Radiopacity and physical properties evaluation of infiltrants with Barium and Ytterbium addition

Radiopaque properties in the infiltrant should be interesting for clinicians to feel more confident to indicate this treatment. Thus, the aim of this study was to evaluate the effect of the incorporation of barium and ytterbium particles on the physical properties of resin infiltrants. Groups were divided according to the addition of ytterbium oxide (Y) alone (30 or 40%) or Y with barium (YB) (15/15% or 20/20% respectively) in the Icon commercial infiltrant and in the experimental infiltrant base. Digital radiography (n=5), Microradiography (n=5), Microtomography (n=3), degree of conversion (n=5), water sorption (n=16), solubility (n=16), contact angle (n=16), flexural strength (n=16), elastic modulus (n=16) and Energy dispersive X-ray Spectroscopy (n=10) were performed. Analyses were performed using the R program, with a significance level of 5%, and microradiography and Microtomography analyses were evaluated qualitatively. In groups with 30 or 40% of ytterbium, radiopacity was higher or equal to enamel. Microradiography and Microtomography appear to have more radiopacity in groups with 40% (Y). Among the groups with no particle addition, those of the experimental infiltrant presented a higher degree of conversion than those of Icon®. In most groups, there was solubility below the ISO-recommended levels. The addition of particles resulted in higher viscosity. Groups with Icon had higher flexural strength and elastic modulus than groups with experimental infiltrant. The addition of 40% (Y) improved polymerization, had low solubility, and had greater radiopacity than enamel, however negatively affected the viscosity increasing then. Experimental groups with the base showed a higher water sorption than Icon groups.

Automatic exposure compensation of digital radiographic technologies does not affect alveolar bone-level measurement

OBJECTIVE

To evaluate whether the automatic exposure compensation in the presence of high-density materials can affect the measurement of alveolar bone level.

METHODS

Thirty regions of seven dry skulls and six mandibles were radiographed with and without a high-density material, using two digital radiographic technologies: photostimulable phosphor plate (PSP, Digora Optime) and sensor (CMOS, Digora Toto), totaling 120 images. The distances from the cement-enamel junction to the alveolar bone crest were measured using cone-beam computed tomography (CBCT) images to represent the reference standard. The same measurements of alveolar bone level and the average of the pixel values of the image were evaluated on the radiographs. Paired t test compared the average pixel values and alveolar bone-level measurements between images with and without high-density material. One-way analysis of variance compared the difference between radiographic and CBCT measurements (α = 0.05).

RESULTS

The high-density material reduced the pixel values in PSP (p = 0.002) and CMOS (p < 0.001) technologies, demonstrating the AEC functioning in both technologies. There was no difference in bone-level measurements between the images without and with the high-density material for both technologies (p ≥ 0.091), or between the tomographic and radiographic measurements (p ≥ 0.319).

CONCLUSION

In the presence of high-density material, the automatic exposure compensation reduces the average pixel values of the images (i.e., images get darker), but does not influence the radiographic measurements of alveolar bone level.

Influence of Incorporating Zirconium- and Barium-based Radiopaque Filler Into Experimental and Commercial Infiltrants

OBJECTIVES

To evaluate how adding different concentrations of particles (barium or zirconium oxide 25%/45% by weight) to a commercial infiltrant (Icon) and an experimental infiltrant influences cohesive strength (CS), degree of conversion (DC), water sorption (WS), solubility (SL), radiopacity, and penetration depth.

METHODS AND MATERIALS

Microtensile CS (n=10) was evaluated using a universal testing machine. DC (n=5) was evaluated in a Fourier-transform infrared spectrometer. Polymerized samples were dissected, weighed, and stored to obtain the final mass for WS and SL tests (n=10). Radiopacity analysis (n=5) was performed using a digital radiography system. Penetration depth analysis (n=5) was performed by confocal laser scanning microscopy. Analyses were performed using the R program, with a significance level of 5%, except for the penetration depth analyses, which were evaluated only qualitatively.

RESULTS

The groups with 45% zirconium showed greater CS values, regardless of the infiltrant. Among the groups with no particle addition, those of the experimental infiltrant presented higher DC than those of Icon. The experimental infiltrant presented lower WS than Icon. All groups had SL below the ISO recommended levels. Radiopacity higher than 2.24 mmAl (enamel radiopacity) was observed only in the groups with 45% zirconium. All the groups achieved similar penetration depth, but the groups containing experimental infiltrant appear to have had longer tag extensions.

CONCLUSIONS

Addition of 45% of zirconium presented good results for CS and WS, as well as SL below the ISO recommended standard, adequate radiopacity, and penetration depth similar to the other groups.

Effect of image acquisition parameters on the radiopacity of bulk-fill and nanocomposite resins

OBJECTIVE

This study evaluated the radiopacity of 2 bulk-fill resins (SonicFill and Filtek Bulk Fill) and a nanocomposite (Filtek Z350 XT) resin compared with enamel, dentin, and aluminum as measured with different exposure parameters.

STUDY DESIGN

Resin disks were radiographed together with a 1-mm human tooth section and an aluminum stepwedge, at exposure times of 0.2 and 0.32 s, and source-image (S-I) distances of 30 and 40 cm, using complementary metal oxide semiconductor (CMOS) and photostimulable phosphor systems. Grayscale values were measured using ImageJ software. Paired Student t tests were used to compare the effect of the receptor on grayscale values for each material. Analysis of variance was used to evaluate the effects of receptor, exposure parameters, and the resins on radiopacity.

RESULTS

All resins exhibited greater radiopacity scores than enamel and were significantly different from each other. Filtek Z350 produced the lowest radiopacity values, whereas SonicFill produced the highest. The radiopacity values were higher on images acquired with CMOS receptors. Receptor type, exposure time, S-I distance, and material, as well as many interactions of these parameters, affected the radiopacity of the resins.

CONCLUSION

The tested resins complied with ISO 4049. Exposure parameters and digital receptors affected their radiopacity.

Fracture Resistance of Endodontically Treated Maxillary Premolars Restored With Different Methods

Purpose:

The purpose of this in vitro study was to evaluate the resistance and patterns of fracture of endodontically treated maxillary premolars (ETPs) restored with different methods.

Methods and Materials:

Mesio-occluso-distal cavities were prepared in 50 extracted caries-free human maxillary premolars after endodontic treatment. The teeth were divided into five groups (n=10), according to the restorative method. G1: intact teeth (control group); G2: conventional composite resin; G3: conventional composite resin with a horizontal glass fiber post inserted between buccal and palatal walls; G4: bulk-fill flowable and bulk-fill restorative composites; and G5: ceramic inlay. For direct restorations, Filtek Z350 XT, Filtek Bulk Fill Flowable Restorative, and Filtek Bulk Fill Posterior Restorative were used. Indirect restorations were fabricated from a pressable lithium disilicate glass-ceramic (IPS e-max Press) and adhesively cemented (RelyX Ultimate). All specimens were subjected to thermocycling (5°C to 55°C/5000 cycles) and additionally submitted to cyclic loading 50,000 times in an Electro-Mechanical Fatigue Machine. Next, the specimens were subjected to a compressive load at a crosshead speed of 1 mm/min until fracture. The fractured specimens were analyzed to determine the fracture pattern using a stereomicroscope, and then representative specimens were carbon coated to allow for the studying of the fracture surface under scanning electron microscopy. One-way analysis of variance (ANOVA) was used to compare fracture resistance of the groups. The results of fracture patterns were submitted to the Fisher exact test (α=0.05).

Results:

All specimens survived fatigue. Mean (standard deviation) failure loads (N) for groups were as follows: G1: 949.6 (331.5); G2: 999.6 (352.5); G3: 934.5 (233.6); G4: 771.0 (147.4); and G5: 856.7 (237.5). The lowest fracture resistance was recorded for G4, and the highest ones were recorded for G2, followed by that of G1 and G3. One-way ANOVA did not reveal significant differences between groups (p&gt;0.05). The highest repairable fracture rates were observed in G1 (100%) and G3 (80%).

Conclusions:

ETPs restored with conventional composite resin with or without horizontal fiber post, bulk-fill composite, and ceramic inlay showed fracture resistance similar to that of sound teeth. Conventional composite resin restorations exhibited the highest prevalence of unrepairable fractures, and the insertion of a horizontal fiber post decreased this prevalence. Intact teeth showed 100% of repairable fractures. It is difficult to extrapolate the results directly to a clinical situation due to the limitations of this study.

Radiopacity and Porosity of Bulk-fill and Conventional Composite Posterior Restorations—Digital X-ray Analysis

Objectives:

To compare radiopacity and porosity as expressed by the presence of voids in restorations carried out using bulk-fill and incremental filling techniques to restore large mesio-occlusal-distal (MOD) cavities.

Methods:

Fifty-five molars with MOD preparations were incrementally filled with Filtek Z-350XT (Z350XT) or bulk-fill composite: Filtek Bulk Fill/Z-350XT (FBF/Z350XT), Venus Bulk Fill/Charisma Diamond (VBF/CHA), SDR/Esthet-X HD (SDR/EST-X), Tetric EvoCeram Bulk Fill (TEC). Digital radiographic images (Vistascan scanner) were taken of restored molars and analyzed at the gingival and isthmus floors. Radiodensity measurements were performed using standardized points symmetrically distributed over each region of composite and tooth structure. Three calibrated evaluators visually assessed the presence of voids. Confidence intervals were calculated, and data were analyzed using analysis of variance and χ2 tests.

Results:

TEC and VBF/CHA showed significantly higher radiodensities, while the lowest values were observed for FBF/Z350XT and Z350XT. Radiodensity at the cervical regions tended to be greater than that found at the isthmus floor. The lowest incidence of voids was found for VBF/CHA, whereas the incremental insertion technique resulted in the highest rate of voids.

Conclusion:

Bulk-fill composite resin demonstrated an adequate level of radiodensity and a reduced presence of voids compared with the incremental filling technique.

Evaluation of Radiopacity of Bulk-fill Flowable Composites Using Digital Radiography

New flowable composites that may be bulk-filled in layers up to 4 mm are indicated as a base beneath posterior composite restorations. Sufficient radiopacity is one of the several important requirements such materials should meet. The aim of this study was to evaluate the radiopacity of bulk-fill flowable composites and to provide a comparison with conventional flowable composites using digital imaging. Ten standard specimens (5 mm in diameter, 1 mm in thickness) were prepared from each of four different bulk-fill flowable composites and nine different conventional flowable composites. Radiographs of the specimens were taken together with 1-mm-thick tooth slices and an aluminum step wedge using a digital imaging system. For the radiographic exposures, a storage phosphor plate and a dental x-ray unit at 70 kVp and 8 mA were used. The object-to-focus distance was 30 cm, and the exposure time was 0.2 seconds. The gray values of the materials were measured using the histogram function of the software available with the system, and radiopacity was calculated as the equivalent thickness of aluminum. The data were analyzed statistically (p<0.05). All of the tested bulk-fill flowable composites showed significantly higher radiopacity values in comparison with those of enamel, dentin, and most of the conventional flowable composites (p<0.05). Venus Bulk Fill (Heraeus Kulzer) provided the highest radiopacity value, whereas Arabesk Flow (Voco) showed the lowest. The order of the radiopacity values for the bulk-fill flowable composites was as follows: Venus Bulk Fill (Heraeus Kulzer) ≥ X-tra Base (Voco) > SDR (Dentsply DeTrey) ≥ Filtek Bulk Fill (3M ESPE). To conclude, the bulk-fill flowable restorative materials, which were tested in this study using digital radiography, met the minimum standard of radiopacity specified by the International Standards Organization.