This work aimed to analyze the micro shear bond strength of ceramic and dental substrates to Multilink® Speed self-adhesive/curing resin cement (Ivoclar Vivadent, Schaan, Liechtenstein).
The groups ...were composed of (1) ceramic/cement interfaces: LD - Lithium Disilicate (IPS e.max CAD®); ZLS - Zirconia-reinforced lithium silicate (Celtra Duo®); Y-TZP MO – Medium Opacity Yttria-stabilized tetragonal zirconia polycrystal (IPS ZirCAD MO®); Y-TZP T - Translucency yttria-stabilized tetragonal polycrystal (IPS ZirCAD MT®), and by (2) cement/dental interfaces (enamel or dentin): E + E – selective phosphoric acid etching enamel; E - unetched enamel; Dentin - middle dentin. Ceramic blocks were sectioned into 2mm thick slices in a cutting machine with a diamond disc under cooling, followed by standardized polishing, crystallization or sintering, PVC inclusion, final polishing, and surface treatments according to each ceramic composition (n=20). Teeth slices (2mm thick) were obtained from human third molars, PVC included, followed by polishing. The cement cylinders (Ø = 1.4; height = 1.0) were bonded to substrates, following the manufacturer's instructions. The specimens were stored in deionized water at 37°C for 24h and subjected to the micro shear bond strength test. Data were submitted to statistical analysis using the Kruskal-Wallis and Dunn tests. Failure types were classified as adhesive, cohesive, and mixed, with a representative specimen of each failure submitted to a scanning electron microscope (SEM). Weibull statistical analysis was performed to obtain the following metrics: the probability of failure, Weibull modulus (m) (reliability), and characteristic strength (σ0).
The E + E group showed the highest median value, lower probability of failure, higher reliability, and higher characteristic strength among all the evaluated groups, with significant similarity to the ZLS and LD groups and a statistically significant difference to the other dental substrates. E and Dentin showed the lowest medians among all substrate types. The Glass-ceramics the ZLS showed high characteristic strength and the LD showed greater reliability. The adhesive failure mode was predominant among the failure types.
Glass-ceramics showed higher characteristic strength, lower probability of failure, and greater reliability, being similar to selectively etched enamel.
Hydroxyapatite (HA) from bovine bone structure has high importance among biomaterials due to its biocompatibility, bioactivity and its sustainable renewable source. However, pure dense HA bioceramics ...still present poor mechanical properties when used in a dense form to be applied as an implant or restoration material. Thus, this study aimed to characterize the thermal behavior of pure bovine HA powder as well as evaluate its behavior when subjected to two sintering methodologies.
Therefore, HA was extracted from bovine bones, turned into nanoparticles in a ball mill and subjected to uniaxial and isostatic pressing into discs, according to the ISO 6872 standard. Two sintering methodologies were used: 1) conventional curve (HA/Conv), in a single curve with a maximum temperature peak of 1300 °C and slow cooling to room temperature; and 2) 2-step curve (HA/2step) with a maximum peak of 950 °C with rapid cooling to 880°C and subsequent slow cooling to room temperature. The nanoparticulate powder was subjected to differential thermal analysis (DTA), dilatometry and x-ray diffractometry (XRD). The sintered samples of both groups were characterized by XRD, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) relative density and biaxial flexural strength.
The dilatometric curve shows the beginning of the sintering process at 1050 °C. In the DTA analysis it was possible to observe a gain in mass in about 650 °C with subsequent loss of part of the acquired mass until reaching a temperature of 1000 °C. The XRD analysis demonstrates the classic crystallographic peaks both before and after the sintering process by the two groups, showing no change in the crystalline characteristic. The FTIR spectrum demonstrated the classical bands of HA-related bonds. The HA/Conv group obtained statistically higher values of relative density (2.92g/cm3) and in flexural strength (109MPa) (p<0.05). The results of the HA/2step group (2.08g/cm3; 25.7MPa) are justified by the SEM images that demonstrate greater porosity and less cohesion between the ceramic grains.
It was possible to conclude that the HA bioceramics submitted to temperatures above 1000 °C, can reach a higher degree of sintering and densification, thus optimizing its mechanical properties.
According to the literature, the occurrence of dysphagia is high in cases of stroke, and its severity can be enhanced by loss of teeth and the use of poorly fitting prostheses.
To verify that the ...status of oral health influences the level of oral intake and the degree of swallowing dysfunction in elderly patients with stroke in chronic phase.
Thirty elderly individuals affected by stroke in chronic phase participated. All subjects underwent assessment of their oral condition, with classification from the Functional Oral Intake Scale (FOIS) and nasoendoscopic swallowing assessment to classify the degree of dysphagia. The statistical analysis examined a heterogeneous group (HG, n=30) and two groups designated by the affected body part, right (RHG, n=8) and left (LHG, n=11), excluding totally dentate or edentulous individuals without rehabilitation with more than one episode of stroke.
There was a negative correlation between the need for replacement prostheses and the FOIS scale for the HG (P=0.02) and RHG (P=0.01). Differences in FOIS between types of prostheses of the upper dental arch in the LHG (P=0.01) and lower dental arch in the RHG (P=0.04). A negative correlation was found between the number of teeth present and the degree of dysfunction in swallowing liquid in the LHG (P=0.05). There were differences in the performance in swallowing solids between individuals without prosthesis and those with partial prosthesis in the inferior dental arch (P=0.04) for the HG.
The need for replacement prostheses, type of prostheses, and the number of teeth of elderly patients poststroke in chronic phase showed an association with the level of oral intake and the degree of oropharyngeal dysphagia.
This study evaluated the five-year clinical performance of ceramic inlays and onlays made with two systems: sintered Duceram (Dentsply-Degussa) and pressable IPS Empress (Ivoclar Vivadent). ...Eighty-six restorations were placed by a single operator in 35 patients with a median age of 33 years. The restorations were cemented with dual-cured resin cement (Variolink II, Ivoclar Vivadent) and Syntac Classic adhesive under rubber dam. The evaluations were conducted by two independent investigators at baseline, and at one, two, three, and five years using the modified United States Public Health Service (USPHS) criteria. At the five-year recall, 26 patients were evaluated (74.28%), totalling 62 (72.09%) restorations. Four IPS restorations were fractured, two restorations presented secondary caries (one from IPS and one from Duceram), and two restorations showed unacceptable defects at the restoration margin and needed replacement (one restoration from each ceramic system). A general success rate of 87% was recorded. The Fisher exact test revealed no significant difference between Duceram and IPS Empress ceramic systems for all aspects evaluated at different recall appointments (p>0.05). The McNemar chi-square test showed significant differences in relation to marginal discoloration, marginal integrity, and surface texture between the baseline and five-year recall for both systems (p<0.001), with an increased percentage of Bravo scores. However, few Charlie or Delta scores were attributed to these restorations. In conclusion, these two types of ceramic materials demonstrated acceptable clinical performance after five years.
A number of prefabricated nonmetallic posts are currently available for use in conjunction with resin composite cores before fabrication of crowns for endodontically treated teeth. Information is ...needed regarding the strength of the composite and the nature of attachment between its components.
The aim of this study was to determine the influence of different types of posts on the fracture resistance of a resin composite core material using the diametral tensile strength (DTS) test.
Cylindrical specimens, 6 mm in diameter and 3 mm high, were prepared from resin composite (Tetric Ceram) and a group of prefabricated posts (n
=
10) as follows: resin composite only (control); Vectrispost (VTS); FiberKor (FKR); Æstheti-Plus post (ATP); Light-Post (LTP); Dentorama post (DRM), and Para-Post (PRP) as a second control. Specimens were stored for 7 days in water at 37°C and then subjected to DTS test in a universal testing machine until failure occurred and load was recorded (N). Mean values and SD for DTS values (MPA) were calculated, and data were analyzed statistically with 1-way analysis of variance, followed by the Tukey test (α
=
.05). Representative specimens from each group were examined with SEM to determine nature of failure.
Mean values (SD) in MPa for DTS were as follow: Control group: 49.64 (3.36); VTS: 29.77 (3.36); FKR: 31.9 (2.39); ATP: 28.92 (2.2); LTP: 34.26 (3.37); DRM: 33.45 (2.46), and PRP: 27.90 (2.40). Analysis of variance indicated significant differences among the groups (
P<.05). SEM examination indicated that for PRP failure was adhesive in nature, whereas with all nonmetallic posts, cohesive failure was more predominant.
The use of posts did not result in reinforcement of resin composite core when diametral tensile force was applied. When used with the core material, LTP, DRM, and FKR resulted in the highest DTS values, whereas PRP resulted in the lowest values.
The development of composite resin cements that chemically bond to dental alloys has improved the construction of resin-bonded prostheses. Composite resins can be selected for various situations, but ...specific clinical situations may required different alloys. This study evaluated the ability of a composite resin cement to bond to various dental alloys of different compositions. Ten pairs of disks for each alloy (two NiCr, two NiCrBe, one CuAl, one gold type IV, and one gold for metal ceramic) were bonded to a composite resin cement after air abrasion was performed with aluminum oxide. The disks were then rinsed in tap water and were ultrasonically cleaned in distilled water for 2 minutes. The tensile tests exhibited greater values for alloys ultrasonically cleaned, and the best results were recorded by NiCr and NiCrBe alloys.
A problem associated with resin-bonded fixed partial dentures is inadvertent dislodgment at the metal/cement interface. It has been suggested that Panavia Ex resinous cement requires only air ...abrasion of the alloy with 50 μm aluminum oxide particles to record reliable bond strength values. The purpose of this study was to discuss the consequences of changes in the type of air abrasion and surface oxidation of the alloy. Fifty pairs of disks of a NiCr alloy were treated by five methods: (1) air abrasion with 50 μm aluminum oxide (control), (2) air abrasion with 50 μm glass beads, (3) air abrasion with a mixture of aluminum oxide and glass beads (ratio 1:1), (4) air abrasion with aluminum oxide and immersion in acid solution of potassium permanganate, and (5) air abrasion with aluminum oxide and immersion in aqueous solution of potassium permanganate. The disks were cemented to each other with Panavia Ex composite resinous cement and tensile tests were conducted at a crosshead speed of 0.5 mm/minute. No statistically significant differences were recorded among the treatments for the alloys used in this study except air abrasion with glass beads, which exhibited the lowest bond strength values.
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