In Vitro Evaluation of the Effect of Different Luting Cements and Tooth Preparation Angle on the Microleakage of Zirconia Crowns

Bond strength and surface roughness assessment of novel antimicrobial polymeric coated dental cement

Resin cement integrated with zein-incorporated magnesium oxide nanoparticles has previously been found to inhibit oral microbes and decrease bacterial biofilm. However, the bond strength and surface features of this biomaterial have yet to be investigated. The objective of this study was to evaluate the shear bond strength, mode of fracture, and surface roughness of resin cement modified with zein-incorporated magnesium oxide nanoparticles. Characterization of the cement was performed by X-ray diffraction, field emission scanning electron microscopy, and Fourier transform infrared spectroscopy. 126 human teeth were divided into 3 groups and cemented to lithium disilicate ceramic using resin cement with zein-incorporated magnesium oxide nanoparticles at concentrations of 0%, 1%, and 2% (n = 42). 21 samples of each group were subjected to the shear bond strength test, while the other 21 underwent thermocycling for 10,000 cycles before the test, after which all samples were evaluated for the mode of fracture. To assess surface roughness, resin cement disks were analyzed by a profilometer before and after undergoing thermocycling for 10,000 cycles. The shear bond strength of the cement with 1% and 2% nanoparticles was significantly higher than the control before thermocycling. The mode of fracture was found to be mainly adhesive with all groups, with the unmodified cement presenting the highest cohesive failure. There was no significant difference in surface roughness between the groups before or after thermocycling. The addition of zein-incorporated magnesium oxide nanoparticles to resin cement improved or maintained the shear bond strength and surface roughness of the resin cement.

Evaluation of Microleakage Using Different Luting Cements in Kedo Zirconia Crowns: An In Vitro Assessment

Introduction A space between the prepared tooth and the cemented crown can cause microleakage, allowing microorganisms to enter, which in turn leads to the breakdown of the luting cement. To achieve an optimum fit, several factors should be considered, including the type of crown used, the taper of tooth preparation, and the type of cementing agent. Aim The purpose of the current study is to evaluate the microleakage of zirconia crowns cemented with glass ionomer cement (GIC), resin-modified GIC (RMGIC), and self-adhesive resin cement. Materials Forty-five primary mandibular molars were divided into three groups: Group I receiving GIC, Group II receiving RMGIC, and Group III receiving self-adhesive resin cement. These cements were used to lute the teeth with Kedo zirconia crowns. The restored samples underwent thermal cycling and were assessed for microleakage under a stereomicroscope. For the statistical analysis, SPSS version 23.0 was used. Descriptive statistics were presented as frequencies and percentages. Analytical statistics, including the Mann Whitney U test, were used to assess the differences in the level of microleakage between the groups at p < 0.05. Results The Mann Whitney U test revealed no significant difference in the level of microleakage between GIC and RMGIC (p = 0.072). However, self-adhesive resin cement showed significantly less microleakage than GIC (p = 0.000). Similarly, when comparing RMGIC and self-adhesive resin cement, the latter showed significantly less microleakage than the former (p = 0.001). Conclusion Microleakage of Kedo zirconia crowns on mandibular first molars was highest when luted with GIC, followed by RMGIC, and was least when luted with self-adhesive resin cement.

Replacement of unsatisfactory ceramic veneers with the aid of a digital workflow

This case report focuses on the replacement of ceramic laminate veneers with suboptimal marginal fit and design, employing a digital workflow and CAD-CAM technology. The patient, a woman in her 30s, expressed concerns about the appearance and hygiene challenges of her existing veneers. A comprehensive assessment, including clinical examination, facial photographs and intraoral scanning, was conducted. Utilising CAD software, facial photographs and 3D models merged to create a digital wax-up, crucial in designing suitable veneers and addressing issues like overcontouring and a poor emergence profile. Following the removal of old veneers, a mock-up was performed and approved. Preparations ensured space for restorations with well-defined margins. The final restorations, milled with Leucite-reinforced vitreous ceramic, were cemented. At the 1 year follow-up, improved aesthetics, gingival health and functional restorations were observed. This report highlights the efficacy of digital workflows in achieving consistent and aesthetically pleasing outcomes in ceramic laminate veneer replacement.

Microleakage of Lithium Disilicate Veneers Bonded to Different Substrates with Light-cure and Dual-cure Resin Cements

Background

This study aimed to evaluate the microleakage of lithium disilicate veneers with finish lines placed cervically in different substrates (enamel, dentin, and resin composite) and bonded with light-cure (LC) and amine-free dual-cure (DC) resin cements.

Material and Methods

Forty-eight human maxillary central incisors were randomly assigned into three groups according to finish line substrate (n=16/group). Each group was subdivided randomly into two subgroups (n=8/subgroup) according to resin cement type: LC resin cement (Variolink Esthetic LC, Ivoclar Vivadent) and DC resin cement (Variolink Esthetic DC, Ivoclar Vivadent). All the specimens received lithium disilicate veneers (IPS e.max Press, Ivoclar Vivadent). After 5000 cycles of thermocycling, the microleakage was measured using the dye penetrating technique. Data were analyzed statistically using Scheirer Ray Hare test, Kruskal-Wallis H-test, and Mann-Whitney U-test. The level of significance was set at p ≤ .05.

Results

There was a statistically significant difference between different substrates in microleakage (p=.001), but there was no statistically significant difference between resin cements (p=.907), and there was no interaction between substrates and resin cements (p=.983). Microleakage was lesser when the finish line was placed at enamel and resin composite than at dentin. Similar leakage scores were observed with LC and DC resin cements.

Conclusions

The finish line of ceramic veneer is suggested to be placed in enamel or good-quality resin composite restoration. Regarding microleakage and durability, LC and amine-free DC resin cements are suggested for ceramic veneer cementation. Key words:Different substrates, Dual-cure resin cement, Light-cure resin cement, Lithium disilicate veneers, Microleakage.

Evaluation of Marginal and Internal Fit of Ceramic Laminate Veneers Fabricated with Five Intraoral Scanners and Indirect Digitization

The long-term success of ceramic laminate veneers (CLVs) is influenced by the marginal and internal fit of the restorations. However, studies comparing the fit of CLVs using different intraoral scanners or the indirect digitization technique are lacking. The purpose of this study was therefore to assess the marginal and internal fit of CAD/CAM-milled CLVs using different intraoral scanners and the indirect digitalization technique. An ivorine typodont maxillary left-central incisor was prepared; the tooth and the neighboring teeth were scanned and used as a template to print ninety 3D partial models. Thereafter, ceramic laminate veneers (CLVs) (N = 90) were milled from IPS-Emax CAD blocks and divided into six equal groups (15 specimens each) according to the type of intraoral scanner (IOS), as follows: Omnicam IOS, SC3600 IOS, Trios 3 IOS, Emerald IOS, I500 IOS. Fifteen further CLVs were fabricated using the conventional indirect digitalization technique. After cementation on the resin dies and embedding in clear epoxy resin, specimens were sectioned inciso-gingivally and mesio-distally. At the incisal and cervical positions, the marginal discrepancy was measured and evaluated in addition to the internal gap at six locations using SEM (200×). Differences between gap measurements among the six groups were determined using ANOVA. Games-Howell multiple comparisons for homogenous variances and LSD multiple comparisons for non-homogenous variances were used with 95% confidence intervals. The significance level was set at 0.05. The lowest mean absolute marginal gap at the incisal margins (AMGI) was recorded for Omnicam group (203.28 ± 80.14) µm, while the highest mean absolute marginal gap at the cervical margins (AMGC) was recorded for Omnicam group (147.16 ± 59.78) µm. The mean AMGC was reported to be significantly different between the conventional technique (146.75 ± 38.43) µm and Trios 3 (91.86 ± (35.51) µm; p = 0.001) and between Emerald (112.37 ± (50.31) µm; p = 0.042) and I500 (86.95 ± (41.55) µm; p < 0.001). The mean MGI was found to be significantly different between the conventional technique (114.11 ± (43.45) µm and I500 group (186.99 ± (73.84) µm) only (p = 0.035). However, no significant differences were found in the mean MGI between all types of IOSs. The means of AMG and MG were significantly different at incisal or cervical areas between the conventional technique and IOSs and within the scanner groups (p > 0.05). Marginal gaps were higher in the incisal region compared to the cervical region with both the indirect digitization technique and the IOSs. Ceramic laminate veneers (CLVs) fabricated using IOSs produced overall internal and marginal fit adaptation results comparable to CLVs fabricated from the indirect digitalization method, and both techniques produced clinically acceptable results.

Update on Dental Luting Materials

A dental luting material aids in the retention and stability of indirect restorations on the prepared tooth structure. In dentistry, clinicians are using a wide range of luting materials for the cementation of indirect restorations. Zinc oxide eugenol and non-eugenol cements, zinc phosphate cement, zinc polycarboxylate cement, glass ionomer cement and resin cements are common dental cements used in dentistry. Each luting material or cement possesses unique properties and clinical implications. An ideal luting cement should be biocompatible, insoluble, resistant to thermal and chemical assaults, antibacterial, aesthetic, simple and easy to use. It should have high strength properties under tension, shear and compression to resist stress at the restoration-tooth interface, as well as adequate working and setting times. So far, no luting material possesses all of these properties of an ideal cement. Scientists have been modifying the conventional luting cements to improve the material's clinical performance and developing novel materials for clinical use. To achieve the best clinical outcome, clinicians should update their knowledge and gain a good understanding of the luting materials so that they can make a wise clinical decision on the material selection and obtain an insight into the development of luting cements. Therefore, the objective of this study is to provide a discussion on the physical, chemical, adhesive and aesthetic properties of common luting materials. The clinical indications of these luting materials are suggested based on their properties. In addition, overviews of the modification of the conventional luting materials and the newly developed luting materials are provided.

Triple scan evaluation of internal and marginal adaptation of overlays using different restorative materials

OBJECTIVE

Problems in the confection of indirect restorations may increase the marginal and internal gap. This study aimed to quantify the marginal and the internal fit of overlays fabricated with three different materials.

MATERIALS AND METHODS

Standardized cavities were prepared on endodontically treated human third molars and digital impressions were done using an intraoral camera (Trios 3). Restorations were designed (n = 15) and fabricated with three materials: Hybrid ceramic (Cerasmart; GC Corp, EUROPE), high-strength lithium disilicate (GC Initial® LiSi Press; GC Corp, Tokyo, Japan), and zirconia reinforced Lithium Silicate Glass Ceramic (Vita Suprinity; Vita, Germany). Axial, marginal, pulpal, and gingival gaps were calculated by measuring the distance between the restoration and the tooth at several reference points. Two-Way analysis of variance was used for statistical analysis. The significance level was set at α = 0.05.

RESULTS

Mean gap was significantly influenced by the material (p < 0.001), gap localization (p < 0.001), and interaction between the factors (p = 0.002). For all materials, the highest gap was observed at gingival and pulpal surfaces (p ≤ 0.015). LiSi Press achieved the overall lowest values at axial values measurements (p ≤ 0.003).

CONCLUSIONS

The performance of a CAD/CAM system relative to marginal adaptation is influenced by the restorative material used. High-strength lithium disilicate seems to be showed the best marginal adaptation.

CLINICAL SIGNIFICANCE

Marginal and internal adaptation of CAD/CAM restorations could be influenced by the type of material chosen.

Internal and Marginal Adaptation of Adhesive Resin Cements Used for Luting Inlay Restorations: An In Vitro Micro-CT Study

Adequate internal adaptation and marginal sealing of resin luting cements are of particular importance for the success of cemented ceramic inlays. The purpose of this study was to investigate the initial adaptation of different resin cements at the tooth-inlay restoration interface at enamel versus dentin surfaces. Thirty-two extracted human molars were allocated to four groups. One Class II cavity was prepared in each tooth. In each group, half of the cavities’ gingival floors were on enamel while the other halves were on cementum. Lava Ultimate CAD/CAM inlays were luted to the cavities using the following adhesive systems: RelyX Unicem, RelyX Ultimate, eCement, and Variolink Esthetic DC. After staining teeth with silver nitrate solution, marginal and internal gap volumes were determined using micro-CT images. Statistical analyses were conducted by independent t test and one-way ANOVA followed by post hoc Tukey test (p < 0.05). The internal and marginal gap volume values were the highest for Variolink Esthetic DC at the dentin surface (0.629 ± 0.363) and (2.519 ± 1.007), respectively, and the lowest for RelyX Unicem at the enamel surface (0.005 ± 0.004) and (0.009 ± 0.003), respectively. The internal and marginal adaptation on the enamel surface for RelyX Unicem and RelyX Ultimate resin cements were comparable to each other and to eCement but significantly better than Variolink Esthetic DC cement. Regardless of the adhesive resin system used, adaptation on enamel is superior to that on dentin surfaces.

Comparison of Microleakage in Nanocomposite and Amalgam as a Crown Foundation Material Luted with Different Luting Cements under CAD-CAM Milled Metal Crowns: An In Vitro Microscopic Study

Microleakage is a persistent problem despite advancement in materials and techniques in fixed prosthodontics. This leads to the importance of sound crown foundation material and luting agents used to maintain the marginal seal. The literature is deficient with studies, comparing microleakage under various crown foundation materials and luting agents, especially with CAD-CAM (computer-aided design and computer-aided manufacturing) metal crowns. This study was aimed to compare microleakage in a nanocomposite/dentinal bonding agent and amalgam/cavity varnish as crown foundation materials luted with two different luting cements: resin-reinforced glass ionomer cement and self-adhesive resin cement, under both dry and contaminated conditions. A hundred intact, caries-free human molars were prepared to receive crown foundation material and extra coronal restorations. Amalgams with cavity varnish and nanocomposites with dentinal bonding agent in both ideal and contaminated conditions were used as crown foundation materials. After restoration, each sample was cemented with a CAD-CAM milled metal crown using two different luting agents—resin-reinforced glass ionomer cement and self-adhesive resin cements both in ideal and contaminated conditions. Cementation was followed by thermocycling of samples, immersion in erythrosine B dye, embedding in clear auto polymerizing acrylic resin and sectioning to evaluate microleakage using stereomicroscope. The mean microleakage between different luting cements on the experimental side of the facial surface was 137.64 μm and 211.01 μm for resin-reinforced GIC and for self-adhesive resin cement was 119.78 μm and 150.42 μm, under ideal and contaminated condition, respectively. There was a significant difference in mean micro-leakage between different crown foundation material and cement groups used in the study. The composites and amalgam, both when used as crown foundation material and luted with use of technically advanced CAD-CAM metal crown with self-adhesive resin cement (in both ideal or contaminated condition), showed less microleakage than in resin-reinforced glass ionomer cement. Overall, the self-adhesive resin cement showed comparatively reduced microleakage in all combinations with different crown foundations. Thus, this combination can be used in daily clinical practice to provide better protection from further decay.

Polyacrylic Acid Nanoplatforms: Antimicrobial, Tissue Engineering, and Cancer Theranostic Applications

Polyacrylic acid (PAA) is a non-toxic, biocompatible, and biodegradable polymer that gained lots of interest in recent years. PAA nano-derivatives can be obtained by chemical modification of carboxyl groups with superior chemical properties in comparison to unmodified PAA. For example, nano-particles produced from PAA derivatives can be used to deliver drugs due to their stability and biocompatibility. PAA and its nanoconjugates could also be regarded as stimuli-responsive platforms that make them ideal for drug delivery and antimicrobial applications. These properties make PAA a good candidate for conventional and novel drug carrier systems. Here, we started with synthesis approaches, structure characteristics, and other architectures of PAA nanoplatforms. Then, different conjugations of PAA/nanostructures and their potential in various fields of nanomedicine such as antimicrobial, anticancer, imaging, biosensor, and tissue engineering were discussed. Finally, biocompatibility and challenges of PAA nanoplatforms were highlighted. This review will provide fundamental knowledge and current information connected to the PAA nanoplatforms and their applications in biological fields for a broad audience of researchers, engineers, and newcomers. In this light, PAA nanoplatforms could have great potential for the research and development of new nano vaccines and nano drugs in the future.