Resin-based Restorative Materials Research Articles

Microhardness and elemental analysis of ion-releasing restoration/ dentin interface following enzymatic chemomechanical caries excavation

BackgroundThis study was conducted to compare chemical, elemental and surface properties of sound and carious dentin after application of two restorative materials resin-modified glassionomer claimed to be bioactive and glass hybrid restorative material after enzymatic chemomechanical caries removal (CMCR) agent.MethodsForty carious and twenty non-carious human permanent molars were used. Molars were randomly distributed into three main groups: Group 1 (negative control) - sound molars, Group 2 (positive control) - molars were left without caries removal and Group 3 (Test Group) caries excavated with enzymatic based CMCR agent. After caries excavation and restoration application, all specimens were prepared Vickers microhardness test (VHN), for elemental analysis using Energy Dispersive Xray (EDX) mapping and finally chemical analysis using Micro-Raman microscopy.ResultsVickers microhardness values of dentin with the claimed bioactive GIC specimens was statistically higher than with glass hybrid GIC specimens. EDX analysis at the junction estimated: Calcium and Phosphorus of the glass hybrid GIC showed insignificantly higher mean valued than that of the bioactive GIC. Silica and Aluminum mean values at the junction were significantly higher with bioactive GIC specimens than glass hybrid GIC specimen. Micro-raman spectroscopy revealed that bioactive GIC specimens showed higher frequencies of v 1 PO 4, which indicated high level of remineralization.ConclusionsIt was concluded that ion-releasing bioactive resin-based restorative material had increased the microhardness and remineralization rate of carries affected and sound dentin. In addition, enzymatic caries excavation with papain-based CMCR agent has no adverse effect on dentin substrate.

Evaluation of color Stability of Different Restorative Materials Used in Pediatric Dentistry

Background: The aim of this study was to evaluate the color changes of restorative materials (Filtek z550, EverX Posterior, Dyract XP, EQUIA Forte Fill), which are frequently used in pediatric dentistry, after aging with beverages (cola, cherry juice) that children and adolescents frequently consume in their daily life. Methods: Four different restorative materials; nanohybrid composite (Filtek Z550), glass fiber reinforced bulk fill composite (EverX Posterior), polyacid modified composite resin (Dyract XP) and glass hybrid glass ionomer cement (EQUIA Forte Fill) were used. A total of 120 samples were prepared for each material using plexiglass molds with a thickness of 2 mm and a diameter of 10 mm. A total of 30 samples from each group were divided into 3 group (n=10) to be immersed in cola, cherry juice and distilled water. After the initial color measurements, the samples were stored in beverages for 7th and 14th days. Color change values (ΔE) were calculated after 7th and 14th days. Results: When the ΔE values of materials were examined, it was observed that EQUIA Forte Fill group had the highest color change and Filtek z550 group had the lowest color change. Conclusion: The glass hybrid GIC showed the most distinct color change in all time periods and beverages. ΔE values in cola and cherry juice of all resin-based restorative materials tested were less than or equal to 3.3. Therefore, color changes were clinically acceptable as they were not visually perceptible Key words: Bulk-Fill Composite Resin, Color Stability, Glass Hybrid Glass Ionomer Cement

The effect of different liquids on the surface roughness and color stability of single shade and nanohybrid resin composites: An AFM and SEM analysis.

The aim of this study is to evaluate the surface roughness (SR) and color changes of single-shade and nanohybrid resin-based restorative materials (RBC) after immersion in liquids at different pH values. For RBCs, a total of 120 specimens, 30 for each material, were prepared using 10 mm diameter and 2 mm thick molds. For flowable bulk fill RBC, a total of 40 specimens, 10 for each material, were prepared using 10 mm diameter and 4 mm thick molds (n = 10). After initial color and SR measurements, samples were stored in the liquids for 14 days and all of the measurements were repeated on 14th days. Scanning electron microscopy and atomic force microscopy analyzes were performed in all groups. When SR results are examined; among all liquids, the highest SR value was observed in the Carisma Diamond One (CDO) group, while the lowest SR value was observed in the Omnichroma Flow Bulk (OMF) group (p < .05). When the color changes (ΔE) results are examined; it was observed that CDO group had highest color change and OMF group had the lowest values. It has been observed that among the liquids, the liquids that affect the ΔE values of the materials the most are coffee and cola. When the ΔE values of the subgroups of the materials were examined, there was a statistically significant difference in all subgroups of RBCs (p < .05). While acidic liquids increased the SR of RBCs, coffee more affected the color change of RBCs. RESEARCH HIGHLIGHTS: Clinicians should keep in mind that the RBCs tested may change their surface properties and colors when exposed to various liquids. People who have RBCs should pay attention to the consumption of acidic and highly pigmented liquids.

Comparative Evaluation of Marginal Leakage of Various Bevel Designs Using Direct Composite Restoration in Fractured Anterior Teeth: An In Vitro Study.

Background and objective Resin-based restorative materials are the backbone of modern restorative dentistry. But in spite of being an excellent material, there are many shortcomings with direct resin restorative materials such as polymerization shrinkage and microleakage that complicate the rate of clinical success. Hence, the aim of the present study is to compare the microleakage caused by composite restorations usingtwo different bevels, primary and zigzag bevels, while restoring fractured anterior teeth. Materials and methodology Thirty non-carious maxillary central incisors were split into two divisions wherein Group I received the primary bevel and Group II received the zigzag bevel. After receiving the bevel, the samples are restored with direct filling composite material (Neo Spectra ST, Dentsply Sirona, Charlotte, NC, USA). The restored samples underwent thermocycling (Holmarc, Kochi, India) and were assessed for microleakage under a stereomicroscope (Leica M205, Wetzlar, Germany).For the statistical analysis, IBM SPSS Statistics for Windows, V. 23.0 (IBM Corp., Armonk, NY) was used. Descriptive statistics were expressed in mean and standard deviation. Analytical statistics including the independent Student t-test was used to assess the difference derived from both groups at p<0.05. The normality of the data was assessed using the Shapiro-Wilk test. Results In the primary bevel, 53.3% of the samples showed first-degree microleakage, and 46.7% showed second-degree microleakage, respectively, and in samples restored using the zigzag bevel, 66.7% of the samples had no microleakage, and 33.3%of the samples had first-degree microleakage. The independent t-test revealed that the microleakage of the zigzag bevel showed a significantdifference, being superior to the primary bevel at p<0.01. Conclusion Acknowledging the limitations of the study conducted, both bevel designs had a certain degree of microleakage when restored with composite material in anterior fractured teeth. However, the zigzag bevel produced significantly lesser microleakage as compared to the primary bevel restorations.

Influence of Specimen Dimension, Water Immersion Protocol, and Surface Roughness on Water Sorption and Solubility of Resin-Based Restorative Materials.

The evaluation of water sorption and solubility is pivotal for the development of new resin-based restorative materials with the potential for clinical application. The purpose of the present study was to evaluate the influence of the specimen dimension, water immersion protocol, and surface roughness on the water sorption and solubility of three resin-based restorative materials. Disk-shaped specimens of 15 mm × 1 mm, 10 mm × 1 mm, and 6 mm × 1 mm were produced with a composite resin (Z100), a resin cement (RelyX ARC), and an adhesive system (Single Bond 2-SB2). The specimens were immersed in distilled water according to four protocols: ISO (all the specimens for each group were vertically immersed in 50 mL); IV-10 (the specimens were individually and vertically immersed in 10 mL); IH-10 (the specimens were individually and horizontally immersed in 10 mL); and IH-2 (the specimens were individually and horizontally immersed in 2 mL). The surface roughness (Sa and Sp) was evaluated using an atomic force microscope, and the degree of conversion was determined using FT-IR spectrometry. The specimen dimension and water immersion protocol had no effect on water sorption and solubility. For the three resin-based restorative materials, Sp was higher than Sa. The degree of conversion was not influenced by the specimen dimension. The variations in the specimen dimension and water immersion protocol compared to those determined by ISO 4049 did not prevent the comparison between the values of water sorption and solubility obtained for a given resin-based restorative material.

In vitro characterization of a novel resin-based restorative material containing alkaline fillers.

In this study, a comparative evaluation of the physicochemical properties of Cention N and other direct restorative materials was performed. Three restorative materials-a resin-modified glass ionomer (Fuji II LC), an alkasite-based resinous material (Cention N), and a resin composite (Tetric N Ceram)-were characterized in terms of degree of conversion, Knoop hardness number (KHN) ratio, flexural strength, elastic modulus, water sorption, water solubility, microshear bond strength to dentin, immediate microleakage, and radiopacity. The microshear bond strength to dentin and microleakage of Cention N were evaluated with and without the application of an adhesive system (Tetric N Bond Universal). A one-way ANOVA test was used to analyze the data in terms of degree of conversion, KHN ratio, water sorption, water solubility, microshear bond strength to dentin, and radiopacity. A two-way ANOVA test (carried out considering the material type and ethanol aging as factors) was used to analyze the data in terms of flexural strength and elastic modulus. The Kruskal-Wallis test was used to statistically analyze the data on microleakage. A significance level of α=0.05 was used for all tests. Fuji II LC was found to have the highest degree of conversion, water sorption, and microleakage, as well as the lowest flexural strength. Cention N had the highest solubility; when used with an adhesive system, it achieved bond strength and microleakage similar to those of the Tetric N Ceram composite. Tetric N Ceram had the highest degree of conversion, KHN ratio, and radiopacity. Conclusion: The properties of Cention N validate its efficacy as an alternative direct restorative material when used in conjunction with an adhesive system.

A Comparative Evaluation of Dissolution Rate of Three Different Posterior Restorative Materials used in Pediatric Dentistry: An In Vitro Study.

The study aimed to compare and assess the dissolution rate, color stability, and other mechanical parameters, such as compressive and flexural strength, of three distinct posterior restorative materials used in pediatric dentistry. The three posterior restorative materials used in pediatric dentistry are divided into group I-Zirconomer, group II-Composite, and group III-Cention N. Around 111 cylindrical specimens were grouped into three groups of 37 each. According to the manufacturer's standards, all materials were proportioned and handled. The materials were thermocycler in a chewing simulator and were subjected to various tests to estimate the dissolution rate, compressive strength, flexural strength, and color stability of the three individual groups. The dissolution rate was highest in Zirconomer, followed by Cention N and Composite, which were highly significant (p = 0.05). Compressive strength was highest with Cention N, followed by Composite and Zirconomer, which was highly important (p = 0.05). Cention N had the greatest flexural strength, followed by Composite and Zirconomer, which were highly significant (p = 0.05). Finally, the Composite had the highest color stability, followed by Cention N and Zirconomer among the three groups. It is concluded that resin-based restorative materials outperform glass ionomer-based Zirconomer cement in terms of dissolution rate, compressive strength, flexural strength, and color stability. Because of the widespread improvement in dental materials, many dental restorative types of cement have emerged on the market. The features of good restorative materials are mechanical strength, fluid dissolution rate, and retention. Raman V, Srinivasan D, AR SE, et al. A Comparative Evaluation of Dissolution Rate of Three Different Posterior Restorative Materials used in Pediatric Dentistry: An In Vitro Study. Int J Clin Pediatr Dent 2023;16(S-1):S20-S26.

Microtensile Bond Strength of Packable and Flowable Bulk-fill Composite Resin-based Restorative Materials to Dentin

Microtensile Bond Strength of Packable and Flowable Bulk-fill Composite Resin-based Restorative Materials to Dentin

Effect of Acidic Beverages on the Hardness, Elastic Modulus and Wear Resistance of Giomer and Nongiomer Bulk-fill Materials.

The aim of this study was to evaluate and compare the effect of acidic beverages on the hardness, elastic modulus, and wear resistance of four different resin-based restorative materials. A total of 128 specimens (10 mm diameter, 4 mm thickness) were prepared from a conventional resin composite (Filtek Z250 [Z250]), a giomer bulk-fill (Beautifil Bulk Restorative [BBR]) and two nongiomer bulk-fill materials (Tetric N-Ceram Bulk Fill [TNC] and SonicFill 2 [SF2]). Each material group was divided into four subgroups (n=8) according to the storage media: artificial saliva (control), orange juice, regular Coke, and sports drink. The experimental specimens were immersed in the solutions for 30 minutes, five times a day for 5 days and kept in artificial saliva for an hour between the immersion periods. Control specimens were stored in artificial saliva for 5 days. The nanoindentation test with a Berkovich diamond tip was used to determine the hardness and elastic modulus before and after the 5-day storage periods. Following the nanoindentation tests, the specimens were subjected to a chewing simulator for 120,000 cycles. The specimens were then scanned with a three-dimensional scanner. The wear resistance was analyzed by measuring the volume and height loss. Specimens were observed by environmental scanning electron microscopy. The statistical analyses were performed by analysis of variance, Tukey HDS test, and paired samples t-test (α=0.05). Z250 showed significantly higher elastic modulus in all groups (p<0.05). After erosive cycles, the greatest decrease in hardness and elastic modulus was observed for BBR. TNC showed higher wear resistance than the other resin-based materials (p<0.05). The BBR specimens immersed in acidic solutions showed higher wear rates than the artificial saliva group (p<0.05). Conventional resin composite showed higher hardness and elastic modulus than bulk-fill materials when exposed to acidic beverages but comparable or lower wear resistance. Degradation due to acidic beverages most affected the mechanical properties of giomer bulk-fill.

Intracoronal tooth bleaching - A review and treatment guidelines.

Intracoronal bleaching is a minimally invasive procedure that was introduced into dentistry in the 19th century. The role of that procedure in enhancing the colour of teeth subjected to internal discolouration while being conservative made it extremely popular amongst dental professionals. Different materials and techniques have been utilized over the years attempting to obtain predictable long-term results while minimizing any associated risks. Contemporarily, bleaching agents are mainly based on peroxide-releasing compounds in different formulations and delivery systems. Different theories have been formulated on the bleaching mechanism of such agents, but the exact mechanism is yet to be proven. The effect of hydrogen peroxide-based bleaching agents on the organic structure of enamel and dentine has been extensively investigated to address the effects of bonding of resin-based restorative materials to hard tooth structure. Multiple case reports raised a concern about the contribution of intracoronal bleaching in developing invasive root resorption. Modification of intracoronal bleaching techniques was thus necessary to address such concerns. This review will provide a summary of the important aspects of intracoronal bleaching, focusing on how it applies to the contemporary clinical setting. © 2023 Australian Dental Association.

Predictable esthetics in hybrid and resin-based CAD/CAM restorative materials: Translucency as a function of material thickness.

The CAM of esthetically pleasing monolithic dental restorations presents with specific challenges. One vital parameter to consider is the translucency of the materials. Previous studies have proven a correlation between translucency and material thickness for various all-ceramic materials. The aim of the present study was to assess and define the relationship between thickness and translucency in modern resin-based restorative materials. Specimens fabricated from two resin nano-ceramics (Cerasmart, Lava Ultimate), a polymer-infiltrated ceramic network (Vita Enamic), and a polymethyl methacrylate (Telio CAD) were examined, representing these different material classes. For each material, 12 specimens (n = 12) were fabricated in five thicknesses (0.4, 0.7, 1.0, 1.3, and 1.6 mm; N = 240). The translucency was measured with a spectrophotometer. The total light transmittance for each specimen was calculated applying specialized software. Regression curves were fitted to the results and their coefficient of determination (R2) fit was determined. Logarithmic regression curves showed the best R2 approximation (Cerasmart: R2 = 0.994; Vita Enamic: R2 = 0.978; Lava Ultimate: R2 = 0.997; Telio CAD: R2 = 0.997) to the light transmission values. The results of the present study indicate that the translucency of resin-based materials can be calculated using a mathematic approach to estimate their optical behavior. Cerasmart, Lava Ultimate, Vita Enamic, and Telio CAD exhibit a logarithmic relationship between material thickness and translucency. By determining material-specific coefficients for this logarithmic function, the resulting translucency can be computed for any given material thickness.

The assessment of internal adaptation and fracture resistance of glass ionomer and resin-based restorative materials applied after different caries removal techniques in primary teeth: an in-vitro study.

The aim of this study was to evaluate the 3-dimensional (3D) internal adaptation (IA) and fracture resistance (FR) of compomer and glass ionomers applied after conventional caries removal to sound dentin (CCRSD) and selective caries removal to firm dentin (SCRFD) in in-vitro. Thirty extracted primary molars were randomly assigned to three main groups (n = 10) as glass hybrid restorative (GHR) (Equia Forte® HT), conventional glass ionomer (CGIR) (Voco Ionofil Molar) and compomer (Dyract XP). Each group was randomly divided into two subgroups according to caries removal technique as CCRSD (n = 5) and SCRFD (n = 5). The restoration procedures were completed after caries removal (CCRSD or SCRFD) in all samples. Then, specimens were subjected to IA and FR tests. Data were analyzed with Student's t, one-way ANOVA, and Kruskal Wallis-H tests. The correlation between IA and FR results was analyzed with a Pearson test. The statistical significance level was considered as 5%. While CCRSD showed superior IA results than SCRFD for all restorative materials (p < 0.05), no statistical difference was found between CCRSD and SCRFD in FR assessment (p > 0.05). In CCRSD, compomer showed superior results for IA and FR than glass ionomers (p < 0.05). In SCRFD, it was found no significant difference between the restoratives for IA (p > 0.05). However, compomer showed superior FR results than glass ionomers (p < 0.05). There was moderate negative correlation between internal voids and FR without statistically significant difference (r = -0.333, p = 0.072). Despite the advantages of SCRFD, it was found to be less superior than CCRSD in IA assessment. Therefore, when SCRFD is preferred, a peripheral seal should be provided for ideal restorative treatment. On the other hand, compomer mostly showed superior results compared to others.

Shade matching potential of one-shade resin composites used for restoration repair.

To evaluate shade matching ability of one-shade composites used for repair of different resin-based restorative materials. Two one-shade composites or one layering composite of 1 mm thickness were placed over non-aged or aged 3 different base materials of 1 mm thickness to simulate repair. Two millimeters thick base samples were prepared and used for reference (n=12). Shade measurements of reference and repair groups were performed with dental spectrophotometer and color difference (ΔE00) were calculated according to CIEDE2000. Data were analyzed using three-way ANOVA followed by Tukey's test (α=0.05). Regardless of aging and base materials, repairing with layering composite yielded lower ΔE00 than repair of one-shade composites (p<0.05). Repair of non-aged and aged GrandioDisc with any repair composite led to higher ΔE00 values than repair of other base materials (p<0.05). Shade matching performance of one-shade composites for repair of different non-aged or aged resin-based material was not clinically acceptable.

Tissue engineering atthe dentin-pulp interface using human treated dentin scaffolds conditioned with DMP1 or BMP2 plasmid DNA-carrying calcium phosphate nanoparticles.

Hard dental tissue pathologies, such as caries, are conventionally managed through replacement by tooth-colored inert biomaterials. Tissue engineering provides novel treatment approaches to regenerate lost dental tissues based on bioactive materials and/or signaling molecules. While regeneration in the form of reparative dentin (osteo-dentin) is feasible, the recapitulation of the tubular microstructure of ortho-dentin and its special features is sidelined. This study characterized in vitro, and in vivo human EDTA-treated, freeze-dried dentin matrices (HTFD scaffolds) conditioned with calcium phosphate nanoparticles (NPs) bearing plasmids encoding dentinogenesis-inducing factors (pBMP2/NPs or pDMP1/NPs). The uptake and transfection efficiency of the synthesized NPs on dental pulp stem cells (DPSCs) increased in a concentration- and time-dependent manner, as evaluated qualitatively by confocal laser microscopy and transmission electron microscopy, and quantitatively by flow cytometry, while, in parallel, cell viability decreased. HTFD scaffolds conditioned with the optimal transfectability-to-viability concentration at 4µg Ca/mL of each of the pBMP2/NPs or pDMP1/NPs preserved high levels of cell viability, evidenced by live/dead staining in vitro and caused no adverse reactions after implantation on C57BL6 mice in vivo. HTFD/NPs constructs induced rapid and pronounced odontogenic shift of the DPSCs, as evidenced by relevant gene expression patterns of RunX2, ALP, BGLAP, BMP-2, DMP-1, DSPP by real-time PCR, and acquirement of polarized meta-mitotic phenotype with cellular protrusions entering the dentinal tubules as visualized by scanning electron microscopy. Taken together, HTFD/NPs constitute a promising tool for customized reconstruction of the ortho-dentin/odontoblastic layer barrier and preservation of pulp vitality. STATEMENT OF SIGNIFICANCE: In clinical dentistry, the most common therapeutic approach for the reconstruction of hard dental tissue defects is the replacement by resin-based restorative materials. Even modern bioactive materials focus on reparative dentinogenesis, leading to amorphous dentin-bridge formation in proximity to the pulp. Therefore, the natural microarchitecture of tubular ortho-dentin is not recapitulated, and the sensory and defensive role of odontoblasts is sidelined. This study approaches the reconstruction at the dentin-pulp interface using a construct of human treated dentin (HTFD) scaffold and plasmid-carrying nanoparticles (NPs) encoding dentinogenic factors (DMP-1 or BMP-2) with excellent in vitro and in vivo properties. As a future perspective, the HTFD/NPs constructs could act as bio-fillings for personalized reconstruction of the dentin-pulp interface.

Mechanical Properties of Giomer After Immersion in Carbonated Drinks

&#x0D; Introduction: Giomer is a resin-based restorative material consisting of prereacted glass ionomer (PRG) filler which can release fluoride. Carbonated beverages, popular beverages which contain acids that rich in H+ ions, can diffuse into the resin-based restoration and cause high solubility. Objective: To analyze the effect of immersion in carbonated drinks on water absorption and diametral tensile strength of giomer. Methods: Giomer was packed into a stainless-steel mold to obtain sample with diameter of 6.0±0.03mm and height of 3.0±0.09mm. The samples were divided into 2 groups for water absorption test and 3 groups for diametrical tensile strength test. Ten samples of giomer were soaked in artificial saliva for 4 days as a control group, 10 giomer samples were immersed in carbonated drinks for 6 hours, then replaced with artificial saliva for 18 hours and repeated for 4 days as a treatment group, and 10 samples of giomer were used as immediate group for direct diametral tensile strength test. Samples were incubated at 37°C. Results: Mann-Whitney test showed no significant difference (p&gt;0.05) in giomer absorption between the control group (0.99±0.54%) and the treatment group (2.37±2.62%). One Way ANOVA test showed significant difference (p&lt;0.05) in giomer diametral tensile strength among the immediate group (29.6±3.7MPa), the control group (51.1±3.9MPa) and the treatment group (44.8±5.3MPa). Conclusion: Immersion in carbonated beverages did not show significant difference with artificial saliva for the water absorption ability of giomer. However, the diametral tensile strength of giomer decreased after immersion in carbonated beverages for 24 hours.

Effect of topical fluoride applications on residual monomer release from resin-based restorative materials

BackgroundThe effects of topical fluoride applications on the release of monomer ingredients from resin-based dental materials by immersion in various extraction solutions are unclear. The aim of this study was to determine the effect of topical fluorides (APF and NaF) on the elution of residual monomers (Bis-GMA, TEGDMA, UDMA, and HEMA) from resin-based materials.MethodsNinety specimens were prepared, 30 bulk-fill composite resin, 30 nanohybrid universal composite resin, and 30 polyacid-modified composite resin (compomer). These were randomly divided into three groups based on fluoride application procedures. Each specimen was kept in 75% ethanol solution, and residual monomers released from materials were analyzed using high-performance liquid chromatography (HPLC) after 10 min, 1 h, 24 h, and 30 days. The groups were compared using the Mann Whitney U and Kruskal Wallis tests. Measurements were analyzed using the Friedman and Wilcoxon signed-rank tests.ResultsFluoride applications generally had no considerable effect on the amount of residual monomer released from resin-based restorative materials. The amount of monomer release after topical APF application was similar to the release in the control group and was lower than the release in the NaF group. The release of monomers from the resin-based material used in the study did not approach toxic levels at the applied time intervals. The compomer released lower amounts of monomer than other resin-based materials.ConclusionsFluoride applications do not increase monomer release from resin-based restorative materials. However, compomers should be employed by clinicians due to their lower monomer release compared to other resin restorative materials. The release of monomers from all the resin-based materials did not approach toxic levels at the applied time intervals.

Influence of Three Different Curing Devices on Microleakage of Two Fluoride-Containing Resin-based Restorative materials .

Influence of Three Different Curing Devices on Microleakage of Two Fluoride-Containing Resin-based Restorative materials .

Towards the development of biostable dental resin systems - design criteria and constraints beyond ester-free chemistries.

The objective of this review article is to summarize the current literature on dental resin-based restorative (RBR) materials specifically from the perspective of emerging resin technologies, and to provide researchers with structured design criteria enabling the effective screening of new RBR developments. The continued failure of newly introduced RBRs to address biostability without compromising function, over the last decade, are presented as a rationale to support different resin-based concepts. Several developments in the field, aimed at addressing the issues facing modern resin-based systems are summarized and their limitations discussed. A design workflow is proposed for evaluating new RBR, considering resource needs. While several alternative resin chemistries have been suggested over the past decade, all have shown serious limitations in replacing MA-based materials, including their limited physical and mechanical properties, and curing kinetics. Additionally, a broad and inconsistent range of laboratory methods have been used to validate these developments, leading to results that are difficult to compare across studies. A design workflow was conceptualized to facilitate the screening of novel RBRs from both a clinical and research perspective. While several alternative chemistries have shown some degree of potential in emulating material property aspects of MA-based resins, a complete restorative system that is resistant to biochemical reactions in saliva has yet to achieve broad clinical adoption. To further spur development, it would be useful to have a more systematic design workflow, that may be used to easily screen new resin technologies effectively early in the design phase, so as to mitigate potential performance failures in the clinic.

Effect of Polymerization on the Color of Resin Composites.

The initial shade of a resin-based restorative material should be the same as that after polymerization. In this study, the color changes of translucent and opaque composites from nine different brands were assessed after polymerization using a spectrophotometer and cross-polarization (CP) photography. Thirteen nano-hybrid (Essentia LE, GC Corp; Ceram.x Duo SphereTEC A2E/A2D, Dentsply Sirona; Harmonize A2E/A2D, Kerr Dental; IPS Empress Direct A2E/A2D, Ivoclar Vivadent; Mosaic EN/A2, Ultradent Products; Clearfil Majesty Es-2 A2E/A2D, Kuraray Noritake; Charisma Topaz A2/OL, Kulzer), two supra nano-hybrid (Estelite Asteria NE/A2B; Tokuyama), two nano-filled (Filtek Ultimate A2E/A2D; 3M) light-curing resin composites, and one micro-hybrid (Essentia MD, GC Corp) light-curing resin composite were tested. Disc-shaped specimens (n=5) were prepared using silicone molds (12 × 5 mm) and polymerized from both sides using an LED curing light (Elipar Deepcure S, 3M) at a light intensity of 1470 mW/cm2. Measurements were performed before and 1 day after polymerization using a contact-type dental spectrophotometer (Easy Shade 5, VITA Zahnfabrik, Bad Säckingen, Germany) and a combination of CP photography and Photoshop CC software (Adobe Inc, San Jose, CA, USA). Spectrophotometry and CP photography ΔE* values were calculated; the perceptibility threshold was a ΔE* value of 1.2. VITA spectrophotometry color change scores were also calculated and evaluated. The overall ΔE* values ranged between 0.34 and 12.56. Two-way analysis of variance (ANOVA) showed that color change was associated most strongly with composite brand (p<0.001), followed by shade (p=0.002). Color change (p=0.002) and degree of darkening/lightening (p<0.001) were significantly greater for dentin compared to enamel shades. Clearfil Majesty Es-2 (Kuraray Noritake) showed significant lightening, whereas all other composites showed darkening after polymerization. All composite brands presented perceptible (ΔE*≥1.2) color changes. Estelite Asteria (Tokuyama), Ceram.x Duo SphereTEC (Dentsply Sirona), and Harmonize (Kerr Dental) were considered the most reliable brands regardless of the shade. The spectrophotometry and CP photography methods were positively correlated (p<0.001). Also, CIEDE2000 and CIELCH (also referred to as CIE L*c*h) color systems were positively correlated based on the ΔE* values (p<0.001). Despite improvements in the chemical composition of, and fillers for, contemporary resin-based composites (RBCs), all tested composite brands showed perceptible color change after polymerization, except for some shades. Under the conditions in this study, it is preferable to polymerize the composite during the trial phase, before identifying the most appropriate shade. CP photography in combination with Photoshop analysis appears to be a reliable and promising approach for color evaluation.

Effects of staining and artificial aging on optical properties of gingiva-colored resin-based restorative materials

ObjectivesTo evaluate CIEDE2000/CIELAB differences in color (ΔE00/ΔEab), and translucency parameter (ΔTP00/ΔTPab), and gloss of gingiva-colored resin-based restorative materials upon staining/aging.Materials and methodsDisc-shaped, 10 mm in diameter, and 2-mm-thick samples (n = 5/group) were made from giomer (Beautifil II gingiva), oligomer-based (crea.lign GUM gel), CAD/CAM polymethyl-methacrylate-based (IvoBase CAD), PMMA-based (ProBase Hot), and dimethacrylate-based (SR Nexco Paste Gingiva). Color and gloss were recording using a benchtop spectrophotometer and gloss meter, respectively, at baseline (T0), and upon staining in coffee or red wine for 60 (T1) and 120 h (T2), or artificial aging of 150 kJ/m2 (T1) and 300 kJ/m2 (T2). Three-way analysis of variance (materials x staining conditions x time intervals), Tukey’s test (α = 0.05), and Pearson’s correlation test were used in analytical statistics.ResultsCIEDE2000 color differences ranged from 1.0 to 4.4 (coffee), 1.5 to 5.3 (wine), and 0.9 to 2.0 after artificial aging, with ΔE00 values being significantly higher for Beautifil than other materials (p < 0.05). ΔTP00 values ranged from 0.2 to 0.7 and were statistically higher upon staining in wine compared to artificial aging (p < 0.05). Gloss values at T0 were 76.7–87.0. Beautifil exhibited the lowest gloss retention (50.8–60.2%) after staining, compared to > 90% of other materials (p < 0.05). ΔE00/ΔEab and ΔTP00/ΔTPab were positively correlated (p < 0.0001).ConclusionsColor, translucency, and gloss changes of gingiva-colored restorative materials were material- and staining/aging-dependent. Generally, wine caused greatest changes in color (with IvoBase CAD being the most color stable) and translucency parameter. All materials except Beautifil gingiva II exhibited staining- and aging-dependent gloss retention greater than 90% for all compared time intervals.Clinical relevanceOptical properties of resin-based gingiva-colored restorative materials depend on material, staining/aging conditions, and exposure time. Certain materials should be avoided in individuals with high consumption of red wine and coffee.