Self-adhesive Composite Cement Research Articles

Fracture resistance of CAD/CAM blocks cemented on dentin using different cementation strategies.

To determine whether the fracture resistance of computer-aided design/computer-aided manufacturing (CAD/CAM) resin-based composites and polymer-infiltrated ceramic network materials cemented on dentin is influenced by the restoration thickness and composite cement application strategy. Disc-shaped specimens (Ø = 7 mm) of 0.8 mm and 1.5 mm thicknesses were milled from two CAD/CAM materials: resin-based composite (RBC, Cerasmart 270) and polymer-infiltrated ceramic network (PICN, Vita Enamic). The discs (n = 8 per group) were cemented on flattened dentin using three different cementation strategies: 1) self-adhesive composite cement (RelyX U200) in light-curing mode (LC-SAC), 2) universal adhesive (Single Bond Universal) with composite cement (RelyX Ultimate) in auto-curing mode (AC cement), and 3) adhesive and composite cement as in 2) but in light-curing mode (LC cement). The restorative surface was indented perpendicularly with a compressive load using a universal testing machine until fracture. The fracture resistance (N) of RBC and PICN was separately analyzed using two-way ANOVA and Tukey's post-hoc test (α = 0.05). The fracture resistance of each material was significantly influenced by the material thickness and cementation strategy (P < 0.05). Irrespective of the material type and cementation strategy, thicker materials exhibit higher fracture resistance. For RBC, the fracture resistance of the LC cement group was significantly higher than that of AC cement only at 0.8 mm thickness. For PICN, the LC-cement cementation strategy produced superior fracture resistance, regardless of the restoration thickness. The fracture resistance of Cerasmart 270 was higher for the thicker material; the fracture resistance of LC cement was higher than that of AC cement at 0.8 mm thickness cemented to dentin. In comparison, LC cement showed the highest fracture resistance for Vita Enamic for both material thicknesses.

The effect of mechanical and chemo-mechanical temporary cement cleaning methods on shear bond strength with self-adhesive resin cement (an in-vitro study)

BackgroundAdhesive tooth-colored restorations are strongly dependent on the substrate surface cleanliness to allow intimate contact between resin cement and dentin surface, so several methods were adopted for the total cleaning of temporary cement residues. This study aimed to assess the effect of mechanical and chemo-mechanical cleaning methods of temporary cement on the immediate shear bond strength of self-adhesive resin cement to dentin surface.MethodsForty freshly extracted lower first premolars were cut to expose a flat dentin surface. Discs of temporary crown composite resin material were constructed and cemented to the flat dentin surface using resin-based and non-eugenol temporary cement then stored at room temperature in distilled water. Dividing of samples into two groups according to the method of temporary cement cleaning. Group I (n = 20) mechanical cleaning using the rotary instrument, and group II (n = 20) chemo-mechanical cleaning using chlorhexidine-containing scrub. CAD/CAM reinforced Composite discs were bonded to the dentin surface using self-adhesive composite resin cement, then measurement of shear bond strength was done using a universal testing machine. Further analysis of failure mode after debonding was performed by Scanning electron microscope.ResultsNo statistically significant difference was found between the mean shear bond strength of the two cleaning methods (P-value = 0.636). Regardless of the cleaning method, the group cemented with resin-based temporary cement showed statistically significantly higher mean shear bond strength than non-eugenol temporary cement (P-value = 0.048).ConclusionBoth cleaning methods (mechanical and chemo-mechanical) applied in this study were effective in cleaning temporary cement remnants from the dentin substrate surface with statistically significant differences between results of shear bond strength with significantly higher values recorded with resin-based temporary cement.

Comparison of Mechanical Properties of a Self-Adhesive Composite Cement and a Heated Composite Material

(1) Background: Due to the limitations of composite cements, the authors carried out tests to compare such materials with preheated composite materials because the latter may be an alternative to cements in the adhesive cementation procedure. (2) Methods: The materials used in the adhesive cementation procedure, i.e., Enamel Plus Hri (Micerium, Avegno, Italy), a heated composite material, and RelyX U200 Automix (3M, Maplewood, MN, USA), a dual composite cement, were tested for microhardness, compressive strength, flexural strength, diametral compressive strength, and elastic modulus. Composite material was heated to the temperature of 50 degrees Celsius before polymerisation. (3) Results: Higher values of microhardness (by 67.36%), compressive strength (by 41.84%), elastic modulus (by 17.75%), flexural strength (by 36.03%), and diametral compressive strength (by 45.52%) were obtained using the Enamel Plus Hri composite material compared to the RelyX U200 self-adhesive cement. The survey results revealed statistically significant differences. (4) Conclusions: Due to its better mechanical properties, the heated composite material (Enamel Plus Hri) is a beneficial alternative to composite cements in the indirect restoration placement procedure. As the strength parameters of the heated composite material increase, a higher resistance to the compressive and bending forces present in the oral cavity, and hence a greater durability of the created prosthetic reconstructions can be expected.

Influence of surface treatment and curing mode of resin composite cements on fibroblast behavior

BackgroundHuman gingival fibroblast (HGF-1) cells in the connective tissue provide an effective barrier between the alveolar bone and the oral environment. Cement margins of restorations with intrasulcular preparation or cemented implant restorations are in contact with HGF cells. However, it is unknown to what extend the cement surface finish affects the behavior of HGF cells. The purpose of this study was to compare the behavior of HGF-1 cells in contact with two different resin composite cements with three different surface treatments after light-curing and autopolymerization, respectively.MethodsDisks of one adhesive (Multilink Automix, Ivoclar Vivadent [MLA]) and one self-adhesive (RelyX Unicem 2 Automix, 3 M [RUN]) resin composite cement were either light-cured or autopolymerized. Specimen surfaces were prepared with the oxygen inhibition layer intact, polished with P2500-grit silicon carbide paper or treated with a scaler. Cells were cultivated on the specimens for 24 h. Viability assay was performed, and cell morphology was examined with scanning electron microscopy. Additionally, roughness parameters of the specimen were analyzed with a 3D laser scanning microscope. Three-way ANOVA was applied to determine the effect of cement material, curing mode and surface treatment (a = 0.05).ResultsOverall, cement material (p = 0.031), curing mode (p = 0.001), and surface treatment (p < 0.001) significantly affected relative cell viability of HGF. The autopolymerized specimen with the oxygen inhibition layer left intact displayed the lowest relative cell viability (MLA 25.7%, RUN 46.6%). Removal of the oxygen inhibition layer with a scaler increased cell viability but also resulted in higher surface roughness values.ConclusionsHGF cell viability is affected by the surface treatment and the curing mode. The oxygen inhibition layer is an inhibitory factor for the viability of HGF cells. Autopolymerization enhances the cytotoxic potential of the oxygen inhibition layer.

Comparative characteristics of the physical and mechanical properties of the self-etchangeable self-adhesive composite cement for indirect restorations "Maxcem Elite TM"

Summary. The article deals with an actual problem of orthopedic dentistry: the choice of a reliable material for fixing indirect restorations by comparing the physical and mechanical properties of self-adhesive self-etching composite cements.&#x0D; The aim of the study – to carry out a comparative analysis of self-etching self-adhesive double-fixation cements for indirect restorations in terms of physical and mechanical properties.&#x0D; Materials and Methods. For comparison, in terms of physical and mechanical parameters, a self-etching self-adhesive composite cement for indirect restorations "Maxcem Elite", Kerr, California, USA was taken. "Maxcem Elite" refers to self-etching self-adhesive composite cements of double fixation, which has a number of positive qualities, such as high physical and mechanical properties, good aesthetic properties, radiopacity. We analyzed the following physical and mechanical parameters: the appearance of the paste, depth of hardening, mm, diametric strength, MPa, conical yield point according to Heppler, MPa, hardness according to Heppler, MPa, water absorption in 7 days, μg/mm3, water solubility in 7 days μg/mm3, adhesive strength, MPa, peel strength, MPa.&#x0D; Results and Discussion. According to the average test depth of hardening (mm) material "Maxcem Elite" is inferior to others: material Bifix QV by 14.9 % and Relyx U 100 by 13.3 %. This does not significantly affect the quality of the connection of the adhesive structure with the hard tissues of the tooth, especially due to the method we have developed for the preparation of abutment teeth in the manufacturing of adhesive pads. On the other hand, according to the average value of the index of diametrical strength (MPa), the studied material "Maxcem Elite" is by 17.2 % better than Bifix QV, and by 17.3 % better than Relyx U 100. Comparing these and other physical and mechanical properties of materials on average, one must bear in mind the random nature of these values. From the results of the study, it can be seen that the difference between the indicators of the Maxcem Elite material and analogues is confirmed at a very high level of significance. The study of the level of water absorption indicates the probable absence of variability of the indicator of the studied material in comparison with comparable analogs. The value of the water solubility index of all the composites under study practically does not differ from the value of "Maxcem Elite" (within (2.5±0.1) %), and corresponds to the requirements of ISO 4046.&#x0D; Conclusions. The research results show that the investigated composite material "Maxcem Elite" in the main parameters corresponds to analogs, in most of the indicators it combines their best characteristics. In it, the adhesive strength of the connection with the hard tissues of the tooth is noticeably enhanced and better peel strength makes it possible to profitably use this material "Maxcem Elite" for fixing the adhesive structures.

Pull-off Force of Four Different Implant Cements Between Zirconia Crowns and Titanium Implant Abutments in Two Different Abutment Heights.

This study evaluated the pull-off force between titanium abutments and zirconia crowns that were bonded using four different cements and two abutment heights (AHs). In total, 24 titanium abutments (3-mm AH: n = 12; 5-mm AH: n = 12; taper: 7.5 degrees) and 24 zirconia crowns were designed, manufactured, cemented with one of four dental cements (one temporary, two semi-permanent, one permanent), stored in water for 24 hours, and thermocycled (37,500 cycles, equal to ~4 years in vivo). The pull-off force needed to separate the abutment and crown in each combination was determined eight times per combination of cement type and abutment height. Statistical analysis was conducted at a significance level of P < .05. The permanent self-adhesive composite cement showed a high pull-off force with a risk for crown fracture (mean: 381 N for 3-mm AH; 617 N for 5-mm AH). In contrast, the temporary zinc-oxide cement showed frequent premature decementation after thermocycling (mean: 14 N with 3-mm AH; 28 N with 5-mm AH). Both semi-permanent methacrylate-based cements ranked between the other cements (mean: 31 N/37 N for 3-mm AH; 120 N/72 N for 5-mm AH). Statistically significant differences were found between all cements (ANOVA P < .001). The abutment heights differed significantly for all cements (P < .005) except for the temporary zinc-oxide cement. Methacrylate-based cements were the most reliable cements for semi-permanent mounting of zirconia crowns on titanium abutments. They provide sufficient retention to avoid unintended loosening and are weak enough to remove the crown without causing damage.

Influence of Dentin Surface Roughness, Drying Time, and Primer Application on Self-adhesive Composite-Cement Bond Strength.

To investigate the effect of roughness and drying time of dentin as well as the number of coats of a self-adhesive composite-cement primer on the bond strength of self-adhesive composite cement. Sixty human teeth were prepared and assigned to 12 groups (n = 5), according to three experimental factors: 1) dentin surface roughness, rough or fine, as achieved by 250- and 600-grit silicon carbide papers, respectively; 2) dentin wetness based on air-drying time (5 or 10 s); and 3) the self-adhesive composite-cement primer applications (no-coat, 1-coat, and 2-coat). Composite resin blocks were made with hybrid composite resin (M1 GraceFil) and cemented with G-CEM ONE (both GC). Cement-dentin sticks (12) were prepared, and the microtensile bond strength (μTBS) test was performed. Failure modes were observed with a stereomicroscope (40X), and bonding interfaces were evaluated with confocal laser scanning microscopy (CLSM). Statistical analysis was performed using three-way ANOVA and Tukey's post-hoc comparisons test (α = 0.05). Dentin roughness (250-grit > 600-grit, p = 0.000), drying time (5-s drying > 10-s drying, p = 0.000), and primer application (no-coat < 1-coat = 2-coat, p = 0.000) had significant effects on bond strength. These factors also showed significant interactions with each other (p = 0.003). The highest μTBS (31.8 ± 3.1 MPa) was observed in the 1-coat/fine roughness/10-s drying group and the lowest μTBS (13.4 ± 2.7 MPa) in the no-coat/coarse roughness/5-s drying group. CLSM showed higher penetration of cement in the primer-coated groups compared to that in the no-coat groups. Bond strength between the self-adhesive composite cement and dentin was higher in the fine-roughness dentin group than in the coarse-roughness dentin group, and in the 5-s drying group compared to the 10-s drying group. Applying a primer to dentin improved bond strength of the self-adhesive composite cement.

Characteristics of the Physical and Mechanical Properties of Self-Etching Self-Adhesive Cements for Indirect Restorations in a Comparative Aspect

The purpose of the study was to carry out a comparative analysis of self-etching self-adhesive double-fixation cements for indirect restorations in terms of physical and mechanical properties. Materials and methods. For comparison, in terms of physical and mechanical parameters, a self-etching self-adhesive composite cement for indirect restorations "Maxcem Elite", Kerr, California, USA was taken. "Maxcem Elite" refers to self-etching self-adhesive composite cements of double fixation, which has a number of positive qualities, such as high physical and mechanical properties, good aesthetic properties, radiopacity. We analyzed the following physical and mechanical parameters: the appearance of the paste, depth of hardening, mm, diametric strength, MPa, conical yield point according to Heppler, MPa, hardness according to Heppler, MPa, water absorption in 7 days, μg/mm3, water solubility in 7 days μg/mm3, adhesive strength, MPa, peel strength, MPa. Results and discussion. According to the average test depth of hardening (mm) material "Maxcem Elite" is inferior to others: material Bifix QV by 14.9% and Relyx U 100 by 13.3%. This does not significantly affect the quality of the connection of the adhesive structure with the hard tissues of the tooth, especially due to the method we have developed for the preparation of abutment teeth in the manufacturing of adhesive pads. On the other hand, according to the average value of the index of diametrical strength (MPa), the studied material "Maxcem Elite" is by 17.2% better than Bifix QV, and by 17.3% better than Relyx U 100. Comparing these and other physical and mechanical properties of materials on average, one must bear in mind the random nature of these values. From the results of the study, it can be seen that the difference between the indicators of the Maxcem Elite material and analogues is confirmed at a very high level of significance. The study of the level of water absorption indicates the probable absence of variability of the indicator of the studied material in comparison with comparable analogs. The value of the water solubility index of all the composites under study practically does not differ from the value of "Maxcem Elite" (within (2.5±0.1) %), and corresponds to the requirements of ISO 4046. Conclusion. The research results show that the investigated composite material "Maxcem Elite" in the main parameters corresponds to analogs, in most of the indicators it combines their best characteristics. In it, the adhesive strength of the connection with the hard tissues of the tooth is noticeably enhanced and better peel strength makes it possible to profitably use this material "Maxcem Elite" for fixing the adhesive structures

Better Glass-fiber Post Preservation in Teeth with Ferrule When Subjected to Chewing.

To evaluate the influence of ferrule effect and mechanical fatigue aging on glass-fiber post push-out bond strength (PBS) to root-canal dentin at different root thirds of premolars. Thirty-two sound maxillary premolar teeth were collected, and randomly assigned to two experimental groups (n=16): 'Remaining Dentin Ferrule' (RDF) = coronal crown cut 2.0 mm above the cementoenamel junction (CEJ); 'Without Dentin Ferrule' (WDF) = coronal crown cut at the cemento-enamel junction. Teeth were endodontically treated, post spaces were prepared up to 10.0-mm depth from CEJ, and glass-fiber posts were cemented using a dual-cure self-adhesive composite cement. Standardized cores were built using a light-cure composite, upon which tooth cores were prepared using a 1.5-mm taper ogival-end diamond bur. Crowns were handmade using self-cure acrylic resin and cemented using the aforementioned composite cement. Half of the specimens were subjected to 1,200,000 cycles of mechanical fatigue in a chewing simulator (F = 'Fatigue'), while the other half were stored in distilled water at 37°C for 1 week (C = 'Control'). All specimens were horizontally sectioned into 1.0-mm thick slices prior to PBS test; the failure modes were assessed using stereomicroscopy and scanning electron microscopy (SEM). Data were analyzed for each root third using two-way analysis of variance (ANOVA) followed by Tukey HSD post-hoc test; frequency distribution was compared by Chi-square test (α=0.05) and post-hoc comparisons with Bonferroni. The mean PBS in MPa (SD) were = RDF_F = 10.4 (2.9); WDF_F = 6.9 (1.7); RDF_C = 14.5 (2.7); WDF_C = 14.2 (2.9). Similar PBS were found for the root thirds. For all root thirds, significant differences were found for both the factors Dentin Ferrule and Fatigue, and their interaction (p<0.05). The lowest PBS was found for specimens without dentin ferrule subjected to chewing fatigue (p<0.001). Most failures occurred at the composite cement/dentin interface, followed by mixed and composite cement/glass-fiber post interfacial failures. There was a significant increase in mixed failures for the WDF_F group (p<0.001). Absence of 2.0-mm remaining dentin ferrule in premolars resulted in a higher decrease of the glass-fiber posts' PBS to dentin after mechanical fatigue, irrespective of root third.

Analiza porównawcza wybranych właściwości mechanicznych podgrzanego materiału złożonego i samoadhezyjnego cementu kompozytowego – badania pilotażowe

Analiza porównawcza wybranych właściwości mechanicznych podgrzanego materiału złożonego i samoadhezyjnego cementu kompozytowego – badania pilotażowe

CLINICAL EVALUATION OF RESTORATIONS OF ENDODONTICALLY TREATED TEETH

For endodontically treated lateral teeth, direct restoration made of photocomposites is most often used, and indirect ceramic restoration appears to be more promising, for which, however, additional retention is required.&#x0D; The aim of the study was the clinical evaluation of direct photocomposite and indirect ceramic restorations of endodontically treated lateral teeth.&#x0D; The object and methods of the research. We examined 118 people aged from 24 to 53 years, in whom 249 lateral teeth with cavities were endodontically treated according to the 2nd class by Black. Group 1 included 38 patients (32.2% of the total number of subjects) who underwent direct restoration of 89 molars (35.7% of the total number of restorations) made of photocomposite; 41 patients (34.7%) with 81 indirect ceramic restorations (32.5%) were included in group 2 according to the generally accepted requirements; group 3 consisted of 39 people (33.1%), who underwent 79 indirect ceramic restorations (31.7%) with the formation of cavities with additional retention elements.&#x0D; Direct restorations in the subjects from group 1 were performed with a photocomposite using a 5th generation adhesive system in a layered technique with light polymerization by “soft start”. In the molars of persons from groups 2 and 3, cavities were prepared taking into account the generally accepted requirements, while in the cavities of the molars in patients from group 3, we formed retention elements in dentin in the form of depressions. Intraoral optoelectronic scanner CEREC AC Connect Omnicam, Dentsply Sirona was used for scanning, restorations were modeled in Exocad software and made of ceramic CAD-blocks based on lithium disilicate using an inLab MC X5 assembler, Dentsply Sirona. The restoration was fixed on a self-adhesive composite cement of double hardening. Clinical evaluation of restoration was performed in 18 and 24 months. Impairments and the number of restorations with them were registered.&#x0D; Research results and their discussion. In the period of 18 months, out of 70 direct photocomposite restorations (78.7% of the initial number) in persons of group 1, 2 restorations (2.2%) were partially absent, in 4 restorations (4.5%) anatomical impairments were revealed, in 5 (5.6%) – impairments of the marginal adaptation, in 8 (9.0%) – marginal color, also in 8 cases (9.0%) there were impairments of contact points. All impairments were identified in 12 restorations (13.5%). In patients of 2 groups, in 78 indirect ceramic restorations (96.3%) we revealed a partial destruction and shift of 1 restoration (1.2%), disturbance of an anatomic form – in 2 restorations (2.5%), in 3 restorations (3.7% each) there were defects of marginal adaptation and marginal color, contact points were impaired in 4 cases (4.9%). In total, impairments were detected in 5 restorations (6.2%). In 77 indirect ceramic restorations (97.5%) in patients of group 3, 1 restoration (1.3% each) had impairments of anatomical shape, marginal adaptation and contact points, 2 restorations (2.5%) had marginal color. Impairments pertained to only 2 restorations (2.5%).&#x0D; In 24 months, out of 58 direct restorations (62.5%) of patients in group 1, 3 restorations (3.4%) were partially or completely absent, anatomical impairments were found in 6 restorations (6.7%), and marginal defects were found in 7 (7.9%), marginal color – in 11 (12.4%), 15 contact points (16.9%) were with impairments. The number of direct restorations with impairments was 20 (22.5%). In 77 indirect restorations (90.1%) in persons of the 2nd group, we revealed a partial destruction and displacement of 3 restorations (3.7%), 2 restorations (2.5% each) had impairments of anatomical shape and marginal adaptation, 4 each (4 , 9%) – marginal color and defects of contact points. In total, there were 7 indirect restorations (8.6%) with impairments. In patients of group 3, among 75 indirect restorations (94.9%) 1 restoration (1.3% each) had disturbances of anatomic shape and marginal adaptation, 2 restorations (2.5%) were with marginal coloring, 3 (3.8 %) – with defects of contact points. There were 3 indirect restorations with impairments (3.8%).&#x0D; Conclusion. During both terms with impairments, we detected 32 direct photocomposite restorations (36.0%), 12 indirect ceramic restorations (14.8%) and only 5 indirect ceramic restorations (6.3%) made with additional retention elements.

Silane-coupling effect of a silane-containing self-adhesive composite cement

ObjectiveHydrofluoric-acid etching followed by silanization is a routine clinical protocol for durable bonding to glass ceramics. Simplifying ceramic-bonding procedures, new technological developments involve the inclusion of a silane coupling agent in a self-adhesive composite cement. To investigate the effectiveness of the incorporated silane coupling agent, shear bond strength (SB) to ceramic and dentin, contact angle of water (CA), transmission electron microscopy (TEM), X-ray diffraction (XRD) and 29Si nuclear magnetic resonance (NMR) assessments were correlatively conducted. Materials and MethodsSB to glass ceramic was measured without (‘immediate’) and with (‘aged’) 50K thermocycles upon application of (1) the silane-containing self-adhesive composite cement Panavia SA Cement Universal (‘SAU’), being light-cured: ‘SAU_light’, (2) ‘SAU_chem’: chemically cured SAU, (3) ‘SAP_light’: light-cured Panavia SA Cement Plus (‘SAP’), and (4) ‘SAP_CP’: SAP light-cured after separate silanization using Clearfil Ceramic Primer Plus (‘CP’). CA was also measured on glass ceramic. The cement pastes before and upon mixing were characterized using 29Si NMR. SB of SAU or SAP onto dentin was measured. Finally, the cement-dentin interface was characterized by TEM and XRD. ResultsThe immediate and aged SB to glass ceramic of SAU did not significantly differ from those of SAP_CP, while they were significantly higher than those of SAP. CA of SAU did not significantly differ from that of SAP_CP, but it was significantly higher than CA of SAP. 29Si NMR revealed siloxane bonds after mixture. SB of SAU and SAP to dentin did not show any significant difference. SEM, TEM and XRD confirmed tight and chemical interaction, respectively. SignificanceIncorporating silane in a 10-MDP-based self-adhesive composite cement combined efficient silane-coupling ability at the ceramic surface with effective bonding ability at dentin.

Effects of Tribochemical Silica Coating and Alumina-Particle Air Abrasion on 3Y-TZP and 5Y-TZP: Evaluation of Surface Hardness, Roughness, Bonding, and Phase Transformation.

To determine and compare the effects of tribochemical silica coating and alumina-particle air abrasion on 3 mol% and 5 mol% yttria-stabilized tetragonal zirconia polycrystals (Y-TZP). Two different 3Y-TZP samples (Lava Plus, 3M Oral Care; Ceramill Zolid, Amann Girrbach) and one 5Y-TZP sample (Katana Zirconia UTML, Kuraray Noritake) were prepared and treated with alumina-particle air abrasion and a 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP)-containing self-adhesive composite cement or with tribochemical silica coating followed by silanization (n = 30). Resin columns were cemented onto the treated ceramic surfaces to form specimens. After 24-h water storage or aging with 10,000 thermocycles plus 60-day water storage, shear bond strength (SBS) testing was conducted. Surface roughness, surface Vickers hardness, and crystallographic phase analyses were also performed. The SBS of tribochemically silica-coated 5Y-TZP before and after aging were 13.8 ± 1.4 and 13.2 ± 1.5 MPa, resp., for Lava Plus (3Y-TZP) 14.4 ± 1.4 and 13.9 ± 1.6 MPa, respectively, and for Ceramill Zolid (3Y-TZP) 14.8 ± 1.1 and 13.9 ± 1.5 MPa, respectively. There was no statistical difference between tribochemical silica coating and alumina air abrasion treatments (p = 0.21) on the bonding performance (SBS) of the 3Y-TZPs and 5Y-TZP (p = 0.25) before and after aging (p = 0.50). After alumina air abrasion, 5Y-TZP showed higher surface roughness (Ra = 1.7 ± 0.1) than did the 3Y-TZPs (Ra = 1.2 ± 0.1 for Lava Plus; Ra = 1.2 ± 0.1 for Ceramill Zolid), while the Vickers hardness was similar among the three materials (p = 0.70). Monoclinic zirconia was not detected in 5Y-TZP irrespective of treatment, with the zirconia being mainly cubic phase. However, the 3Y-TZPs were mainly tetragonal phase with some monoclinic zirconia; the latter increased after being alumina-particle air abraded. The bond strength to 5Y-TZP is similar to those of the 3Y-TZPs under the same bonding strategies. Durable bonding can be achieved both by alumina air abrasion combined with a 10-MDP-containing self-adhesive composite cement and by tribochemical silica coating followed by silanization for both the 3Y-TZPs and 5Y-TZP.

Can Fiber-post Placement Reinforce Structurally Compromised Roots?

Immature teeth are characterized by short roots, thin root canal walls, and open apices, which makes them prone to fracture. The aim was to investigate whether fiber-post placement had an influence on the fracture resistance of endodontically treated immature teeth. To simulate immature teeth, the apical third of 20 intact mandibular premolars was resected. After the access cavity was prepared, root canals and apices were enlarged. A 4-mm apical barrier was placed using calcium-silicate based material (Biodentine, Septodont). The teeth were then randomly assigned to two groups (n = 10). Root canals in group 1 were sealed using Acroseal (Septodont, France) and gutta-percha, followed by composite resin for the coronal restoration (Evetric, Ivoclar Vivadent). In group 2, fiber posts (FRC Postec Plus, Ivoclar Vivadent) were luted using self-adhesive composite cement (SpeedCEM Plus, Ivoclar Vivadent), followed by the same coronal restoration. The teeth were then subjected to fatigue and static load testing. The average loads (± SD) that led to tooth fracture were: 401.40 ± 296.83 N in group 1 and 636.20 ± 204.95 N in group 2. Unfavorable fractures were noted in 9 specimens from group 1 and in 7 specimens in group 2. No statistically significant difference in fracture resistance or fracture mode was found between the groups. Fiber-post placement had no significant influence on the fracture resistance of endodontically treated immature teeth.

Effect of Firing Cycle and Etching Protocols on Tensile Bond Strength of Composite Cement to Zirconium-incorporated Lithium-Silicate Glass Ceramic.

Purpose: To evaluate whether the composite cement tensile bond strength is affected by different firing cycles or etching conditions on zirconium-incorporated lithium-silicate glass ceramics. Materials and Methods: Specimens (N=53) were prepared from blocks of zirconium-incorporated lithium-silicate glass ceramic (ZLS, Dentsply Sirona) with specimen dimensions of 12.5 x 14 x 2 mm (L x W x H, respectively). The specimens were subjected to different firing cycles and etching conditions. They were subsequently cemented onto titanium rods (grade V Ti-alloy, 4.8 mm in diameter, and 25.4 mm in length) with self-adhesive composite cement (TheraCem, Bisco), and then tested for tensile bond strength (TBS). The least-square means linear regression model was used to analyze the effects on TBS using JMP Pro 14 (SAS) and the post-hoc Tukey test with α = 0.05. Results: The TBS was significantly affected by etching duration (p < 0.001) and firing cycles (p < 0.001), but was not significantly affected by etchant concentration (p = 0.31). The highest TBS peak (4.83 MPa) on the fit curve was observed at 45 s of etching time. The lowest TBS was observed at 20 s (3.02 ± 0.28 MPa) etching time. In terms of firing cycles, 1 firing cycle (4.00 ± 0.71 MPa) provided the highest TBS. In contrast, the lowest TBS was observed for as-machined ZLS specimens but without a firing step (3.29 ± 0.53 MPa). Conclusions: Changing the etching time and firing conditions of the specimens had a significant effect on the composite cement tensile bond strength to zirconium-incorporated lithium-silicate glass ceramic. In contrast, etching the specimens with different acid concentrations, 5% or 9.6% of HF, did not significantly change the composite cement tensile bond strength.

Effect of Root Canal Irrigants on Fiber Post Bonding Using Self-adhesive Composite Cements.

To evaluate the effect of different irrigation solutions on the bonding of self-adhesive composite cements to the root canal during fiber-post cementation. One hundred twenty single-rooted human teeth were endodontically treated. The post spaces were prepared and specimens were randomly divided into ten groups, according to the combination of the factors: post space irrigation (distilled water, 2.5% NaOCl, 17% EDTA, 26% polyacrylic acid, and 17% EDTA + 2.5% NaOCl) and self-adhesive composite cement (RelyX U200 [3M Oral Care] and Multilink Speed [Ivoclar Vivadent]). The proportion of open dentinal tubules was evaluated by SEM. After fiber post cementation, six slices were obtained from each root (coronal, middle, and apical thirds) for evaluation of push-out bond strength (BS), nanoleakage (NL), and Vickers microhardness (VHN) of the composite cement. Data from open dentinal tubules were submitted to Kruskal-Wallis and Student-Newman-Keuls tests (α = 0.05). Data from BS, NL, and VHN were evaluated by two-way ANOVA and Tukey's test (α = 0.05). Irrigation with EDTA, polyacrylic acid, and EDTA + NaOCl increased the proportion of open dentinal tubules. For RelyX U200, NaOCl, distilled water and EDTA resulted in the highest BS and VHN values, while for Multi- link Speed, these values were higher only for distilled water. Both composite cements presented lower BS and VHN with polyacrylic acid. NL did not differ between experimental groups (p > 0.05). For both composite cements tested, distilled water showed better results in push-out and microhardness tests.

Evaluation of the effect of dentin surface treatment by air abrasion and Er:YAG laser on the retention of metal crowns luted with glass ionomer cement in teeth with reduced crown height: An in vitro study.

Aim and Objectives:The purpose of this study was to investigate the effect of dentin surface treatment with aluminum oxide air abrasion and Er:YAG laser on tensile bond strength of metal crowns. Metal crowns were luted with conventional glass ionomer cement (GIC) in the teeth with reduced crown height, where preparation geometry did not provide optimal retention form.Materials and Methods:Forty-eight human premolars were prepared to receive metal crowns and were randomly divided into four groups for tensile bond strength testing. Group A: Untreated dentin luted with self-adhesive composite resin cement as positive control; Group B: Untreated dentin luted with GIC as negative control; Group C: Surface treatment with 50 μm aluminum oxide air abrasion and luted with GIC; Group D: Surface treatment with Er:YAG laser (λ =2.94 mm) with a total energy 84.88 J/cm2 of (60 mJ/pulse, 10 Hz, 60 pulses, and 100 μs pulse width) and luted with GIC. The cemented specimens were thermocycled and later subjected to axial load in a universal testing machine at 0.5 mm/min cross-head speed for tensile testing. Scanning electron microscopic evaluation of dentin surface treatment and cement–dentin interface was also done in representative specimens.Results:One-way analysis of variance showed statistically significant difference among/within the groups (P < 0.001). Tukey's post hoc test presented significant increased tensile bond strength of Er:YAG laser group. Air abrasion group showed no significant increase in tensile bond strength values (P = 0.033).Conclusion:Dentin surface treatment with Er:YAG laser significantly improved the tensile bond strength of luting GIC compared to air-abraded and untreated dentin.

Bond Strength of Individually Formed and Prefabricated Fiber-reinforced Composite Posts.

To investigate the micro push-out bond strength of individually formed (everStick Post) and prefabricated (GC Fiber Post) fiber-reinforced composite (FRC) posts cemented with three different types of self-adhesive composite cements. Forty-two single-rooted human teeth were decoronated, endodontically treated, and had post spaces prepared for everStick Post (n = 21) or GC Fiber Post (n = 21). The teeth were randomly divided into three subgroups (n = 7), and posts were cemented either with G-CEM LinkAce (GC), SpeedCEM (Ivoclar Vivadent) or RelyX U200 (3M Oral Care). Specimens were then perpendicularly sectioned and divided at the cementoenamel junction into two root levels: coronal or apical. A micro push-out test was performed using an 0.8-mm-wide stainless steel plunger. Bond strength was calculated in MPa by dividing the fracture load (N) by the bonded surface area (mm2). Log-transformed data was statistically analyzed using factorial ANOVA and Tukey's post-hoc test (α < 0.05). Fracture modes were determined employing a stereomicroscope, and differences were evaluated using a likelihood ratio test and Pearson's chi-squared test. Specimens were also observed using SEM. Bond strengths were significantly affected by both post type and root level (p < 0.05), but not by self-adhesive cement (p > 0.05). Fracture types showed a significantly higher prevalence of adhesive fractures at the apical level, with all fractures starting at the cement-dentin interface. Individually formed FRC posts demonstrated greater bond strength than their prefabricated FRC counterparts. The apical level of the luted posts yielded lower bond strengths than the coronal level. Failures were predominantly adhesive at the cement-dentin interface.

Chemical interaction of glycero-phosphate dimethacrylate (GPDM) with hydroxyapatite and dentin

ObjectivesAlthough the functional monomer glycero-phosphate dimethacrylate (GPDM) has since long been used in several dental adhesives and more recently in self-adhesive composite cements and restoratives, its mechanism of chemical adhesion to hydroxyapatite (HAp) is still unknown. We therefore investigated the chemical interaction of GPDM with HAp using diverse chemical analyzers and ultra-structurally characterized the interface of a GPDM-based primer formulation with dentin. MethodsHAp particles were added to a GPDM solution for various periods, upon which they were thoroughly washed with ethanol and water prior to being air-dried. As control, 10-methacryloyloxydecyl dihydrogen phosphate (MDP) was used. The molecular interaction of GPDM with HAp was analyzed using X-ray diffraction (XRD) and solid-state nuclear magnetic resonance (NMR) spectroscopy. Crystal formation upon application of GPDM onto dentin was analyzed using thin-film XRD (TF-XRD). Its hydrophobicity was measured using contact-angle measurement. The interaction of GPDM with dentin was characterized using transmission electron microscopy (TEM). ResultsXRD revealed the deposition of dicalcium phosphate dihydrate (DCPD: CaHPO4·2H2O) on HAp after 24h. NMR confirmed the adsorption of GPDM onto HAp. However, GPDM was easily removed after washing with water, unlike MDP that remained adhered to HAp. Dentin treated with GPDM appeared more hydrophilic compared to dentin treated with MDP. TEM disclosed exposed collagen in the hybrid layer produced by the GPDM-based primer formulation. Significance: Although GPDM adsorbed to HAp, it did not form a stable calcium salt. The bond between GPDM and HAp was weak, unlike the strong bond formed by MDP to HAp. Due to its high hydrophilicity, GPDM might be an adequate monomer for an etch-and-rinse adhesive, but appears less appropriate for a ‘mild’ self-etch adhesive that besides micro-retention ionically interacts with HAp, or for a self-adhesive restorative material.

Clinical follow-up evaluation of Dalbo®-Rotex® retention elements in the private practice

The aim of this retrospective study was to investigate the clinical outcome of Dalbo®-Rotex® retention elements in a private practice. The majority of the retention elements was fixed with self-adhesive composite cement, and in almost 40% the exposed root surface was additionally covered with composite. The success rate of 96.3% after 24 months in a total of 50 included patients (response rate 48.5%) demonstrated that a simple and cost-effective fixation of removable dentures using prefabricated, chair-side inserted retention elements is feasible. Maintenance care comprised single or repeated replacement and activation of the female part in 12.3% and 39.4% of the cases, respectively. Fractures were rare, occurring in 3.4% of the cases and more likely in patients with parafunctional habits. Frequent oral hygiene correlated with probing depths up to 3 mm at the maxi- mum, while the risk of greater probing depths associated with less frequent oral hygiene increased by a factor of 2.4. Patients’ assessment of the parameters handling and wearing comfort, chewing ability and prosthesis retention was predominantly positive. Based on the findings of the study, covering of exposed dentin areas with composite resin and regular recall comprising professional cleaning, fluoride application and oral hygiene instruction are recommended.