in the inorganic filler content. The flexural strength of each resin composite was significantly decreased after water storage. There has a positive correlation between flexural strength and dynamic hardness but a negative correlation between flexural strength and maximum wear depth. The types and contents of the inorganic fillers, the composition of the monomer in the resin matrix, and the addition of plasticizers can affect the properties of the material.

"Comparative evaluation of effect of toothbrush-dentifrice abrasion on surface roughness of resin composites with different filler loading:" An in vitro study

Objectives:

This in vitro study evaluated the effect of toothbrush-dentifrice abrasion on the surface roughness of two restorative posterior resin composites, Filtek Z250 and Z350 after simulated toothbrushing twice daily for a period of 3 months.

Methods:

All the specimens were polished and cleaned and surface topography was evaluated by Veeco di CP-II Atomic Force Microscope (AFM) at six different points; similarly, these specimens were again subjected to evaluation after simulated toothbrushing using dentifrice. The surface roughness evaluation was done for AFM images using software made available and the factor measured were average roughness (Ra) and maximum peak to valley distance R(p v). Data were normally distributed as tested using the Shapiro–Wilk W-test (P > 0.05). Therefore, analysis was performed using the parametric tests, i.e., independent “t”-test (for comparing two groups). The level of statistical significance was set at P < 0.05.

Results:

The mean change in Ra and the mean change in Rp-v for Z350 were less as compared to Z250, and this difference was statistically significant.

Conclusions:

Within the limitation of the present study, it can be concluded that toothbrushing increased the roughness in Z250 in comparison to Z350.

Influence of cleaning methods after 3D printing on two-body wear and fracture load of resin-based temporary crown and bridge material

OBJECTIVES

To investigate the impact of different cleaning methods on the fracture load and two-body wear of additively manufactured three-unit fixed dental prostheses (FDP) for long-term temporary use, compared to the respective outcomes of milled provisional PMMA FDPs.

MATERIALS AND METHODS

Shape congruent three-unit FDPs were 3D printed using three different resin-based materials [FPT, GCT, NMF] or milled [TEL] (N = 48, n = 16 per group). After printing, the FDPs were cleaned using: Isopropanol (ISO), Yellow Magic 7 (YEL), or centrifugal force (CEN). Chewing simulation was carried out with a vertical load of 50 N (480,000 × 5 °C/55 °C). Two-body wear and fracture load were measured. Data were analyzed using global univariate ANOVA with partial eta squared, Kruskal-Wallis H, Mann-Whitney U, and Spearman's rho test (p < 0.05).

RESULTS

TEL showed less wear resistance than FPT (p = 0.001) for all cleaning methods tested. Concerning vertical material loss, NMF and GCT were in the same range of value (p = 0.419-0.997), except within FDPs cleaned in ISO (p = 0.021). FPT showed no impact of cleaning method on wear resistance (p = 0.219-0.692). TEL (p < 0.001) showed the highest and FPT (p < 0.001) the lowest fracture load. Regarding the cleaning methods, specimens treated with ISO showed lower fracture load than specimens cleaned with CEN (p = 0.044) or YEL (p = 0.036).

CONCLUSIONS

The material selection and the cleaning method can have an impact on two-body wear and fracture load results.

CLINICAL RELEVANCE

Printed restorations showed superior two-body wear resistance compared to milled FDPs but lower fracture load values. Regarding cleaning methods, ISO showed a negative effect on fracture load compared to the other methods tested.

Wear Properties of Different Additive Restorative Materials Used for Onlay/Overlay Posterior Restorations

The purpose of this laboratory study was to compare the two-body wear resistance of different restorative materials commonly used for the indirect restoration of posterior teeth. The tested materials, based on ceramic (Imagine Press X, IPS e.max CAD, Milled Celtra Duo, Glaze-Fired Celtra Duo, Vita Mark II) and composite (Enamel Plus HRi, Enamel Plus HRi Bio-Function, Filtek Supreme XTE, Lava Ultimate), were compared with the wear properties of a type III gold alloy (Aurocast 8). Flat samples were prepared with a 6-mm thickness (n=10). Composite samples were tested after a heat polymerization cycle. All samples were exposed to a two-body wear test in a dual axis chewing simulator performing over 120,000 loading cycles. The opposing abrader cusps were fabricated from yttria-stabilized tetragonal zirconia polycrystal. The vertical substance loss (mm) and the volume loss (mm3) were recorded, as was the wear of the antagonist cusp (mm). Mean values were analyzed by one-way analysis of variance. Significant differences among materials were detected. The heat-cured resin-based composite material Enamel Plus Bio-Function and the type III gold alloy demonstrated similar mean values for wear depth and volumetric loss.

Recent advances in understanding the fatigue and wear behavior of dental composites and ceramics

Dental composite and ceramic restorative materials are designed to closely mimic the aesthetics and function of natural tooth tissue, and their longevity in the oral environment depends to a large degree on their fatigue and wear properties. The purpose of this review is to highlight some recent advances in our understanding of fatigue and wear mechanisms, and how they contribute to restoration failures in the complex oral environment. Overall, fatigue and wear processes are found to be closely related, with wear of dental ceramic occlusal surfaces providing initiation sites for fatigue failures, and subsurface fatigue crack propagation driving key wear mechanisms for composites, ceramics, and enamel. Furthermore, both fatigue and wear of composite restorations may be important in enabling secondary caries formation, which is the leading cause of composite restoration failures. Overall, developing a mechanistic description of fatigue, wear, and secondary caries formation, along with understanding the interconnectivity of all three processes, are together seen as essential keys to successfully using in vitro studies to predict in vivo outcomes and develop improved dental restorative materials.

Effect of filler size and filler loading on wear of experimental flowable resin composites

The relationship between wear resistance and filler size or filler loading was clarified for the universal resin composite; however, their relationship in flowable resin composites has not been clarified.

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.

Texture of Composite Resins Exposed to Two- and Three- Body Wear in vitro

Purpose

To analyze on scanning electron microscopy (SEM) pictures from eight composite resins, taken in the centers of the initial, the middle and the terminal thirds of in vitro produced wear tracks morphological features to explain causative mechanisms for the material wear observed under two- and three-body wear.

Materials and methods

In vitro wear behavior of eight composite resins, three conventional and five nanofiller containing marketed products was evaluated using a custommade Zr-ball-on-disk sliding device. The composite specimens were subjected to 50,000 one-way sliding cycles (1.2 Hz, 50 N load), either simulating two-body wear with water as the intermediate medium or three-body wear using aqueous suspensions of polymethyl methacrylate (PMMA) beads and poppy seeds, respectively. Volume loss of the materials was determined in previous study. Representative specimens were selected for inspection by scanning electron microscopy at 500-fold magnification. From each of the 24 wear tracks microphotographs were taken in the central deepest parts of the initial, middle and terminal thirds of the tracks.

Results

For most materials morphological differences were detected depending on the location within the wear track. As a rule, the surface deterioration found increased toward the final part of the wear scar. According to common classification in tribology abrasive wear and fatigue wear, or a combination of both mechanisms were found for all materials tested. Wear was dependent both on the testing mode and on the composition of the individual composite resin material.

Conclusion

The morphological assessment of wear tracks reflects the nature of the abrasive and reveals insight into the mechanism generating wear patterns. Morphological details confirmed abrasive and fatigue-related wear as main failure mechanisms. Selection of food-like slurries as third-body media, such as poppy seed suspension is mandatory to simulate wear of composite restorations in occlusal cavities where three-body wear is the dominating determinant of loss of substance and surface deterioration.

How to cite this article

Iwasaki N, Takahashi H, Koottathape N, Kanehira M, Finger WJ, Sasaki K. Texture of Composite Resins Exposed to Two- and Three-Body Wear in vitro. J Contemp Dent Pract 2014;15(2):232-241.

Two- and three-body wear of composite resins

OBJECTIVE

The aim of the present study was to investigate two- and three-body wear of microfilled, micro-hybrid and nano-hybrid composite resins using a ball-on-disc sliding device.

METHODS

One microfilled (Durafill VS), one micro-hybrid (Filtek Z250), one hybrid (Clearfil AP-X), one nanofilled (Filtek Supreme XT), and two nano-hybrid (MI Flow, Venus Diamond) composite resins were examined. The composites were filled in a cylindrical cavity, and light polymerized. After storage in 37°C distilled water for 7days, all specimens were tested with a custom-made ball-on-disc sliding device with a zirconia ball as antagonist (50N loads, 1.2Hz, 10,000 cycles) immersed in water, poppy seed slurry and polymethyl methacrylate slurry, respectively. Maximum wear depth and volume loss of worn surfaces were quantified by a digital CCD microscope and analyzed with two-way analysis of variance.

RESULTS

The interactions between composite resin and condition of their maximum wear depth and volume loss were significant (p<0.01). The abrasive wear produced at three-body loading with poppy seed slurry was very large for the microfilled composite, and small for all other composites tested. In contrast, two-body wear of the microfilled composite, and one nano-hybrid composite was very low.

SIGNIFICANCE

The ball-on-disc sliding device used is considered suitable to simulate sliding of an antagonist cusp on an opposing occlusal composite restoration, either in the two- or the three-body wear mode. All tested materials except for the microfilled composite showed low surface wear when exposed to poppy seed as the third-body medium.

Wear of composite resin veneering materials and enamel in a chewing simulator

OBJECTIVES

The purpose of this in vitro study was to evaluate the wear of six composite resins for the veneering of crowns compared with the wear of human and bovine enamel, tested in a dual-axis chewing simulator.

METHODS

Eight specimens of six different composite resins (Targis I+II, Solidex, BelleglassHP, Estenia, Solidex) and of human and bovine enamel were prepared. Steatite ceramic balls served as antagonistic specimens. Specimens were dynamically loaded in a dual-axis chewing simulator with 49 N up to 1,200,000 loading cycles with additional thermal cycling between 5 and 55 degrees C. After 120,000, 240,000, 480,000, 840,000 and 1,200,000 loading cycles, an impression of the specimens' surface and the antagonistic specimen was taken using a polyvinylsiloxane impression material. The substance loss at the surface was measured with computer-aided laser profilometry. Data were analyzed using ANOVA and the Tukey test.

RESULTS

The wear of the ultra fine compact filled composite resins Solidex and BelleglassHP was not statistically significantly different from that of human enamel. The other composite resins and bovine enamel showed a wear statistically significantly higher than human enamel.

SIGNIFICANCE

Comparing six composite resins for the veneering of crowns, ultra fine compact filled composite resins BelleGlassHP and Solidex showed a wear not significantly different from the wear of human and bovine enamel.

Comparative study of the wear behavior of composites for posterior restorations

This investigation sought to compare the abrasive wear rates of resin composites designed for posterior applications. Seventy-five specimens were fabricated with conventional hybrid (Charisma and Filtek Z250) or packable composites (Filtek P60, Solitaire II and Tetric Ceram HB), according to a randomized complete block design (n = 15). Specimens were finished and polished metallographically and subjected to abrasive wear which was performed under a normal load of 13N at a frequency of 2 Hz using a pneumatic device (MSM/Elquip) in the presence of a mucin-containing artificial saliva. Wear was quantified profilometrically in five different locations of each specimen after 1,000, 5,000, 10,000, 50,000 and after every each 50,000 through 250,000 cycles. A split-plot ANOVA showed a significant difference between the wear resistance of composites (alpha = 0.05). Tukey's test ascertained that while the composites Filtek Z250 and Charisma wore significantly less than any other of the materials tested, Tetric Ceram HB experienced the greatest wear rates. Filtek P60 and Solitaire II showed intermediate rates of material removal. The wear pattern of composites proved to be biphasic with the primary phase having the faster wear rate. In conclusion, packable resin composites may not have superior wear compared to conventional hybrid composites.

Analysis of potential lubricants for in vitro wear testing

OBJECTIVES

A critical testing aspect for a reliable two-body wear simulation may be the lubricity condition. The main hypothesis tested in this study was that, over the experiment duration, the presence or absence of lubricants would provide to a composite similar wear rates to those observed under human saliva lubrication.

METHODS

Seventy specimens, fabricated from a minifill composite, were tested in a programmable logic controlled wear simulator with human saliva (HS), mucin-based artificial saliva (MC), carboxymethylcellulose-containing saliva (CM), deionized water (DW) or with no lubrication (UN). Wear depth was quantified at the end of 1000, 5000, 10,000 and 50,000 cycles and at each 50,000 through 250,000 cycles.

RESULTS

Over all the test period, UN led to the greatest wear. Initially, lubrication resulted in no significant differences among the wear rates. Subsequently, up to 50,000 cycles, depths of wear provided by HS and MC were still similar, being the lowest, whereas DW yielded greater wear than CM. Later, interposition of CM and HS resulted in equivalent wear. At 250,000 cycles, wear of the composite ranked as follows: MC<HS<CM<DW<UN. Regression analyses showed that for all lubricity conditions wear of the composite rose logarithmically with number of cycles.

SIGNIFICANCE

The role of the interposed lubricant was of importance for the wear testing. The present findings supported by studies on the lubricity ability of mucin-based artificial saliva, allowed to conclude that this preparation may be considered as a potential lubricant for in vitro wear test purposes.