Dual-cure Resin Cement Research Articles

Effect of Different Cleaning Methods on Shear Bond Strength of Resin Cement to Contaminated Zirconia

The aim of this study was to evaluate the effect of different cleaning methods on the shear bond strength (SBS) of resin cement to contaminated zirconia specimens. Eighty rectangular-shaped specimens (2 × 5 × 10 mm) were fabricated from Zirconia blocks (IPS e.max ZirCAD) and randomly divided into 8 groups (n = 10). Group A (control) was not exposed to contaminants. The following tests specimens were contaminated with saliva and silicone indicating paste. Group B was coated with ceramic primer, then subjected to contamination. Groups C, D, E, F, G, and H were contaminated; cleaned with water rinse, Ivoclean, air particle abrasion, hydrofluoric acid, KATANATM Cleaner and ZirCleanTM, respectively, and then coated with ceramic primer and bonded to dual cure resin cement cylinders. All the specimens were subjected to artificial aging and surviving specimens were subjected to the SBS test. For statistical analysis, ANOVA and multiple comparison methods at the 0.05 significance level were used. There was no statistically significant difference among Ivoclean (21.48 ± 2.90 MPa), air particle abrasion (21.92 ± 2.85 MPa), and the control group (24.68 ± 5.46). The application of ceramic primer before contamination did not preserve the SBS of resin cement to zirconia. Cleaning the contaminated zirconia surface with hydrofluoric acid (15.03 ± 3.63) or KATANATM Cleaner (17.27 ± 7.63) did not restore SBS to the uncontaminated state, but it was significantly higher than simply rinsing with water (12.46 ± 5.17) or the use of ZirCleanTM (11.59 ± 5.53). The bond strength of resin cement to zirconia was influenced by cleaning methods.

FARKLI ŞEKİLLERDE POLİMERİZE OLAN İKİ REZİN SİMANIN DEĞİŞİK SERAMİK SİSTEMLER İLE ÜRETİLEN LAMİNATE VENEERLERİN BAĞLANMA DAYANIMLARINA ETKİSİ

Amaç: Bu çalışmanın amacı; ışıkla ve dual olarak polimerize olan iki rezin simanın farklı seramik sistemleri ile üretilmiş laminate veneerlerin mikroçekme bağlanma dayanımları üzerindeki etkilerini karşılaştırmalı olarak incelemektir. Yöntemler: Altmış maksiller santral diş mine-sement birleşiminin 2 mm apikalinden akrilik rezin içine gömüldü ve laminate veneer preparasyonları tamamlandı. Restorasyonların mum modelajları 3B yazıcı yardımıyla üretildi. Dişler rastgele 3 gruba ayrıldı (n = 20) ve lityum disilikat, yüksek yoğunluklu mikronize lityum disilikat ve zirkonya ile güçlendirilmiş lityum silikat seramiklerden restorasyonlar üretildi. Seramik örnekler ayrıca rezin siman tipine göre ışıkla polimerize ve dual polimerize rezin siman olarak 2 alt gruba (n = 10) ayrıldılar ve simantasyonları yapıldı. Daha sonra dişler 1 yıllık klinik kullanıma eşdeğer hızlandırılmış yapay yaşlandırmaya maruz bırakıldı. Her dişin kronunun tam ortasından 1’er tane mikrobar elde edildi (n = 10) ve örneklere kopma gerçekleşene kadar 0,5 mm/dk yükleme hızında çekme kuvveti uygulandı. İstatistiksel analizler iki yönlü varyans analizi ve Tukey's Post-hoc testi kullanılarak yapıldı (P ≤ ,05). Bulgular: Seramik ve rezin siman alt grubundaki örnekler karşılaştırıldığında aralarında istatistiksel olarak anlamlı fark bulunmuştur (P < ,001). Zirkonya ile güçlendirilmiş lityum silikat seramiklerin mikroçekme bağlanma dayanımları hem ışıkla polimerize olan hem de dual polimerize olan rezin siman gruplarında lityum disilikat seramiklere göre anlamlı seviyede düşük bulunmuştur (P < ,001). Dual polimerize olan rezin siman grubunun bağlanma dayanımı, ışıkla polimerize olan rezin siman grubundan istatistiksel olarak anlamlı seviyede düşük bulunmuştur (P < ,001). Sonuç: Lityum disilikat laminate veneerler, zirkonya ile güçlendirilmiş lityum silikat veneerlerden daha yüksek bağlanma dayanımı göstermiştir. Yine ışıkla polimerize olan rezin siman, dual polimerize olan rezin simana göre daha etkili bağlanma dayanımı sağlamıştır. Anahtar Kelimeler: Laminate veneer, lityum disilikat, mikro gerilim bağlanma dayanımı, rezin siman, zirkonya ile güçlendirilmiş lityum silikat Abstract Objective: The aim of this study was to compare the effects of two resin cements polymerized in different ways on the microtensile bond strength of laminate veneers produced with different ceramic materials. Methods: Sixty maxillary central incisor teeth were embedded in an acrylic resin 2 mm below the enamel-cement junction and laminate veneer preparations were completed. The wax models of the restorations were produced with a 3D printer. The teeth were randomly divided into 3 groups (n = 20) and restorations were produced with lithium disilicate, high-density micronized lithium disilicate and zirconia reinforced lithium silicate ceramics. Ceramic specimens were further divided into two groups (n = 10) according to the resin cement type as light-cure and dual-cure resin cement, and their cementation was performed. The teeth were then subjected to accelerated artificial aging equivalent to 1 year of clinical use. One microbar was obtained from the middle of the crown of each tooth (n = 10) and tensile force was applied to the specimens at a loading speed of 0.5 mm/min until the fracture occurred. Statistical analyzes were performed using two-way analysis of variance and Tukey's Post-hoc test (P ≤ .05). Results: Statistically significant difference was found between the ceramic type and resin cement subgroups (P < .001). The bond strength of laminate veneers produced with zirconia reinforced lithium silicate ceramic group was found significantly lower than that of lithium disilicate ceramic’s groups in both light-cured and dual-cured resin cement groups (P < .001). The dual-cure resin cement groups showed statistically significantly lower bond strength than the light-cure resin cement groups (P < .001). Conclusion: The laminate veneers fabricated from lithium disilicate ceramics showed higher bond strength than that of zirconia reinforced lithium silicate veneers. Also, the light-cure resin cement provided more effective bond strength than dual-cure resin cement. Keywords: Laminate veneer, lithium disilicate, microtensile bond strength, resin cement, zirconia reinforced lithium silicate

Extrusion bond strength of glass fiber post to radicular dentin after final irrigation using MTAD, EDTA, Pineapple peel extract, and Riboflavin

IntroductionThe present study aims to determine the effect of different post-space final irrigants ethylenediaminetetraacetic acid (EDTA), a mixture of Doxycycline citric acid and detergent (MTAD), Riboflavin (RF) and Pineapple peel extract (PPE) on the bond integrity of GFPs bonded to radicular dentin. Materials and methodsCrowns of forty human mandibular premolars teeth were sectioned up to cementoenamel junction CEJ. Root canal treatment was performed. Gates Glidden drills were used to retrieve gutta-percha from the canal. All the specimens were randomly divided into four groups based on the final irrigant used. Group 1 (NaOCl with EDTA), group 2 NaOCl+ MTAD, group 3 NaOCl+RF and group 4 NaOCl+PPE. Cementation of glass fiber posts (GFPs) was performed using self-etch dual-cure resin cement. Sectioning was performed using a slow-speed saw from the coronal, middle, and apical third under constant water irrigation. A universal testing machine was used to assess push-out bond strength (PBS) and failure mode was evaluated using a Stereomicroscope at 40x magnification. One-way analysis of variance (ANOVA) and Tukey multiple comparison tests were used for statistical analysis (p = 0.05). ResultsGroup 4 (2.5% NaOCl+ PPE) displayed the highest PBS at all three root levels (Cervical: 11.22 ± 0.74 MPa, Middle: 8.99 ± 0.97 MPa, and Apical: 6.00 ± 0.88 MPa). However, Group 1 (2.5% NaOCl+17% EDTA) demonstrated the lowest EBS (Cervical: 9.25 ± 0.17 MPa, Middle: 7.01 ± 1.84 MPa, and Apical: 4.41 ± 0.17 MPa). Inter-group comparison displayed that PBS to be comparable between group 1 and group 3 (2.5% NaOCl+ Riboflavin) (Cervical: 9.74 ± 0.41 MPa, Middle: 7.44 ± 1.18 MPa, and Apical: 4.21 ± 0.05 MPa) (p > 0.05). Whereas, group 2 (1.3% NaOCl+ MTAD) (Cervical: 9.32 ± 1.36 MPa, Middle: 7.17 ± 1.75 MPa, and Apical: 4.85 ± 0.19 MPa) and group 4 demonstrated comparable values of PBS (p > 0.05). ConclusionPineapple peel extract and a mixture of Doxycycline citric acid and a detergent when used as a final irrigant demonstrated better bond integrity of GFPs to radicular dentin at all three levels coronal, middle and apical.

Fracture resistance of endodontically treated teeth and restored with different fiber posts in distinct diameters

Objective: The aim of this in vitro study was to evaluate the fracture resistance of endodontically treated teeth restored with different intraradicular posts (carbon fibers, glass, or quartz) with varying post diameters (narrow, medium, or large). Methodology: One hundred and twenty bovine incisors were endodontically treated and the post space was prepared. The teeth were classified according to distinct diameters post space [Narrow (0.91-1.49mm), Medium (1.5-2.08mm), Large (2.09mm-2.67mm)] and randomly allocated to four restorative treatments: control (CO) - without post; and glass fiber (GF), carbon (CF) or quartz (QF) posts. The posts were cemented with dual-cure resin cement (Duo Link, Bisco, Schaumburg, United States) and the coronary portion was reconstructed with dual-cure resin composite (Bis-Core, Bisco, Schaumburg, United States). Fracture resistance values (N) were analyzed by two-way ANOVA and Bonferroni test (α=0.05). Results: The carbon fiber post (CF) was mechanical behavior similar to the other evaluated posts, regardless of the diameter. The control group (without post) showed the highest values of fracture resistance (1013.8 - 1127.2 N) in relation to the groups with the different evaluated posts (236.1 - 615.1 N). Within the same material, the diameter influenced the fracture strength only of the quartz fiber post, with the highest values for diameter large. Conclusion: A larger diameter only gives greater fracture resistance for QF; CF posts have similar resistance to other posts, regardless of diameter; and for large diameter, the type of post used does not differ in fracture resistance.

A comparative study of retention of cement retained implant prosthesis cemented with different luting cements

Purpose: The study was conducted to evaluate the retentiveness of specifically formulated implant cements and compare its retentiveness with a commonly used noneugenol zinc oxide luting cement and also to assess the influence of abutment height on the retentiveness of these cements. Materials and Methods: A master stainless steel mold was used to mount snappy abutment-implant analog complex in acrylic resin. A total of six stock abutments (Osstem TS®) of 4 mm and 5.5 mm height with their analogs were used. A total of 66 ceramill® Sintron metal copings fabricated using computer-aided design/computer-aided manufacturing system and divided into six groups (n = 11) according to the height (three 4 mm abutment and three 5.5 mm abutment). The cements that were compared were a Noneugenol zinc oxide provisional cement , Dual Cure Resin Cement and a Zinc Phosphate Cement . After cementation samples were immersed in artificial saliva for 7 days and subjected to a pull-out test using a universal testing machine at a crosshead speed of 1 mm/min. The load required to de-cement each coping was recorded and analyzed using one-way ANOVA, post hoc multiple comparison, and independent t-test.

Bond strength of silane-containing adhesive to glass-ceramic material

The objective this study was to assess the effect of silane-containing universal adhesive (UA) on theshear bond strength (SBS) of dual-cure resin cement to glass-ceramic material. IPS e.max CAD, IvoclarVivadent blocks were prepared, polished, acid etched with a 5% hydrofluoric acid etchant and then randomly distributed into three groups (n = 15) according to the priming material applied for each material. In group 1 (control), no priming was performed prior to the application of a resin cement (Multilink automix, Ivoclarvivadent). In group 2, a silane-based primer (Monobond Plus, IvoclarVivadent) was applied onto the ceramic surface while in group 3, a silane-containing universal adhesive, single bond universal, 3m was used as a primer. The resin-ceramic bonded specimens were subjected to artificial aging via 10k thermocycling before the SBS was assessed using a universal testing machine at a crosshead speed of 1 mm/min. Failure mode patterns were evaluated using a scanning electron microscope. The SBS data were statistically analysed using one-way analysis of variance (ANOVA) (α = 0.05).

Incorporation of a β-AgVO3 Semiconductor in Resin Cement: Evaluation of Mechanical Properties and Antibacterial Efficacy.

This in vitro study aimed to investigate the effect of incorporating the semiconductor nanostructured silver vanadate decorated with silver nanoparticles (β-AgVO3) in a dual-cure resin cement on the degree of conversion (DC), microhardness, roughness, color, adhesion properties before and after artificial aging, and antimicrobial efficacy. Three test groups were established: control (without β-AgVO3), with the incorporation of 2.5% and 5% (by weight) of β-AgVO3 in dual-cure resin cement (Allcem, FGM). The degree of conversion was measured using Fourier transform infrared spectroscopy (FTIR). To evaluate roughness (n = 10), microhardness (n = 10), color (n = 10), and to perform agar disk diffusion (n = 8), disks of 6-mm diameter and 2-mm height were manufactured using the same concentrations. For the color and shear bond strength test (n = 6), orthodontic brackets (Morelli) were used, which were cemented to natural human enamel and evaluated before and after artificial aging via thermocycling at 5°C and 55°C for 1000 cycles. For color measurements, a portable spectrocolorimeter and the CIE-Lab method were used. Data were analyzed using Student's t-test, ANOVA, and Tukey's multiple comparisons with significance set at α = 0.05. Semiconductor incorporation did not influence the cements's DC. The incorporation of 2.5% and 5% of β-AgVO3 resulted in a significant increase in Knoop microhardness and surface roughness. Significant changes were observed in the color of the specimens when the semiconductor was incorporated. Adhesion after aging remained within the clinically recommended values in all groups, and antimicrobial activity was observed against Staphylococcus aureus, Streptococcus mutans, and Enterococcus faecalis at both concentrations tested. It is suggested to incorporate the semiconductor β-AgVO3 in the dual-cure resin cement at both concentrations. Moreover, the physical-mechanical properties remained satisfactory for the proposed application.

Aesthetic management of anterior cantilever bridge with ovate pontic: a case report

This article describes a 16-year-old male who was referred to the Prosthodontics Department due to avulsion of the right upper central incisor and fracture of the left central incisor; the avulsed tooth was lost at the accident site. The patient refused to have his teeth prepared except for broken teeth so a single cantilever retainer denture bridge was made with fiber post design and ovate pontic. Radiographic examination was performed to evaluate the apical condition of the fractured tooth followed by initial im-pression for diagnostic wax-up, treated endodontically to prevent pulp necrosis. Preparation was carried out on tooth 21 using gingival retraction floss and the patient using provisory for 4 weeks. The final impression of the double impression technique was carried out with polyvinylsiloxane. The bridge is cemented using dual-cure resin cement. It is concluded that this ovate pontic design is very suitable for the treatment of the anterior region to achieve the best esthetic result as the main requirement.

Effect of chlorhexidine application on shear bond strength of self-adhesive dual cure resin cement

The present study evaluates the impact of 2% chlorhexidine (CHX) on bond strength of self-adhesive dual-cure resin cement. In the current in vitro study, 40 freshly extracted human sound premolar teeth were selected. Cavity preparations were performed and the teeth were divided into 4 groups (n =10). Group 1:1 mm cavity without 2% CHX; Group 2:1 mm cavity with 2% CHX; Group 3:3 mm cavity without 2% CHX; and Group 4:3 mm cavity with 2% CHX. In all groups, self-adhesive was added. The shear bond strength (SBS) of all the groups was statistically assessed. Comparison of mean maximum load among different groups showed significant difference (p &lt; 0.05). Similarly, shear bond strength differed significantly between 3 mm without CHX group and 1 mm without CHX group (p &lt; 0.05) and the mean difference of load differed significantly among 3 mm without CHX group and 1 mm with CHX group (p &lt; 0.05). Although, there appears to be an influence of 2% CHX on shear bond strength and maximum load, however more studies are necessary to explore the effect of 2% CHX along with self-adhesive on shear bond strength.

Effect of Composite or Ceramic Thickness on the Polymerization Hardness of 5 Different Dual-cured Resin Luting Cements

Objective: The aim of the present study was to evaluate the influence of ceramic and composite thickness on polymerization hardness of five different dual-cure resin cements. Materials and Methods: A total of 100 disc-shaped spacer, 10-mm in diameter and five varying thicknesses (1.0mm, 2.0mm, 3.0mm, 4.0mm, 5.0mm) were fabricated from ceramic and composite materials. Dual-cure resin cement specimens with 8-mm diameter were prepared using metal brass mold and activated by light beneath the composite and ceramic disc shaped spacers. A total of 100 specimens of five different dual-cure resins (RelyX, Variolink, NX3, Calibra, Panavia F2.0) were prepared. Knoop hardness of each dual-cure resin cement was measured at five different point using a microhardness device with a 500 gm load, after 1 hr, 1 day, and 1 week polymerization. All data were statistically evaluated using one-way ANOVA. Results: Multivariate analysis of variance revealed significant differences in hardness of specimens dual-cured under composite resin or ceramic spacers and different time intervals (P&amp;lt;.001). Specimens cured through composite resin spacers showed less hardness values than ceramic spacers, with increasing thickness of the spacer. Also increasing the thickness of the composite or ceramic spacers produced a statistically significant decrease in microhardness of the dual-cure cements (P&amp;lt;.05). Conclusions: Hardness values significantly reduced when composite spacers were thicker than 2 mm and ceramic spacers thicker than 3 mm. Dual-cured resin cements are needed to be improved to achieve sufficient degree of hardening under composite and ceramic restorations. Different commercially available brands have different polymerization properties.

Influence of curing modes on monomer elution, sorption and solubility of dual-cure resin-cements

ObjectiveTo explore the effect of two curing modes, for dual-cure resin cements, on their monomer elution, water sorption and solubility after 30 d water storage and 30 d dry reconditioning. MethodsEight dual-cure resin-cements were investigated (Bifix SE, Nexus Third Generation, PANAVIA SA, PANAVIA V5, RelyX Ultimate Universal, RelyX Unicem 2, RelyX Universal and SpeedCEM Plus). Six disk-shaped specimens were made per curing mode: light-cure (LC) versus self-cure (SC) to measure amounts of eluted monomers after 30 d of water storage at 37 °C. Ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC MS/MS) was performed to identify and quantify three eluted monomers (Bis-GMA, UDMA and TEGDMA). Water sorption/ solubility specimens were prepared according to ISO 4049. Specimens from each curing mode (LC/SC) were immersed separately in distilled water for 30 d and then reconditioned for 30 d; all at 37 °C. Mass change was measured at different time intervals. Data were analyzed via one-way ANOVA, Tukey post-hoc tests and independent sample t-tests (α = 0.05). ResultsAfter 30 d of water storage, the three monomers Bis-GMA, UDMA and TEGDMA were detected in water. All monomers showed a variable extent of elution into water and were significantly higher (p < 0.0001) with SC compared to LC curing modes. BSE had the highest quantity of eluted monomers. After 30 d of water sorption (μg/mm3), all rein-cements showed significantly higher sorption (p < 0.05) of SC compared to LC curing modes except for PV5, RXU and CEM (p > 0.05). After 30 d of water solubility (μg/mm3), all resin-cements showed significantly higher solubility (p < 0.0001) of SC compared to LC curing mode. BSE had the highest water sorption and solubility. The total amounts of eluted monomers correlated positively with solubility: r2 = 0.95 for LC and r2 = 0.93 for SC. SignificanceWhenever light access is possible, light curing remains beneficial to reduce the extent of resin degradation and related properties of dual-cure resin cements. BSE showed statistically the highest extent of eluted monomers, sorption and solubility.

Surface Treatment and Cementation of Lithium Silicate Ceramics Containing ZrO2.

To evaluate the effect of different surface treatments on the shear bond strength (SBS) of lithium silicate (LS) and lithium disilicate (LD) ceramics, after thermocycling. For SBS test, 72 ceramic blocks (18×14×2 mm) were made (24 blocks from each ceramic material): VITA Suprinity (LSS), Celtra Duo (LSC), and Lithium disilicate (LD). The blocks were polished with sandpaper of increasing grit (#280, #400, #800, and #1200) and embedded in chemically activated acrylic resin. Afterwards, they were randomly divided into 12 groups (6 blocks per group) according to: "Ceramic" (LD, LSC, and LSS) and "Surface treatment" (HFS: hydrofluoric acid + silane; MEP: Monobond Etch & Prime/Ivoclar). From each treated surface ceramic block, four dual-curing resin cement cylinders (RelyX U200, 3M Oral Care) were prepared using a Tygon tube (Ø=3 mm and h=2 mm) and light cured for 40 seconds (1000 mW/cm2) (N=288/n=24). All specimens were submitted to thermocycling (10,000 cycles, 5°C and 55°C, 30 seconds) and then to SBS test at a crosshead speed of 1 mm/min using a 50-kgf load cell. Forty-five additional blocks were made for roughness and SEM analysis. Failure mode was also performed. The data (MPa) were statistically analyzed by oneway analysis of variance (ANOVA), Tukey test (5%), and Weibull analysis. The Ra was analyzed by Kruskal-Wallis and Dunn Test (5%). The other variables were analyzed qualitatively. ANOVA revealed that "surface treatment" was significant for all ceramic materials (p<0.05). The LD-HFS (18.66±3.49), LSC-HFS (16.81±2.62), and LSS-HFS (16.33±3.08) groups had significantly higher SBS than the LD-MEP (7.00±4.2), LSCMEP (14.12±3.51), and LSS-MEP (13.87±2.52) groups. Complete adhesive failures at the cement-dentin interface were more frequent. Weibull modulus was superior for the LD-HFS (6.22), LSC-HFS (8.8), and LSS-HFS (7.4) groups. HF followed by silanization is the most suitable surface treatment for the cementation of LS and LD glass ceramics.

Comparison of retention and fracture load of endocrowns made from zirconia and zirconium lithium silicate after aging: an in vitro study

BackgroundThis study aimed to compare retention and fracture load in endocrowns made from translucent zirconia and zirconium lithium silicate.MethodsFifty-six intact human maxillary molars after being mounted in acrylic resin, were scanned to acquire biogeneric copies. Specimens underwent standard endodontic treatment and were prepared for endocrown up to 2 mm above the cementoenamel junction. The specimens were randomly divided into two groups of 28, and endocrowns were designed using biogeneric copies and milled from high-translucent zirconia disks (Zr) and zirconium lithium silicate blocks (ZLS). After cementation with dual-cure resin cement, all the specimens underwent thermomechanical aging, and pull-out retention test and compressive test were conducted (14 specimens were used for each test in each group, n = 14), and failure modes in both tests were evaluated.ResultsIndependent samples t-test showed significant difference between the retention of Zr (271.5 N ± 114.31) and ZLS (654.67 N ± 223.17) groups (p value = 0.012). Compressive test results were also significantly different between Zr (7395.07 N ± 1947.42) and ZLS (1618.3 N ± 585) (p = 0.002). Failure mode of retention test was primarily adhesive failure at the cement-restoration interface in Zr group and cement-tooth interface in ZLS group. Failure modes of fracture test for Zr group were 7 non-restorable fractures and one restorable fracture while 6 specimens resisted compressive loads up to 8500 N without fracture. ZLS group showed 7 restorable and 7 non-restorable failures.ConclusionsZr endocrowns showed significantly lower retention and higher fracture strength. Both materials seem to be suitable for fabrication of endocrown in clinical setup.

Effect of mechanical cleaning protocols in the fiber post space on the adhesive interface between universal adhesive and root dentin.

The aim of this study was to evaluate the effects of cleaning protocols on the presence of residues, open dentinal tubules, and bond strength of a self-etch adhesive plus a dual-cure resin cement to dentin in the fiber-post space. The methods for cleaning utilized were conventional irrigation (CI), rotary brush with continuous rotary movement (RB), and continuous ultrasonic irrigation (CUI). Sixty bovine incisors were used for fiber-post space preparation. Thirty roots were divided into three groups (n=10) according to the cleaning protocols and submitted to scanning electron microscope to evaluate presence of residues and relative quantity of open dentinal tubules on dentin surface. Similar protocols were performed in the other thirty roots (n=10) using a self-etching adhesive system (Scotchbond Universal) and a dual-cure resin cement (Relyx Unicem 2). After 6months cervical, middle, and apical thirds sections of fiber-post space were submitted to push-out testing. To data ANOVA and Tukey's test were employed (α=5%). RB and CUI showed the lowest presence of residues on dentin surface (p=.015) and the highest bond strength values (p < .001), regardless of the dentin third. CUI presented the highest quantity of open dentinal tubules in middle and apical thirds (p < .001). CI presented the lowest bond strength value of resin cement, regardless of dentin third (p < .001). Mechanical cleaning protocols, such as RB and CUI, presented better surface cleaning capabilities and higher bond strength than CI with dual-cure resin cement employed. The use of a mechanical cleaning protocol seems to cause appropriate condition on the root dentin surface. Mechanical cleaning of root dentin provided greater bond strength of the self-etching system with dual resin cement. Conventional irrigation did not provide adequate root dentin cleaning. RESEARCH HIGHLIGHTS: • The use of a mechanical cleaning protocol seems to cause appropriate condition on the root dentin surface. • Mechanical cleaning of root dentin provided greater bond strength of the self-etching system with dual resin cement. • Conventional irrigation did not provide adequate root dentin cleaning.

Effect of aging on color stability and bond strength of dual-cured resin cement with amine or amine-free self-initiators.

This study aimed to evaluate the effect of aging on the color stability and bond strengths of dual-cured resin cements containing amine or amine-free self-initiators. Three dual-cured and one light-cured resin cements were used. The covered (by lithium disilicate ceramic disks) and uncovered groups (n=10) were included. Color measurements were tested after 24 h, 10,000 and 20,000 thermal cycles (TCs). Micro-shear bond strengths (µSBS) were tested after 24 h, 10,000 and 20,000 TCs, and failure modes were analyzed (n=14). Two-way ANOVA and Tukey's test were implemented for color difference (ΔE*ab) and µSBS (α=0.05). The mean ΔE*ab difference was significant among groups (p<0.001). The lowest ΔE*ab values were obtained for dual-cured resin cement with amine-free self-initiators dual-cured cement after aging in all dual-cured resin cements, and the µSBS of the dual-cured resin cements on ceramic was significantly higher than that of the light-cured ones after aging (p<0.001).

Comparison of the Bond Strength of Circular and Oval-Shaped Fiber-Reinforced Composite Posts in Oval Shaped Canals

Background: Fiber reinforced composite resin (FRC) posts are used to restore endodontically treated teeth. Many factors affect the bond strength of posts; however, there is a concern regarding the mismatch between the posts and oval root canals and its effect on posts retention. Aim: To compare the bond strength of circular and oval-shaped fiber-reinforced composite posts in oval shaped canals. Materials and Methods: Forty Five extracted single rooted human premolars with single oval-shaped root canals were decorated, endodontically treated and prepared to receive quartz reinforced composite resin posts, then they were randomly assigned to three groups, the posts in the first group (control) (n=15) were parallel with circular cross section (Match post, RTD, France), the posts in the second group (n=15) were taper with circular cross section (DtLight Illusion post, RTD, France), The posts in the third group were oval shaped (Macro lock oval post, RTD, France). The posts in the three groups were cemented with dual cure resin cement (Permflo DC Composite Luting, Ultra dent, USA). All samples were then stored in 100% relative humidityat at room temperature for 24 hours then pull-out test was performed and data were analyzed using one-way analysis of variance (ANOVA) followed by Bonferonni's post hoc test (a = 0.05). Results: Oval shaped posts showed higher bond strength values than circular posts, whether the circular posts were conical(taper)or parallel (control) (p&lt;0.05).Conclusions: The bond strength of fiber reinforced composite resin posts in oval root canals increased when the posts were oval-shaped.

Evaluation of Microshear Bond Strength of Four Different CAD-CAM Polymer-Infiltrated Ceramic Materials after Thermocycling.

To evaluate the bond strength of three monolithic hybrid ceramics/resin nanoceramics and a zirconia-reinforced lithium silicate to resin cement after thermocycling. Using four materials, including Vita Enamic (VITA Zahnfabrik), Lava Ultimate (3M ESPE), Crystal Ultra (Digital Dental), and Vita Suprinity (VITA Zahnfabrik), 64 specimens were prepared with dimensions of 4 mm × 3 mm × 1.5 mm. Vita Suprinity samples were sintered at 840°C for 8 min. After polishing and cleaning all the samples in each group (n = 16), they were subjected to their recommended surface treatment: 10% hydrofluoric acid for Vita Enamic (60s) and Vita Suprinity (20s); air abrasion of Lava Ultimate and Crystal Ultra with 50 u Al2 O3 particles. Then, tygon tubes were filled with dual cure resin cement (Panavia F2.0), cured and then subjected to thermal cycling (2000 cycles; 5-55°C). The microshear bond strength was measured using microtensile testing machine. The data were analyzed using Welch and Games-Howell tests (α = 0.05). The mode of failure was also evaluated using a stereomicroscope. The highest and the lowest mean microshear bond strength belonged to the Crystal Ultra (7.71 ± 1.54 MPa) and Vita Suprinity (4.73 ± 1.87 MPa) groups, respectively. The differences between groups were significant and Crystal Ultra had higher bond strength in comparison to all three materials (p < 0.05). Hybrid ceramics showed higher bond strength to resin cements in comparison to resin nanoceramics and zirconia-reinforced lithium silicate materials.

In-vitro cytocompatibility of self-adhesive dual-curing resin cements on human mesenchymal stem cells (hMSC) and periodontal ligament cells (PDL-hTERT)

ObjectivesSelf-adhesive dual cured resin cements provide easier clinical application than conventional resin cements but release higher amounts of unreacted monomers, potentially affecting their biocompatibility. This study aimed to compare the cytotoxic effects of self-adhesive dual cured resin cements with two conventional resin cements. MethodsSamples of four resin cements, two self-adhesive dual cured cements (group A: RelyX Unicem, group B: SmartCem), and two conventional resin cements (group C: Panavia 2.0, group D: Variolink Esthetic DC) were prepared with a similar dimension under standardized polymerization conditions and stored in water. For each material 18 samples were used and cell cultures of human mesenchymal stem cells (hMSCs) or periodontal ligament cells (PDL-hTERT) were added under appropriate conditions. One experimental group (group E) was left untreated as control. A cell viability WST test, was performed in each experimental group at day 1, 7, 14 and 21. Moreover, microscopic examination of cells was performed using cell viability staining. ResultsViability of both cell types as determined by WST test was significantly impaired at all time periods by the four different cement materials compared to the untreated control. Comparison between the four materials revealed different inhibition of the viability of both, PDL-hTERT and hMSC cells (group C > group B > group A > group D; p < 0.0001). SignificanceAll resin-based cements caused significant impairment of cell viability, reflecting considerable cytotoxicity. Variolink caused significantly smaller changes of viability than the other tested materials.

4 - Degree of Conversion of Resin-Based Luting Materials Containing Alternative Photoinitiators

Evaluate the degree of conversion (DC) of pre-heated composites, light- and dual-cured resin cements containing alternative photoinitiators under lithium disilicate ceramic with different thicknesses light cured using single-peak and dual-peak light curing units (LCUs). Thirty rectangular (12 ×14 mm; n= 5) lithium disilicate ceramic (IPS e.max CAD MT A2) specimens in six different thicknesses (0.5, 1.0, 1.5, 2.0, 2.5 and 3.0 mm) were cut using a precision saw machine. The spectral irradiance (mW/cm 2 /nm) of a single-peak (SmartLite Pro Cure) and a dual-peak (SmartLite Pro Polycure) LCUs and the light transmittance through the ceramic with different thicknesses were evaluated using a spectrophotometer (MARC Light Collector). LCU beam profile was also evaluated (ZWO ASI). The DC of a pre-heated dental composite (TPT, Tetric Prime T using the CalSet at 68 C), a light-cured resin cement (VLC, Variolink LC) and a dual-cured resin cement (VDC, Variolink DC) was evaluated using FTIR spectroscopy. The luting agents were light cured with no ceramic interposed for 10 s and 40 s and through the ceramics with different thicknesses for 10 s using both LCUs. Statistical analyses were performed according to the different experimental designs with a level of significance of α= 0.05. The single-peak LCU emitted an irradiance of 1335 7 mW/cm2 with 98.4% of the irradiance within the blue spectrum. The dual-peak emitted an irradiance of 1192 4 mW/cm2 with 72.6% of the irradiance within the blue spectrum and 27.4% within the violet spectrum. The ceramic thickness has an exponential effect on the decrease of the light transmitted. VLC had a higher DC when using dual-peak and presented a maximum DC ratio above 80% up to 2 mm of ceramic thickness; VLC DC with single-peak LCU only cured efficiently up to 1 mm of ceramic thickness. There were no significant differences on the VDC DC when light cured with both LCUs at any thickness and VDC cured above the 80% of the maximum DC in all conditions, except for the single-peak LCU with a 3 mm thick ceramic. No differences were found for the TPT using both LCUs and TPT can be efficiently cured through a ceramic with up to 1 mm thickness. Dual-peak LCUs were more efficient than single-peak on curing light- and dual-cured resin cements containing alternative photoinitiators, but there is no difference on the DC of pre-heated composites light cured with single- or dual-peak LCUs.

Degree of conversion of resin-cements (light-cured/dual-cured) under different thicknesses of vitreous ceramics: systematic review.

This systematic review synthesized and analyzed the scientific evidence on the degree of conversion (DC) obtained by Fourier-transform infrared spectroscopy (FTIR) of light-cured and dual-cured resinous cements, photopolymerized under different thicknesses of vitreous ceramics. The study protocol of this systematic review was registered at the International Prospective Register of Systematic Reviews (PROSPERO) (CRD42017069319). A comprehensive search (PubMed/MEDLINE, Scopus, EMBASE, and LILACS) was performed for papers including an in vitro design and indexed from January 2007 to December 2020 according to the study purposes. A quality appraisal (specific instrument) and descriptive analysis of the articles that met the inclusion criteria were conducted. Nine included studies were analyzed. Two of them used feldspathic ceramics, six used lithium disilicate, and one used both (comparing different types and opacities of ceramics). Three studies found a higher DC in dual cements, while one did not find any significant differences, and five studies found a higher DC in light-cured resin cements. Light-cured cements showed a better DC in relation to dual-cured cements in vitreous ceramic restorations with thicknesses up to 2 mm. According to the findings, the use of good photoactivation is the most relevant variable to achieve an adequate DC in light-cured and dual-cured resin cements. The use of vitreous ceramic restorations with a thickness of less than 2 mm (light-curing cements) shows a better DC. Standardized in vitro studies are required to generate accurate scientific evidence.