Evaluation of F, Ca, and P release and microhardness of eleven ion-leaching restorative materials and the recharge efficacy using a new Ca/P containing fluoride varnish

Is Cention-N comparable to other direct dental restorative materials? A systematic review with network meta-analysis of in vitro studies

OBJECTIVES

To compare the performance of Cention-N® with direct restorative materials used at the daily practice (e.g., resin-based composites/RBC, glass ionomer cements/GIC, bioactive resins, silver amalgam) via a systematic review study.

METHODS

The review followed the PRISMA-NMA recommendations, and the protocol of the review was published at osf.io/ybde8. The search was conducted in PubMed/MEDLINE, Scopus, Web of Science, Embase, Lilacs, and SciELO databases, as well as in the grey literature (Open Grey, Proquest, and Periódicos CAPES). Studies with an in vitro experimental design evaluating the characteristics and properties of Cention-N in comparison to other restorative materials were included. The risk of bias of included studies was assessed using the RoBDEMAT tool, and meta-analyses were conducted using Review Manager 5.4 and MetaInsight V3 tools.

RESULTS

A total of 85 studies were included in the review, from which 79 were meta-analyzed. Several characteristics of direct restorative materials were analyzed, including physical (color change, degree of conversion, hardness, microleakage, polymerization rate, roughness, water solubility, water sorption), mechanical (bond strength to dentin, compressive strength, diametral tensile strength, flexural modulus, flexural strength, load-to-fracture, wear), and biological (alkalinizing effect, antibacterial activity, calcium and fluoride release) properties.

SIGNIFICANCE

Cention-N presented similar physico-mechanical properties compared to RBCs, but a stronger behavior than GICs. Despite the Alkasite nature of Cention-N, GICs may still demonstrate the greatest fluoride releasing ability from all direct restorative materials. This review confirmed the adequate behavior of Cention-N when compared to several other more traditionally used materials, confirming its applicability for the permanent restoration of decayed or fractured teeth.

The Effects of Khat Chewing among Djiboutians: Dental Chemical Studies, Gingival Histopathological Analyses and Bioinformatics Approaches

This study examined the effects of khat chewing on oral gingival conditions by adopting a targeted process which combined physicochemical analyses of the teeth, histopathological examinations of the gums, and bioinformatics modeling. The physicochemical evaluation of teeth in khat consumers compared to non-consumers was carried out using specific analytical techniques; hence, the results of this initial investigation revealed significant erosion of the tooth enamel due to khat chewing, as well as an alteration of the essential chemical composition of the teeth. Additionally, the histopathological analyses complemented preliminary studies by showing severe inflammation of the gums and oral mucosa in khat users. The understanding of these studies was enriched by bioinformatics analysis, where modeling was carried out via computational methods. This analytical phase examined molecular docking mechanisms, including the interaction between cathinone, the main alkaloid of khat, and the protein receptors involved in the protection of gingival tissues against infections. In summary, this multidisciplinary research provided an in-depth view of the oral health issues related to khat chewing, combining experimental studies with bioinformatics perspectives.

Evaluation of setting kinetics, mechanical strength, ion release, and cytotoxicity of high-strength glass ionomer cement contained elastomeric micelles

BACKGROUND

Low mechanical properties are the main limitation of glass ionomer cements (GICs). The incorporation of elastomeric micelles is expected to enhance the strength of GICs without detrimentally affecting their physical properties and biocompatibility. This study compared the chemical and mechanical properties, as well as the cytotoxicity, of elastomeric micelles-containing glass ionomer cement (DeltaFil, DT) with commonly used materials, including EQUIA Forte Fil (EF), Fuji IX GP Extra (F9), and Ketac Molar (KT).

METHOD

Powder particles of GICs were examined with SEM-EDX. Setting kinetics were assessed using ATR-FTIR. Biaxial flexural strength/modulus and Vickers surface microhardness were measured after immersion in water for 24 h and 4 weeks. The release of F, Al, Sr, and P in water over 8 weeks was analyzed using a fluoride-specific electrode and ICP-OES. The toxicity of the material extract on mouse fibroblasts was also evaluated.

RESULTS

High fluoride levels in the powder were detected with EF and F9. DT demonstrated an initial delay followed by a faster acid reaction compared to other cements, suggesting an improved snap set. DT also exhibited superior flexural strength than other materials at both 24 h and 4 weeks but lower surface microhardness (p < 0.05). EF and F9 showed higher release of F, Al, and P than DT and KT. There was no statistically significant difference in fibroblast viability among the tested materials (p > 0.05).

CONCLUSIONS

Elastomeric micelles-containing glass ionomer cement (DT) exhibited satisfactory mechanical properties and cytocompatibility compared with other materials. DT could, therefore, potentially be considered an alternative high-strength GIC for load-bearing restorations.

Clinical performance of two ion-releasing bulk-fill composites in class I and class II restorations: A two-year evaluation

OBJECTIVES

This randomized clinical trial evaluated and compared the 2-year clinical performance of two ion-releasing bulk-fill composites (Cention N and Surefil One) with that of a conventional bulk-fill resin composite (Powerfil) in Class I and II cavities.

METHODS

Thirty-two patients, each with 3 Class I and/or Class II cavities under occlusion, were enrolled in this trial. A total of 96 restorations were placed, 32 for each material, as follows: a self-adhesive composite; Surefil-one, alkasite; Cention N, and a bulk-fill resin composite; Powerfil. The restorations were placed by a single operator. Clinical evaluation was performed at baseline (1-week), 6-months, 1-year, and 2-years by two independent examiners using the FDI criteria. Intergroup and intragroup comparisons were analyzed using the Kruskal-Wallis and Friedman Tests. Multiple comparisons between groups were analyzed using the Mann-Whitney and Wilcoxon-rank tests. The level of significance was set at α = 0.05.

RESULTS

Twenty-seven patients with a total of 81 restorations were evaluated at the end of the 2-years with 84.35% recall rates. Clinical success rates were 100%, 100%, and 96.3% for Powerfil, Surefil-one, and Cention N, respectively. Cention N showed a statistically significant (p < 0.05) decreased marginal integrity in comparison with resin composite at the 2-year evaluation. No recurrent decay was detected in any restoration.

CONCLUSIONS

Both ion-releasing bulk-fill composites provided acceptable clinical performance similar to bulk-fill composite in Class I and II restorations over a 2-year period.

CLINICAL RELEVANCE

The results of this trial suggests that there is a promising evidence supporting the use of ion-releasing composites.

Effect of radiotherapy on the surface roughness and microhardness of contemporary bioactive restorative materials

OBJECTIVE

The aim of this in vitro study was to evaluate the effect of radiotherapy on the surface microhardness and roughness of different bioactive restorative materials.

MATERIALS AND METHODS

A total of 60-disc specimens (5 mm × 2 mm) were performed in four groups (n = 15 each) from Equia Forte HT, Cention N, Activa Bioactive Restorative, and Beautifil II. Following the polishing procedure (600, 1000, 1200 grit silicon carbide papers), all specimens were irradiated at 2 Gy per fraction, five times a week for a total dose of 70 Gy in 30 fractions over 7 weeks. Before and after the irradiation, the specimens were analyzed regarding the surface roughness and microhardness. Surface morphology was also analyzed by scanning electron microscopy. Kruskal-Wallis test, Wilcoxon test, and paired sample t-test were used for statistical analysis.

RESULTS

Significant differences were found after radiation with increased mean roughness of both Cention N (p = 0.001) and Beautifil II (p < 0.001) groups. In terms of microhardness, only the Beautifil II group showed significant differences with decreased values after radiation. There were statistically significant differences among the groups' roughness and microhardness data before and after radiotherapy (p < 0.05).

CONCLUSION

The effect of radiotherapy might differ according to the type of the restorative material. Although results may differ for other tested materials, giomer tends to exhibit worse behaviour in terms of both surface roughness and microhardness.

CLINICAL RELEVANCE

In patients undergoing head and neck radiotherapy, it should be taken into consideration that the treatment process may also have negative effects on the surface properties of anti-caries restorative materials.

Effect of different storage media on elemental analysis and microhardness of cervical cavity margins restored with a bioactive material

Objectives

This study aimed to investigate the elemental analysis and microhardness of a bioactive material (Activa) and marginal tooth structure after storage in different media.

Materials and Methods

Fifteen teeth received cervical restorations with occlusal enamel and gingival dentin margins using the tested material bonded with a universal adhesive, 5 of them on the 4 axial surfaces and the other 10 on only the 2 proximal surfaces. The first 5 teeth were sectioned into 4 restorations each, then stored in 4 different media; deionized water, Dulbecco's phosphate buffered saline (DPBS), Tris buffer, and saliva. The storage period for deionized water was 24 hours while it was 3 months for the other media. Each part was analyzed by scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) analysis for different substrates/distances and the wt% of calcium, phosphorus, silica, and fluoride were calculated. The other 10 teeth were sectioned across the restoration, stored in either Tris buffer or saliva for 24 hours or 3 months, and were evaluated for microhardness of different substrates/areas. Data were analyzed using analysis of variance and Tukey's post hoc test.

Results

Enamel and dentin interfaces in the DPBS group exhibited a significant increase in calcium and phosphorus wt%. Both silica and fluoride significantly increased in tooth structure up to a distance of 75 μm in the 3-month-media groups than the immediate group. Storage media did not affect the microhardness values.

Conclusions

SEM-EDS analysis suggests an ion movement between Activa and tooth structure through a universal adhesive while stored in DPBS.

Effect of a demineralization model on the microhardness, surface roughness and topography of giomers: An in vitro study

The purpose of this study is to compare the effect of a demineralization model on the microhardness, surface roughness, and topography of giomers.Seventy-two discs of six different dental materials in three different presentations (pit and fissure sealant (PFS), flowable and restorative materials) were divided into six groups (n = 12 p/g). Three experimental groups (giomers) consisted of BeautiSealant, Beautifil Flow Plus, and Beautifil II, and three control groups (resin-based materials) were formed using ClinproTM, FiltekTM Z350 XT Flow, and Filtek™ Bulk Fill materials. Vickers microhardness, surface roughness, and topographic analysis with atomic force microscopy were measured at the beginning (0) after four (1) and 7 days (2) of immersion in a demineralizing model. Statistical analysis was performed using One-way and Repeated Measures ANOVA and Pearson's correlation coefficient (p ≤ .05). The microhardness values showed significant variations, except for the G_RM group. All the groups presented significant increases in roughness through the experiment stages, except for RB_PFS in the Ra parameter. The topographic analysis showed variations in the micromorphology, especially in the experimental group at the end of the demineralization model. Finally, there was no correlation between microhardness and surface roughness. The demineralization model decreased the microhardness, with the lowest reductions in the giomers groups. The effect of the demineralizing model on the surface roughness and topography showed an increase in specific patterns for the experimental and control groups. Therefore, their clinical use is recommended. RESEARCH HIGHLIGHTS: The demineralization model decreased the microhardness property of the evaluated materials, with better performance for the giomer groups. The effect of the demineralizing model on surface roughness showed an increase with specific patterns for the experimental and control groups. Although the materials presented changes in their microhardness, roughness, and topography, their clinical use is recommended.

Clinical performance of an alkasite-based bioactive restorative in class II cavities: a randomized clinical trial

OBJECTIVE

This clinical study aimed to evaluate the clinical performance of an alkasite-based bioactive material by comparing it with a resin composite (RC) in the restoration of Class II cavities over a year.

METHODOLOGY

A hundred Class II cavities were restored at 31 participants. Groups were as follows: Cention N (CN) (Ivoclar Vivadent, Schaan, Liechtenstein) and G-ænial Posterior (GP) (GC, Tokyo, Japan) in combination with G-Premio Bond (etch&rinse). Restorative systems were applied following manufacturers' instructions. They were finished and polished immediately after placement and scored based on retention, marginal discoloration, marginal adaptation, sensitivity, surface texture, and color match using modified USPHS criteria after 1 week (baseline), 6 months, and 12 months. Statistical analyses were performed using chi-square, McNemar's, and Kaplan Meier tests.

RESULTS

After 12 months, the recall rate was 87%. Survival rates of CN and GP restorations were 92.5% and 97.7%, respectively. Three CN and one GP restorations lost retention. Seven CN (17.9%) and five (11.6%) GP restorations were scored as bravo for marginal adaptation and no significant difference was seen between groups (p=0.363). One (2.7%) CN and two GP (4.7%) restorations were scored as bravo for marginal discoloration, but no significant difference was observed between groups(p=1.00). For surface texture, three (8.1%) CN and three (7%) GP restorations were scored as bravo (p=1.00). None of the restorations demonstrated post-operative sensitivity or secondary caries at any examinations.

CONCLUSION

The tested restorative materials performed similar successful clinical performances after 12 months. ClinicalTrials.gov (NTC04825379).

Surface Properties and Streptococcus mutans Biofilm Adhesion of Ion-Releasing Resin-Based Composite Materials

OBJECTIVE

To evaluate the adhesion of Streptococcus mutans (S. mutans) and related surface properties of ion-releasing resin-based composite (RBC) restorative materials.

METHODS

Two ion-releasing RBCs, Activa (ACT) and Cention-N (CN), were compared to a conventional RBC (Z350) and a resin-modified glass ionomer cement (Fuji-II-LC). Ten disk-shaped specimens were fabricated for each material (n=40). After standardized surface polishing procedure, the surface properties of the specimens were evaluated using surface roughness measurements by a profilometer and hydrophobicity using water contact angle measurements. To assess bacterial adhesion, the number of S. mutans bacteria was calculated from colony-forming units (CFU). Confocal laser scanning microscope analysis was done for qualitative & quantitative assessment. The data were analyzed using One-way ANOVA followed by Tukey's post-hoc test to compare the mean values of surface roughness, water contact angle and CFU values. To compare the mean dead cell percentage Kruskal-Wallis rank test and Conover test were used. A p-value of ≤ 0.05 was used to report the statistical significance.

RESULTS

Z350 and ACT had the smoothest surfaces, followed by CN, and the roughest surface was seen in FUJI-II-LC. The lowest water contact angles were seen in CN, and Z350, and the highest were in ACT. S. mutans counts were the highest in ACT and the lowest in Z350 and CN. CN and Fuji-II-LC registered the highest percentage of dead bacterial cells, while the lowest were in ACT.

SIGNIFICANCE

Surface properties did not significantly influence bacterial adhesion. More S. mutans bacteria accumulated on ACT than on the nanofilled composite and on CN. CN had antibacterial effects against Streptococcus mutans biofilms.

Effect of monodisperse mesoporous bioactive glass spheres (MBGs) on the mechanical properties and bioactivity of dental composites

Secondary caries is one of the main reasons for the failure of dental resin composites, and adding bioactive fillers such as bioactive glass and amorphous calcium phosphate to the resin composites has been proved to be an effective solution for this problem. In the present study, we investigated the effect of monodisperse mesoporous bioactive glass spheres (MBGs) we prepared on the mechanical properties and bioactivity of dental resins. The results revealed that compared with traditional bioactive glass (BG), MBGs fillers significantly enhanced the mechanical properties of the dental resin composites, whether they were added alone or as functional fillers together with nonporous silica particles. The dental resins filled with bimodal fillers (mass ratio of MBGs: nonporous silica = 10:50, total filler loading 60 wt%) exhibited the best mechanical performance. Their flexural strength was 37.66% higher than the samples with BG at the same filling proportion. Furthermore, the prepared MBGs possessed excellent monodispersity and sufficient apatite formation performance, and the biocompatibility of the composites were also improved by MBGs fillers. These suggest the potential use of the prepared MBGs as multifunctional fillers for the improvement of the performance of dental resins.

Leaching components and initial biocompatibility of novel bioactive restorative materials

OBJECTIVES

Bioactive restorative materials were developed on the premise that direct restorations should not only serve the purpose of reconstructing dental hard tissue defects but also exhibit biological features that prevent secondary caries development, without having adverse effects on the host cells. This study focuses on assessing the in vitro biocompatibility of two novel bioactive restorative materials.

METHODS

Specimens of the bioactive restorative materials, Cention Forte (CF) and ACTIVA BioACTIVE RESTORATIVE (AB), a glass ionomer cement/glass hybrid (EQUIA Forte HT, EF) and an established nanohybrid composite (Venus Diamond, VD) were produced and finished. The specimens were eluted in water and methanol and the resulting eluates were analyzed via gas chromatography-mass spectrometry. hGF-1 cells were exposed to eluates prepared in cell culture medium. Cellular ATP levels, oxidized glutathione concentration, caspase-3/7 activity and the inflammatory response (IL-6 and PGE₂ levels) were determined. Microscopic images were taken to examine the cell morphology.

RESULTS

Methyl methacrylate and 2-Hydroxyethyl methacrylate were the main monomers detected in CF and AB eluates. All materials inhibited cell proliferation and led to significantly reduced ATP-levels. The cells exhibited a healthy morphology in the presence of CF and AB. Cells exposed to VD showed increased oxidized glutathione levels. Only EF led to enhanced caspase-3/7 activity. CF and AB caused IL-6 levels to increase, while EF and AB led to enhanced PGE₂ levels.

SIGNIFICANCE

CF and AB are promising materials from a biological point of view and seem to have improved bioactive properties compared to glass ionomer cements.

Fluoride and Calcium Release from Alkasite and Glass Ionomer Restorative Dental Materials: In Vitro Study

This study evaluated the effect of pH and temperature on the ion (F^- and Ca²⁺) release of a resin-based material containing alkaline fillers and a self-setting high-viscous glass ionomer cement. Disks were prepared according to manufacturers' instructions for both materials: the EF group (Equia Forte HT filling, GC) and the CN group (Cention N, Ivoclar). Specimens were immersed in 50 mL buffer solution with three different pHs (4.8, 6.8, and 8.8), and stored at 0°, 18°, 37°, and 44 °C. After 24 h, 7 d, and 28 d, cumulative F^- and Ca²⁺ releases were analyzed by chromatography and mass spectrometry, and pH was measured. Both materials showed minimal changes in pH with final values after 28 d of 5.17 ± 0.56 for CN and 5.12 ± 0.24 for EF. In all experimental conditions, the percentages of ion release were higher for EF than for CF. In particular, both materials showed a significant difference in temperature in F^- release. Regardless of the pH values, the highest Ca²⁺ ion release was after 28 days, with a significant difference in temperature for CN and EF. Within the limit of this study, the temperature storage influenced ion release and the high-viscous glass ionomer showed the maximum values.

The Fluoride Ion Release from Ion-Releasing Dental Materials after Surface Loading by Topical Treatment with Sodium Fluoride Gel

The study aimed to investigate the rechargeability of ion-releasing dental material specimens immersed in distilled water for 25 months, which depleted their ion-releasing ability. Four restorative dental materials (alkasite composite, giomer, glass-ionomer, and composite material) presented with 24 specimens were studied after topical treatment with a concentrated fluoride gel. The effect of resin coating on the ion uptake and release was investigated on additional 42 specimens of restorative dental materials with coatings. The composite materials were coated with two adhesive systems, whereas the glass-ionomer was coated with the special coating resin. After topical fluoride exposure, ion release and specimen mass were measured at 1, 2, 3, 4, 5, 6, 7, and 14-day intervals using an ion-selective electrode and an analytical balance, respectively. The cumulative fluoride levels for the uncoated specimens of alkasite composite were significantly higher than those of giomer and glass-ionomer cement, with no statistically significant difference between the latter two materials. The conventional composite had the lowest cumulative concentration of fluoride ions (p < 0.05). The adhesive systems affected the fluoride recharge and reduced the ion concentrations absorbed by the specimens. Specimens coated with universal adhesive showed significantly higher ion release compared to universal fluoride-releasing adhesive or special coating resin for glass-ionomers (p < 0.05). No statistically significant change in specimen mass was observed during the 14-day period. Surface coating with adhesive systems as well as special coating resin for glass-ionomers affects the fluoride recharge process.

Periodontopathic bacterial adhesion to different restorative materials used to elevate proximal subgingival margins

This study compared the periodontopathic bacterial adhesion to four restorative materials used for deep margin elevation at 2, 24, and 48-h after incubation. Discs were produced from four restorative materials: resin modified glass ionomer, glass hybrid, flowable bulk fill resin composite, and bioactive ionic resin. Root dentin was used as control. Specimens were coated with saliva and used to culture a biofilm comprised of three strains of periodontopathic bacteria; Porphyromonas gingivalis, Prevotella intermedia, and Aggregatibacter actinomycetemcomitans. Bacterial adherence was assessed by colony count assay, crystal violet staining, and visualized using confocal laser scanning microscopy. Data were analyzed by two-way ANOVA followed by Tukey's post hoc tests. The adhesion values for the control specimens were significantly higher than for other materials, while those for the flowable bulk fill were significantly lower than for any other material within all evaluation assays. The 2-h incubation period showed the lowest adhesion values regardless of the group. The 48-h adhesion values were higher than the 24-h results in all groups except the flowable bulk fill. Microscopic imaging partially supported the findings of the measurements. In terms of periodontopathic bacterial adhesion, the tested flowable bulk fill may be preferable for subgingival use over other tested materials.

Resin-Based Bulk-Fill Composites: Tried and Tested, New Trends, and Evaluation Compared to Human Dentin

A more-and-more-accepted alternative to the time-consuming and technique-sensitive, classic, incremental-layering technique of resin-based composites (RBCs) is their placement in large increments. The so-called bulk-fill RBCs had to be modified for a higher polymerization depth and already have a 20-year history behind them. From the initial simple mechanisms of increasing the depth of cure by increasing their translucency, bulk-fill RBCs have evolved into complex materials with novel polymerization mechanisms and bioactive properties. However, since the materials are intended to replace the tooth structure, they must be comparable in mechanical behavior to the substance they replace. The study compares already established bulk-fill RBCs with newer, less-studied materials and establishes their relationship to dentin with regard to basic material properties such as hardness and indentation modulus. Instrumented indentation testing enables a direct comparison of tooth and material substrates and provides clinically relevant information. The results underline the strong dependence of the measured properties on the amount of filler in contrast to the small influence of the material classes into which they are classified. The main difference of RBCs compared to dentin is a comparable hardness but a much lower indentation modulus, emphasizing further development potential.

Development and characterization of ion-releasing fiber-reinforced flowable composite

OBJECTIVE

This study aimed to develop and characterize an ion-releasing experimental fiber-reinforced flowable composite (Bio-SFRC) and dentin treatment solution made of poly(acrylic acid) (PAA) with a high molecular weight. In addition we also evaluated the interface structure and mineralization potential between the Bio-SFRC and dentin.

METHODS

Some mechanical properties (flexural properties and fracture toughness) of Bio-SFRC in comparison with commercial inert (G-aenial Flo X) and ion-releasing materials (ACTIVA-BioActive Base/Liner and Fuji II LC) were assessed (n = 8/group). Calcium-release at different time-points was measured during the first six weeks by using a calcium-ion selective electrode. Surface analysis of composites after being stored in simulated body fluid (SBF) was investigated by using SEM/EDS. Dentin disks (n = 50) were prepared from extracted sound teeth and demineralization was simulated by acid etching. SEM/EDS was used to evaluate the microstructure of dentin on the top surface and at interface with composites after being stored in SBF.

RESULTS

Bio-SFRC showed higher fracture toughness (1.6 MPa m^1/2) (p < 0.05) compared to Flo X (1.2 MPa m^1/2), ACTIVA (1 MPa m^1/2) and Fuji II LC (0.8 MPa m^1/2). Accumulative calcium release after six weeks from Bio-SFRC (15 mg/l) was higher than other tested ion-releasing materials (≈ 6 mg/l). Mineralization was clearly seen at the interface between treated dentin and Bio-SFRC. None of the commercial tested materials showed signs of mineralization at the interface and dentinal tubules remained open.

SIGNIFICANCE

Developing such reinforced ion-releasing flowable composite and PAA solution might offer the potential for mineralization at the interface and inside the organic matrix of demineralized dentin.

Effect of adhesive coating on calcium, phosphate, and fluoride release from experimental and commercial remineralizing dental restorative materials

This study investigated the potential of adhesive coating for hindering the reactivity of ion-releasing dental restorative materials. Experimental composites were prepared by replacing 10 or 20 wt% of reinforcing fillers with two types of bioactive glass. A glass ionomer, a giomer, and an alkasite were used as representatives of commercial ion-releasing materials. Restorative material specimens were coated with an etch-and-rinse adhesive, 1-step self-etch adhesive, 2-step self-etch adhesive, or left uncoated. The specimens were immersed in a lactic acid solution and ion concentrations were measured in 4 days intervals for 32 days (atomic absorption spectrometry for calcium, UV–Vis spectrometry for phosphate, ion-selective electrode for fluoride, and pH-meter for pH values). The adhesive coating reduced ion release between 0.3 and 307 times, in a significantly material- and adhesive-dependent manner. Fluoride release was most highly impaired, with the reduction of up to 307 times, followed by phosphate and calcium release, which were reduced up to 90 and 45 times, respectively. The effect of different adhesive systems was most pronounced for phosphate release, with the following rankings: uncoated ≥ 2-step self-etch adhesive ≥ 1-step self-etch adhesive ≥ etch-and-rinse adhesive. The differences among adhesives were less pronounced for calcium and fluoride. It was concluded that the resinous adhesive layer can act as a barrier for ion release and diminish the beneficial effects of remineralizing restorative materials.

Influence of Manual and Ultrasonic Scaling on Surface Roughness of Four Different Base Materials Used to Elevate Proximal Dentin-Cementum Gingival Margins: An In Vitro Study

AIM

To evaluate and compare the effects of both manual and ultrasonic scaling on surface roughness of four different base materials, used for elevating dentin/cementum gingival margins of proximal cavities.

METHODS AND MATERIALS

Eighty human upper molars with compound Class II mesial cavities, with gingival margins 1 mm below the cemento-enamel junction (CEJ), were divided into four different groups according to the type of the base material used; resin-modified glass ionomer (RMGI), glass hybrid (HV-GIC), flowable bulk-fill resin composite (Bulk Flow) and bioactive ionic resin (Activa). This was followed by completing the restorations with the same resin composite. All materials were used according to the manufacturers' instructions. All groups were further subdivided into two subgroups according to the scaling technique: manual (hand) or ultrasonic. All restorative and scaling procedures were performed after fixation of specimens with acrylic beside neighboring teeth to simulate natural contact. The mean surface roughness (Ra, μm) of all specimens was measured quantitatively and qualitatively by a three-dimensional (3D) surface analyzer system at two stages; (1) after thermal cycling for 5000 cycles without scaling and (2) after scaling. Data were statistically analyzed using analysis of variance (ANOVA), Tukey post hoc tests, and paired sample t-tests (at α=0.05).

RESULTS

For baseline readings, the Bulk Flow group had the lowest Ra values, while HV-GIC group had the highest. RMGI and Activa groups had no statistical significant difference between their Ra values (p>0.05). For post scaling readings, hand scaling had significantly lower Ra values than ultrasonic scaling in all the material groups (p<0.05), except in the Bulk Flow group, where both scaling methods were not significantly different from each other (p>0.05).

CONCLUSION

Bulk Flow had the smoothest surfaces when cured against a matrix band compared with the other tested base materials. When hand and ultrasonic scaling methods were compared, the latter technique had more detrimental effect on the surface texture of the four tested base materials.

An alkasite restorative material effectively remineralized artificial interproximal enamel caries in vitro

OBJECTIVE

To evaluate the remineralization of artificial interproximal enamel caries (AIEC) adjacent to alkasite, high viscous glass ionomer cement (HVGIC), and resin composite in class II restorations.

MATERIALS AND METHODS

Human enamel specimens were randomly assigned to 3 groups (n = 22): Filtek™ Z350, EQUIA Forte^®, and Cention N^®. The baseline hardness was determined using a Knoop microhardness assay. AIEC was formed in the specimens, and they were placed in contact with the proximal restorative materials then subjected to a 7-day pH cycling. Microhardness was determined post-artificial caries formation and post-pH cycling. The differences in the percentage of surface hardness recovery (%SHR) between the groups were compared using the Kruskal-Wallis test. The Dunn's test was used for between-group comparisons (p < 0.05). Specimen surface morphology was evaluated using scanning electron microscopy (SEM), and the calcium, phosphorus, and fluoride contents were analyzed by energy-dispersive spectroscopy (EDS). ANOVA with the post hoc Tukey multiple comparison test was used to evaluate the differences between groups (p < 0.05).

RESULTS

The Cention N^® %SHR was the highest, followed by EQUIA Forte^®, and Filtek™ Z350. There was a significant difference in the %SHR between Cention N^® and Filtek™ Z350 (p < 0.05). In contrast, there were no significant difference between Cention N^® and EQUIA Forte^®. Significantly increased enamel surface fluoride content was observed in the Cention N^® compared with Filtek™ Z350 specimens (p < 0.05). The SEM image of the Cention N^® specimens demonstrated the greatest mineral deposition.

CONCLUSIONS

Cention N^® markedly increased the surface hardness and fluoride content of adjacent AIEC compared with Filtek™ Z350 restorations.

CLINICAL RELEVANCE

Cention N^® is a promising alternative restorative material to remineralize initial enamel lesions in approximal adjacent surfaces, especially in high-risk caries patients.

Ion release and hydroxyapatite precipitation of resin composites functionalized with two types of bioactive glass

OBJECTIVES

To prepare experimental composites with bioactive glass (BG) and investigate their release of calcium (Ca), phosphate (PO₄), and fluoride (F), as well as pH changes and apatite precipitation after immersion.

METHODS

Experimental composites were prepared with 0, 10, or 20 wt% of either BG 45S5 or a customized low-Na F-containing BG. Three commercial ion-releasing materials were used for reference. Material specimens were immersed in lactic acid (pH = 4.0) and artificial saliva (pH = 6.4). Ion concentrations (atomic absorption spectrometry for Ca, UV-vis spectrometry for PO₄, and ion-selective electrode for F) and pH were measured after 4, 8, 12, 16, 20, 24, 28, and 32 days. After immersion, composite specimens were analyzed using scanning electron microscopy (SEM) and Fourier-transform infrared (FTIR) spectroscopy.

RESULTS

Material-dependent concentrations of Ca, PO₄, and F were measured in the lactic acid solution, while a decrease of Ca and PO₄ concentrations was observed in artificial saliva. The uptake of ions from artificial saliva indicates their precipitation on specimen surfaces, which was supported by the results of SEM and FTIR investigations. In experimental composites functionalized with both bioactive glass types and a commercial "alkasite" material, apatite was precipitated not only in artificial saliva but also in the lactic acid solution.

CONCLUSIONS

Experimental BG-containing composites and selected commercial restorative materials demonstrated the potential for releasing multiple ion types and increasing pH.

CLINICAL SIGNIFICANCE

The observed effects can be beneficial for preventing demineralization and promoting remineralization of dental hard tissues, while apatite precipitation can additionally help in sealing marginal discontinuities.

Clinical Evaluation of Bioactive Restorative Material versus Resin Modified Glass Ionomer in Cervical Restorations: A Randomized Controlled Clinical Trial

Abstract: Objective: In the context of great attention given to fluoride containing restorative material and development of easily applied and reliable material for different clinical situations. This current study aimed to compare Bioactive resin-based composite (ACTIVA) to Resin modified glass ionomer (RMGI) in cervical restorations. Materials and methods:  Fuji II LC® capsules (conventional resin modified glass ionmer), or ACTIVA™ BioACTIVE-RESTORATIVE™ (enhanced resin-modified glass-ionmer) with using Etch-Rite™ and Prime&Bond universal (universal adhesive system) were applied randomly in thirty anterior teeth and six premolars with class V cavities; all materials were applied according to manufacturers’ instructions. Restorations were evaluated at baseline (one week), after six months, and after 12 months by two blinded assessors using modified USPHS criteria. Results:  The results in this study were ordinal data, so Mann-Whitney test was used to compare between tested materials. Freidman test was used to test the effect of time within tested materials. Kruskal Wallis test used to compare the interaction between variables for all tested parameters. The results were statistically significant when p≤0.05. There was no significant difference between interaction of both restorations and time in marginal discoloration (p=0.051), recurrent caries (p=1.00) and retention analysis (p=1.00), but there was a significant change in marginal adaptation (p=0.001), surface roughness (p=0.017), color change (p= 0.004) and surface luster (p=0.017) with 100 % survival rate in this study. Conclusions: Both conventional resin-modified glass ionmer and enhanced resin-modified glass ionomer are acceptable as intermediate restoration. Bioactive restorations proved to retain its esthetic characteristics over the conventional one. Bioactive restorations with an adhesive system can be used as long-term restoration in small-defined cavities, not in stress-bearing areas.   Clinical relevance: Within the limitations of this study, ACTIVA BIO-ACTIVE Restorative showed similar results to FUJI II LC in class V cavity restorations.  

Fracture and viscoelastic behavior of novel self-adhesive materials for simplified restoration concepts

OBJECTIVE

The aim of the study was to offer a comparative perspective on the mechanical and viscoelastic behavior of currently developed materials for simplified restoration concepts. These materials have not yet been clearly assigned whether they are complex hybrids of already known material categories or new material classes.

METHODS

A dual-cured, bulk-fill, bioactive resin-based composite (alkasite), a resin-modified glass ionomer cements (RM-GIC) with novel polymerizable acid polymers, and a glass ionomer cement (GIC) with improved adaptation to an acidic environment were compared with regard to their macro-mechanical parameters (3-point bending test, 3-PBT), fracture mechanism, quasi-static and viscoelastic behaviour (instrumented indentation test, IIT), morphology and structural appearance of the filler system (SEM analysis). The influence of surface finishing was quantified on the outcome of the 3-PBT, while the influence of aging and frequency was monitored on the outcome of the IIT. One and multiple-way analysis of variance (ANOVA) with Tukey honestly significant difference (HSD) post-hoc tests (α = 0.05) and Weibull analysis were applied.

RESULTS

Surface finishing strongly influenced the outcome of the 3-PBT for RM-GIC and GIC but not of the alkasite. The highest material reliability (Weibull parameter m) was found with the alkasite, irrespective of the curing mode. Ground specimens showed decrease reliability, except for the alkasite in the light-cured mode. The predominant failure mode originated from sub-surface defects (52.5%), followed by corner (25%), edge (18.1%), and crack arrest (4.4%). The effect of the parameter material on the quasi-static outcome of the IIT was highest on elastic/plastic parameters (p < 0.001; e.g. elastic indentation work, η_P² = 0.875), was moderate on the Martens Hardness (η_P² = 0.420), and was low on the Vickers hardness (η_P² = 0.218). The viscoelastic parameters, in particular the loss factor (tan δ) allow a clear documentation of the ongoing acid-base setting reaction during aging of one month, which was more pronounced in the GIC than in the RM-GIC. The decrease in tan δ with aging for GIC and RM-GIC reflects the maturation process and increased brittleness, while the increase in tan δ with aging reflects the polymer plasticization in the polymer-based alkasite.

CONCLUSIONS

The mechanical and viscoelastic behavior depending on surface refinement, aging and frequency clearly allow to classify the currently developed materials for simplified restoration concepts into known material categories such as RBCs (alkasite), RM-GIC or GIC.

Demineralization Inhibition by Two Calcium-releasing Restorative Materials

OBJECTIVE

To compare the ability of two calcium-releasing restorative materials to inhibit root dentin demineralization in an artificial caries model.

METHODS AND MATERIALS

Preparations were made at the cementum-enamel junction of extracted human molars (40, n=10/material) and restored with two calcium-releasing materials (Experimental composite, Pulpdent Corporation and Cention N, Ivoclar Vivadent), a resin composite (Filtek Supreme Ultra, 3M Oral Care), and a resin-modified glass ionomer (RMGI) (Fuji II LC, GC). All materials (other than the RMGI) were used with an adhesive (Scotchbond Universal Adhesive, 3M Oral Care) in the self-etch mode, which was light cured for 10 seconds. All restorative materials were light cured in 2-mm increments for 20 seconds and then finished with a polishing disc. Teeth were incubated (37°C) for 24 hours in water. An acid-resistant varnish was painted onto the teeth around the restoration, leaving a 2-mm border of uncovered tooth. A demineralization solution composed of 0.1 M lactic acid, 3 mM Ca3(PO4)2, 0.1% thymol, and NaOH (to adjust pH=4.5), and a remineralization solution composed of 1.5 mM Ca, 0.9 mM P, and 20 mM Tris(hydroxymethyl)-aminomethane (pH=7.0) were prepared. Specimens were placed in the demineralization solution for 4 hours, followed by the remineralization solution for 20 hours and cycled daily for 30 days. The specimens were embedded, sectioned into 100-μm sections, and the interface between the restorative material and root dentin was viewed with polarized light microscopy. A line was drawn parallel with the zone of demineralization for each tooth. The area of "inhibition" (defined as the area external to the line) or "wall lesion" (defined as the area internal to the line) was measured with image evaluation software. Areas of inhibition were measured as positive values, and areas of wall lesions were measured as negative areas.

RESULTS

A one-way analysis of variance (ANOVA) found significant differences between materials for "inhibition/wall lesion" areas in root dentin (p<0.001). Tukey post hoc analysis ranked materials (μm2, mean ±SD): Fuji II LC (5412±2754) > Cention N (2768±1576) and experimental composite (1484±1585) > Filtek Supreme Ultra (-1119±1029).

CONCLUSION

The experimental composite and Cention N materials (used with an adhesive) showed net areas of inhibition greater than a reference resin composite, albeit at a lower level than a reference RMGI material (used with no adhesive).

Remineralization potential and mechanical evaluation of a bioactive glass containing composite (An ex vivo study)

Abstract AIM: The aim of this study was to compare the remineralization ability, ion release, microshear bond strength and wear resistance of a claimed bioactive restorative material (ACTIVA BioACTIVE Restorative, Pulpdent Corporation, Watertown, USA) with the conventional resin composite (​Filtek Z350 XT, 3M ESPE Elipar, Germany). MATERIALS AND METHODS: The remineralization ability was evaluated after 28 days using Energy Dispersive X-Ray (EDX) analysis. Ion release was investigated at three-time intervals: 1, 14 and 28 days. Calcium and phosphate ions release were determined by using ion chromatography system. Microshear bond strength was assessed using Universal Testing Machine. A wear test was conducted using a dual axis chewing simulator. RESULTS: ACTIVA™ was found to induce remineralization to the demineralized dentin. Results revealed that ACTIVA™ released Ca2+ and PO4-3 ions, whilst Filtek Z350 XT did not. Concerning microshear bond strength ACTIVA™ without adhesive application showed unacceptable failure. Regarding wear resistance there was no statistically significant difference between them. CONCLUSION: ACTIVA™ bioactive restorative material seems promising bioactive restorative materials. Clinical trials are recommended to compare clinical performance of ACTIVA™ with the other restorative materials.

Scoping review of trials evaluating adhesive strategies in pediatric dentistry: where do simplified strategies lie?

BACKGROUND

Adhesive restorations allow a conservative approach to caries management and are increasingly used as a restorative option in pediatric dentistry. Placement can be difficult in children because of the cooperation required for multiple bonding steps. Due to this, it is vital to assess if novel, simpler strategies have been featured in clinical trials and if clinical trials are researching the different existing adhesive strategies.

METHODS

This review followed Preferred Reporting Items for Systematic Reviews and Meta-analysis adapted for Scoping Reviews (PRISMA-ScR) guidelines. PubMed/Medline, Cochrane Central, Scopus and EMBASE were used for systematic search, using free keywords and controlled search terms. Clinical trials of children requiring a restorative intervention which featured adhesive strategies were included. Only peer-reviewed trials of primary teeth restored with resin composites, published in the last 10-year period were eligible. Data charting was accomplished independently by two reviewers, and studies were summarized according to their date, type, intervention, sample size, observation period, outcomes and conclusions. Quality assessment was performed using Cochrane's Risk of Bias 2.0 tool.

RESULTS

700 potentially relevant references were found, which after a rigorous inclusion scheme, resulted in a total of 8 eligible clinical trials. Out of these, 7 were randomized clinical trials. Most trials featured a split-mouth design and the observation period ranged from 12 to 36 months. The trials evaluated interventions of two self-adhesive composites, two bulk-fill composites, two novel composites, one compomer and eight adhesives from different strategies. Most studies (4/8) included were judged to raise some concerns regarding risk of bias, while two were classified as high risk and two as low.

CONCLUSION

Few studies comparing adhesive strategies were found, especially adhesives in sound substrates. The existing studies do not reflect all current approaches that could be used in pediatric dentistry. Further studies addressing bioactive composites and contemporary adhesives are necessary.