Ketac Cem Research Articles

Bonding Strength of Various Luting Agents between Zirconium Dioxide Crowns and Titanium Bonding Bases after Long-Term Artificial Chewing

The use of hybrid abutment crowns bonded extraorally to a titanium bonding base has aesthetic and biological benefits for the prosthetic rehabilitation of oral implants. The objective of this study was to evaluate the effects of luting agents between a zirconium dioxide crown and the titanium bonding base on crown/abutment retention and the subsequent durability of the prosthetic superstructure. Fifty-six implant abutment samples, all restored with a lower first premolar zirconium dioxide crown, were used and divided into seven groups (n = 8/group) according to the type of luting agent used: group 1, SpeedCEM Plus; group 2, Panavia SA Cement Universal; group 3, Panavia V5; group 4, RelyX Unicem 2 Automix; group 5, VITA ADIVA IA-Cem; group 6, Ketac CEM; and group 7, Hoffmann’s Phosphate Cement. All specimens were subjected to thermomechanical loading (load of 49 N, 5 million chewing cycles and 54.825 thermocycles in water with temperatures of 5 °C and 55 °C). The surviving samples were exposed to a pull-off force until crown debonding from the bonding base. Overall, 55 samples survived the thermomechanical load. Group 2 showed the highest mean pull-off force value (762 N), whereas group 6 showed the lowest mean value (55 N). The differences between the seven groups were statistically significant (ANOVA, p < 0.001). The debonding failure pattern was mainly adhesive and was noticed predominantly at the zirconium dioxide–luting agent interface. Within the scope of the present investigation, it was shown that most of the luting agents are suitable for “cementation” of a zirconium dioxide crown onto a titanium base since the debonding forces are above a recommended value (159 N).

Using Functionalized Micron-Sized Glass Fibres for the Synergistic Effect of Glass Ionomer on Luting Material.

This laboratory experiment was conducted with the objective of augmenting the mechanical properties of glass ionomer cement (GIC) via altering the composition of GIC luting powder through the introduction of micron-sized silanized glass fibres (GFs). Experimental GICs were prepared through the addition of two concentrations of GFs (0.5% and 1.0% by weight) to the powder of commercially available GIC luting materials. The effect of GF in set GIC was internally evaluated using micro-CT while the mechanical attributes such as nano hardness (nH), elastic modulus (EM), compressive strength (CS), and diametral tensile strength (DTS) were gauged. Additionally, the physical properties such as water solubility and sorption, contact angle (CA), and film thickness were evaluated. Reinforced Ketac Cem Radiopaque (KCR) GIC with 0.5 wt.% GF achieved improved nH, EM, CS, and DTS without affecting the film thickness, CA or internal porosity of the set GIC cement. In contrast, both GF-GIC formulations of Medicem (MC) GIC showed the detrimental effect of the GF incorporation. Reinforcing KCR GIC with 0.5 wt.% silanized GFs could improve the physical and mechanical attributes of luting material. Silanized GF, with optimal concentration within the GIC powder, can be used as a functional additive in KCR GIC with promising results.

A comparative evaluation of microleakage in three different luting agents used for posterior full metal crown: An in vitro study

The purpose of the study was to evaluate and compare the microleakage at the margins of nickel – chromium full metal crowns cemented with Zinc Phosphate cement, glass ionomer cement. And resin cement.: thirty freshly extracted human molars were selected for the study. Standardized tooth preparation is done with the help of customized metal zig attached to dental surveyor. On prepared teeth castings were fabricated and devided into three groups for the three luting agents namely zinc phosphate cement – Harvard, Glass ionomer cement – Ketac Cem and Resin cement – Rely X U200, each containing 10 samples. After cementation the cemented specimens were stored in artificial saliva for 24 hours. The teeth were then thermocycled between 5°C and 50°C and then treated with 50% silver nitrate stain for 60 minutes. Samples were placed under 150 watt flood lamp for 5 minutes to allow proper fixation of unfixed stain. Then they were embedded in clear acrylic resin and sectioned twice longitudinally. The sections were observed under the stereomicroscope and stain penetration were recorded at tooth cement interfaces. The readings were tabulated and analyzed statistically using Mann-Whitney U test and Kruskal-Wallis H test. .Zinc phosphate cement showed significantly maximum microleakage as compared to glass ionomer cement and resin cement. Resin cement showed significantly less microleakage as compared to glass ionomer cement and zinc phosphate cement. Glass ionomer cement showed more microleakage as compared to resin cement but less as compared to zinc phosphate cement

Effect of Fluoride Release on Enamel Demineralization Adjacent to Orthodontic Brackets.

This study aimed to evaluate the ability of fluoride-releasing adhesives to inhibit enamel demineralization surrounding orthodontic brackets. Two groups of 40 sound human premolars were sectioned mesio-distally. The halves were varnished, and orthodontic brackets were bonded with different adhesive materials. An area 1 mm wide surrounding the brackets was left exposed. Each specimen was immersed daily in a pH cycle for 28 days. In the second group, the specimens were exposed daily to a fluoride solution (250 ppm F-) at 37°C. The fluoride release from different groups was measured. Quantitative light-induced fluorescence (QLF) was used to quantify fluorescence loss of enamel surfaces adjacent to the brackets. Results were statistically analyzed using ANOVA at (p<0.05). Fluoride released from the three fluoride-releasing adhesives was significantly higher (p<0.001) in the group with daily fluoride exposures than in the group without fluoride exposures. Enamel adjacent to brackets bonded with Fuji Ortho LC, Ketac Cem, and Dyract Cem showed significantly less (p<0.001) changes in (ΔQ) value (less demineralization) than enamel bonded with Transbond, the control adhesive material. Using fluoride-releasing adhesives significantly reduced the level of demineralization adjacent to orthodontic brackets.

Utilizing an Oxidized Biopolymer to Enhance the Bonding of Glass Ionomer Luting Cement Particles for Improved Physical and Mechanical Properties.

This study aimed to determine the reinforcing effect of two weight ratios of Gum Arabic (GA) natural biopolymer, i.e., 0.5% and 1.0% in the powdered composition of glass ionomer luting cement. GA powder was oxidized and GA-reinforced GIC in 0.5 and 1.0 wt.% formulations were prepared in rectangular bars using two commercially available GIC luting materials (Medicem and Ketac Cem Radiopaque). The control groups of both materials were prepared as such. The effect of reinforcement was evaluated in terms of microhardness, flexural strength (FS), fracture toughness (FT), and tensile strength (TS). The internal porosity and water contact angle formation on the study samples were also evaluated. Film thickness was measured to gauge the effect of micron-sized GA powder in GA-GIC composite. Paired sample t-tests were conducted to analyze data for statistical significance (p < 0.05). The experimental groups of both materials containing 0.5 wt.% GA-GIC significantly improved FS, FT, and TS compared to their respective control groups. However, the microhardness significantly decreased in experimental groups of both cements compared to their respective control groups. The addition of GA powder did not cause a significant increase in film thickness and the water contact angle of both 0.5 and 1.0 wt.% GA-GIC formulations were less than 90o. Interestingly, the internal porosity of 0.5 wt.% GA-GIC formulations in both materials were observed less compared to their respective control groups. The significantly higher mechanical properties and low porosity in 0.5 wt.% GA-GIC formulations compared to their respective control group indicate that reinforcing GA powder with 0.5 wt.% in GIC might be promising in enhancing the mechanical properties of GIC luting materials.

Oxidized Natural Biopolymer for Enhanced Surface, Physical and Mechanical Properties of Glass Ionomer Luting Cement.

This laboratory investigation aimed to synthesize and characterize micron-sized Gum Arabic (GA) powder and incorporate it in commercially available GIC luting formulation for enhanced physical and mechanical properties of GIC composite. Oxidation of GA was performed and GA-reinforced GIC in 0.5, 1.0, 2.0, 4.0 & 8.0 wt.% formulations were prepared in disc-shaped using two commercially available GIC luting materials (Medicem and Ketac Cem Radiopaque). While the control groups of both materials were prepared as such. The effect of reinforcement was evaluated in terms of nano hardness, elastic modulus, diametral tensile strength (DTS), compressive strength (CS), water solubility and sorption. Two-way ANOVA and post hoc tests were used to analyze data for statistical significance (p < 0.05). FTIR spectrum confirmed the formation of acid groups in the backbone of polysaccharide chain of GA while XRD peaks confirmed that crystallinity of oxidized GA. The experimental group with 0.5 wt.% GA in GIC enhanced the nano hardness while 0.5 wt.% and 1.0 wt.% GA in GIC increased the elastic modulus compared to the control. The CS of 0.5 wt.% GA in GIC and DTS of 0.5 wt.% and 1.0 wt.% GA in GIC demonstrated elevation. In contrast, the water solubility and sorption of all the experimental groups increased compared to the control groups. The incorporation of lower weight ratios of oxidized GA powder in GIC formulation helps in enhancing the mechanical properties with a slight increase in water solubility and sorption parameters. The addition of micron-sized oxidized GA in GIC formulation is promising and needs further research for improved performance of GIC luting composition.

Comparative evaluation of the main properties of dental cements for permanent fixation of non-removable denture structures

The study was conducted to compare the main characteristics of dental cements for permanent fixation of fixed dentures. Some materials, formed by the reaction of weak polymeric acids with inorganic glass powder. Dental cements have a number of advantages: due to adhesion, the material "join" the surface of the abutment tooth and the inner surface of the artificial structure; some permanent cements slowly release fluoride ions over time to maintain dental health; they do not dissolve in the oral fluid. Despite the advantages, these materials need further improvement in their mechanical performance. Laboratory tests were carried out in the conditions of the accredited in the system of UKR-SEPRO and licensed research laboratory of JSC "Stoma". The following basic properties were studied: mixing time (Tm, s), curing time (Tc, s), film thickness (μm), compressive strength (MPa), acid solubility (mm/h), adhesion to metal/dentin (MPa). The process of mixing the components of the "Compomer" material is 2.5 s longer than that of "Ketac Cem" and 7.7 s longer than that of "Fuji Plus". In the case of the "curing time" indicator, the "Fuji Plus" material is significantly different, with a curing time that is 4.5 s faster than that of "Ketac Cem" and half the "curing time" compared to "Compomer". "Ketac Cem" has the lowest "film thickness" value – (21.8±0.8) μm, which significantly differs (p≤0.05) from the materials selected for the study. The study of the compression resistance of the cements revealed their full compliance with the standard value according to ISO-9917-1:2007. The acid solubility of the tested cements is at the level of (0.14÷0.29) mm/h. The adhesion index of the tested cements fully meets the requirements of international standards. Keywords: permanent cement, non-removable denture structures, properties, adhesion, international standards.

Morphological, chemical and antimicrobial analysis of glass ionomer cements used for ART in posterior primary teethGlass ionomer cements (GICs) have been gaining prominence as material for atraumatic restorative treatment (ART) due to their acceptable ph

Glass ionomer cements (GICs) have been gaining prominence as material for atraumatic restorative treatment (ART) due to their acceptable physicochemical and biological properties. Objective: To analyze the surface morphology, chemical constitution, and antimicrobial action of GICs used for ART in posterior primary teeth. Material and methods: The tested materials were Vitro Molar®, Ketac Cem Easymix® and Riva Self Cure®. For the structural and chemical analysis, polyethylene tubes with an internal diameter of 3 mm and 3 mm in length were prepared, filled, and then transferred to a chamber with 95% relative humidity and a temperature of 37oC. The surface morphology of the tested materials was examined by scanning electron microscopy (SEM) and main components were investigated by energy-dispersive X-ray microanalysis. For the antimicrobial efficacy analyses, strains of Streptococcus mutans (ATCC 27853) were used. Petri dishes with brain heart infusion agar (BHIA) were inoculated with the microbial suspensions and three cavities were made in each agar plate and filled with one of the GICs. The plates were pre-incubated for 1 hour at room temperature and then incubated at 37oC for 24 to 48 hours. The inhibition zone around each well was recorded in mm. Results: SEM revealed irregular and rough external surface. Cracking was not observed. The main constituents were found to be aluminum, silicon, sodium, and fluoride. Barium was only observed in Vitro Molar®, while lanthanum was only observed in Ketac Cem Easymix®. Elemental mapping of the outer surface revealed high concentration of aluminum and silicon. Inhibition halos were only observed in Riva Self Cure®. Conclusion: The GICs presented irregular outer surfaces and similar chemical elements. Only Riva Self Cure® showed antibacterial action against the S. mutans.

In Vitro Mastication Simulation and Wear Test of Virgilite and Advanced Lithium Disilicate Ceramics.

To compare wear behavior, durability during in vitro mastication simulation, and fracture force of an established and a novel lithium disilicate CAD/CAM material, as well as to examine the impact of cementation and reduced ceramic thickness on durability and fracture force. Specimens (n = 8 per group) were prepared from lithium disilicate (LS2; IPS e.max, Ivoclar Vivadent) and advanced lithium disilicate (ALD; Cerec Tessera, Dentsply Sirona). Specimens were polished, and two-body wear test and thermocycling were performed (50 N, 120,000 cycles, 1.6 Hz, H2O dist., 5°C/55°C, 600 cycles). Maximum vertical loss, surface roughness, surface roughness depth, and antagonist wear were determined. Single crowns (n = 8 per group; thickness 1.5 mm/1.0 mm) were manufactured from LS2 and ALD and mounted on human molar teeth with adhesive resin (AB; CalibraCeram, Dentsply Sirona), glass-ionomer cement (GIC; Ketac Cem, 3M ESPE), and hybrid glass-ionomer cement (HGIC; Calibra Bio, Dentsply Sirona). Thermocycling and mechanical loading (2 × 3000 × 5°C/55°C, 2 minutes, H20 dist., 1.2 × 106 50 N) were performed. Fracture force was determined by a universal testing machine (1446, ZwickRoell), and one-way analysis and Bonferroni post hoc test (α = .05) were used for statistical analyses. Mean (ALD: 210 ± 42.4 μm; LS2: 264.3 ± 56.1 μm) and maximum (ALD: 391.1 ± 86.3 μm; LS2: 518.3 ± 113.2 μm) wear between groups were significantly different (P ≤ .047). Fracture force varied between 1,911.4 ± 468.4 N (ALD/AB 1 mm) and 2,995.3 ± 880.6 N (LS2/GIC), without significant differences (P ≥ .152). ALD showed better wear behavior than LS2, but provided similar fracture force. Cementation and reduction of ceramic thickness had only minor effects on fracture force.

Compressive strength of premolars restored with ceramic crowns and supported with a glass fiber post using different luting agents

ObjectiveThe retention of glass fiber post (GFP) is considered a key factor for the long-term success of restorations of endodontically treated teeth. This study aimed to compare the compressive strength of a ceramic crown supported by a GFP using different luting agents. MethodsForty single-rooted premolars were randomly divided into four groups (n = 10 each): control group (teeth without a GFP), Ketac Cem group (glass ionomer), RelyX ARC group (conventional dual-curing resin), and RelyX U200 group (self-adhesive dual-curing resin). After luting of the posts and placement of all-ceramic crowns made using feldspathic porcelain (Noritake EX-3), they were exposed to thermocycling for 1000 cycles and compressive strength tests. Statistical analysis included Kruskal–Wallis test with Dunn’s multi-comparison test. ResultsThe Ketac Cem group and RelyX U200 group showed significantly greater fracture resistance to compressive loading than the control group. ConclusionThis study indicates a possible role of the luting agent used with the GFP in influencing the compressive strength of the restored teeth. In this study, the self-adhesive dual-curing resin and glass ionomer both offered resistance to fractures.

Effect of water absorption and hydroxyapatite addition on mechanical and microstructural properties of dental luting cements

Abstract In recent years, dental cements have gained more and more importance due to the increasing clinical expectations. They are used as restorative materials and as materials providing critical functions such as chemical and physical adhesion in restorations and protective lining in the cavity. In this work, the effect of water absorption on the mechanical and microstructural properties of different commercial dental cements is systematically investigated. Furthermore, the effect of addition of biocompatible hydroxyapatite on the mechanical and microstructural properties of the cements is characterized. The results show that Voco Meron containing glass ionomer provides the highest values in water absorption and volume change tests. Ketac Cem Radiopaque (209 HV) containing glass ionomer exhibits the highest hardness increase after immersion for 28 days in water, whereas the highest water uptake value is observed in Adhesor Carbofine cement containing zinc polycarboxylate. The hardness of Adhesor ZincPhospate increases with increasing content of hydroxyapatite, whereas in Ketac Cem Radiopaque, the hardness decreases with increasing content of hydroxyapatite significantly. Test results are verified by microstructural analysis of different types of dental cements using scanning electron microscopy and the effect of particle size/distribution on the properties that are of crucial clinical importance is characterized in detail.

Influence of fluoride-releasing materials in the inhibition of enamel and dentin demineralization around restoration

Objective: The aim was to evaluate the influence of fluoride-releasing restorative materials in enamel and dentinmicrohardness. Material and Methods: 40 blocks (5x5x3 mm) from cervical third of human molars received a cavitypreparation between the enamel and dentin, and the restorations were subjected to in vitro caries model. Specimenswere randomly restored with (n=10): conventional glass ionomer cement (Ketac Cem, 3M ESPE); polyacid-modifiedcomposite resin (Ionoseal, VOCO); resin-modified glass ionomer cement (Ionofast, Biodinâmica); or microhybridcomposite resin (Filtek Z250, 3M ESPE). The specimens were sectioned longitudinally and enamel and dentinKnoop microhardness were determined at different distances from the restorative material (100, 200 and 300 um)and depth of surface (20, 40 and 60 um). The data were submitted to three-way repeated measures ANOVA andTukey´s test (a=0.05). Results: For enamel, the double interactions between material x distance and material xdepth were statistically significant. In all depths and distances, the highest values of enamel microhardness wereobserved for Ketac Cem. In dentin, the materials differed statistically from each other, and Ionoseal obtained highermicrohardness values than those found in Ionofast. Conclusion: Conventional glass ionomer cement is more effectivein preventing enamel demineralization around restoration followed by the polyacid-modified composite resin. Indentin, the polyacid-modified composite resin obtained better performance than resin-modified glass ionomer cement.KEYWORDSCompomers; Dental caries; Glass ionomer cements; Hardness tests; Composite Resins.

Effect of Luting Cement and Convergence Angle of the Preparation on the Internal Fit of Zirconia Restorations.

The objective was to evaluate the effect of luting agents and the preparation design on the internal fit of zirconia restorations. Sixty dies were prepared and divided in occlusal convergence angle of 6° (OC6) and 12° (OC12). CAD/CAM zirconia copings were fabricated (Lava All-Ceramic System). A zinc phosphate cement (ZPC); a glass ionomer cement (GIC); and a resin cement (RC) were studied. Specimens were sectioned and coping/die discrepancies were evaluated through Stereoscopic Microscopy. A closer fit was observed in OC12 when compared to OC6 (p < 0.001). For OC6 no significant differences were observed in between ZPC, GIC, and RC (p > 0.05). For OC12, a significantly closer fit was recorded on the ZPC subgroup when compared to the GIC subgroup (p < 0.001). Preparations of 12 degrees demonstrated a closer internal fit when compared to 6 degrees. Preparations of 12 degrees achieved better internal fit values with ZPC (Fortex) followed by RC (RelyX Unicem), and GIC (Ketac Cem). No differences were found when comparing different luting agents over 6° degrees preparations.

Post-Fatigue Fracture and Marginal Behavior of Endodontically Treated Teeth: Partial Crown vs. Full Crown vs. Endocrown vs. Fiber-Reinforced Resin Composite.

Objectives: To investigate in vitro post-fatigue fracture behavior of endodontically treated molars having been differently restored. Methods: A total of 120 extracted human molars were used. A total of 120 specimens in 14 test groups and one control group (n = 8) were root canal treated. After postendodontic sealing and build-up (AdheSE Universal, SDR), additional MOD preparations were cut. Postendodontic restorations were: Direct restorations (Tetric EvoCeram BulkFill bonded with AdheSE Universal and EverX Posterior/Essentia bonded with G-Premio Bond; as filling (F) or direct partial crown (DPC) after reducing the cusps 2 mm; indirect adhesive restorations (partial crown/PC vs. full crown/FC): e.max CAD, Celtra Duo, both luted with Variolink Esthetic; indirect zirconia restorations (partial crown/PC vs. full crown/FC), luted with RelyX Unicem 2; indirect non-bonded cast gold restorations (partial crown/PC vs. full crown/FC; Degunorm), luted with Ketac Cem. Before and after 300,000 thermocycles (5/55 °C) and 1.2 Mio. A total of 100 N load cycles, replicas were analyzed under a SEM for marginal quality in enamel and dentin (where applicable) and finally, specimens were loaded until fracture. Results: In direct groups, there was no difference between RC and FRC in fracture strength (p > 0.05); however, direct partial crowns showed higher post-fatigue fracture resistance. Regarding marginal quality, intracoronal FRC restorations exhibited more gap-free margins in enamel than RC. In the indirect groups, there was no significant difference between partial and full crowns in any of the adhesively luted ceramic groups regarding post-fatigue fracture resistance. Zirconia partial crowns exhibited significantly lower marginal quality in enamel. Indirect groups performed significantly better than direct groups in fracture resistance. Within the indirect restorations, both cast gold groups and zirconia full crowns exhibited the highest fracture resistance being superior to control teeth. Significances: Within the limits of this in vitro investigation, it can be concluded that any kind of indirect restoration with cusp replacement is suitable for ETT restoration when a certain cavity extension is exceeded. All indirect restorations, i.e., endocrowns, partial crowns, and full crowns showed a promising performance after in vitro fatigue-loading.

Evaluation of Shear Peel Bond Strength of Different Adhesive Cements Used for Fixed Space Maintainer Cementation: An In Vitro Study.

Aim and objectiveThis study aims to compare the retentive strength of different adhesive cements used for band cementation of fixed space maintainer by comparing the shear peel bond strength and mode of failure for each adhesive material using three different adhesive cements.Materials and methodsEighty intact extracted teeth were used to assess the shear peel bond strength. Preformed bands were adapted to each tooth. Three cements compared in this in vitro study are glass ionomer cement [Ketac Cem radiopaque (3M ESPE)], resin-modified glass ionomer cement [RelyX luting 2(3M ESPE)], and self-adhesive resin cement [RelyX U200 (3M ESPE)]. The teeth were randomly divided to four groups of 20 samples each. All samples were stored at 37°C for 24 hours before testing. All specimens were tested in a tensile mode using a universal testing machine to determine shear peel bond. After debonding procedure, each specimen was visually assessed at the site of cement.ResultsThe results of our study showed that the greatest resistance to decementation was shown by self-adhesive resin cement (256.85 N) followed by resin-modified GIC (165.40 N) and GIC (127.40 N) (p < 0.001). Self-adhesive resin cement has the greatest shear peel bond strength (2.36 MPa) followed by resin-modified GIC (1.53 MPa), conventional GIC (1.22 MPa), and bands without cementation (0.29 MPa) (p < 0.001). In terms of adhesive remnant index (ARI) scores, it was seen that the decementation of bands of both conventional GIC and self-adhesive resin cements occurred at the band/enamel interface. However, resin-modified GIC showed varied results in the ARI scores.ConclusionThe findings of our study suggest that self-adhesive resin cements can be used for cementation of bands of fixed space maintainers. However, further research with short-term and long-term data is required to evaluate the ability of these cements for its application in vivo.How to cite this articleKaur J, Singh A, Sadana G, et al. Evaluation of Shear Peel Bond Strength of Different Adhesive Cements Used for Fixed Space Maintainer Cementation: An In Vitro Study. Int J Clin Pediatr Dent 2021;14(2):175–179.

Machine-driven simulation of removing luting agent remnants from implant surfaces: An investigator-independent assessment of cleaning protocols

IntroductionTo simulate removing luting agent remnants from crowns fixed onto implant-abutment analogs using a standardized machine-driven protocol including a scaler and air polishing or sonic. Material and methodsA motor-driven device was constructed that controlled the rotational speed of the specimens, machining distance, contact pressure, and working time. A standardized layer of cement (Provicol, VOCO; Cuxhaven, G; Ketac Cem, 3MEspe; Seefeld, G; or Rely X Unicem, 3MEspe, Seefeld, G) was placed onto the finishing line of the crowns luted onto titanium-abutment analogs. The cement layer was scaled with a fresh titanium scaler maneuvered by the motor-driven device and treated with air polishing or sonic. Protocol 1: Scaling only for 20s, 40s, or 60s; n=20; protocol 2: 40s of scaling plus 20s of air polishing; protocol 3: 20s of scaling plus 40s of air polishing; protocol 4: 20s of scaling plus 40s of sonic; protocol 5: 40s of scaling plus 20s of sonic; protocols 2–5: n=10. Cement remnants were counted digitally as “percentage of remnants”. Statistics: mean, standard deviation, Bonferroni post hoc tests; α=0.05. ResultsKetac Cem was easily removed by scaling only and Provicol by scaling and air polishing, but the self-adhesive resin composite cement Rely X Unicem was not removable with the device. Only remnants of Provicol could be significantly reduced by further treatment after scaling (p<0.001). ConclusionThe presented motor-driven device enables reproducible investigations of various cleaning protocols and is thus useful to create an overview of cleaning protocols needed for the different types of cement.

Occlusal Thickness and Cement-Type Effects on Fracture Resistance of Implant-Supported Posterior Monolithic Zirconia Crowns.

To evaluate the factors that could influence the fracture resistance of implant-supported posterior monolithic zirconia crowns. Sixty zirconia molar crowns with three different occlusal thicknesses of 0.5, 1.0, and 1.5 mm (20 samples per group) were prepared for implant abutments using a CAD/CAM system. In each group, 10 crowns were luted on the abutment with resin cement (Panavia F), and the other 10 crowns were luted with resin-modified glass-ionomer cement (Ketac Cem Plus). Dynamic loading (1.2 × 106 cycles; 70 N) and thermal cycling were applied to the samples using a chewing simulator before evaluating their fracture resistance with a universal testing machine and examining their fracture type using a stereomicroscope. One-way analysis of variance (ANOVA), the Duncan test, and two-way ANOVA were used for data evaluation (α = .05). The occlusal thickness (P < .001) and cement type (P < .01) affected the fracture load of the monolithic zirconia crowns. The highest fracture resistance was found in 1.5-mm-thick crowns luted with resin cement (4,212 ± 501 N), and the lowest fracture resistance was found in 0.5-mm and 1-mmthick crowns luted with resin-modified glass-ionomer cement (1,198 ± 116 N and 1,197 ± 66 N). A significant difference was not found in the mean maximum fracture load between the 1.5-mm-thick crowns cemented with resin cement and glass-ionomer resin cement. Both the occlusal thickness and cement type remarkably affected the fracture resistance of the crowns, but occlusal thickness was more significant. Implant-supported posterior zirconia crowns can withstand physiologic occlusal forces even with a thickness as low as 0.5 mm. Resin luting cement is recommended for implant-supported posterior zirconia crowns with reduced occlusal thickness.

Adhesion between Biocomposites and Different Metallic Structures Additive Manufactured

This study was concerned with the adhesion of resin cement to metal surfaces obtained by selective laser melting process (SLM), and how it could be improved the bond strength at the biocomposite-metal junction. The SLM substrates were manufactured out of pure titanium (Ti), Ti6Al7Nb, and CoCr alloys. The metallic surfaces were covered with 5 types of biocomposites: 2 commercially resin-modified glass-ionomer cements (GC Fuji Plus and KETAC CEM) and 3 types of in-house developed materials. These biocomposites were mechanical characterized under compression and bending trials. The biocomposites-metal adhesion was settled both on as built metallic surfaces and after they were sandblasted with alumina. All the sandblasted SLM surfaces presented higher adhesion strength in comparison with the untreated specimens. The CoCr specimens show the highest bonding value. Additionally, the morphological aspects of joining interfaces were investigated using a scanning electron microscope (SEM). The mechanical properties and metal adhesion of these biocomposites were influenced by the liquid powder ratio. It is essential to apply a surface treatment on SLM substrate to achieve a stronger bond. Also, the chemical composition of biocomposite is a major factor which may improve the adhesion of it on different metallic substrates.

Fluoride release from two types of fluoride-containing orthodontic adhesives: Conventional versus resin-modified glass ionomer cements-An in vitro study.

IntroductionDevelopment of white spot lesions (WSLs) during orthodontic treatment is a common risk factor. Fixation of the orthodontic appliances with glass ionomer cements could reduce the prevalence of WSL’s due to their fluoride release capacities. The purpose of this study was to evaluate differences of fluoride release properties from resin-modified and conventional glass ionomer cements (GICs).MethodsThe resin-modified GICs Fuji ORTHO LC (GC Orthodontics), Meron Plus QM (VOCO), as well as the conventional GICs Fuji ORTHO (GC Orthodontics), Meron (VOCO) and Ketac Cem Easymix (3M ESPE) were tested in this study. The different types of GICs were applied to hydroxyapatite discs according to the manufacturer’s instructions and stored in a solution of TISAB III (Total Ionic Strength Adjustment Buffer III) and fluoride-free water at 37°C. Fluoride measurements were made after 5 minutes, 2 hours, 24 hours, 14 days, 28 days, 2 months, 3 months and 6 months. One factor analysis of variance (ANOVA) was used for the overall comparison of the cumulative fluoride release (from measurement times of 5 minutes to 6 months) between the different materials with the overall level of significance set to 0.05. Tukey’s post hoc test was used for post hoc pairwise comparisons in the cumulative fluoride release between the different materials.ResultsThe cumulative fluoride release (mean ± sd) in descending order was: Fuji ORTHO LC (221.7 ± 10.29 ppm), Fuji ORTHO (191.5 ± 15.03 ppm), Meron Plus QM (173.0 ± 5.89 ppm), Meron (161.3 ± 7.84 ppm) and Ketac Cem Easymix (154.6 ± 6.09 ppm) within 6 months. Analysis of variance detected a significant difference in the cumulative fluoride release between at least two of the materials (rounded p-value < 0.001). Pairwise analysis with Tukey’s post hoc test showed a significant difference in the cumulative fluoride release for all the comparisons except M and MPQM (p = 0.061) and KCE and M (p = 0.517).ConclusionFluoride ions were released cumulatively over the entire test period for all products. When comparing the two products from the same company (Fuji ORTHO LC vs. Fuji ORTHO from GC Orthodontics Europe GmbH and Meron Plus QM vs. Meron from VOCO GmbH, Mannheim, Germany), it can be said that the resin-modified GICs have a higher release than conventional GICs. The highest individual fluoride release of all GICs was at 24 hours. A general statement, whether resin-modified or conventional GICs have a higher release of fluoride cannot be made.

Biocompatibility of self-adhesive resin cement with fibroblast cells

Statement of problemDental cements that release monomers that negatively impact adjacent oral soft tissues may adversely affect clinical outcomes. However, in vitro studies evaluating the cytotoxic and genotoxic potential of substances released from dental cements are lacking. PurposeThe purpose of this in vitro study was to define and compare the cytotoxicity and genotoxicity of the eluates of a self-adhesive resin cement (RelyX Unicem 2 Automix) autopolymerized and light polymerized with 2 other types of luting cements: a glass ionomer cement (Ketac Cem Easymix) and a resin-modified glass ionomer cement (Ketac Cem Plus). Material and methodsThe eluates were prepared, and 3T3 mouse fibroblast cells were exposed for 24 hours to serial eluate dilutions of the 3 types of cement. Cytotoxicity was determined by using a cell viability assessment through 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and crystal violet assays. Genotoxic effects were determined by using the cytokinesis-block micronucleus assay. ResultsCell viability was higher in the presence of the glass ionomer cement eluate than of the resin-modified glass ionomer cement and resin cement eluates. A pronounced decrease in viability was found when the cells were exposed to undiluted samples of resin-modified glass ionomer cement (around 50%) or resin cement (around 80% to 90%). No significant difference in cell viability was found between autopolymerized and light-polymerized resin cements. All cements induced a dose-dependent response of mononucleated cell formation. However, only the resin cements showed double strand breaks significant differences in the deoxyribonucleic acid (DNA) molecules against the basal DNA lesions that occurred spontaneously. ConclusionsThe glass ionomer cement was not found to be cytotoxic or genotoxic, whereas the eluates derived from the resin-modified glass ionomer cement and resin cement, independently of the polymerization method, were cytotoxic in fibroblast cells. Maximum cytotoxicity was observed in the presence of resin cement, which also showed genotoxicity, independently of being light polymerized.