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Objectives: To proof the feasibility of direct colour printing on 3Y-TZP using 222 nm UV-C through investigating the degree and durability of the colour changes, and testifying whether surface, mechanical and biological properties are influenced by the treatment., Methods: 222 nm UV-C light (Irradiance: 1.870 mW/cm 2 ) was used to treat 3Y-TZP for durations from 15 min to 24 h. ΔE*, TP, crystalline structure, surface morphology, S a , BFS and biological activities were investigated before and after irradiation. SPSS 28.0 was used for statistical analysis (α = 0.05)., Results: 222 nm UV-C irradiation was capable to shade white 3Y-TZP into tooth colours. With the increase of ΔE*, TP decreased, such that the longer the irradiation time, the higher the ΔE* (logarithmic relationship) and lower the TP. Despite the induced optical changes being prone to fade, the process can be predicted by inversely proportional relationships between ΔE*, TP and the testing points. The treated surface exhibited enhanced hydrophilicity, while the recovery phenomenon was observed. Other properties were not altered by the treatment., Significance: This is the seminal study demonstrating the feasibility of direct colour printing on 3Y-TZP using 222 nm UV-C. The new relationship between the colour centre and E g of 3Y-TZP was established, whereas the induced optical changes were stabilised after a certain period and were highly predictable by controlling the irradiation periods. The irradiation was only correlated to the electron excitation and oxygen vacancies, and would not lead to any changes of other properties. A simple, safe and promising approach to achieve satisfactory colours on 3Y-TZP in clinical practice can be developed., Competing Interests: Declaration of Competing Interest There are no known conflicts of interest associated with this publication and there has been no significant financial support for this work that could have influenced its outcome., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Objective: The commonly used base monomer utilized in resinous commercial dental restorative products is bis-GMA which is derived from bisphenol-A (BPA) - a well-known compound which may disrupt endocrine functions. To address concerns about its leaching into the oral environment and to optimize the quality of dental composites, a BPA-free alternative base monomer, fluorinated urethane dimethacrylate (FUDMA), was designed by modifying a UDMA monomer system., Methods: Nine groups of composites were prepared by mixing the base monomers and TEGDMA in a ratio of 70/30 wt% to which were added silanized glass particles (mean diameter: 0.7 µm) in 3 different volume fractions (40, 45, and 50 vol%). Bis-GMA and UDMA base monomers were used as control groups in the same ratios. Various properties including degree of conversion (DC), flexural strength (FS) and flexural modulus (FM), water sorption (WS), solubility (SL), surface hardness and roughness, and initial adhesion property against S.mutans were investigated. One-way analysis of variance followed by Bonferroni test at α = 0.05 was used to analyze the results., Results: A significant difference in FS between FUDMA-based composite with 40 vol% filler (120.3 ± 10.4 MPa) and Bis-GMA-based composite with the same filler fraction (105.8 ± 10.0 MPa) was observed but there was no significant difference among other groups. The UDMA based group exhibited the highest WS (1.3 ± 0.3 %). Bis-GMA showed greater initial bacterial adhesion but was not statistically different from the other groups (p = 0.082)., Significance: FUDMA-based resin composites exhibit comparable mechanical and bacterial adhesion properties compared with Bis-GMA and UDMA-based composites. The FUDMA composites show positive outcomes indicating they could be used as substitute composites to Bis-GMA-based composites., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Objectives: To evaluate the mechanical, wear, antibacterial properties, and biocompatibility of injectable composite materials., Methods: Two injectable composite resins (GU and BI), one flowable composite resin (FS), and one flowable compomer (DF), in A2 shade, were tested. Mechanical properties were tested via three-point bending test immediately after preparation and after 1-day, 7-day, 14-day, and 30-day water storage. Under water-PMMA slurry immersion, specimens were subjected to a 3-body wear test (10,000 cycles) against stainless steel balls, while the roughness, wear depth, and volume loss were recorded. After 1-day and 3-day MC3T3-E1 cell culture, cell viability was evaluated with CCK-8 test kits, while the cell morphology was observed under CLSM and SEM. Antibacterial properties on S. mutans were assessed via CFU counting, CLSM, and SEM observation. SPSS 26.0 was used for statistical analysis (α = 0.05)., Results: The mechanical properties were material-dependent and sensitive to water storage. Flexural strength ranked GU > FS > BI > DF at all testing levels. Three nanocomposites had better wear properties than DF. No significant difference on 1-day cell viability was found, but DF showed significantly lower cell proliferation than nanocomposites on 3-day assessment. GU and FS had more favourable cell adhesion and morphology. CFU counting revealed no significant difference, while FS presented a slightly thicker biofilm and BI showed relatively lower bacteria density., Conclusions: Injectable nanocomposites outperformed the compomer regarding mechanical properties, wear resistance, and biocompatibility. The tested materials presented comparable antibacterial behaviours. Flowable resin-based composites' performances are affected by multiple factors, and their compositions can be attributed., Clinical Significance: A profound understanding of the mechanical, wear, and biological properties of the restorative material is imperative for the clinical success of dental restorations. The current study demonstrated superior properties of highly filled injectable composite resins, which imply their wider indications and better long-term clinical performances., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: This study is partially funded, with the materials supported, by GC Corporation., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Objectives: To investigate and compare the chemical and optical stability of four restorative composite materials: two injectable resins, one flowable resin and one compomer., Methods: Two injectable nano-filled composite resins: G-aenial Universal (GU) and Beautifil Injectable XSL (BI), a flowable composite resin: Filtek Supreme Flowable (FS) and a compomer: Dyract Flow (DF), in A2 shade were tested and compared. Water sorption and solubility were conducted according to ISO4049:2019 standard; ICP-OES and F-ion selective electrode were used to test the elemental release; Degree of conversion (DC) was obtained by using FTIR; water contact angle was obtained by static sessile drop method, and a spectrophotometer was used for optical properties (ΔE ⁎ , ΔL ⁎ and TP). SPSS 28.0 was used for statistical analysis and the significant level was pre-set as α = 0.05., Results: GU performed the best in water sorption and solubility, FS had the lowest elemental release, the best colour stability, and the highest DC IM and DC 24-h . DF, the compomer had the lowest, and GU and BI, the injectable composites had the largest water contact angle, respectively. Correlations were found between water sorption and water solubility., Conclusions: The four composite restorative materials showed different chemical and optical behaviours. Overall, composite resins performed better than compomer, while additional laboratory and in vivo tests are necessary to obtain a more comprehensive comparison between injectable and flowable composite resins. W sp and W sl are influenced by many common factors, and the values are highly positively related., Clinical Significance: A comprehensive understanding of materials is crucial before selecting materials for clinical practice. Composite resins rather than compomers are recommended because of their exceptional properties, which make them eligible for a wide range of clinical applications and an elongated lifespan., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: This study is partially funded, and the materials were provided, by GC Corporation., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Objectives: This study aimed to investigate the effect of a customized low-sodium bioactive glass (BG) fillers in experimental resin composites on their bond strength to dentin after 12 months of artificial aging. Specifically, it evaluated whether the bond strength was affected by different BG concentrations (0, 10, 20, 40 wt%) and artificial aging durations (1, 6, and 12 months)., Materials and Methods: Experimental composites were prepared with 10, 20, and 40 wt% of a customized low-sodium fluoride-containing BG. The experimental composite with 0 wt% BG was used as a control, while Beautifil II (Shofu) was used as an external reference material. A universal adhesive system was applied to dentin substrates and composite build-ups were made. Bond strength was measured using a macro-shear bond strength test, and Weibull statistics were used to assess the reliability of the materials. Failure modes were analyzed to evaluate the type of the fracture., Results: After 12 months, the bond strength of all experimental composites remained stable and comparable to the control material, with statistically significant improvements between 6 and 12 months for all experimental materials. The bond strength was statistically similar across materials, except at the 12-month point, where the 20 wt% BG-composite showed significantly higher bond strength than the 40 wt% BG-composite. The frequency of mixed failures in composite increased after 12 months, particularly in experimental composites containing higher BG content., Conclusions: The incorporation of a customized low- sodium BG into resin composites did not negatively impact their bond strength to dentin over 12 months. Instead, bond strength improved over time, and the composites remained mechanically stable, although a higher incidence of mixed failures was observed with increased BG content., Clinical Relevance: The customized low-sodium BG demonstrated stable bond strength over the 12-month period, offering a promising option for functional fillers in restorative composites without compromising the longevity of the adhesive-dentin interface., Competing Interests: Declarations. Ethical approval: Not applicable. Informed Consent: Not applicable. Competing interests: The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

This study aimed to evaluate the shear bond strength (SBS) when bonding a universal resin cement to a disilicate glass-ceramic using different adhesive protocols. Sixty specimens were etched with 10% hydrofluoric acid (HF) for 20 s and assigned to one of four treatment protocols (n = 15): The Positive control protocol comprised use of a universal adhesive system + adhesive resin cement; the Test1 protocol comprised use of a new universal adhesive system + universal resin cement; the Test2 protocol comprised use of a silane coupling agent + universal resin cement; and the use of a universal resin cement without adhesive and silane served as the Negative control. One of the two resin cement cylinders built on each specimen in each group was used to test for 24-h SBS, while the other was thermocycled and then tested for SBS. Data were submitted to two-way ANOVA, Tukey's test, and Weibull analysis. The negative control (24 h) showed the lowest SBS mean value. The Test2 protocol resulted in the highest SBS mean value after thermocycling. Adhesive and mixed failures were prevalent in all groups. No statistical difference in m values was observed among the groups at 24 h. After thermocycling, the two Test protocols showed the highest m values. The m values were significantly lower after thermocycling than at 24 h for all groups. After thermal aging, The Test2 protocol resulted in a statistically significantly higher SBS mean value after thermal aging than seen for the other groups., (© 2024 Scandinavian Division of the International Association for Dental Research. Published by John Wiley & Sons Ltd.)

Objective: The objective of this study is to evaluate the effectiveness of two different viscosities of short fiber-reinforced composite resin (SFRC) cores and two different viscosities of veneering composite resins on the fracture strength of direct occlusal veneers., Materials and Methods: One maxillary premolar was virtually prepared for an occlusal veneer and printed into resin dies. In total, (n = 48) resin dies were printed and assigned into three groups according to the type of core material of the occlusal veneer; mono-structured without a SFRC core, a high viscosity SFRC core, and a low viscosity SFRC core. Each group was re-divided into two subgroups (n = 8) according to the veneering composite resin; packable composite resin and injectable composite resin. Mono-structured and bi-structured direct occlusal veneers were fabricated on the resin dies using the mentioned core and veneering materials with the occlusal replica technique. Fracture strength was evaluated using a universal testing machine and the mode of failure was inspected. Statistical analysis to compare the core and veneering materials was performed using independent t test (P ≤ 0.05) and one-way ANOVA followed by tukey's post hoc test (Pa ≤ 0.0166) when appropriate. Interactions between subgroups were tested using two-way ANOVA, and one-way ANOVA was used to compare all subgroups followed by tukey's post hoc test (Pa ≤ 0.0033). Intergroup comparison between failure modes were performed using chi square test (Pa ≤ 0.0033)., Results: The presence of a SFRC core significantly improved the fracture strength of the specimens. There was no significant difference between the fracture strength of high viscosity SFRC and low viscosity SFRC cores. Specimens veneered with injectable composite resin had significantly superior fracture strength compared to packable composite resin. Additionally, there was a weak correlation between fracture strength and mode of failure., Conclusion: Short fiber reinforced composite resin significantly increases the fracture strength of direct occlusal veneers. Injectable composite resin has significantly higher fracture strength than packable composite resin as veneering materials of direct occlusal veneers., Clinical Relevance: Bi-structured direct occlusal veneers fabricated of injectable composite resin with low viscosity SFRC cores can withstand high masticatory forces in stress-bearing areas., Competing Interests: Declarations Ethics approval and consent to participate This study did not include any human participants, the human premolar tooth used in this study was extracted for orthodontic purposes and obtained with the approval of the Research ethics committee of Ain Shams University (FDASU) whom exempted this study (file number: FDASU-Rec EM012349) in accordance with the ethical standards as laid down in the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards. Competing interests The authors declare no competing interests., (© 2024. The Author(s).)

Background: Home bleaching is a promising option for addressing discolored teeth conservatively. However, its impact on the physical and mechanical properties of indirect restorations remains unknown. This study provides comparative insights into the material responses to aesthetic treatments by assessing the effects of home bleaching agents on two hybrid ceramics: VITA ENAMIC® and Grandio Blocs. The focus is on evaluating color stability and biaxial flexural strength. Methods: 60 discs (12 × 1 mm) were prepared from hybrid ceramics. Specimens were divided into two groups according to type of hybrid ceramic (30 specimens in each group); group A: VITA ENAMIC®, group B: Grandio Blocs. Each group was further subdivided into 3 subgroups according to the concentration of home bleaching agents used (10 specimens in each subgroup); subgroup C: unbleached control group, subgroup C10%: carbamide peroxide 10% bleaching agent, and subgroup C35%: carbamide peroxide 35% bleaching agent. Samples of subgroup C10% were bleached with Home Bleaching Opalescence PF (10%) for 8 h per day for 14 days, as directed by the manufacturer. Samples of subgroup C35% were bleached using WHITEsmile Carbamide Peroxide (35%), following the manufacturer's directions for 30 min every day for 14 days. Color change (ΔE) was assessed using of the CIE L*a*b* system. Then, the biaxial flexural strength test was done. The data were analyzed using two-way ANOVA tests and Weibull analysis. Results: VITA ENAMIC samples exhibited significantly higher color change than Grandio Blocs (p < 0.001), while Grandio Blocs showed significantly higher biaxial flexural strength (p < 0.001). The concentration of the bleaching agent had no significant effect on color change (p = 0.086). However, regardless of its concentration, bleaching significantly reduced biaxial flexural strength in both materials (p < 0.001). Weibull analysis showed that Grandio Blocs had higher characteristic strength, while VITA ENAMIC demonstrated more reliable failure behavior. Conclusions: Compared to Grandio Blocs, VITA ENAMIC® exhibited a greater color change with both 10% and 35% carbamide peroxide home bleaching agents. Additionally, both concentrations of carbamide peroxide reduced the biaxial flexural strength of hybrid ceramics. These findings can guide clinicians in selecting hybrid ceramics based on clinical demands for aesthetics and durability. VITA ENAMIC® offers greater structural reliability and predictability for aesthetic restorations, while Grandio Blocs provide superior durability and stress resistance for high-stress clinical applications. [ABSTRACT FROM AUTHOR]

Purpose: The current study aimed to compare modified Polyether-ether-ketone's fracture resistance and failure mode versus lithium disilicate glass–ceramic endocrowns. Materials and methods: A total of 16 butt-joint endocrown specimens on mandibular second molar teeth were fabricated and divided into two equivalent groups; Pressable modified Polyether-ether-ketone (PEEK) (BioHPP®) and Pressable lithium disilicate glass ceramic (IPS e.max® Press). A computer-aided design/computer-aided manufacturing system was used to digitally create and milled wax patterns. Final restorations were cemented each to its corresponding prepared tooth. Thermomechanical cycling loading representing one year of clinical service was done in a chewing simulator. Fracture resistance was evaluated utilizing a universal testing machine. The failure mode was evaluated by inspecting fractured surfaces using a Stereomicroscope and further examined by a Scanning Electron Microscope (SEM) amongst both groups. Results: A statistically significant variation in fracture resistance was recorded with a mean load of (2762.96 ± 216.15 N) for modified PEEK and (2175.91 ± 267.72 N) for lithium disilicate glass–ceramic endocrowns. Conclusion: Modified PEEK endocrowns have higher fracture resistance than lithium disilicate glass–ceramic endocrowns. Moreover, the likeliness of catastrophic fracture in molars receiving endodontic treatment restored by modified PEEK is less than teeth restored with lithium disilicate glass ceramics. [ABSTRACT FROM AUTHOR]

Objective: To determine the effects of conventional cigarette smoking (CS) and recent heated tobacco products (HTPs) on the surface roughness and color stability of different indirect restorative materials. Materials and methods: One hundred disc-shaped samples were constructed of three different restorative CAD/CAM materials: lithium disilicate glass–ceramic (IPS e.max CAD; Ivoclar Vivadent, Liechtenstein), zirconia (BruxZir® Zirconia, Glidewell, USA) and polyetheretherketone (BioHPP® bredent GmbH, Germany). Of the IPS e.max CAD and the Bruxzir samples, 20 samples were glazed, and 20 samples were polished, while the BioHPP samples were all polished according to the manufacturer's instructions. Fifty samples were subjected to conventional cigarette smoking (LM, Philip Morris International Inc., Egypt) (Groups: IPS e.max CAD_Glazed exposed to CS (LD_G_Cig), IPS e.max CAD_Polished exposed to CS (LD_P_Cig), Bruxzir_Glazed exposed to CS (Zr_G_Cig), Bruxzir _Polished exposed to CS (Zr_P_Cig) and BioHPP exposed to CS (PEEK_Cig) and fifty samples were exposed to heated tobacco product smoking (Heets, Russet selection, Philip Morris International Inc., Italy) (Groups: IPS e.max CAD_Glazed exposed to HTP (LD_G_HTP), IPS e.max CAD_Polished exposed to HTP (LD_P_HTP), Bruxzir_Glazed exposed to HTP (Zr_G_HTP), Bruxzir CAD_Polished exposed to HTP (Zr_P_HTP) and BioHPP exposed to HTP (PEEK_HTP).. Six hundred cigarettes/heets representing 30 days of medium smoking behavior (20 cigarettes/day) were used. Before and after exposure to smoke, the surface roughness of all the samples was measured using JITAI8101 surface roughness tester (Beijing Jitai Tech Detection Device Co., Ltd, China, and the color parameters were assessed using VITA Easyshade Advance 4.01 (VITA shade, VITA made, VITA). The data were analyzed using One-way ANOVA, paired sample t-test and independent sample t-test. The significance level was set at α < 0.05. The surface topography was evaluated by scanning electron microscopy (SEM) and analyzed using energy-dispersive X-ray (EDX) spectroscopy to determine changes in the surface chemical composition. Results: Both types of smoking caused significant increases in the surface roughness of all the samples. There was a significant difference in color change between CS and HTP for all materials with different surface finish (P < 0.01) and zirconia had the greatest effect on color change (P < 0.001). In contrast, polyetheretherketone (PEEK) "BioHPP" had the least effect (P < 0.001). Conclusion: Exposure to different types of smoking induce changes in the surface topography and color of different esthetic restorative materials. Compared with HTP, conventional cigarette smoke has a greater effect on the surface roughness and color stability of esthetic restorative materials. The glazed surfaces showed less change in surface topography than did the polished surfaces. Zirconia showed better color stability when compared to polyetheretherketone (PEEK). [ABSTRACT FROM AUTHOR]

Objective: This study aimed to compare the remineralization effects of a calcium silicate-based cement (Biodentine) and of a glass ionomer cement (GIC: Fuji IX) on artificially demineralized dentin. Methods: Four standard cavities were prepared in dentin discs prepared from 34 extracted sound human third molars. In each disc, one cavity was covered with an acid-resistant varnish before demineralization (Group 1). The specimens were soaked in a chemical demineralization solution for 96 h to induce artificial carious lesions. Thereafter, one cavity each was filled with Biodentine (Group 2) and GIC (Group 3), respectively, and one carious lesion was left unrestored as a negative control (Group 4). Next, specimens were immersed in simulated body fluid (SBF) for 21 days. After cross-sectioning the specimens, the Ca/P ratio was calculated in each specimen by using scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM-EDX). Finally, data were analyzed using repeated-measures ANOVA with post-hoc Bonferroni correction. Results: Both cement types induced dentin remineralization as compared to Group 4. The Ca/P ratio was significantly higher in Group 2 than in Group 3 (p < 0.05). Conclusion: The dentin lesion remineralization capability of Biodentine is higher than that of GIC, suggesting the usefulness of the former as a bioactive dentin replacement material. Clinical relevance: Biodentine has a higher remineralization ability than that of GIC for carious dentin, and its interfacial properties make it a promising bioactive dentin restorative material. [ABSTRACT FROM AUTHOR]

Background: Zinc-oxide eugenol (ZOE) cements are among the most used temporary materials in dentistry. Although ZOE has advantages over other temporary fillers, its mechanical strength is weaker, so researchers are working to improve it. E-glass fibers have emerged as promising reinforcing fibers in recent years due to their strong mechanical behavior, adequate bonding, and acceptable aesthetics. Objectives: To evaluate and compare the compressive strength, surface microhardness, and solubility of the ZOE and those reinforced with 10 wt.% E-glass fibers. Methods: A total of 60 ZEO specimens were prepared; 30 specimens were reinforced with 10 wt.% E-glass fibers, considered modified ZOE. The characterization of the E-glass fibers was performed by XRF, SEM, and PSD. The compressive strength, surface microhardness, and solubility were evaluated. Independent sample t-tests were used to statistically assess the data and compare mean values (P ≤ 0.05). Results: The results revealed that the modified ZOE showed a significantly higher mean value of compressive strength and surface microhardness while having a significantly lower mean value of solubility compared to unmodified ZOE (P ≤ 0.05). Conclusion: The modified ZOE with 10 wt.% E-glass fibers had the opportunity to be used as permanent filling materials. [ABSTRACT FROM AUTHOR]

Statement of problem: CAD/CAM occlusal veneers have been developed for minimally invasive prosthetic restoration of eroded teeth. Marginal adaptation and fracture resistance are crucial for the long-term survivability and clinical success of such restorations. Virgilite-based lithium disilicate glass-ceramic is a newly introduced material with claims of high strength. However, constructing occlusal veneers from this material of varying thickness has not been investigated. Purpose: The current study aimed to assess the impact of CAD/CAM occlusal veneer thickness and materials on marginal adaptation and fracture resistance. Materials and methods: Thirty-two occlusal veneers were constructed and divided into two groups (n = 16) based on the CAD/CAM material into Brilliant Crios and CEREC Tessera. Each group was further subdivided into two subgroups (n = 8) according to the thickness: 0.6 and 0.9 mm. Occlusal veneers were bonded to epoxy resin dies. The marginal gap was evaluated before and after thermodynamic aging. Fracture resistance and failure mode were evaluated for the same samples after aging. Marginal adaptation was analyzed using the Mann-Whitney U test. Fracture resistance was analyzed using Weibull analysis (α = 0.05). Results: The marginal gap was significantly increased following thermodynamic aging for tested groups (P < 0.001). CEREC Tessera showed a significantly higher marginal gap than Brilliant Crios before and after aging for both thicknesses (P < 0.05). CEREC Tessera recorded lower significant fracture load values compared to Brilliant Crios (P < 0.05). Conclusions: Both CEREC Tessera and Brilliant Crios demonstrated clinically accepted marginal gap values. All groups showed fracture resistance values higher than the average masticatory forces in the premolar region except for 0.6 mm CEREC Tessera. Clinical implications: Reinforced composite occlusal veneers demonstrated more favorable outcomes in terms of marginal gap and fracture resistance at both tested thicknesses compared to virgilite-based lithium disilicate glass-ceramic. Additionally, caution should be exercised during the construction of occlusal veneers from virgilite-based lithium disilicate glass-ceramic with reduced thickness. [ABSTRACT FROM AUTHOR]

Background: This study aimed to investigate different surface treatments thought to increase the bond strength between zirconia ceramic and adhesive resin cement. Methods: The samples were prepared in 15 × 10 × 2 mm dimensions by cutting off monolithic zirconia ceramic blocks (Incoris TZI; Sirona, Germany). Surface roughness measurements were made with a profilometer, the average surface roughness (Ra1) was recorded, and five different surface treatments were applied. Group 1: Control group. No surface treatment was applied. Group 2: Sandblasted with Al2O3 under pressure of 50 μm. Group 3: Sandblasted with 30 μm Al2O3 - SiOx under pressure, then tribochemical silica coating, silane bonding agent, and ceramic primer were applied. Group 4: Samples were etched in a hot acid solution containing methanol, HCl, and chloride at 100 °C. Group 5: Samples were coated in a solution containing Grade C Aluminum Nitrite at 75 °C for 15 Sects. 12,000 thermal aging was carried out to all samples. Then, samples were bonded to a composite surface (Filtek Z250) with two different types of adhesive cement (Panavia F 2.0, Rely X U200) (n = 10). A load was applied to the samples attached to the Universal Test Device for the SBS, and the SBS was recorded. The surface roughness measurements of all samples were made again, and the average surface roughness Ra2 was recorded. The data was analyzed with a two-way ANOVA test. Bonferroni correction was used for multiple comparisons of the groups. p = 0.005 was accepted as the statistically significant value. Results: There was no statistically significant difference between the groups in the Ra1 measurements (p = 0.031). There was a statistically significant difference between the Ra2 values of Groups 4 and 5 and the Ra2 values of Groups 1,2 and 3 in the Ra2 measurements (p < 0.001). There was no statistically significant difference between the SBS values of the groups (p > 0.005). Also, there was no statistically significant difference in the SBS values of all groups for the two different cements tested (p > 0.005). Conclusions: None of the surface treatments applied to monolithic zirconia ceramic samples increased the SBS between ceramic and adhesive resin cement. [ABSTRACT FROM AUTHOR]

Purpose: To assess and compare the impact of various computers aided design/manufacturing (CAD/CAM) materials on internal and marginal discrepancies, fracture resistance and failure probability of Endocrown restorations with 3D Finite Element analysis. Material and methods: Forty devitalized human maxillary first molars were collected. After endodontic treatment, they classified into 4 groups (n = 10) based on the materials used for endocrown fabrication. Group V (Vita-Enamic), Group N (Nacera Hybrid), Group T (Translucent Prettau Zirconia) and Group P (Pekkton ivory). All samples were exposed to artificial aging method simulating one year of clinical service. Silicone replica technique and stereomicroscope (25X) utilized to evaluate the marginal and internal gaps of endocrowns at different areas. Fracture resistance test used for cemented specimens followed by qualitative investigation utilizing Stereomicroscopy. Four models representing four endocrown systems used for restoration of severely-damaged endodontically treated upper first molar were generated for finite element analysis (FEA). Axially and centrally static occlusal compressive load was applied. Modified Von Mises and maximum principal stress values on the remaining tooth structure, cement lines and restorative materials were assessed independently. Resulted data were statistically analyzed at P-value ≤ 0.05. Results: In the current study, the highest mean values of internal and marginal discrepancies (μm) among studied groups were reported for Zirconia group (100.300 and 102.650) respectively, while the lowest mean value of internal discrepancy (μm) was observed for Nacera group (69.275) and the lowest mean value of marginal discrepancy (μm) was observed for PEKK group (78.4750). Regarding internal discrepancy, Vita-Enamic and PEKK groups did not exhibit any statistically significant differences (P = 0.293), however zirconia and the other tested groups exhibited statistically significant differences in the mean values of the marginal gap region (p 0.05).On the other hand, PEKK group showed the highest mean value of fracture resistance (1845.20 N) and the lowest value was observed for Vita-Enamic group (946.50 N). Regarding to stress distributions through 3D FEA, and according to modified von Mises (mvM) analysis, the greatest possible stress values were noticed in PEKK model in relation to tooth structure, cement line, and flowable composite as the following: (93.1, 64.5, 58.4 MPa) respectively, while Zirconia revealed lower maximum stress values (11.4, 13.6, 11.6 MPa) respectively. Conclusions: Statistically excellent marginal and internal fit was observed for PEKK in relation to other used endocrown materials. Also, PEKK material explained fracture resistance comparable to zirconia value while the lowest value was detected for Vita Enamic material. [ABSTRACT FROM AUTHOR]

Background: Resin composite restorations are highly esthetic restorations, which should have and maintain high surface polish. However, esthetic restorations are subjected to different beverages at variable temperatures, which may affect their surface roughness. This study aimed to evaluate the surface roughness of single-shade (Omnichroma) and multi-shade (Filtek Z350XT) composite materials, following aging by immersion and thermocycling in different beverages, simulating one year of clinical service. Methods: Thirty specimens of each material were prepared and divided into 6 subgroups (n = 5). In each material, the grouping of the specimens was as follows: the first subgroup was the as-prepared specimens stored dry without immersion or thermocycling. The second, third, and fourth subgroups were immersed in saliva, tea, and red wine, respectively, for 12 days at 37 °C. The fifth and sixth subgroups were thermocycled for 10,000 cycles, in tea (the fifth between 37 and 57 °C) and in red wine (the sixth between 37 °C and12°C). The resultant surface roughness was measured by two different methods, stylus profilometer and atomic force microscopy (AFM). Intergroup comparison was performed using independent t test, while intragroup comparison was performed using one-way analysis of variance (ANOVA) followed by Tukey's post-hoc test. Results: Intergroup comparison between both composites showed no statistically significant differences in all groups using the stylus profilometer roughness measurements (P>0.05), while the AFM measurements showed significant difference (P ≤ 0.05) within all storage media except the as-prepared control (P = 0.0645), where nanofilled Filtek Z350 XT showed lower nano-roughness. Intragroup comparison data were variable, depending on the material, aging conditions, and roughness assessment tool. However, the resultant average surface roughness (Ra) values in all groups did not exceed the threshold value of Ra 0.2 μm. Conclusions: Both resin composites attained and retained a clinically acceptable surface finish after immersion and thermocycling in different beverages. [ABSTRACT FROM AUTHOR]

Background: The purpose of the current study was to assess the impact of restoration thickness, surface conditioning and the interaction between them on the fracture resistance of CAD/CAM fabricated lithium disilicate occlusal veneers. Methods: A total of 42 maxillary molars were prepared to receive CAD/CAM fabricated lithium disilicate occlusal veneer either with 0.5 mm (n = 21) or 1 mm (n = 21) thickness. Each main group was divided into 3 subgroups (n = 7), according to surface treatment, HF acid (HF-1, HF-0.5), acidulated phosphate fluoride (APF-1, APF-0.5) and Monobond etch & prime (MON-1, MON-0.5). Multilinik N (Ivoclar-Vivadent) adhesive resin cement was used for bonding according to the manufacturer instructions. One hour after bonding, specimens were stored in water bath for 75 days followed by cyclic loading fatigue for 240,000 cycles to simulate clinical situation. Finally, specimens were fractured under compressive load in (N) using a universal testing machine. Two and one-way ANOVA and Post Hoc Tukey test were used for statistical analysis. Results: The means ± SD (N) fracture load for each group were calculated. MON-1 group showed the highest fracture load (1644.7 ± 155.3) followed by HF-1 group (1514.6 ± 212.5). Meanwhile, APF-0.5 showed the lowest fracture load (962 ± 249.6). Conclusion: CAD/CAM fabricated lithium disilicate occlusal veneers can be used with a thickness of 0.5 mm instead of conventional crowns. Monobond etch & prime is recommended as a surface treatment for CAD/CAM fabricated lithium disilicate occlusal veneer due to biological hazards of Hydrofluoric acid. [ABSTRACT FROM AUTHOR]

Background: This study evaluated the effect of ceramic primers containing 10-methacryloyloxydecyl phosphate (10-MDP) and γ-methacryloxypropyl trimethoxysilane (γ-MPTS) agents on the shear bond strength (SBS) of CAD/CAM ceramics with different chemical structures and resin cement. Methods: A total of 640 CAD/CAM ceramic specimens were obtained from Vita Mark II (VM), IPS E.max CAD (EM), Vita Suprinity (VS) and Vita Enamic (VE). The specimens were divided into two groups: etched with hydrofluoric acid (HF) and unetched. Each group was treated with a different ceramic primer (Clearfil Ceramic Primer Plus, G-Multi Primer and Monobond S), except for an untreated group (n = 10). After ceramic primers and resin cement were applied to each ceramic surface, half of the specimens were thermally aged at 10,000 cycles, 5–55 ± 1 °C, with a dwell time of 30 s. The SBS was tested with a universal testing machine at a 0.5 mm/min crosshead speed. Data were analysed by using statistical software (SPSS 20). Normal data distribution was checked with the Shapiro‒Wilk test. Three-way ANOVA was used to analyse the difference between the numeric data of the HF etched and thermally aged groups. A post hoc Tukey test was applied in the paired comparison of significant difference. The statistical significance level was accepted as p < 0.05. Results: The highest SBS values were obtained in the HF etched G-Multi primer applied nonaged EM group (28.3 ± 2.62 MPa), while the lowest values were obtained in the nonetched and thermally aged EM group that received no treatment (2.86 ± 0.04 Mpa). The SBS significantly increased in all specimens on which the ceramic primer was applied (p < 0.001). Thermal ageing had a significant negative effect on the SBS values in all groups (p < 0.001). Conclusion: The positive combined effects of the 10-MDP and γ-MPTS agents resulted in a significant increase in the bonding strength of the resin cement to the CAD/CAM ceramics. In addition, the increase in the amount of inorganic filler provided a favourable effect on durable adhesion. [ABSTRACT FROM AUTHOR]

In the present study are depicted valuable observations for practitioners, obtained from an in vitro study which aims to evaluate the compressive strength of occlusal veneers fabricated from 3 type of restorative materials, before and after 1 month of acidic artificial saliva exposure (pH = 2.939). In this context, 90 extracted human molars were prepared to receive computer-aided design/computer-aided manufacturing (CAD/CAM) occlusal veneers. The restorative materials considered in this study were: Cerasmart; Straumann Nice and Tetric CAD. The occlusal veneers were designed, milled and cemented with an adhesive dual-cure resin cement. From all the extracted human molars, only sixty specimens were immersed in acidic artificial saliva, for 1 month, at 37 °C ± 1 °C and part of this specimens were also thermo-cycled, between 5 and 55 °C ± 2 °C, before compressive strength test. The results showed a lower compressive strength for both the samples exposed to acidic artificial saliva as well as for the samples exposed to acidic artificial saliva and thermo-cycled. Scanning electron microscopy (SEM) showed that after compressive strength, all the specimens non-exposed to acidic artificial saliva, present extensive cracks formation at the surface of the restorations, and after exposure to acidic artificial saliva for 1 month, the surface damage was characterized by longitudinal and profound fractures of the restoration, as well as the fracture of the tooth structure. Between CAD/CAM materials tested, nanoceramic resin shows more favorable fracture patterns, both before and after acidic artificial saliva exposure. [ABSTRACT FROM AUTHOR]

Objective: To compare the color stability, translucency, and biaxial flexural strength (BFS) of differently glazed advanced lithium disilicate (ALDS) with those of lithium disilicate (LDS) and zirconia‐reinforced lithium silicate (ZLS) after coffee thermocycling. Materials and methods: Forty disk‐shaped specimens were prepared from three lithium silicate based materials (CEREC Tessera, ALDS; IPS e.max CAD, LDS; Vita Suprinity, ZLS). ALDS specimens were divided into two subgroups according to glazing procedures (reduced glaze duration, ALDS‐S and normal glaze duration, ALDS‐N), while LDS and ZLS specimens were crystallized and glazed. Color coordinate measurements were performed before and after coffee thermocycling. Color differences (ΔE00) and relative translucency parameters (RTP) were calculated. Specimens were then subjected to BFS test. Statistical analysis was performed by using 1‐ (ΔE00 and BFS) and 2‐way (RTP) ANOVA tests (α = 0.05). Results: ΔE00 values of tested materials were similar (df = 3, F = 0.150, p = 0.929). Two‐way ANOVA showed the significant effect of material type, coffee thermocycling, and the interaction between these parameters on RTP values (p < 0.001). Both before and after thermocycling, LDS had the highest (p ≤ 0.001) and ZLS had the lowest (p < 0.001) RTP values, while ALDS‐N had higher RTP than ALDS‐S (p ≤ 0.001). Among tested materials, only LDS had similar RTP values before and after thermocycling (p = 0.865) as the other materials had lower RTP values after thermocycling (p < 0.001). ALDS‐N had higher BFS values than ALDS‐S (p = 0.005), while LDS had similar values to ALDS specimens (p ≥ 0.201). ZLS had the highest BFS (p ≤ 0.007). Conclusions: ALDS had comparable values to those of other materials. However, reduced glazing duration resulted in decreased translucency and BFS of ALDS. Clinical significance: ALDS may be an appropriate restorative material for those patients with increased coffee consumption considering its color stability and ability to maintain translucency, particularly when glazed by using a conventional porcelain furnace. [ABSTRACT FROM AUTHOR]

Background: Evaluating the effect of different surface treatment methods on the micro-tensile bond strength (µTBS) of two different resin-matrix computer-aided design/computer-aided manufacturing (CAD/CAM) ceramics (RMCs). Methods: A standardized inlay preparations were performed on 100 intact maxillary premolars. According to the type of the restorative material, the teeth were randomly divided into two equally sized groups (n = 50): (polymer-infiltrated ceramic (Vita Enamic) and resin-based composites (Lava Ultimate)). The inlays were fabricated using CAD/CAM technology. In each group, the specimens were randomly assigned to five subgroups (n = 10) according to the surface treatment method: group 1 used was the control group (no surface treatment); group 2, was treated with air abrasion with 50 μm Al2O3 (A) and universal adhesive (UA); group 3, was treated with air abrasion with 50 μm Al2O3 (A) and silane coupling agent (S); group 4, was treated with hydrofluoric acid (HF) and universal adhesive (UA) and group 5, was treated with Hydrofluoric acid (HF) + silane coupling agent (S). The inlays were then cemented to their respective preparations using dual-cure self-adhesive resin cement (RelyX U200, 3 M ESPE) according to the manufacturer's instructions. The µTBS test was conducted in all groups, and stereomicroscope and scanning electron microscope were used to inspect the failure mode. The data were statistically analyzed using a two-way analysis of variance (ANOVA) and Tukey's post-hoc multiple comparison tests at a significance level of p < 0.05. Results: Surface treatments significantly increased the µTBS of the materials compared to the control group (p < 0.05). For CAD/CAM RBCs, the µTBS value highest in group 2 whereas, for PICN, the µTBS value was highest in group 3. Cohesive failure of CAD/CAM restorative material was the most predominant mode of failure in all treated groups, whereas adhesive failure at restoration-cement interface was the most predominant failure mode in the control group. Conclusion: Surface treatments increase the µTBS of resin-matrix CAD/CAM ceramics to tooth structure. Air abrasion followed by universal adhesive and hydrofluoric acid followed by silane application appears to be the best strategies for optimizing the bond strength of CAD/CAM RBCs and PICN respectively. [ABSTRACT FROM AUTHOR]

Objective: To compare in vitro the accuracy of fit of a reference prosthesis seated on three‐dimensional (3D) printed casts generated from digital implant scans vs stone casts made by conventional implant impressions. Material and Methods: A partially edentulous maxillary master cast with two internal connection implants was generated, while a reference implant‐supported prosthesis was fabricated. Conventional splinted open‐tray impressions were taken to create stone casts (n = 10) (control group). A digital scan was taken of the master cast using a white light intraoral optical scanner (IOS) (TRIOS, 3Shape), and a Standard Tessellation Language (STL) file was obtained. Four 3D printers were used to print the casts (n = 10 from each 3D printer): Straumann® P30+, Varseo S, Form 3b+and M2 Carbon. Accuracy of fit of the reference prosthesis on all control and test casts was assessed using the screw resistance test and radiographic test. Additionally, all casts were digitized using the same IOS, and the STL files were superimposed to the master cast STL file (reference) to evaluate the 3D accuracy with inspection Geomagic Control software using the root‐mean‐square (RMS) error. Results: The reference prosthesis presented with clinically acceptable fit on all casts. The highest median RMS error was found in the stone cast group (94.6 μm) while the lowest median was in the M2 Carbon group (46.9 μm). The Kruskal–Wallis test revealed a statistically significant difference between the groups (p < 0.001). For post hoc comparisons, Dunn's test with the Holm–Bonferroni correction resulted in a statistically significant difference in four tests, with M2 Carbon exhibiting lower RMS error than the stone cast (p < 0.001) and P30+ (p < 0.001) groups, Form 3b exhibiting lower RMS error than the stone cast (p < 0.001) group, and Varseo S exhibiting lower RMS error than the stone cast (p = 0.006) group. Conclusion: Using the screw‐resistance test and radiographic assessment, the reference prosthesis fit presented with clinically acceptable accuracy of fit on all casts. Printed casts from 3 different printers demonstrated statistically significant lower 3D deviations than stone casts generated using a conventional implant impression for the present partially edentulous scenario with two implants, but this did not affect prosthesis fit. Clinical Significance: Even though there were 3D deviations between the master cast and all control and test casts generated from conventional impressions and digital scans respectively, the reference prosthesis presented with accurate fit on all casts. This indicates that there is a threshold for clinically acceptable accuracy of fit and that 3D‐printed casts may be used as definitive master casts to fabricate implant‐supported fixed dental prostheses for the partially edentulous anterior maxilla. [ABSTRACT FROM AUTHOR]

Glass ionomer (GI) cements and self‐etch (SE) or universal adhesives after etching (ER) adapt variably with dentine. Dentine characteristics vary with depth (deep/shallow), location (central/peripheral), and microscopic site (intertubular/peritubular). To directly compare adhesion to dentine, non‐destructive imaging and testing are required. Here, GI, ER, and SE adapted at different dentine depths, locations, and sites were investigated using micro‐CT, xenon plasma focused ion beam scanning electron microscopy (Xe PFIB‐SEM), and energy dispersive X‐ray spectroscopy (EDS). Extracted molars were prepared to deep or shallow slices and treated with the three adhesives. Micro‐CT was used to compare changes to air volume gaps, following thermocycling, and statistically analysed using a quantile regression model and Fisher's exact test. The three adhesives performed similarly across dentine depths and locations, yet no change or overall increases and decreases in gaps at all dentine depths and locations were measured. The Xe PFIB‐SEM‐milled dentine‐adhesive interfaces facilitated high‐resolution characterization, and element profiling revealed variations across the tooth‐material interfaces. Dentine depth and location had no impact on adhesive durability, although microscopic differences were observed. Here we demonstrate how micro‐CT and Xe PFIB‐SEM can be used to compare variable dental materials without complex multi‐stage specimen preparation to minimize artefacts. [ABSTRACT FROM AUTHOR]

To examine the effect of mold enclosure and chisel design on macro shear fatigue bond strengths of dental adhesive systems. The fatigue bond strength testing was conducted with two commercially available dental adhesive systems, (1) OptiBond eXTRa and (2) Scotchbond Universal, for bonding a resin composite (Filtek Supreme Ultra) to both enamel and dentin using a mold enclosure and a non‐mold enclosure with a knife‐edge and two sized notched‐edge chisel assemblies for loading. As a loading reference for the fatigue testing, macro shear bond strengths of the adhesive systems to enamel and dentin were conducted using a mold enclosure and a knife‐edge chisel assembly. The shear bond strengths with the mold enclosure using knife‐edge chisel assembly did not exhibit a significant difference between the adhesive systems for either enamel or dentin. The fatigue bond strengths of bonded specimens demonstrated significant differences when comparing the mold enclosure and non‐mold enclosure, but not between knife‐edge and notched‐edge chisel assemblies. The fatigue bond strengths of dental adhesive systems demonstrated significantly higher values when using mold‐enclosed bonded specimens than a non‐mold enclosure, regardless of type of chisel assembly. [ABSTRACT FROM AUTHOR]

Objectives: This review aimed to summarize contemporary evidence related to dental composite resin derived from rice husk biowaste and its potential future advancement. This review paper included the techniques for synthesis, characterization, and preparation of rice husk composite resin. Focus was also given to the flexural strength and modulus, compressive strength, wear rate, hardness, surface roughness, color stability, polymerization shrinkage, degree of conversion, and their application onto root canal treated teeth. Material and Methods: A search of English peer‐reviewed literature (January 1960–February 2021) was conducted from electronic databases (PubMed Central, Cochrane, LILACS, Science Direct, Web of Science, SIGLE, EMBASE, EBSCO, Medline, and Google Scholar). Results: 11 articles and a book section were finally selected for qualitative analysis. Studies concluded that the physicomechanical properties and the color stability of rice husk dental composites showed comparable results to conventional dental composites. Incorporation of zirconia nanopowder into rice husk dental composite increased the compressive strength and hardness values, associated with lower shrinkage, a high degree of conversion, and improved fracture strength when applied on root canal treated teeth. Conclusions: Due to its low cost, eco‐friendliness, and acceptable clinical performances, rice husk dental composite resin can be considered as an alternative to conventional composites. Clinical Significance: Dental composite resin derived from rice husk silica demonstrated excellent performance, which could potentially substitute currently available composite resins. This review will give new insight to clinicians and researchers on the usage of natural biowaste mass in the field of dental restorative materials. [ABSTRACT FROM AUTHOR]

Material properties are of high clinical relevance, even though in vitro laboratory setups may differ from clinical conditions. Therefore, the aim of the present study was to investigate the fracture behavior of three-unit bridge restoration (Telio CAD) with different test velocities (1.0 mm/min International Organization for Standardization (ISO) standard speed/ 130 mm/s mean chewing velocity) and to provide crucial validation experiments for the upcoming Part 2 of our study, in which FEA on such temporary restorations will be conducted. Local strains were detected using digital image correlation (DIC). The material exhibited significantly different responses at different test velocities, and the forces at fracture were found to be much smaller at chewing velocity (130 mm/s) than in the quasi- static test. Overall, the results of the present study show that characteristics pertaining to material behavior can change significantly with increasing chewing velocity, and that fracture forces decrease with increasing test velocity. [ABSTRACT FROM AUTHOR]

Objectives: To compare the shear bond strength (SBS) of the CAD/CAM material-bracket interface using three surface treatments: following manufacturers' instructions (MI), Monobond Etch & Prime (MEP) and 9.6% hydrofluoric acid plus silane (9.6% HF), after 24 h of water storage (24 h) and 10,000 cycles of thermocycling (TC). Materials and methods: A total of 126 crowns with four identical buccal surfaces were fabricated using seven different CAD/CAM materials: CEREC Blocs unglazed (CBU), CEREC Blocs glazed (CBG), IPS Empress CAD (EMP), IPS e.max CAD (EMA), VITA SUPRINITY PC (SUP), inCoris TZI (TZI) and VITA ENAMIC (ENA). A total of 504 APC Flash-Free (APC FF)-precoated brackets were bonded applying three surface treatments: (1) MI; (2) MEP and (3) 9.6% HF. SBS was performed after 24 h and TC. Results were analyzed by Kruskal-Wallis and Mann-Whitney U tests (p < 0.05). Results: MEP conditioning yielded lower SBS results compared with MI and 9.6% HF for CBG (24 h and TC) and EMA (TC) materials. EMP conditioning with MEP after 24 h obtained lower SBS values compared with MI; however, after TC, SBS was similar to MI group and higher than with 9.6% HF. After TC for TZI ceramic, MI protocol (sandblasting) obtained higher SBS scores than MEP, but similar than 9.6% HF. Treatment of ENA with MI and MEP produced higher results than 9.6% HF after TC. SBS results were similar for CBU and SUP, regardless of the treatment. Conclusions: Although each CAD/CAM material requires specific surface treatment to obtain the highest SBS of APC FF brackets, the treatment with MEP is a valid orthodontic alternative for most of the materials tested. TC significantly decreased SBS for most of the materials. Clinical relevance: MEP can be considered a valid and promising product to condition most of the CAD/CAM ceramics evaluated for APC FF bracket bonding purposes, allowing a faster and safer procedure. [ABSTRACT FROM AUTHOR]

The identification of metal ions and particles in the vicinity of failed implants has raised the concern that biomedical titanium alloys undergo corrosion in healthy and infected tissues. Various surface modifications and coatings have been investigated to prevent the deterioration and biocorrosion of titanium alloys but so far with limited success. Graphene is a cytocompatible atom-thick film made of carbon atoms. It has a very high surface area and can be deposited onto metal objects with complex shapes. As the carbon lattice has a very small pore size, graphene has promising impermeability capacity. Here, we show that graphene coating can effectively protect Ti-6Al-4V from corrosion. Graphene nanocoatings were produced on Ti-6Al-4V grade 5 and 23 discs and subjected to corrosive challenge (0.5M NaCl supplemented with 2-ppm fluoride, pH of 2.0) up to 30 d. The linear polarization resistance curves and electrochemical impedance spectroscopy analysis showed that the graphene-coated samples presented higher corrosion resistance and electrochemical stability at all time points. Moreover, the corrosion rate of the graphene-coated samples was very low and stable (~0.001 mm/y), whereas that of the uncoated controls increased up to 16 and 5 times for grade 5 and 23 (~0.091 mm/y) at the end point, respectively. The surface oxidation, degradation (e.g., crevice defects), and leaching of Ti, Al, and V ions observed in the uncoated controls were prevented by the graphene nanocoating. The Raman mappings confirmed that the graphene nanocoating presented high structural stability and resistance to mechanical stresses and chemical degradation, keeping >99% of coverage after corrosion challenge. Our findings open the avenues for the use of graphene as anticorrosion coatings for metal biomedical alloys and implantable devices. [ABSTRACT FROM AUTHOR]

Objective: Evaluate the effect of staining and repeated firings on color, translucency and surface proprieties of CAD/CAM lithium disilicate (LD). Material and Methods: One hundred eighty LD discs were made (ISO 6872) and distributed in different groups (n = 20): control (CO)—no treatment; single‐step characterization (SC)—crystallization and staining fired together; and double step characterization (DC)—crystallization and then staining. The samples were submitted to two, four, or six firings, resulting in nine groups: COII, COIV, COVI, SCII, SCIV, SCVI, DCII, DCIV, and DCVI. The color and translucency were measured by a reflectance spectrophotometer. Surface roughness (Ra) and Vickers nano‐hardness were also measured. ANOVA and Tukey statistical tests were used (α =.05). Results: Only CO and DC demonstrated significant color alterations (ΔE00 > 1.8). SC and DC did not show changes in translucency by the number of firings (P >.05); however, for CO (P =.02) these values increased. Nano‐hardness was similar in all groups (P >.05). Ra values indicated differences due to the type of characterization (SC presented the highest values) and number of firings (CO and DC groups) (P <.01). Conclusion: SC promoted color, translucency, and roughness stability after repeated firings. Clinical Significance: The single characterization technic in CAD/CAM lithium disilicate presents good color, translucency, and hardness stability, which promote predictable results to monolithic restoration. [ABSTRACT FROM AUTHOR]

Objective: To investigate the influence of surface treatments conducted in presintering and postsintering stages on flexural strength and optical properties of zirconia. Materials and methods: Specimens were milled from partially sintered zirconia blocks in different geometries and divided into three main groups as presintered, postsintered, and control groups. Test groups were further divided into three subgroups (n = 10) according to the surface treatments conducted (grinding, Er,Cr:YSGG laser irradiation, air‐borne particle abrasion [APA]). Four‐point flexural strength (σ) test and Weibull analysis were conducted. Color differences (ΔE00) and translucency parameter (TPab) were calculated with a spectrophotometer. Surfaces of specimens were scrutinized under FESEM. Data were statistically analyzed. Results: Postsintered groups exhibited higher σ values (P <.05). Within all groups, highest and lowest σ values were detected at postsintered and presintered APA groups, respectively (P <.05). All ΔE00 values were above the perceptibility threshold (ΔE00 > 0.8). Higher TPab values were obtained and deeper scratches were observed in presintered groups. Conclusions: Surface treatments performed at postsintering stage had a favorable effect on the flexural strength of all specimens. Surface treatments performed before sintering increased translucency and caused higher ΔE00 values. Clinical significance: Surface treatments performed at different sintering stages can alter mechanical and optical properties of zirconia. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to compare the integrity of zirconia, lithium disilicate, and zirconia‐reinforced lithium silicate CAD‐CAM crowns after being subjected to cyclic loading and then subjected to static loading until fracture. Material and Methods: Zirconia (Zirkonzahn), lithium disilicate (LDS, Ivoclar Vivadent AG), and zirconia‐reinforced lithium silicate glass ceramic (ZLS) (Vita Suprinity, Vita Zahnfabrik) monolithic crowns were milled (n = 6). The crowns were bonded using composite resin cements and subjected to cyclic loading under wet conditions. Three specimens from each group were loaded for 10 000 cycles, and the other three specimens were loaded for 50 000 cycles with 250 N. Specimens were subjected to loading until fracture. Load‐to‐fracture values were analyzed with 2‐way (ANOVA) and Tukey‐Kramer post hoc test (α = 0.05). Specimens from each group were examined using an SEM. Results: Mean load‐to‐fracture values among materials were significantly different from each other (P < 0.05). No significant effect of the number of cycles was found on the load‐to‐fracture values of crowns (P > 0.05). Conclusion: Load‐to‐fracture values of zirconia were higher than those of LDS, which were higher than those of ZLS. The number of fatigue loading cycles did not affect the load‐to‐fracture of the tested crowns for a given material. Clinical Significance: More research needs to be conducted before considering the routine use of ZLS for molars in patients with high risk of parafunctional habits. [ABSTRACT FROM AUTHOR]

To assess the contrast-to-noise ratio (CNR) of four different types of dental implant materials in CT and cone beam CT (CBCT) images with varying scan settings. Four different types of implants: zirconium (Zr), titanium (Ti) Grade 4 and 5 and titanium–zirconium (Ti–ZrO2) alloy were placed in a 3% gelatin phantom in a cylindrical plastic container and scanned with two different CT machines (GE Medical systems and Toshiba Medical Systems) and one CBCT machine (I-CAT, Imaging Sciences International) with different voxel sizes of 0.2, 0.25, 0.3 and 0.4 mm. Images were analyzed using ImageJ software with the purpose of estimating the CNR. The CNR obtained from images acquired with CT was lower than the CBCT with all voxel sizes tested. 0.3 and 0.4 mm voxel sizes exhibited the highest CNR (p < 0.05) that gives the best image quality. Among the implant materials tested, titanium Grade 5 has the highest levels of CNR while Zirconium has the lowest (p < 0.05). The optimum protocol for radiographic follow-up in areas near implants on the I-CAT is low-resolution settings (0.3 and 0.4 mm voxel sizes) which gave the highest CNR thus image quality. In presence of Zr implants, an alternative imaging modality (i.e., MRI) may be considered to avoid low-quality images. [ABSTRACT FROM AUTHOR]