Composite-veneering of polyether-ether-ketone (PEEK): evaluating the effects of different surface modification methods on surface roughness, wettability, and bond strength.

This study aimed to evaluate the effects of different surface modification methods on the surface roughness, contact angle, and bond strength of composite-veneer materials of polyether-ether-ketone (PEEK). Fifty-five specimens (n = 11) with a size of 7 × 7 × 2 mm were cut out from PEEK discs. The specimens were divided into five groups with different surface treatments: no treatment (NO) (control group), sulfuric acid (SA), plasma (P), femtosecond laser (FS), and Nd-YAG laser (NY). After the surface treatments, the specimens were checked for roughness, contact angle, and bond strength of the composite-veneer material. Data were analyzed with the Welch test for roughness, contact angle, and bond strength parameters. Individual Pearson correlation tests were executed for all surface treatment groups to determine any significant correlations among roughness, contact angle, and bond strength parameters (P < .001). Roughness, contact angle, and bond strength values were affected by surface modification methods (P < .001). In comparison to the control group, NY and FS treatments increased the surface roughness and bond strength; they also provided bond strength values comparable to the SA group. When the relationship between the variables was examined, no correlation was seen between roughness, contact angle, and bond strength values for the NY, SA, and control groups (P > .05); however, significant correlations were determined between the contact angle and surface roughness values for the P and FS groups (P < .05). Femtosecond and Nd-YAG laser treatments are viable surface modification alternatives to the sulfuric acid treatment for the PEEK material.

Turkish adaptation and validation of the Short-UPPS-P in adolescents and examination of different facets of impulsivity in adolescents with ADHD.

The short form of the Impulsive Behavior scale (S-UPPS-P) is a widely used scale to measure multiple impulsive personality traits; although it has been translated into many languages, no Turkish translation has been studied to date. Our study had two aims. First, we tested the validity and reliability of the Turkish version of the S-UPPS-P for adolescents. Second, we examined impulsive trait characteristics exhibited by adolescents with ADHD, compared to a community sample. We evaluated the psychometric properties of the Turkish S-UPPS-P scale in 384 adolescents aged 11-18 and tested correlations with ADHD symptoms by assessing 41 adolescents diagnosed with ADHD. Our results showed that with a few slight modifications the Turkish translation of the S-UPPS-P scale can validly assess impulsive trait characteristics for Turkish adolescents. The subscales of lack of premeditation, positive urgency, and negative urgency efficiently distinguished between adolescents with ADHD and control subjects. This is the first scale to evaluate the multidimensional nature of impulsivity in Turkish adolescents. This scale is capable of screening various facets of impulsivity in typically developing adolescents as well as those with ADHD, enabling us to enhance our understanding of possible risks for comorbid diseases in the latter group.

Molecular level nucleation mechanisms of hierarchical MFI and MOR zeolite structures via non-stochastic pathways.

Understanding the chemical mechanism of crystal nucleation at the molecular level is crucial for the design of architectural structures of valuable materials in the future. In this study, it has been revealed that amorphous silicate precursors, which play a role in the nucleation processes of zeolitic frameworks, can be regularly fragmented in mass spectroscopy due to the hydroxyl functional groups in their molecular structures. In this way, by using the mass spectra acquired from LDI-TOF MS, the systematic evolution stages of a common 1D precursor converting to the 3D unit cells of MFI and MOR zeolite structures observed in the same reaction medium were constructed through a nucleation mechanism at the molecular level for the first time. Here we show a novel nucleation pathway that does not occur via stochastic assembly of atoms or distinct building blocks by molecular recognition. Each of the proposed nucleation mechanisms of these different frameworks carrying structural similarities is from different combinations of sequential self-attaching intramolecular covalent couplings of identical origin precursors. The dynamic molecular structure capable of forming finite building units of target frameworks during the nucleation process of this precursor, which is the polymerized form of simple 6-membered siloxane chains, has been arranged around structure directing agents before a hydrothermal reaction.

Preschoolers' Thoughts on the Concept of Time.

This study aimed to examine preschool children's epistemological views in the context of the concept of time via their drawings of the time machine. The study was conducted with 30 five-year-old children (17 girls and 13 boys) attending state and private preschools in the academic year 2018/2019. The data collection tools used in the study were the Test for Creative Thinking - Drawing Production TCT-DP, Children's Thoughts on Time Questionnaire (CTTQ) and Children's Epistemological Views Questionnaire (CEVQ). Of the mixed methods typologies, the fully mixed sequential dominant status-qualitative design was employed. The results obtained from the study indicated that the time machine drawings of almost half the participating children included creative elements and logical thinking products. In addition, 40% of the children's responses reflected sophisticated epistemological views such as scientific, imaginative/science fiction-based, divergent and eccentric approaches and non-authority figures regarding the concept of time. In conclusion: contrary to Piegatian interpretation, our results show that five-year old children can demonstrate abstract scientific understanding regarding the concept of time and preschoolers' epistemic approach has a critical role in determining their development of abstract cognitive concepts.

Effect of Various Treatment Modalities on Surface Characteristics and Shear Bond Strengths of Polyetheretherketone-Based Core Materials.

PURPOSE: To investigate the effect of different surface treatments on the surface roughness (Ra), wettability, and shear bond strength of polyetheretherketone (PEEK) to composite resin. MATERIALS AND METHODS: One hundred ninety eight PEEK specimens were divided into six groups (n = 33). Specimen surfaces were treated with the following surface treatment modalities: silicoating (CoJet), acetone treatment, acid etching (H2 SO4 ), airborne particle abrasion (Al2 O3 ), laser irradiation (Yb:PL laser), and the nontreated surface serving as the control. Surface roughness was measured with an profilometer (n = 11) and a goniometer was used to measure the surface wettability through contact angle (θ)(n = 11). PEEK surfaces were veneered with a composite resin (n = 11). The specimens were then thermocycled for 10,000 cycles at 5 to 55°C. Shear bond strengths between the PEEK and composite resin were measured with an universal test machine. One-way ANOVA was used to analyze the data. Tukey's post-hoc test was used to determine significant differences between groups (α = 0.05). RESULTS: Surface roughness and wettability of PEEK surfaces along with shear bond strength of PEEK to composite resin were influenced by the surface treatments. (p < 0.01) Highest mean Ra values were obtained for PEEK surfaces treated by laser irradiation (2.85 ± 0.2 µm) followed by airborne particle abrasion (2.26 ± 0.33 µm), whereas other surface treatment modalities provided similar Ra values, with the acid-etched PEEK surfaces having the lowest mean Ra values (0.35 ± 0.14 µm). Silicoating provided the most wettable PEEK surfaces (48.04 ± 6.28º), followed by either acetone treatment (70.19 ± 4.49º) or acid treatment (76.07 ± 6.61º). Decreased wettability was observed for airborne particle abraded (84.83 ± 4.56º) and laser-treated PEEK surfaces (103.06 ± 4.88º). The highest mean shear bond strength values were observed for acid-etched PEEK surfaces (15.82 ± 4.23 MPa) followed by laser irradiated (11.46 ± 1.97 MPa), airborne particle abraded (10.81 ± 3.06 MPa), and silicoated PEEK surfaces (8.07 ± 2.54 MPa). Acetone-treated (5.98 ± 1.54 MPa) and untreated PEEK surfaces (5.09 ± 2.14 MPa) provided the lowest mean shear bond strengths. CONCLUSIONS: The highest mean shear bond strengths were observed for acid-etched PEEK surfaces, followed by laser-irradiated, airborne particle abraded, and silicoated PEEK surfaces providing similar mean shear bond strengths. Since shear bond strengths higher than 10 MPa are considered acceptable, acid etching, laser irradiation, and airborne particle abrasion of PEEK surfaces may be considered viable surface treatment modalities for the PEEK material tested.

Effect of storage time on mechanical properties of extended-pour irreversible hydrocolloid impression materials.

STATEMENT OF PROBLEM: Recent commercial extended-pour irreversible hydrocolloid impression materials (EPIHIMs) claim to maintain dimensional stability up to 120 hours. However, data regarding their mechanical properties and performance after 120 hours of storage are lacking. PURPOSE: The purpose of this in vitro study was to test the elastic recovery, strain in compression, and tear strength properties of 5 commercially available EPIHIMs, immediately after preparation and after 120 hours of storage under specific storage conditions. MATERIAL AND METHODS: A total of 150 specimens were prepared in accordance with the ISO 21563:2013 standard from 5 commercially available EPIHIMs (Blueprint Xcreme, Kromopan, Alginmax, Hydrogum 5, and Alginelle). The specimens were subjected to elastic recovery, strain in compression, and tear strength tests immediately after specimen preparation (n=5) and after 120 hours of storage inside clear plastic zipper bags held at 23 °C (n=5). Data were analyzed with a multivariate analysis of variance (MANOVA) test for brand and duration parameters. Normality of data was analyzed with the Shapiro-Wilk test. The Duncan test or Games-Howell test was used for multiple comparisons (α=.05). RESULTS: Elastic recovery and strain in compression values of the EPIHIMs tested were affected by brand and duration parameters (P<.001). Tear strength values of the EPIHIMs tested were affected by brand (P<.001); however, they were not affected by duration (P>.05). Data distribution was normal except for Alginmax in terms of the elastic recovery values and Blueprint Xcreme in terms of the strain in compression values (P<.05). Significant interactions were present between brand and duration for the strain in compression and tear strength values of the EPIHIMs tested (P<.05). Statistically significant difference was not found among mean elastic recovery values of the tested EPIHIM brands (P<.001). Moreover, a statistically significant increase was present in elastic recovery values of the tested EPIHIMs after 120 hours of storage (P<.001). Statistically significant difference was not found among mean strain in compression values of the tested EPIHIM brands tested immediately after preparation (P>.05). However, 120 hours of storage led both to a statistically significant decrease in mean strain in compression values of the tested EPIHIMs (P<.001) except for Alginelle (P>.05) and a statistically significant difference among mean strain in compression values of the tested EPIHIM brands (P<.001). Storage time did not influence mean tear strength values of the EPIHIMs tested (P>.05). However, statistically significant differences were present among mean tear strength values of the tested EPIHIM brands tested immediately after preparation (P<.001) and after 120 hours of storage (P<.001). CONCLUSIONS: Despite variations in elastic recovery, strain in compression, and tear strength properties of the EPIHIMs tested, all the materials fulfilled the requirements to comply with the ISO 21563:2013 standard even after 120 hours of storage.

The effect of repetitive firings on the color of an alumina ceramic system with varying ceramic shade and thickness.

OBJECTIVE: The color of all-ceramic restorations is one of the main criteria to achieve esthetical success. Many factors such as ceramic thickness, condensation techniques, firing temperature, and numbers can affect the final color of restoration. The purpose of this study was to investigate the color changes in alumina-based ceramic system according to ceramic shade and thickness during the multiple firings. MATERIALS AND METHODS: Sixty disc-shaped specimens with two different veneering porcelain shades (A1 or A3), and with three different ceramic thicknesses (0.5, 1, or 1.5 mm), were fabricated from an alumina-based ceramic system. Multiple firings (3, 5, 7, or 9 firings) were performed, and color changes (ΔE00 ) were determined using a spectrophotometer. Repeated-measures ANOVA were used to analyze the data. The Duncan test was used for multiple comparisons (α = .05). RESULTS: The L*a*b* values of the specimens were affected by the number of firings (3, 5, 7, or 9), veneering ceramic shades (A1 or A3) and veneering ceramic thicknesses (0.5, 1, or 1.5 mm). Significant interactions were present between the number of firings, veneering ceramic shade, and veneering ceramic thickness for L* (p < .001), a* (p < .001), and b* (p < .001) values. CONCLUSIONS: No statistically significant color change was observed between 3rd and 9th firings. CLINICAL SIGNIFICANCE: Veneering ceramic shade, veneering ceramic thickness, and number of firings should be carefully considered to obtain an acceptable color match of the definitive restorations.

A technique for retrofitting a metal ceramic crown to an attachment-retained removable partial denture: a clinical report.

In dental applications, precision attachments have been used to retain removable partial dentures (RPDs) for several decades. Various types of extracoronal attachments are commonly used in combination with fixed partial dentures and RPDs to achieve retention and stability. Fracture of the framework, fracture of the roots or teeth, and irretrievable decrease of retention are common reasons for a failed attachment-retained RPD. Another complication of metal ceramic crowns with precision attachment is decementation of the crowns. When fixed components of the attachment-retained RPD fail, the traditional treatment approach requires remaking both the fixed and removable components of the attachment-retained RPD. This technique describes retrofitting of a metal ceramic crown to a resilient attachment-retained RPD.

Microleakage of inlay ceramic systems luted with self-adhesive resin cements.

PURPOSE: To evaluate the microleakage of Cerec 3, IPS e.max Press, and Turkom-Cera inlays cemented with three self-adhesive resin cements. MATERIALS AND METHODS: Ninety standardized class III MOD cavities were prepared in intact human mandibular third molars. Ceramic inlays were fabricated according to the manufacturer's instructions and were cemented using three self-adhesive resin cements (RelyX Unicem, Smartcem 2, and SpeedCEM). The specimens were stored in distilled water at 37°C for 24 h and subjected to 1000 thermocycles in water between 5°C and 55°C with a dwell time of 30 s. Subsequently, the specimens were subjected to 100,000 cycles of mechanical loading of 50 N at 1.6 Hz in 37°C water. The specimens were immersed in 0.5% basic fuchsine for 24 h and were sectioned using a low-speed diamond blade. The percentage of dye leakage at the tooth/restoration interface was measured and compared by Kruskal-Wallis tests with Bonferonni correction and Mann-Whitney U-tests at a significance level of p<0.05. RESULTS: Microleakage at the RelyX Unicem interface was lower than that with Smartcem 2 and SpeedCEM resin cements (p<0.05). Microleakage of the Turkom-Cera system was higher than Cerec 3 and IPS e.max Press ceramic inlays (p<0.05). CONCLUSIONS: Regardless of the ceramic system and self-adhesive resin cement used, dentin margins were associated with higher microleakage than enamel margins.

Effects of implant angulations and attachment configurations on the retentive forces of locator attachment-retained overdentures.

PURPOSE: The aim of this study was to evaluate the effects of different implant angulations and attachment configurations on the retentive forces of locator attachment-retained overdentures over a simulated time period of 6 months. MATERIALS AND METHODS: Two acrylic resin models (models 1 and 2) were fabricated to represent an edentulous mandible. In model 1, the midline implant (in the central region) was vertical and the other two implants (in the canine regions) were 20 degrees divergent from the midline, reaching a total divergence of 40 degrees. In model 2, all three implants were vertically oriented, perpendicular to the occlusal plane and parallel to each other. Three-point vertical pull-out forces were employed in a universal testing machine at a constant crosshead speed of 50 mm/min after overdenture construction and a simulation of 6 months of repeated insertions/removals of the overdenture. Locator attachments with different male combinations and bar and clip attachments were tested in model 1. Clear locator attachments and bar and clip attachments were tested in model 2 and served as controls. RESULTS: The initial retentive forces of all attachments in both models ranged from 26.58 to 62.05 N, whereas the initial retentive forces of the attachments for only model 1 ranged from 49.58 to 62.05 N. The highest retention value was recorded for clear green locator attachments and the lowest for hader bar yellow clip attachments. Locator attachments showed higher retention values than hader bar yellow clip attachments. CONCLUSION: All attachment systems demonstrated a decrease in retention over time. Locator attachments provided better retention than hader bar yellow clip attachments. The highest retention values were obtained when green male locators were used in combination with male attachments.

A simplified technique for solving the transfer problem of implant-supported fixed partial dentures for patients with microstomia.

Techniques for treating a fully or partially edentulous patient with microstomia have been developed to overcome the challenge of accessing the oral cavity. Management of the problems associated with providing implant-supported fixed partial dentures for patients with microstomia has not been well reported. This article describes a solution for the transfer problem that occurs when making an impression of an implant-supported fixed partial dentures for patients with microstomia.

A technique for constructing a new maxillary overdenture to a nonretrievable implant connecting bar.

The most frequent mechanical complications of the bar-implant-retained overdentures are loosening of the bar screws and the need to reactivate the retentive clips. This article describes a technique to construct a new maxillary overdenture to a nonretrievable round-profile implant connecting bar with 2 distally placed attachments. The retainer round-profile bar was nonretrievable due to a worn retaining screw head. Attachment transfer analogs are used to transfer the position of the attachments to the master cast. The technique allows the clinician to construct new overdentures without the need for removal of the implant connecting bar. Reduced chairside time, reduced treatment cost, and increased patient satisfaction are the major advantages of the technique.

A technique for fabrication of an extracoronal attachment-retained removable partial denture to fit an existing fixed partial denture.

Precision attachments have been used for many years to retain removable partial dentures (RPDs). Common reasons for a failed attachment-retained RPD are fracture of the framework, fracture of the roots or teeth, and irretrievable decrease of retention. When an RPD framework major connector has been fractured, it should be remade. This article describes a technique to remake a fractured mandibular RPD using cast round profile attachment analogs without the need for replacement of the fixed partial denture.

Replacement of a lost removable partial dental prosthesis using ball-attachment analogs: a clinical report.

Attachment-retained removable partial dental prostheses (RPDPs) may be lost. Although in such situations, the RPDP should be remade, no method has yet been described for replacing lost attachment-retained RPDPs. This report describes a method for fabrication of a replacement for a lost maxillary RPDP using ball-attachment analogs.

Symphyseal bone cylinders tapping with the dental implant into insufficiency bone situated esthetic area at one-stage surgery: a case report and the description of the new technique.

Periodontal defects and trauma at the anterior maxillary region can cause a severe alveolar ridge deficiency resulting in an unesthetic view. Ideal implant positioning can be compromised by inadequate alveolar bone in terms of height and width. Reconstruction of osseous defects with autogenous bone allows ideal implant positioning and creates a more natural soft and hard tissue profile, which influences esthetic crown anatomy at the anterior maxillary region. In this case report, an alveolar ridge defect due to periodontally compromised tooth extraction was filled with autogenous bone cylinder and dental implant at one-stage surgery. In the presented case, a new technique was described which included bone reconstruction of the defects at the anterior maxillary region and simultaneous placement of the dental implant.

The effect of ceramic thickness and number of firings on the color of two all-ceramic systems.

STATEMENT OF PROBLEM: All-ceramic restorations have been advocated for superior esthetics, and various materials have been used to improve ceramic core strength, but there is a lack of information on how color is affected by different core substructures and fabrication procedures. PURPOSE: The purpose of this study was to evaluate the effects of various dentin ceramic thicknesses and repeated firings on the color of lithium disilicate glass-ceramic (IPS e.max Press) and zirconium-oxide (DC-Zirkon) all-ceramic systems. MATERIAL AND METHODS: Thirty disc-shaped specimens, 4 mm in diameter with a 1-mm core thickness, and 0.5-, 1-, or 1.5-mm dentin ceramic thicknesses, were made from each of 2 ceramic systems (n=10). Repeated firings (3, 5, 7, or 9) were performed, and the color of the specimens was compared with the color after the initial firing. Color differences among ceramic specimens were measured using a spectrophotometer (VITA Easyshade), and data were expressed in CIELAB system coordinates. Repeated measures ANOVA was used to analyze the data (number of firings, ceramic composition, and ceramic thickness) for significant differences. The Tukey HSD test and paired 2-tailed tests were used to perform multiple comparisons (alpha=.05). RESULTS: L*a*b* values of the ceramic systems were affected by the number of firings (3, 5, 7, or 9 firings) (P<.001), ceramic composition (DC-Zirkon or IPS e.max Press) (P<.001), and ceramic thickness (0.5, 1, or 1.5 mm) (P<.001). Significant interactions were present in L*a*b* values between the number of firings and ceramic composition (P<.001) and between the number of firings and ceramic thickness (P<.001). Significant interactions were present between the number of firings and ceramic thickness and ceramic composition (P<.05) in L* and b* values, but not for the a* value (P=.068). As the ceramic thickness increased, significant reductions in L* values (P<.01) were recorded for IPS e.max Press and DC-Zirkon specimens. For IPS e.max Press specimens, there were significant increases in a* and b* values (P<.01). For DC-Zirkon specimens, significant increases in a* values were observed; however, no significant differences were recorded for b* values. CONCLUSIONS: The analysis revealed that there were significant changes in L*a*b* color data as the number of firings increased, which resulted in perceptual color changes in L*a*b* color parameters.

Technical tips for constructing a maxillary implant-supported overdenture by using a double-impression technique.

Implant-supported overdentures have become a popular treatment option for completely edentulous patients. Functional loads should be optimally distributed to the mucosa and the abutments. This article describes a functional double-impression technique for fabricating a maxillary implant-supported overdenture.

The effect of repeated firings on the color of an all-ceramic system with two different veneering porcelain shades.

STATEMENT OF PROBLEM: Color matching between a restoration and natural teeth is a common clinical problem. Despite careful shade selection, color of the restoration may be affected by fabrication procedures. PURPOSE: The purpose of this study was to determine the color changes of an all-ceramic restoration with 2 different veneering porcelain shades after repeated firings. MATERIAL AND METHODS: Twenty disc-shaped ceramic specimens, 4 mm in diameter with a 1-mm core thickness and 2 different veneering porcelain shades (A1, A3), were fabricated from a zirconia-based porcelain (DC-Zirkon) (n=10). Repeated firings (3, 5, 7, or 9 firings) were performed for the specimens, and color differences (DeltaE) were determined using a spectrophotometer. Repeated measures ANOVA was used to analyze the data (number of firings, veneering porcelain color). The Tukey HSD test and paired 2-tailed tests were performed for multiple comparisons (alpha=.05). RESULTS: The L*a*b* values of the ceramic system were affected by the number of firings (3, 5, 7, or 9) (P<.001) and the veneering porcelain shade (P<.001). Significant interactions were present between the number of firings and veneering porcelain shade for L* (P=.003) and b* (P=.042) values, but not for the a* value (P=.82). An increase in the number of firings of the specimens with both A1 and A3 veneering porcelain shades produced an increase in the L* value, resulting in lighter specimens (P<.001). For both A1 and A3 veneering porcelain shades, the a* value decreased after repeated firings, which resulted in more green specimens (P=.002). The b* value did not change after repeated firings (P=.09) for the A1 veneering porcelain shade; however, it increased for the A3 veneering porcelain shade, which resulted in more yellow specimens (P=.001). CONCLUSIONS: The color of the all-ceramic specimens with different veneering porcelain shades is influenced by repeated firings. However, color changes that occurred are clinically acceptable.

Fabrication of zirconium primary copings to provide retention for a mandibular telescopic overdenture: a clinical report.

Because of their strength, zirconia ceramics may be used to restore removable partial denture abutments. This carries the advantages of elimination of the galvanic current between primary and secondary copings, along with thermal protection of abutment teeth. This article describes the fabrication of zirconium primary copings to provide retention for a mandibular telescopic overdenture.

Fabrication of implant-assisted restorations utilizing functional impression techniques: case reports.

This article describes the fabrication of implant-supported overdentures and removable partial dentures attached to anterior fixed partial dentures utilizing impression techniques to transfer the position of implants and record soft tissue areas in a functional state.