Effect of different surface roughening treatment on polyether ether ketone and acrylic resin bonding: A pilot study.

BACKGROUND: As polyether ether ketone (PEEK) is a relatively new material in dentistry, its bonding properties with regard to dental acrylic base materials are not fully known. To ensure the long-term success of removable dentures with a PEEK framework, the base materials must be well bonded to each other. OBJECTIVES: The study aimed to investigate the effects of different kinds of surface roughening treatment on PEEK and acrylic resin bonding. MATERIAL AND METHODS: Eighty PEEK specimens (N = 80) were randomly divided into 5 groups (n = 16 per group) and subjected to various surface roughening treatment (control, grinding, sandblasting, tribochemical silica coating (CoJet), and sulfuric acid etching). Heat-polymerized acrylic resin was applied to the treated surfaces of the PEEK specimens. The shear bond strength (SBS) test, environmental scanning electron microscopy (ESEM) analysis and three-dimensional (3D) surface topography analysis were performed. The statistical analysis of the data was conducted using the analysis of variance (ANOVA) and Tukey's multiple comparison test. RESULTS: The one-way ANOVA showed significant differences in the SBS values between the groups (p = 0.001). Sandblasting, tribochemical silica coating and sulfuric acid etching resulted in high SBS values (p = 0.001). The highest SBS values were observed in the sulfuric acid etching group (8.83 ±3.63 MPa), while the lowest SBS values were observed in the control group (3.33 ±2.50 MPa). CONCLUSIONS: The additional roughening treatment applied to the PEEK surface increases the bond strength with heat-polymerized acrylic resin.

Comparison of artifact values of prosthodontic materials with 2 different cone beam computed tomography devices.

STATEMENT OF PROBLEM: Prosthodontic materials may cause unexpected artifacts in cone beam computed tomography (CBCT) images, but studies quantifying these artifacts are sparse. PURPOSE: The purpose of this in vitro study was to compare the artifact expression of fixed prosthodontic materials with different CBCT devices. MATERIAL AND METHODS: Ten prosthodontic materials (Co-Cr-Mo alloy, interim acrylic resin, polyetheretherketone, feldspathic ceramic, lithium disilicate glass-ceramic, zirconia-reinforced lithium silicate ceramic, zircon core, and 3 monolithic zirconias) were scanned with 2 CBCT devices. The materials were placed in polymethyl methacrylate resin to simulate clinical conditions. To assess the impact of the devices on artifacts, the gray values of 8 areas in each material image were analyzed. The data were analyzed with the Kruskal-Wallis and Wilcoxon Signed-Rank tests (α=.05). RESULTS: Statistically significant differences were found in the artifact expression of the materials (P<.001) and between CBCT devices (P<.001). CONCLUSIONS: The artifact expression of polymeric and ceramic materials in CBCT images was less than that of other materials. The milliampere-second (mAs) value of CBCT devices had a significant impact on the artifact level.

Dental implant brand and angle identification using deep neural networks.

STATEMENT OF PROBLEM: Determining the brand and angle of an implant clinically or radiographically can be challenging. Whether artificial intelligence can assist is unclear. PURPOSE: The purpose of the present study was to determine the brand and angle of implants from panoramic radiographs with artificial intelligence. MATERIAL AND METHODS: Panoramic radiographs were used to classify the accuracy of different dental implant brands through deep convolutional neural networks (CNNs) with transfer-learning strategies. The implant classification performance of 5 deep CNN models was evaluated using a total of 11 904 images of 5 different implant types extracted from 2634 radiographs. In addition, the angle of implant images was estimated by calculating the angle of 2634 implant images by applying a regression model based on deep CNN. RESULTS: Among the 5 deep CNN models, the highest performance was obtained in the Visual Geometry Group (VGG)-19 model with a 98.3% accuracy rate. By applying a fusion approach based on majority voting, the accuracy rate was slightly improved to 98.9%. In addition, the root mean square error value of 2.91 degrees was obtained as a result of the regression model used in the implant angle estimation problem. CONCLUSIONS: Implant images from panoramic radiographs could be classified with a high accuracy, and their angles estimated with a low mean error.

Effects of repetitive firings on mechanical, optical, and phase formation changes of ceramic materials.

STATEMENT OF PROBLEM: Studies are sparse on how rapid heating and cooling negatively affect optical properties, including color and transparency, and mechanical properties, including hardness and durability, that affect esthetics and shorten the clinical usage period of the ceramics. PURPOSE: The purpose of this in vitro study was to determine the effects of repeated firing on the color difference, mechanical properties, and phase formation of different ceramic materials. MATERIAL AND METHODS: A total of 160 disks (12×1.35 mm) were produced from 4 different ceramic materials: lithium disilicate glass-ceramic, zirconia-reinforced lithium silicate ceramic, zirconia core, and monolithic zirconia. Specimens from all groups were divided into 4 groups (n=10) with a different number of veneer porcelain firings (1 to 4) by simple randomization. After the firings, color measurement, X-ray diffraction analysis, environmental scanning electron micrograph analysis, surface roughness evaluation, Vickers hardness evaluation, and biaxial flexural strength tests were performed. Data were analyzed with analysis of variance (2-way ANOVA) (α=.05). RESULTS: Repeated firing did not affect the flexural strength of the specimens in any of the groups (P>.05), while the color, surface roughness, and surface hardness were significantly affected (P<.05). The specimens fired 4 times showed the highest mean Vickers hardness and ΔE00 values but the lowest mean surface roughness values. Zirconia core specimens showed the highest mean ΔE00 and flexural strength values, and lithium disilicate glass-ceramic specimens had the highest mean Vickers hardness values. CONCLUSIONS: The increase in the number of firings affected the color, mechanical properties, and phase formation of the specimens; this change differed according to the ceramic tested.

Effectiveness and safety of bleaching agents on lithium disilicate glass ceramics.

Background: Aesthetic expectations have increased the use of aesthetic materials in dentistry. Lithium disilicates are frequently used materials for these expectations. Bleaching is another method used to provide aesthetics. Bleaching processes on restorative materials are not fully known. This study investigated the effect of at-home and in-office bleaching methods on the color change, surface roughness, and topography of lithium disilicate glass-ceramic materials produced with two different techniques and subjected to different polishing procedures. Methods: A total of 144 disc-shaped pressed and computer-aided design (CAD) lithium disilicate glass-ceramic specimens were randomly divided into four groups. Glazing and three different chair-side polishing procedures were performed. The specimens in each group were randomly divided into two groups and subjected to at-home and in-office bleaching processes (n=9). The home bleaching process was repeated with 16% carbamide peroxide agent for six hours for seven days, while the in-office bleaching process was applied with 40% hydrogen peroxide agent for two sessions of 20 minutes. After the bleaching processes, the final color and surface roughness experiments of the specimens were carried out, and the results were recorded. ANOVA and Tukey multiple comparison tests were used FOR the statistical analysis of the data (α=0.05). Results: The material*polish*bleaching, polish*bleaching, material*bleaching, and material*polishing interactions were not statistically significant regarding color and roughness changes of both specimens (P>0.05). Conclusion: Both bleaching processes can be safely applied to lithium disilicate glass-ceramic materials.

Effects of different polishing procedures on the surface roughness and hardness of polyether ether ketone (PEEK) / Efecto de diferentes procedimientos de pulido en la rugosidad y dureza de superficie de un material a base de poliéter éter acetona (PEEK)

ABSTRACT: There is insufficient information about the chairside polishing methods of polyether ether ketone material. Therefore, it is aimed in this study to investigate the effects of different polishing processes on polyether ether ketone surface roughness and hardness. A total of 66 disc-shaped specimens made of polyether ether ketone were used in this study. The specimens were polished conventionally and randomly divided into three groups (n=22). One group was designated as the control group, and no further treatment was applied. In the other two groups, the specimens' surfaces were abraded with diamond burs and polished using two different polishing kits. Their surface roughness and Vickers hardness were measured, and environmental scanning electron microscopy and atomic force microscopy examinations were performed. The data were statistically analysed using analysis of variance and Tukey's honest significant difference test (α=0.05). There were no statistically significant differences between the control and polishing kit groups in terms of either surface roughness or Vickers hardness (p>0.05). The polishing kits can be used reliably and effectively for polishing polyether ether ketone materials.

RESUMEN: No existe información suficiente sobre los métodos de pulido del material poliéter éter cetona. Por tanto, este estudio tiene como objetivo evaluar el efecto de diferentes procedimientos de pulido sobre la rugosidad y dureza de superficie de un material a base de poliéter éter acetona. Un total de 66 muestras en forma de disco fueron realizadas. Los especímenes fueron divididos en tres grupos (n=22). Un grupo fue designado como grupo de control, siendo que no se aplicó ningún tratamiento. En los otros dos grupos, las superficies de las muestras se lijaron con fresas de diamante y se pulieron con dos kits de pulido diferentes. Se investigó la rugosidad de superficie y la dureza Vickers en los diferentes grupos. También fueron evaluadas muestras representativas en microscopía electrónica de barrido y microscopía de fuerza atómica. Los datos se analizaron estadísticamente mediante el análisis de varianza (ANOVA) y el método de Tukey (α=0.05). No hubo diferencias estadísticamente significativas entre los grupos en términos de rugosidad de superficie o Dureza Vickers (p>0,05). Los kits de pulido se pueden utilizar de forma eficaz para el pulido de materiales a base de poliéter éter acetona.

Effects of multiple firing processes on the mechanical properties of lithium disilicate glass-ceramics produced by two different production techniques.

STATEMENT OF PROBLEM: Repeated firings cause materials to be exposed to additional heat treatments. The effect of these additional heat treatments on the mechanical properties of lithium disilicate glass-ceramics is not fully known. PURPOSE: The purpose of this in vitro study was to determine the effects of repeated firing on the mechanical properties of lithium disilicate glass-ceramics produced by 2 different techniques, press and computer-aided design and computer-aided manufacturing (CAD-CAM). MATERIAL AND METHODS: Eighty rectangular (25×4×2 mm) lithium disilicate glass-ceramic specimens were used in this study, 40 produced by heat pressing and 40 by milling, and divided into 4 groups (n=10) with a different number of veneer porcelain firings (1 to 4). After firing, the Vickers hardness, flexural strength (3-point bend test), and fracture toughness were determined, and the specimens were analyzed with an environmental scanning electron micrograph. Data were analyzed with analysis of variance (ANOVA) (α=.05). RESULTS: The repeat firing processes did not affect the flexural strength of the specimens in either group (P>.05), while the surface hardness and fracture toughness were significantly changed (P<.05). CONCLUSIONS: Increasing the number of firings adversely affected the mechanical properties of lithium disilicate glass-ceramics.

The effects of repetitive firing processes on the optical, thermal, and phase formation changes of zirconia.

PURPOSE: The aim of this study was to investigate the effect of different numbers of heat treatments applied to superstructure porcelain on optical, thermal, and phase formation properties of zirconia. MATERIALS AND METHODS: Forty zirconia specimens were prepared in the form of rectangular prism. Specimens were divided into four groups (n = 10) according to the number of firing at heating values of porcelain. Color differences and translucency parameter were measured, and X-ray diffraction (XRD) analysis and differential scanning calorimetry (DSC) were performed. Data were analyzed with analysis of variance (ANOVA). RESULTS: There were no statistically significant differences in ΔE, TP, L, a, and b value changes of the zirconia specimens as a result of repetitive firing processes (P>.05). CONCLUSION: Although additional firing processes up to 4 increase peak density in thermal analysis, additional firing processes up to 4 times can be applied safely as they do not result in a change in color and phase character of zircon frameworks.

Investigating the Effect of Different Surface Treatments on Vickers Hardness and Flexural Strength of Zirconium and Lithium Disilicate Ceramics.

PURPOSE: To investigate the effect of different surface treatments on Vickers hardness and flexural strength of zirconia and lithium disilicate ceramics. MATERIALS AND METHODS: 50 zirconia and 50 lithium disilicate ceramic specimens were used. After identifying one group as the control, grinding, sandblasting, CoJet, and Er:YAG laser were applied on the surface of specimens (n = 10). After applying Vickers hardness test to specimens, flexural strength test was performed. The data were analyzed with two-way ANOVA and Duncan's multiple comparisons tests. RESULTS: There were statistically significant differences found between surface treatment groups in terms of Vickers hardness of zirconia and lithium disilicate ceramics (p < 0.001), but there were no statistically significant differences found between surface treatment groups in terms of flexural strength (p > 0.05). CONCLUSIONS: Surface treatments could affect the hardness of ceramics. Therefore, was zirconia found to be harder and more durable than lithium disilicate ceramics.

Effect of Super-Bond C&B and self-adhesive dual-cured resin cement on the fracture resistance of roots with vertical root fracture.

Background. Vertical root fracture might occur during root canal preparation, obturation, post procedures or endodontic treatment. Methods. Fifty-four single-rooted human teeth were decoronated to obtain a standardized length. The root canals were enlarged up to #50 and obturated with gutta-percha and root canal sealer. Eighteen teeth were used as a control group, and vertical root fracture was induced in the remaining teeth. The samples were randomly divided into three groups, as follows: control group (without vertical root fracture), Super-Bond C&B group (fragments were attached with Super-Bond C&B), and self-adhesive dual-cured resin cement group (fragments were attached with self-adhesive dual-cured resin cement). Each specimen was subjected to a fracture resistance test, and data were statistically analyzed using chi-squared test, one-way ANOVA and post hoc Tukey tests (P=0.05). Results. The fracture resistance values of the control and Super-Bond C&B groups were higher than those of the self-adhesive dual-cured resin cement group (P<0.05). However, there were no significant differences between the control and Super-Bond C&B groups (P>0.05). Conclusion. Within the limitations of the present study, Super-Bond C&B was beneficial in obtaining higher fracture resistance in endodontically treated roots with vertical root fracture.

Effect of different bleaching agents on the surface roughness and color stability of feldspathic porcelain / Efeito de diferentes agentes de clareamento na rugosidade superficial e estabilidade de cor da porcelana feldspática

Objective: The aim of this study was to evaluate the effect of different bleaching agents on the surface roughness and color stability of feldspathic porcelain. Material and Methods: In this study, totally 40 discshaped Noritake and Ceramco 3 feldspathic porcelain and two bleaching agents (Opalescence Boost and Opalescence Pf) were used. Bleaching agents were exposed to specimens according to their protocol. Then, the surface roughness of the specimens was evaluated with profilometer and the color of the specimens was recorded by colorimeter. Statistical analysis of the data was performed with IBM SPSS Statistics 20. Results: The results showed that that there were statistically significant differences between the bleaching agents on the surface roughness of feldspathic porcelain (p0.05). Conclusion: The obtained data presented that the bleaching agents increased the surface roughness and not affect the color stability of the feldspathic porcelain. (AU)

Objetivo: O objetivo deste estudo foi avaliar o efeito de diferentes agentes clareadores sobre a rugosidade superficial e estabilidade de cor da porcelana feldspática. Material e Métodos: Neste estudo, foram utilizados 40 porcelanas feldspáticas Noritake e Ceramco 3, em forma de disco, e dois agentes clareadores (Opalescence Boost e Opalescence Pf). Os agentes clareadores foram expostos às amostras de acordo com seu protocolo. Em seguida, a rugosidade superficial dos corpos de prova foi avaliada com perfilômetro e a cor dos corpos de prova foi registrada por colorímetro. A análise estatística dos dados foi realizada com o IBM SPSS Statistics 20. Resultados: Os resultados mostraram que houveram diferenças estatisticamente significantes entre os agentes clareadores na rugosidade superficial da porcelana feldspática (p 0,05). Conclusão: Os dados obtidos mostraram que os agentes clareadores aumentaram a rugosidade superficial e não afetaram a estabilidade de cor da porcelana feldspática.(AU)

Evaluating the microleakage between dentin and composite materials.

BACKGROUND: For successful restoration, it is necessary to minimize the microleakage between dentin and the composite material. OBJECTIVES: The purpose of this study was to evaluate the microleakage of 2 different resin cements (self-adhesive and conventional) on dentin treated with acid, sodium hypochlorite (NaOCl), the acid-NaOCl mixture, the erbium-doped yttrium aluminum garnet (Er:YAG) laser, and their combination. MATERIAL AND METHODS: Seventy dentin specimens were divided into 7 groups (n = 10) according to the surface treatment. Then, the specimens were divided into 2 subgroups (n = 35) according to the resin cement used during cementation with prepared composite resin blocks 5 mm × 11 mm × 3 mm: self-adhesive resin cement or conventional resin cement. Microleakage was scored and recorded at the occlusal and gingival levels, along the resin-dentin interfaces. The data was analyzed with the use of univariate analysis of variance (two-way ANOVA) and the Kruskal-Wallis test for both resin subgroups. RESULTS: The obtained results revealed that self-adhesive resin cement and conventional resin cement showed similar microleakage. Etching with sodium hypochlorite, the Er:YAG laser, the acid-NaOCl mixture, and their combination resulted in microleakage comparable to that achieved in acid etching, which is the conventional method of surface treatment. CONCLUSIONS: Microleakage exhibited by self-adhesive resin cement was similar as in the case of conventional resin cement.

Bond Strength of Resilient Lining Materials to Denture Base Resin: A Systematic Review and Meta-Analysis.

PURPOSE: Bond strength of resilient lining materials with denture base materials is continuously under development. The purpose of this systematic review is to perform a meta-analysis to find out which form of resilient lining bonds better to the denture base, what surface treatments have the highest efficacy to increase the bonding, and what is the most commonly preferred test method to measure bond strength. MATERIALS AND METHODS: Based on a search of PubMed, EMBASE, and Google Scholar, 57 articles were included in this study. A meta-analysis was performed on the results of the 57 articles. RESULTS: The most commonly used test method was the tensile test. Effective surface treatments for bond strength vary depending on the type of the test applied and the type of the attached resilient lining material. Silicone-based resilient lining materials are more commonly preferred than acrylic-based resilient lining materials. While chemical agents and chemicals of resilient lining materials were the most commonly applied surface treatments, a very limited number of studies preferred applying CoJet and laser. CONCLUSIONS: The efficacy of surface treatments varies depending on the resilient lining materials and the test type. More successful results can be achieved by selecting the appropriate surface treatment according to the type of the resilient lining material to increase the bond strength. In particular, when used alone, laser appears to be more effective. Chemical agents and laser are the most effective surface treatments for both silicone- and acrylic-based liners. Moreover, new studies are required to determine the efficacy of CoJet. These findings should help clinicians select a suitable surface treatment to increase the bond strength of resilient lining materials to denture base materials.

Resistance to vertical root fracture of apicoected teeth using different devices during two root canal irrigation procedures.

The aim of the present work was to measure the fracture resistance of endodontically treated teeth that were apicoected with different procedures. Seventy-two extracted human maxillary anterior teeth were included in this study. The specimens were randomly assigned to three main groups according to the apical surgery procedures and then two subgroups according to the irrigation protocols during root canal treatment and total of six groups were obtained (n = 12). Group 1: served as a control and apical surgery process was not performed in this group. Group 2: apical surgery process was performed with tungsten carbide fissure bur Group 3: apical surgery process was performed with Er:YAG laser. Subgroup a: In this group, the specimens were irrigated with %5 NaOCl. Subgroup b: 15% EDTA solution was filled into the root canal and then agitated using a 1.5 W/100 Hz diode laser. The specimens were filled and mounted in acrylic resin blocks and compression strength test was performed. Statistical analysis was performed using two-way ANOVA. The statistical analysis revealed that there were no statistical significant differences between apical surgery procedures (groups 1, 2, and 3) (p < 0.05). Apical resection procedures did not affect the fracture resistance Significant differences were determined between the subgroups (p < 0.05). Agitation of the EDTA with the diode laser reduced the fracture resistance of the specimens. The different canal irrigation techniques altered resistance to fracture; however, apical surgery procedures did not altered the resistance to fracture when compared with the control group.

The effect of heat treatments applied to superstructure porcelain on the mechanical properties and microstructure of lithium disilicate glass ceramics.

The aim of this study was to investigate that heat treatments with different numbers applied to superstructure porcelain whether effects microstructure and mechanical properties of lithium disilicate ceramic (LDC). Eighty disc-shaped specimens were fabricated from IPS e.max Press. Specimens were fired at heating values of porcelain in different numbers and divided four groups (n=5). Initial Vickers hardness were measured and X-ray diffraction (XRD) analysis was performed. Different surface treatment were applied and then Vickers hardness, surface roughness and environmental scanning electron microscopy (ESEM) analysis were performed. Data were analyzed with Varyans analysis and Tukey HSD test (α=0.05). Initial hardness among groups was no significant different (p>0.05), but hardness and surface roughness after surface treatments were significant different (p<0.05). Lithium disilicate (LD) peaks decrease depended on firing numbers. ESEM observations showed that firing number and surface treatments effect microstructure of LDC. Increasing firing numbers and surface treatments effect the microstructure of LDC.