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This study evaluated the shear bond strength of different repair systems to nickel-chromium (NiCr) alloy after storage in water for either 24 hours or six months. One hundred cylindrical specimens (3 mm thick x 9 mm diameter) were fabricated using an NiCr alloy and embedded in a PVC ring, where they received one of five bonding and resin composite repair treatments (n = 20): Clearfil SE Bond/Clearfil AP-X (Group 1), Bistite II DC/Palfique (Group 2), CoJet/Z100 (Group 3), Scotchbond Multi-Purpose Plus/Z100 (Group 4; reference group), and CoJet Sand plus Scotchbond Multi-Purpose Plus/Z100 (Group 5). The specimens were stored in distilled water for 24 hours at 37°C, thermocycled for 1,000 cycles in two baths (at 5°C and 55°C) with a dwell time of 30 seconds for each bath, and stored in distilled water at 37°C for either 24 hours or six months.At 24 hours, Group 3 presented the highest mean values (P < 0.001); at six months, Group 5 demonstrated the highest mean values (P < 0.001). At six months, Group 5 presented a significant increase in shear bond strength (P < 0.001), while Groups 1 and 3 showed a significant reduction (P < 0.001). There were no significant differences between the storage times for Group 2 (P = 0.064) or Group 4 (P = 0.490). [ABSTRACT FROM AUTHOR]

OBJECTIVES: To evaluate, at different times, the diametral tensile strength (DTS) of dual-curing resin cements that were not photopolymerized. METHOD AND MATERIALS: Equal amounts of base and catalyst pastes of Panavia F (Kuraray), Variolink II (Vivadent), Rely X (3M ESPE), and Enforce (Dentsply) were mixed and inserted into cylindrical molds (4 x 2 mm) (n = 10). Cements were not photopolymerized. DTS test was performed in a testing machine at 30 minutes, 1 hour, 24 hours, and 7 days. The specimens were stored in light-proof containers with distilled water at 37 degrees C until the time of assay. An autopolymerizing resin cement (Cement-It, Jeneric Pentron) and a zinc phosphate cement served as controls. One-way analysis of variance (ANOVA) and Tukey test were performed separately for each cement and for each time (P <.05). RESULTS: All cements showed an increase in DTS when tested at 1 and 24 hours. Tests at 24 hours and 7 days revealed no statistically significant differences. In all groups, the zinc phosphate cement had the lowest DTS mean values (2.1 MPa, 3.6 MPa, 6.5 MPa, and 6.9 MPa), while Cement-It (35.1 MPa, 33.6 MPa, 46.9 MPa, and 46.3 MPa) and Enforce (31.9 MPa, 31.7 MPa, 43.4 MPa, and 47.6 MPa) presented the highest DTS mean values. CONCLUSION: All cements presented maximal strength at 24 hours. The dual-curing resin cements, even when nonphotopolymerized, demonstrated higher DTS than the zinc phosphate cement and similar or lower values than the autopolymerizing resin cement. [ABSTRACT FROM AUTHOR]

Although at-home bleaching can recover the optical properties of stained CAD-CAM monolithic materials, little is known about its impact on their surface and mechanical properties, especially when successive sessions are performed. This study evaluated the effect of successive at-home bleaching sessions on the microhardness, roughness, topography, biaxial flexural strength (BFS), and reliability of CAD-CAM monolithic materials. Disks from Lava Ultimate (LU), Vita Enamic (VE), and IPS Empress CAD (EMP) were fabricated and submitted to up to three bleaching sessions. At-home bleaching was performed with 10% carbamide peroxide, and each session consisted of one application for 10 hours/day for 14 days. The analyses of the aforementioned parameters were assessed before and after the first, second, and third bleaching sessions, except for BFS, which was evaluated at baseline and after the third session. The Weibull modulus was calculated from the BFS data. The microhardness of the three materials as well as the roughness of LU were not affected by the sessions, whereas the roughness of VE and EMP increased from the second session. All materials displayed topographic changes, which became more pronounced with the increase in the number of sessions. Although bleaching decreased the BFS of the materials, it did not adversely affect their reliability. Successive at-home bleaching sessions with the protocol used in the present study cannot be considered a safe procedure for the materials evaluated., (©Operative Dentistry, 2024.)

Objectives: To assess the probability of survival of crowns made with a 3Y-TZP, a 5Y-TZP, and a lithium disilicate., Materials and Methods: CAD-CAM premolar crowns with occlusal thicknesses of 1.0 mm or 1.5 mm and cemented on a metal dye. Step-stress accelerated life testing (SSALT) was performed to access the use level probability Weibull curves and reliability were calculated for the completion of a mission of 100,000 cycles at 300 to 1200 N., Results: All ceramics showed a high probability of survival (87-99%) at 300 N, irrespective of thickness. 3Y-TZP shows no significant decrease in the probability of survival up to 1200 N (83-96%). Lithium disilicate presented lower reliability than zirconia under the 600 N mission. 5Y-TZP showed lower reliability than 3Y-TZP at 1200 N. There was no significant difference in the Weibull modulus (3.23-7.12). 3Y-TZP had the highest characteristic strength (2483-2972 N), followed by 5Y-TZP (1512-1547 N) and lithium disilicate (971-1154 N)., Conclusion: Zirconia ceramics have a high probability of survival (up to 900 N-load), while lithium disilicate survives up to 300 N load only, irrespective of the thickness (1.0 mm or 1.5 mm)., Clinical Relevance: The probability of survival of posterior crowns made with zirconia ceramics resists extreme loads while glass ceramics resist normal chewing loads. In addition, crowns with thinner occlusal face showed sufficient mechanical behavior., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Statement of Problem: Fully stabilized monolithic zirconia (FSZ) has been developed as an alternative to zirconia veneered with porcelain. However, how sintering conditions might affect its microstructure and optical and mechanical properties is unclear., Purpose: The purpose of this in vitro study was to determine the effect of different sintering temperatures on the microstructure and optical and mechanical properties of FSZ., Material and Methods: Bar-shaped FSZ specimens were prepared and divided into 2 groups (n=15) according to final sintering temperatures (1450 °C and 1600 °C). The average reflectance, opacity, translucency parameter, and sum of light absorption-scattering values were obtained by using a spectrophotometer, and ΔE 00 was calculated. The 3-point bend test was performed in a universal testing machine. Scanning electron microscopy (SEM) was conducted for microstructure analysis. Crystalline phase quantification was obtained by X-ray diffraction (XRD). Data were analyzed by using D'Agostino-Pearson and Student t tests (α=.05)., Results: A significant difference was detected in the reflectance and sum of light absorption-scattering values between the 2 groups. The translucency parameter, opacity, and flexural strength showed no statistical differences. ΔE 00 was 0.98. XRD indicated cubic (47.41% for 1450 °C; 46.04% for 1600 °C) and tetragonal content (52.59% for 1450 °C; 53.96% for 1600 °C). No monoclinic content was found. SEM images showed more definite grain boundaries in the 1600-°C group. Mean grain size was 0.49 μm for the 1450-°C group and 1.99 μm for the 1600-°C group., Conclusions: Higher sintering temperatures increased the grain size but did not change the crystal phase concentration. A significant difference was found in the reflectance and sum of light absorption-scattering, but no differences were found among the translucency parameter, opacity, or flexural strength., (Copyright © 2019 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

Statement of Problem: How occlusal adjustments and finishing of high-translucent monolithic zirconia restorations affect their mechanical behavior is unclear., Purpose: The purpose of this in vitro study was to investigate the effect of grinding, finishing, and hydrothermal degradation on the roughness, flexural strength, and reliability of fully stabilized zirconia (FSZ) and partially stabilized zirconia (PSZ) for monolithic restorations., Material and Methods: Specimens of PSZ and FSZ were divided into 5 groups: control (Ctrl); those ground by using coarse diamond rotary instrument (Gr); those that underwent grinding, polishing (diamond rubber), and glazing (GrPolGl); those that underwent grinding and glazing (GrGl); and those that underwent grinding and polishing (GrPol). These groups were subdivided into nonaged and hydrothermally aged in autoclave (134 °C, 200 kPa). Three-point bend tests (flexural strength [FS]) were performed (n=30), and roughness (Ra) was measured by using a contact profilometer (n=30). The Weibull moduli were obtained from the FS data. The intergroup FS was analyzed by the Kruskal-Wallis test and Student-Newman-Keuls method, and the intragroup FS, Mann-Whitney tests (α=.05)., Results: The median FS for PSZ (MPa) for the aforementioned groups is as follows: Gr (1147.8)=GrPol (1210.3)>GrPolGl (815.6)>GrGl (569.7)=Ctrl (583.0). The FS for FSZ (MPa) for the aforementioned groups is as follows: GrPolGl (404.2)=GrGl (427.0)

Statement of Problem: Information concerning the effect of airborne-particle abrasion before zirconia sintering on its strength after aging is lacking., Purpose: The purpose of this in vitro study was to determine the influence of airborne-particle abrasion moment (before or after zirconia sintering), particle size, and aging on the mechanical strength of a yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP) ceramic., Material and Methods: Four hundred presintered zirconia disks were allocated to nonabraded (control) and abraded groups with 50 μm or 120 μm Al 2 O 3 particles before (50/BS or 120/BS) or after sintering (50/AS or 120/AS). The disks were aged by storing them in distilled water for 24 hours at 37 °C (24 h) (control); mechanical cycling (MC) (1×10 6 cycles; 2 Hz; 100 N); hydrothermal aging (HA) (134 °C; 0.2 MPa; 20 hours); or by both methods (MC+HA), totaling 20 groups (n=20). The specimens were subjected to biaxial flexural strength (BFS) testing. Fractographic analysis was performed to identify the fracture origin. Tetragonal to monoclinic transformation was determined by X-ray diffraction. The BFS data (MPa) were analyzed by 2-way ANOVA and the Games-Howell post hoc test (α=.05). Weibull statistics was also applied., Results: The BFS and characteristic strength (σ0) of the 120/AS groups were significantly higher compared with the other abraded groups and statistically similar or higher compared with the respective nonabraded groups. In contrast, the 120/BS/24 h and all the 50/BS groups presented the lowest values. In all groups, the initial defect had its origin on the tensile stress side. Neither airborne-particle abrasion nor aging (except for the 50/AS/MC+HA) reduced the zirconia reliability compared with the respective controls. Abrading the zirconia in its presintered stage or after sintering increased the monoclinic phase content, and the sintering process eliminated this phase., Conclusions: Airborne-particle abrasion before zirconia sintering yields an inferior performance compared with that after sintering under aging challenges. The BFS and σ0 were strongly determined by the particle size and airborne-particle abrasion moment, while aging mainly acted in the nonabraded zirconia or when this material was abraded before sintering., (Copyright © 2018 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

Statement of Problem: The longevity of dental implants depends on the maintenance of peri-implant tissue and absence of inflammation. How the physical-chemical properties intrinsic to each material over time can affect adhesion, given constant cell turnover and biofilm development, remains unclear., Purpose: The purpose of this in vitro study was to evaluate the influence of aging on the viability, adhesion, and proliferation of normal oral keratinocytes (Nok-si) and on the multispecies biofilm formation of Fusobacterium nucleatum (F. nucleatum), Porphyromonas gingivalis (P. gingivalis), and Streptococcus sanguinis (S. sanguinis)., Material and Methods: Zirconia (ZrO 2 ) and titanium (Ti) disks were analyzed by surface roughness, water contact angle, and X-ray diffraction before and after aging in an autoclave. The Nok-si cell viability was evaluated by using a 3-(4.5-dimethylthiazole-2-yl)2.5-diphenyl tetrazolium bromide assay (MTT), morphology by scanning electron microscopy (SEM), and proliferation and adhesion by using a confocal microscope. Multispecies biofilms were analyzed quantitatively by colony-forming units per milliliter (CFU/mL) and qualitatively by SEM., Results: For Ti, the aging process affected the roughness and wettability. However, for ZrO 2 , the aging did not affect roughness but did affect wettability and the ratio of the tetragonal to monoclinic phase (P<.05). A significant difference was found in the bacterial growth for Ti (nonaged and aged) in relation to the control, and no differences were found in Ti before and after aging; however, ZrO 2 had increased growth of microorganisms after aging. For ZrO 2 , a statistically significant difference was found between aged ZrO 2 and the control (P<.001)., Conclusions: The results indicate that, after the aging, Ti showed better cell adhesion and proliferation and lower biofilm adhesion than zirconia., (Copyright © 2019 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

The objective of this study was the development of a bioactive glass coating on zirconia (Zr) to modulate the gingival fibroblast phenotype. For this purpose, Biosilicate® (BS) particles in a water/isopropyl alcohol (1:1) vehicle (6 mg/mL) were applied to zirconia discs followed by thermal treatment at 1100 °C for 20 min. The surface topography (SEM), chemical composition (EDX), surface roughness (Ra; confocal microscopy), surface free energy (goniometry), and color alteration (UV-vis spectrophotometry) were assessed (n=6). Thereafter, L929 fibroblasts were seeded onto Zr and Zr+BS discs, and cell proliferation (Alamar Blue; n=6), morphology (SEM; n=2), migration (wound healing; n=4), and collagen synthesis (Sirius Red; n=6) were evaluated up to 7 days. Data were analyzed by ANOVA/Tukey tests (a=5%). A homogeneous coating consisting of Si, Na, O, and Ca was detected on the Zr surface after thermal treatment with BS, which led to a significant increase in surface roughness and free energy (p<0.05). No change in color parameters was observed (p>0.05). Cells seeded on the Zr+BS surface featured increased proliferation, collagen expression, and migration capability in comparison with those cultured on plain Zr (p<0.05). SEM images revealed that cell spreading occurred faster in the presence of BS. Therefore, it was concluded that thermal treatment of the Zr surface with BS led to the deposition of a bioactive coating, which induced gingival fibroblast spread, proliferation, migration, and collagen expression in vitro.

Statement of Problem: The effect of clinical adjustments on the strength of cemented computer-aided design and computer-aided manufacturing (CAD-CAM) monolithic materials under aging challenge is unclear., Purpose: The purpose of this in vitro study was to assess the surface roughness and fracture resistance (with or without mechanical aging) of cemented CAD-CAM monolithic materials submitted to grinding and polishing procedures., Material and Methods: Disks of Lava Ultimate, Vita Enamic, crystallized Vita Suprinity, and IPS e.max CAD were analyzed for roughness after polishing by using silicon carbide papers (Lava Ultimate and Vita Enamic) or glazing (IPS e.max CAD and Vita Suprinity) (control), after grinding by using 30-μm grit diamond rotary instruments, and after grinding and polishing by using a polishing kit. For fracture resistance, a simplified trilayer model consisting of a restorative disk, an epoxy resin disk, and a steel ring was used. The bonded trilayer disks received the same treatments described for the roughness analysis. Half of the specimens underwent mechanical aging for 1×10 6 cycles. All specimens were loaded until failure. The Weibull modulus was calculated., Results: The IPS e.max CAD and Vita Suprinity showed the highest roughness after grinding and the lowest at baseline. For the Lava Ultimate and Vita Enamic, polishing provided lower roughness than at baseline. Grinding, followed or not by polishing, and mechanical aging did not adversely affect the fracture resistance or the reliability of the materials., Conclusions: Polishing did not recover the initial surface roughness of the glass-ceramic materials. Fracture resistance was not affected by grinding, followed or not by polishing, even after mechanical aging., (Copyright © 2019 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

Purpose: To evaluate the influence of particle and air-abrasion on the surface characterization and shear bond strength (SBS) of a Y-TZP ceramic with a resin cement., Materials and Methods: Y-TZP specimens were air-abraded with 50 μm alumina particles; 120 μm alumina particles; 30 μm silica-coated alumina particles (Rocatec Soft); 110 μm silica-coated alumina particles (Rocatec Plus). Air-abrasion was performed before (BS); after (AS); before and after (BAS) zirconia sintering. Surface characterization included roughness (n = 10), wettability (n = 10), morphology (n = 2), and elemental composition (n = 2). For SBS (n = 11), composite resin discs were bonded to the air-abraded and silane-treated zirconia surface, with the resin cement RelyX ARC. Failure mode was determined. Roughness, wettability, and SBS data were analyzed by two-way ANOVA with pairwise interaction and Tukey's test (α = 0.05)., Results: Air-abrasion performed with coarser particles at BS and BAS moments provided the highest roughness values, while the lowest roughness values were observed with particles combined with AS moment (p < 0.01). Rocatec Plus provided lower contact angle than the 120 μm alumina particles (p = 0.013), and BAS exhibited lower contact angle than BS (p = 0.002). The combinations 120 μm/BS and the silica-coated alumina particles/AS and /BAS showed the highest SBS (p < 0.05). The combination of each particle/BAS was statistically similar to the same particle/AS. Failure mode was 100% adhesive for all groups. The interaction particle size/air-abrasion moment determined the morphological pattern. Silicon was observed only in the Rocatec groups., Conclusions: Roughness was influenced by the particle size and was higher when the zirconia was air-abraded in its green stage. The particle composition played an important role in the wettability and both studied air-abrasion moments provided similar wettability than the one in which air-abrasion is usually performed. The highest SBS values were observed in the three moments, by using certain particles for each moment., (© 2017 by the American College of Prosthodontists.)

Prosthodontic treatment for edentulous maxillae with severe bone loss is a challenge to clinicians. Although implant-supported, fixed maxillary complete dentures are increasingly common, they are not always able to provide adequate lip support without a buccal overextension in patients with bone loss. The overextended buccal flange makes it difficult for patients to clean under the prosthesis. This case report describes rehabilitation of an atrophic maxilla through an implant-supported double-bar overdenture designed to resolve difficulties in oral hygiene maintenance that were caused by the buccal overextension of the prosthetic flange in a previous implant-supported fixed complete denture. In addition to reestablishing lip support, overdentures with a double-bar system provide retention and stability, because the prosthesis is only removed for cleaning by the patient with the help of a specific key. Implant-supported double-bar overdentures represent a viable and versatile option for rehabilitation of atrophic maxillae., Competing Interests: Disclaimer: The authors report no conflicts of interest pertaining to any of the products or companies discussed in this article.

Statement of Problem: Studies of composite resin repairs of yttrium-tetragonal zirconia polycrystal (Y-TZP) are usually performed in its tetragonal phase, but it may be partially transformed into a monoclinic phase in a clinical fracture., Purpose: The purpose of this in vitro study was to evaluate the effect of airborne-particle abrasion (APA) and a bonding agent on the shear bond strength (SBS) between a composite resin and hydrothermally aged Y-TZP., Material and Methods: Specimens (7.0×7.0×1.7 mm, N=112) of Y-TZP Lava were obtained, and 50% were aged in an autoclave at 134°C at 300 kPa for 8 hours. The surfaces were treated with APA 50-μm Al 2 O 3 particles (ALU) or Rocatec Soft (30 μm) (ROC) followed by Clearfil SE Bond Primer (10-methacryloyloxydecyl dihydrogen phosphate [10-MDP]) plus Clearfil porcelain bond activator (3-methacryloxypropyl-trimethoxy silane [3-MPS]) (CLE) or RelyX Ceramic Primer plus a layer of RelyX U100 adhesive-resin cement (REL). Composite resin cylinders were built on the Y-TZP treated surfaces. After thermocycling (6000 cycles, 5°C and 55°C, 30-second dwell time), an SBS test was carried out (n=14). Data were analyzed by 3-way ANOVA and the Tukey honest significant differences test (α=.05). The failure mode was analyzed., Results: The 3-way ANOVA was not significant for aging (P>.05), but the APA (P<.001), bonding agent (P<.001), and their interaction (P<.001) were significant. APA with ALU or ROC did not influence the SBS of the groups bonded with CLE, but the REL APA with ROC provided higher SBS. The failure mode was adhesive for all specimens., Conclusions: Adhesion was not different on monoclinic partially transformed Y-TZP. The APA with ROC followed by REL was the most effective treatment for repairing Y-TZP., (Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

Objectives: To evaluate the effect of hydrothermal aging (H), mechanical cycling (M), and the combination of hydrothermal plus mechanical cycling (H+M) on biaxial flexural strength (BFS) and microstructure of two monolithic zirconias, indicated for anterior (AMZ) or posterior restorations (PMZ) and a conventional zirconia (IZr)., Methods: Disc specimens of each material (n=12) were submitted to: i) H (8h in autoclave at 134°C); ii) M (10 6 cycles, at 40% of BFS); and iii) H+M. BFS was measured (ISO-6872) and Weibull modulus (m) and the characteristic strength (σ 0 ) were calculated. crystalline phase composition analyzed by XRD, and grain size measured by MEV analysis., Results: XRD analysis showed AMZ was not susceptible to monoclinic transformation in any treatment. Conventional zirconia (IZr) and PMZ had monoclinic transformation only after H and H+M. BFS of AMZ was lower than PMZ and IZr. Cubic phase was found in all conditions for AMZ and IZr, while it was identified in PMZ only after H and H+M. BFS of AMZ was affected by M and H+M. For IZr and PMZ the unique difference detected in BFS was in the comparison of H to M. H treatment induced lower Weibull modulus, but characteristic strength was compatible with the BFS results. AMZ grain size (μm 2 ) was 8.6 times larger than PMZ grains, and 13.6 times larger than IZr grains., Conclusions: AMZ showed the largest mean grain size, had the lowest BFS values, and was affected when mechanical cycling was involved. Monoclinic transformation was not found in any treatment for AMZ, but was found in IZr and PMZ when hydrothermal aging was used alone or when combined with mechanical cycling. PMZ showed similar behavior to the IZr. H induced to higher fracture probability., Clinical Significance: Translucent monolithic dental zirconia available on the market may behave differently under simulated oral aging. The relationship between composition and microstructure determines their properties presumably, and clinical performance., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

The aim of this study was to characterize a conventional and a pressed porcelain for zirconia core as to biaxial flexural strength (BFS), apparent fracture toughness (FT) and microstructure composition, and to investigate the effect of glaze cooling rate on the BFS of the zirconia/porcelain bilayers. Monolayers of conventional porcelain Vita VM9 and pressed porcelain Vita PM9 (n=15) (12 mm diameter x 1.2 mm thick) were prepared for the BFS test (MPa). Apparent fracture toughness (MPa.m1/2) was measured by indentation technique (n=15). t-Student test was performed for statistical analysis. Scanning electron microscopy and x-ray diffraction were used to analyze the porcelain's microstructure. For the BFS of bilayers, zirconia discs (12 mm diameter x 1 mm thick) (Vita In-Ceram YZ) were veneered with the two porcelains (1 mm thick). After the glaze firing simulation, the specimens were submitted to fast or slow cooling (n=15). Apparent fracture toughness (MPa.m1/2) was measured on the porcelain surface of bilayers (n=15) and residual stress was calculated. Two-way ANOVA (porcelain and cooling method) was used for the bilayer analysis (a=0.05). Vita PM9 monolayer exhibited significantly higher BFS (p<0.01), but there was no significant difference (p=0.41) in the FT between the porcelains. For bilayer specimens, the two-way ANOVA for BFS was significant for the porcelain variable only (p<0.01) better for Vita PM9/zirconia. Two-way ANOVA for the FT for the bilayers was not significant for any variable. All groups showed compressive residual stresses. The pressed porcelain seems to be mechanically more effective for zirconia veneering.

Statement of Problem: Because zirconia is a glass-free material, alternative surface treatments such as airborne-particle abrasion or silica coating should be used for long-term bonding. However, these surface treatments in combination with different bonding agents and luting cements have not yet been studied., Purpose: The purpose of the study was to evaluate the effect of surface treatments on the shear bond strength (SBS) of luting cements to Y-TZP ceramic., Material and Methods: Zirconia disks (N=240) were airborne-particle abraded with the following particles (n=48): 50 μm Al2O3; 120 μm Al2O3; 30 μm silica-coated Al2O3 (Rocatec Soft); 120 μm Al2O3+110 μm silica-coated Al2O3 (Rocatec Plus); and Rocatec Plus. After silanization of the zirconia surface, composite resin disks were bonded with (n=12) RelyX Luting 2; RelyX ARC; RelyX U100; and Panavia F. The bonded specimens were thermocycled (10 000 cycles) and tested for SBS. Failure mode was determined with a stereomicroscope (×20). The morphology and elemental composition of airborne-particle abraded surfaces were evaluated with scanning electron microscopy (×500) and energy-dispersive x-ray spectroscopy (×50)., Results: Surface treatments, cements, and their interaction were significant (P<.001). For RelyX ARC, Rocatec Soft and Rocatec Plus provided the highest SBS. In general, surface treatments did not influence the SBS of RelyX U100 and Panavia F. Regardless of the cement, no significant difference was found between 50 μm and 120 μm Al2O3 particles, between Rocatec Soft and Rocatec Plus, or between Rocatec Plus and 120 μm Al2O3 particles+Rocatec Plus. All groups showed adhesive failures. Different particle sizes provided differences in morphological patterns. The elemental composition comprised Al and Al/Si for alumina and silica-abraded zirconia., Conclusions: Particle size did not influence the SBS of the groups abraded exclusively with alumina or silica-coated particles. RelyX ARC was more surface-treatment dependent than RelyX U100 or Panavia F., (Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

Crowns made from an yttria-stabilized tetragonal zirconia polycrystals (3Y-TZP) core with a porcelain veneer have shown high clinical failure rates. Manifestations of clinical failure in veneering ceramic ranges from a single chip to an extended fracture. Core failures are uncommon but usually are catastrophic. This article examines the possible causes of failure in zirconia systems and presents a case report involving the diagnosis and repair of three different types of failure in six 3Y-TZP/porcelain crowns.

Objectives: This study investigated the effect of extreme cooling methods on the flexural strength, reliability and shear bond strength of veneer porcelain for zirconia., Methods: Vita VM9 porcelain was sintered on zirconia bar specimens and cooled by one of the following methods: inside a switched-off furnace (slow), at room temperature (normal) or immediately by compressed air (fast). Three-point flexural strength tests (FS) were performed on specimens with porcelain under tension (PT, n=30) and zirconia under tension (ZT, n=30). Shear bond strength tests (SBS, n=15) were performed on cylindrical blocks of porcelain, which were applied on zirconia plates. Data were submitted to one-way ANOVA and Tukey's post hoc tests (p<0.05). Weibull analysis was performed on the PT and ZT configurations., Results: One-way ANOVA for the PT configuration was significant, and Tukey's test revealed that fast cooling leads to significantly higher values (p<0.01) than the other cooling methods. One-way ANOVA for the ZT configuration was not significant (p=0.06). Weibull analysis showed that normal cooling had slightly higher reliability for both the PT and ZT configurations. Statistical tests showed that slow cooling decreased the SBS value (p<0.01) and showed less adhesive fracture modes than the other cooling methods., Clinical Significance: Slow cooling seems to affect the veneer resistance and adhesion to the zirconia core; however, the reliability of fast cooling was slightly lower than that of the other methods., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Purpose: To assess the influence of fluoride on the adhesion of Streptococcus mutans to titanium using an experimental paradigm simulating 10 years of brushing., Materials and Methods: Commercially pure titanium (cpTi) and titanium alloy (Ti-6Al-4V) disks (6 mm in diameter and 4 mm thick) were mirror-polished and randomly assigned to one of the following six groups (n = 6): immersion (I) or brushing (B) in deionized water (groups IW [control] and BW), fluoride-free toothpaste (groups IT and BT), or fluoridated toothpaste (groups IFT and BFT). Specimens subjected to immersion were statically submerged into the solutions without brushing. For the brushed specimens, a linear brushing machine with a soft-bristled toothbrush was used. The experiments lasted a total of 244 hours. Before and after treatment, the specimens were analyzed under an atomic force microscope to determine the mean roughness (Ra) and the mean of the maximum peak-to-valley heights of the profile (Rtm). The disks were contaminated with standard strains of S mutans in well plates with brain-heart infusion broth. Adhesion was analyzed based on the numbers of colony-forming units (CFU/mL) of adhered viable cells using scanning electronic microscopy. Differences in CFU/mL between the groups were analyzed by one-way analysis of variance., Results: Immersion did not affect either surface. As suggested by Ra and Rtm, BW, BT, and BFT induced changes on the surface of cpTi, whereas only BT and BTF induced changes on the surface of Ti-6Al-4V. No significant differences were observed regarding CFU/mL among the cpTi or Ti-6Al-4V groups. S mutans adhesion was similar for all surfaces., Conclusions: The changes in titanium induced by 10 years of simulated brushing with fluoride toothpaste did not increase the adhesion of S mutans.

Statement of Problem: Although titanium presents attractive physical and mechanical properties, there is a need for improving the bond at the titanium/luting cement interface for the longevity of metal ceramic restorations., Purpose: The purpose of this study was to evaluate the effect of surface treatments on the shear bond strength (SBS) of resin-modified glass ionomer and resin cements to commercially pure titanium (CP Ti)., Material and Methods: Two hundred and forty CP Ti cast disks (9.0 × 3.0 mm) were divided into 8 surface treatment groups (n=30): 1) 50 µm Al(2)O(3) particles; 2) 120 µm Al(2)O(3) particles; 3) 250 µm Al(2)O(3) particles; 4) 50 µm Al(2)O(3) particles + silane (RelyX Ceramic Primer); 5) 120 µm Al(2)O(3) particles + silane; 6) 250 µm Al(2)O(3) particles + silane; 7) 30 µm silica-modified Al(2)O(3) particles (Cojet Sand) + silane; and 8) 120 µm Al(2)O(3) particles, followed by 110 µm silica-modified Al(2)O(3) particles (Rocatec). The luting cements 1) RelyX Luting 2; 2) RelyX ARC; or 3) RelyX U100 were applied to the treated CP Ti surfaces (n=10). Shear bond strength (SBS) was tested after thermal cycling (5000 cycles, 5°C to 55°C). Data were analyzed by 2-way analysis of variance (ANOVA) and the Tukey HSD post hoc test (α=.05). Failure mode was determined with a stereomicroscope (×20)., Results: The surface treatments, cements, and their interaction significantly affected the SBS (P<.001). RelyX Luting 2 and RelyX U100 exhibited similar behavior for all surface treatments. For both cements, only the group abraded with 50 μm Al(2)O(3) particles had lower SBS than the other groups (P<.05). For RelyX ARC, regardless of silane application, abrasion with 50 μm Al(2)O(3) particles resulted in significantly lower SBS than abrasion with 120 μm and 250 μm particles, which exhibited statistically similar SBS values to each other. Rocatec + silane promoted the highest SBS for RelyX ARC. RelyX U100 presented the highest SBS mean values (P<.001). All groups showed a predominance of adhesive failure mode., Conclusions: The adhesive capability of RelyX Luting 2 and RelyX U100 on the SBS was decisive, while for RelyX ARC, mechanical and chemical factors were more influential., (Copyright © 2012 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.)

Purpose: To evaluate the effect of surface treatments on the shear bond strength (SBS) of a resin cement to commercially pure titanium (CP Ti)., Materials and Methods: Two hundred cast CP Ti disks were divided into 5 groups (n = 40), which were treated with one of the following air-abrasion techniques: (1) 50-µm Al2O3 particles; (2) 120-µm Al2O3 particles; (3) 250-µm Al2O3 particles; (4) 30-µm silica-modified Al2O3 particles (Cojet Sand); (5) 50-µm Al2O3 particles followed by 110-µm silica-modified Al2O3 particles (Rocatec Plus). For each air-abrasion technique, the following additional surface treatments were used (n = 10): (1) none; (2) adhesive Adper Single Bond 2; (3) silane RelyX Ceramic Primer; (4) silane plus adhesive. RelyX ARC resin cement was bonded to CP Ti surfaces. All specimens were thermocycled (5,000 cycles) before being tested in shear mode. Data (MPa) were analyzed using two-way ANOVA and Tukey's test (α = 0.05). Failure mode was determined with a stereomicroscope (20X)., Results: The results revealed that the air-abrasion technique (p < 0.001), additional surface treatment (p < 0.001) and their interaction were significant (p < 0.001). Except for the 50-µm Al2O3 + adhesive group, 250-µm Al2O3 particles promoted significantly higher SBS than 50-µm Al2O3 particles (p < 0.001), while Rocatec Plus provided bond strengths that were similar to or higher than those of Cojet Sand. Of the additional surface treatments, the adhesive provided the best results in combination with the 3 air-abrasion techniques (50-µm, 120-µm, and 250-µm Al2O3), whereas in the groups abraded with silica-modified Al2O3 particles (Cojet Sand and Rocatec Plus), the best results were obtained with additional silane. The two combinations that promoted the highest SBS were 250-µm Al2O3 + adhesive and Rocatec Plus + silane. All groups showed 100% adhesive failure., Conclusion: The selection of the best additional surface treatment varied according to the air-abrasion technique. Particle size was the decisive factor in determining the bond strength when micromechanical retention was the only bonding mechanism. When both mechanisms were present, in addition to particle size, the material applied as the additional surface treatment also contributed to determining the bond strength.

Statement of Problem: Coatings of zirconite, Y(2)O(3) or ZrO(2) on wax patterns before investing in phosphate-bonded investments have been recommended to reduce the reaction layer in titanium castings, but they are not easily obtainable. Spinel-based investments are relatively stable with molten titanium and could be used as coatings to improve the quality of castings made with those investments., Purpose: The purpose of this study was to evaluate the effect of pattern coating with a commercial spinel-based investment before investing in 1 of 3 phosphate-bonded inves tments on the marginal coping fit and surface roughness of commercially pure titanium castings., Material and Methods: Ten square acrylic resin patterns (12 × 12 × 2 mm) per group were invested in the phosphate-bonded investments Rematitan Plus (RP), Rema Exakt (RE), and Castorit Super C (CA) with or without a coating of the spinel-based investment, Rematitan Ultra (RU). After casting, the specimens were cleaned and the surface roughness was measured with a profilometer. Copings for dental implants with conical abutment were invested, eliminated, and cast as previously described. The copings were cleaned and misfit was measured with a profile projector (n=10). For both tests, the difference between the mean value of RU only and each value of the phosphate-bonded investment was calculated, and the data were analyzed by 2-way ANOVA and Tukey's HSD test (α=.05). In addition, the investment roughness was measured in bar specimens (30 × 10 × 10 mm), and the data (n=10) were analyzed by 1-way ANOVA and Tukey's HSD post hoc test (α=.05)., Results: Two-way ANOVA for casting surface roughness was significant because of the investment, the coating technique, and the interaction between variables. One-way ANOVA was performed to prove the interaction term, and Tukey's post hoc test showed that RP with coating had the lowest mean, while RP had the highest. CA with coating was not different from RP with coating or CA without coating. RE with coating was similar to CA, while RE was different from all groups. For coping marginal fit, the 2-way ANOVA was significant for the investment, the coating technique, and the interaction between variables. The interaction was analyzed by1-way ANOVA and Tukey's HSD test that showed no significant difference among the coated groups, which had better marginal fit than the groups without coating. Among the groups without coating, CA had significant lower marginal misfit than RP, while RE was not different from CA and RP. For the investment surface roughness, the 1-way ANOVA was significant. CA and RU were smoother than RE and RP (P<.001)., Conclusions: The coating technique improved the quality of castings fabricated with phosphate-bonded investments., (Copyright © 2012 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.)

Objectives: To conduct a controlled study contrasting titanium surface topography after procedures that simulated 10 years of brushing using toothpastes with or without fluoride., Methods: Commercially pure titanium (cp Ti) and Ti-6Al-4V disks (6 mm Ø×4 mm) were mirror-polished and treated according to 6 groups (n=6) as a function of immersion (I) or brushing (B) using deionised water (W), fluoride-free toothpaste (T) and fluoride toothpaste (FT). Surface topography was evaluated at baseline (pretreatment) and post-treatment, using atomic force microscope in order to obtain three-dimensional images and mean roughness. Specimens submitted to immersion were submerged in the vehicles without brushing. For brushed specimens, procedures were conducted using a linear brushing machine with a soft-bristled toothbrush. Immersion and brushing were performed for 244 h. IFT and BFT samples were analysed under scanning electron microscope with Energy-Dispersive X-ray Spectroscopy (EDS). Pre and post-treatment values were compared using the paired Student T-test (α=.05). Intergroup comparisons were conducted using one-way ANOVA with Tukey post-test (α=.05)., Results: cp Ti mean roughness (in nanometers) comparing pre and post-treatment were: IW, 2.29±0.55/2.33±0.17; IT, 2.24±0.46/2.02±0.38; IFT, 2.22±0.53/1.95±0.36; BW, 2.22±0.42/3.76±0.45; BT, 2.27±0.55/16.05±3.25; BFT, 2.27±0.51/22.39±5.07. Mean roughness (in nanometers) measured in Ti-6Al-4V disks (pre/post-treatment) were: IW, 1.79±0.25/2.01±0.25; IT, 1.61±0.13/1.74±0.19; IFT, 1.92±0.39/2.29±0.51; BW, 2.00±0.71/2.05±0.43; BT, 2.37±0.86/11.17±2.29; BFT, 1.83±0.50/15.73±1.78. No significant differences were seen after immersions (p>.05). Brushing increased the roughness of cp Ti and of Ti-6Al-4V (p<.01); cp Ti had topographic changes after BW, BT and BFT treatments whilst Ti-6Al-4V was significantly different only after BT and BTF. EDS has not detected fluoride or sodium ions on metal surfaces., Conclusions: Exposure to toothpastes (immersion) does not affect titanium per se; their use during brushing affects titanium topography and roughness. The associated effects of toothpaste abrasives and fluorides seem to increase roughness on titanium brushed surfaces., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Purpose: This study evaluated the effect of pattern coating with spinel-based investment Rematitan Ultra (RU) on the castability and internal porosity of commercially pure (CP) titanium invested into phosphate-bonded investments. The apparent porosity of the investment was also measured., Materials and Methods: Square patterns (15 × 15 × 0.3 mm(3)) were either coated with RU, or not and invested into the phosphate-bonded investments: Rematitan Plus (RP), Rema Exakt (RE), Castorit Super C (CA), and RU (control group). The castings were made in an Ar-arc vacuum-pressure machine. The castability area (mm(2) ) was measured by an image-analysis system (n = 10). For internal porosity, the casting (12 × 12 × 2 mm(3) ) was studied by the X-ray method, and the projected porous area percentage was measured by an image-analysis system (n = 10). The apparent porosity of the investment (n = 10) was measured in accordance with the ASTM C373-88 standard., Results: Analysis of variance (One-way ANOVA) of castability was significant, and the Tukey test indicated that RU had the highest mean but the investing technique with coating increased the castability for all phosphate-bonded investments. The analysis of the internal porosity of the cast by the nonparametric test demonstrated that the RP, RE, and CA with coating and RP without coating did not differ from the control group (RU), while the CA and RE casts without coating were more porous. The one-way ANOVA of apparent porosity of the investment was significant, and the Tukey test showed that the means of RU (36.10%) and CA (37.22%) were higher than those of RP (25.91%) and RE (26.02%)., Conclusion: Pattern coating with spinel-based material prior to phosphate-bonded investments can influence the castability and the internal porosity of CP Ti., (© 2010 by The American College of Prosthodontists.)

Statement of Problem: A new short-cycle, spinel-based investment was developed to minimize the long heating cycle generally required for conventional investments for titanium castings, but the quality of castings made using this material has yet to be evaluated., Purpose: The purpose of this study was to compare the Vickers hardness, castability, surface roughness, in vitro marginal misfit, and internal porosity of castings made using silica phosphate-based and spinel-based investments., Material and Methods: The specimens were commercially pure titanium cast using silica phosphate-based investment, Rematitan Plus (RP), and spinel-based investments, Rematitan Ultra (RU) or short-heat-cycle Trinell (TR). Disc-shaped patterns (6 × 3 mm) were cast, and Vickers hardness was measured at the surface, and 50, 100, 150, and 200 μm beneath the surface (n=10). Microstructure was analyzed by optical microscopy (×100). Mesh patterns (14 × 14 × 0.5 mm) were used for castability testing (n=10). Surface roughness (Ra) was measured on disc-shaped patterns (13 × 3 mm) with a profilometer (n=8). Wax copings were cast, screwed to implant abutments, and the marginal misfit was measured using image analysis software (n=10). Internal porosity of the copings was evaluated by density comparisons (n=10). Hardness data were analyzed by 2-way ANOVA and the Tukey HSD test. Castability, surface roughness, and marginal misfit were analyzed by 1-way ANOVA and the Tukey HSD test, and internal porosity by Kruskal-Wallis and Student-Newman-Keuls tests (α=.05)., Results: RP had the highest hardness values at the surface and 50 μm beneath, but the hardness values of TR, RU, and RP were statistically equivalent at 100, 150, and 200 μm. Significant differences were seen when comparing RU and TR with RP for castability (P<.001), surface roughness (P<.001), and marginal misfit (P<.001). No significant differences were seen for internal porosity., Conclusions: The quality of castings made from the new investment, TR, was similar to the quality of those made using the conventional spinel-based investment, RU, and superior to those made using RP., (Copyright © 2010 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.)

This study analyzed the reaction layer and measured the marginal crown fit of cast titanium applied to different phosphate-bonded investments, prepared under the following conditions (liquid concentration/casting temperature): Rema Exakt (RE) - 100%/237 degrees C, 75%/287 degrees C, Castorit Super C (CS)-100%/70 degrees C, 75%/141 degrees C and Rematitan Plus (RP)- 100%/430 degrees C (special to titanium cast, as the control group). The reaction layer was studied using the Vickers hardness test, and analyzed by two way ANOVA and Tukey's HSD tests (alpha = 0.05). Digital photographs were taken of the crowns seated on the die, the misfit was measured using an image analysis system and One-way ANOVA, and Tukey's test was applied (alpha = 0.05). The hardness decreased from the surface (601.17 VHN) to 150 microm (204.03 VHN). The group CS 75%/141 degrees C presented higher hardness than the other groups, revealing higher surface contamination, but there were no differences among the groups at measurements deeper than 150 mum. The castings made with CS - 100%/70 degrees C presented the lowest levels of marginal misfit, followed by RE -100%/237 degrees C. The conventional investments CS (100%) and RE (100%) showed better marginal fit than RP, but the CS (75%) had higher surface contamination.

Investigation of the effectiveness of surface treatments that promote a strong bond strength of resin cements to metals can contribute significantly to the longevity of metal-ceramic restorations. This study evaluated the effect of surface treatments on the shear bond strength (SBS) of a resin cement to commercially pure titanium (CP Ti). Ninety cast CP Ti discs were divided into 3 groups (n=30), which received one of the following airborne-particle abrasion conditions: (1) 50 microm Al(2)O(3) particles; (2) 30 microm silica-modified Al(2)O(3) particles (Cojet Sand); (3) 110 microm silica-modified Al(2)O(3) particles (Rocatec). For each airborne-particle abrasion condition, the following post-airborne-particle abrasion treatments were used (n=10): (1) none; (2) adhesive Adper Single Bond 2; (3) silane RelyX Ceramic Primer. RelyX ARC resin cement was bonded to CP Ti surfaces. All specimens were thermally cycled before being tested in shear mode. Failure mode was determined. The best association was Rocatec plus silane. All groups showed 100% adhesive failure. There were combinations that promote higher SBS than the protocol recommended by the manufacturer of RelyX ARC.

Objective: This study compared the cutting capacity of carbide burs sterilized with microwaves and traditional sterilization methods., Material and Methods: Sixty burs were divided into 5 groups according to the sterilization methods: dry heat (G1), autoclave (G2), microwave irradiation (G3), glutaraldehyde (G4) or control - no sterilization (G5). The burs were used to cut glass plates in a cutting machine set for twelve 2.5-min periods and, after each period, they were sterilized (except G5) following the protocol established for each group. The cutting capacity of the burs was determined by a weight-loss method. Data were analyzed statistically by Kruskal-Wallis and Dunn's test., Results: The means of the cutting amount performed by each group after the 12 periods were G1 = 0.2167 +/- 0.0627 g; G2 = 0.2077 +/- 0.0231 g; G3 = 0.1980 +/- 0.0326 g; G4 = 0.1203 +/- 0.0459 g; G5 = 0.2642 +/- 0.0359 g. There were statistically significant differences among the groups (p<0.05); only dry heat sterilization was similar to the control., Conclusion: Sterilization by dry heat was the method that least affected the cutting capacity of the carbide burs and microwave sterilization was not better than traditional sterilization methods.

Statement of Problem: A strong and durable bond between a metal framework and a resin-based luting agent is desired. Metal primers have been shown to be very effective on noble alloys. However, there is insufficient information about their effect on base metals., Purpose: The purpose of this study was to evaluate the effect of metal primers on the shear bond strength of resin cements to base metals., Material and Methods: A total of 160 cast commercially pure titanium (CP Ti) and NiCr alloy (VeraBond II) disks were embedded in a polyvinyl chloride ring, and their surfaces were smoothed with silicon carbide papers (320, 400, and 600 grit) and airborne-particle abraded with 50-mum aluminum oxide. Specimens of each metal were divided into 4 groups (n=20), which received one of the following luting techniques: (1) Panavia F, (2) Alloy Primer plus Panavia F, (3) Bistite II DC, or (4) Metaltite plus Bistite II DC. Forty minutes after preparation, all specimens were stored in distilled water at 37 degrees C for 24 hours and then thermal cycled (1000 cycles, 5-55 degrees C). After thermal cycling, the specimens were stored in 37 degrees C distilled water for an additional 24 hours or 6 months before being tested in shear mode. Data (MPa) were analyzed using 3-way ANOVA and the post hoc Tukey test (alpha=.05). Each specimen was examined under an optical microscope (x30), and the failure mode was classified as adhesive, cohesive, or a combination of these., Results: The only significant difference between the Panavia F and Alloy Primer plus Panavia F groups occurred in the NiCr alloy at 24 hours, at which point Panavia F demonstrated superior bond strength compared to Alloy Primer plus Panavia F (P<.001). The Bistite II DC and Metaltite plus Bistite II DC groups were not significantly different. The Bistite II DC and Metaltite plus Bistite II DC groups demonstrated significantly lower bond strength to CP Ti (P<.001) than the Panavia F and Alloy Primer plus Panavia F groups, and significantly lower bond strength to NiCr alloy (P<.001) than Panavia F. The Panavia F (P<.01) and Alloy Primer plus Panavia F groups' bond strength to titanium presented a significant increase (P<.001) in shear bond strength at 6 months. In general, the groups exhibited higher shear bond strength to CP Ti than to NiCr alloy (P<.01). The failure mode was 100% adhesive for all groups., Conclusions: The metal primers did not promote an increase in adhesive bonding of resin cements to NiCr alloy and to CP Ti. Water storage had no adverse effect on the shear bond strength of the groups. The shear bond strengths to titanium were significantly higher than those to the NiCr alloy.

Objective: To assess the effect of metal conditioners on the bond strength between resin cements and cast titanium., Method and Materials: Commercially pure titanium (99.56%) was cast using an arc casting machine. Surfaces were finished with 400-grit silicon carbide paper followed by air abrasion with 50-Microm aluminum oxide. A piece of double-coated tape with a 4-mm circular hole was then positioned on the metal surface to control the area of the bond. The prepared surfaces were then divided into 4 groups (n=10): G1, unprimed Panavia F; G2, Alloy Primer-Panavia F; G3, unprimed Bistite DC; G4, Metaltite-Bistite DC. Forty minutes after insertion of the resin cements, the specimens were detached from the mold and stored in water at 37 degrees C for 24 hours. Shear bond strength was performed in a testing machine (MTS 810) at a crosshead speed of 0.5 mm/min. Data were analyzed using ANOVA and Tukey's test with a .05 significance level. The fractured surfaces were observed through an optical microscope at 103 magnification., Results: The G1 group demonstrated significantly higher shear bond strength (17.95 MPa) than the other groups. G3 (13.79 MPa) and G4 (12.98 MPa) showed similar mean values to each other and were statistically superior to G2 (9.31 MPa). Debonded surfaces generally presented adhesive failure between metal surfaces and resin cements., Conclusion: While the Metaltite conditioner did not influence the bond strength of the Bistite DC cement, the Alloy Primer conditioner significantly decreased the mean bond strength of the Panavia F cement.

As the adaptation of titanium crowns obtained by Rematitan Plus investment, specific for titanium, is not recognized to be suitable, this study evaluated the effect of the concentration of the specific liquid and the temperature of the mold of investments on the internal misfit of crowns cast on commercially pure titanium. Individual dies of epoxy resin were obtained, representing teeth prepared for full-crown restoration with a 6-degree axial surface convergence angle and shoulder (1.0 mm). For the waxing of each crown, a ring-shaped stainless steel matrix (8.0mm internal diameter; 7.5 mm height) was adapted above the individual dies of epoxy resin. The Rematian Plus investment was mixed according to the manufacturer's instructions using two different concentrations of the specific liquid: 100%, 75%. Casting was performed in a Discovery Plasma Ar-arc vacuum-pressure casting machine with molds at temperatures of 430 degrees C, 515 degrees C and 600 degrees C. The crowns were cleaned individually in a solution (1% HF + 13% HNO3) for 10 min using a ultrasonic cleaner, with no internal adaptations, and luted with zinc phosphate cement under a 5 kg static load. The crown and die assemblies were embedded in resin and sectioned longitudinally. The area occupied by cement was observed using stereoscopic lens (10X) and measured by the Leica Qwin image analysis system (mm(2)). The data for each experimental condition (n=8) were analyzed by Kruskal-Wallis non-parametric test (á=0.05). The results showed that liquid dilution and the increase in mold temperature did not significantly influence the levels of internal fit of the cast titanium crowns. The lowest means (+/-SD) of internal misfit were obtained for the 430 degrees C/100%: (7.25 mm(2) +/-1.59) and 600 degrees C/100% (8.8 mm(2) +/-2.25) groups, which presented statistically similar levels of internal misfit.

Statement of Problem: There are few studies on titanium casting shrinkage, and phosphate-bonded investments for titanium casting have not produced appropriate marginal fit., Purpose: The purpose of this study was to determine the thermal shrinkage of titanium and the setting and thermal expansion of 3 phosphate-bonded investments., Material and Methods: The thermal shrinkage between the melting temperature and room temperature was calculated using a titanium thermal expansion coefficient. The thermal and setting expansion were measured for 3 phosphate bonded investments: Rematitan Plus (RP) specific for titanium, Rema Exakt (RE), and Castorit Super C (CA), using different special liquid concentrations (100%, 75%, and 50%). Setting expansion was measured for cylindrical specimens 50 mm long x 8 mm in diameter with a transducer. The heating and cooling curves were obtained with a dilatometer (DIL 402 PC). The total expansion curve was drawn using software, and temperatures to obtain expansion equivalent to titanium casting shrinkage were determined (n=5). In addition, the total expansion of the control group (RP at 430 degrees C) was measured, as well as the temperatures at which the other groups achieved equivalent total expansion (n=5). Data were analyzed by 1-way ANOVA and the Tukey HSD test (alpha=.05)., Results: Titanium casting shrinkage was estimated as 1.55%. RP did not achieve this expansion. RE achieved expansion of 1.55% only with a special liquid concentration of 100% at 594 degrees C. CA with all special liquid concentrations attained this expansion (351 degrees C to 572 degrees C). Total expansion of the control group was 0.86%, and the other groups reached that expansion within the range of 70 degrees C to 360 degrees C., Conclusions: Only RE and CA demonstrated sufficient expansion to compensate for titanium casting shrinkage. All groups reached total expansion equivalent to that of the control group at significantly lower temperatures.

The aim of the work was to evaluate the influence of the temperature of investment healting on the tensile strength and Vickers hardness of CP Ti and Ti-6Al-4V alloy casting. Were obtained for the tensile strength test dumbbell rods that were invested in the Rematitan Plus investment and casting in the Discovery machine cast. Thirty specimens were obtained, fifteen to the CP Titanium and fifteen to the Ti-6Al-4V alloy, five samples to each an of the three temperatures of investment: 430 degrees C (control group), 480 degrees C and 530 degrees C. The tensile test was measured by means of a universal testing machine, MTS model 810, at a strain of 1.0 mm/min. After the tensile strength test the specimens were sectioned, embedded and polished to hardness measurements, using a Vickers tester, Micromet 2100. The means values to tensile tests to the temperatures 430 degrees C, 480 and 530: CP Ti (486.1 - 501.16 - 498.14 -mean 495.30 MPa) and Ti-6Al-4V alloy (961.33 - 958.26 - 1005.80 - mean 975.13 MPa) while for the Vickers hardness the values were (198.06, 197.85, 202.58 - mean 199.50) and (352.95, 339.36, 344.76 - mean 345.69), respectively. The values were submitted to Analysis of Variance (ANOVA) and Tukey Test that indicate differences significant only between the materials, but not between the temperature, for both the materials. It was concluded that increase of the temperature of investment its not chance the tensile strength and the Vickers hardness of the CP Titanium and Ti-6Al-4V alloy.

Objective: The aim of this study was to evaluate the castability of CP titanium and Ti-6Al-4V alloy castings into Rematitan Plus investment at three different mold temperatures., Methods: A nylon mesh pattern (20 mm with 64 squares and wire of 0.7 mm in diameter) was used for the castability testing. Initially, an image of the wax pattern was obtained by means of a digital camera and the total extension of filaments (mm) was then measured, using the Leica Qwin image analysis system. The mesh sprued was placed in the Rematitan Plus investment material and the castings were made in a Discovery Plasma machine at three different mold temperatures: 430 degrees C (control group), 480 degrees C or 530 degrees C. Ten castings were made for each temperature. The images of the castings were analyzed (Leica Qwin) and the castability index determined by the number of the completely cast segments as a percentage of the wax pattern. Data were analyzed by two-way ANOVA and Tukey's multiple comparison test (a = 0.05) using materials and temperatures as discriminating variables., Results: The Ti-6Al-4V alloy (60.86%) presented a better castability index than CP Ti (48.44%) (p < 0.000001). For CP Ti, the temperature of 530 degrees C (23.96%) presented better castability than at other temperatures, 480 degrees C (14.66%) and 430 degrees C (12.54%), with no difference between them (p < 0.001). For Ti-6Al-4V alloy, there was a statistically significant difference among the three temperatures: 530 degrees C (28.36%) > 480 degrees C (19.66%) > 430 degrees C (15.97%) (p < 0.002)., Significance: Within the limitations of this study, the increase in the mold temperature of the Rematitan Plus investment resulted in a better castability index for both materials, and Ti-6Al-4V presented a better castability index than CP Ti.

Statement of Problem: When clinical fractures of the ceramic veneer on metal-ceramic prostheses can be repaired, the need for remake may be eliminated or postponed. Many different ceramic repair materials are available, and bond strength data are necessary for predicting the success of a given repair system., Purpose: This study evaluated the shear bond strength of different repair systems for metal-ceramic restorations applied on metal and porcelain., Material and Methods: Fifty cylindrical specimens (9 x 3 mm) were fabricated in a nickel-chromium alloy (Vera Bond II) and 50 in feldspathic porcelain (Noritake). Metal (M) and porcelain (P) specimens were embedded in a polyvinyl chloride (PVC) ring and received 1 of the following bonding and resin composite repair systems (n=10): Clearfil SE Bond/Clearfil AP-X (CL), Bistite II DC/Palfique (BT), CoJet Sand/Z100 (CJ), Scotchbond Multipurpose Plus/Z100 (SB) (control group), or CoJet Sand plus Scotchbond Multipurpose Plus/Z100 (CJSB). The specimens were stored in distilled water for 24 hours at 37 degrees C, thermal cycled (1000 cycles at 5 degrees C to 55 degrees C), and stored at 37 degrees C for 8 days. Shear bond tests between the metal or ceramic specimens and repair systems were performed in a mechanical testing machine with a crosshead speed of 0.5 mm/min. Mean shear bond strength values (MPa) were submitted to 1-way ANOVA and Tukey honestly significant difference tests (alpha=.05). Each specimen was examined under a stereoscopic lens with x30 magnification, and mode of failure was classified as adhesive, cohesive, or a combination., Results: On metal, the mean shear bond strength values for the groups were as follows: MCL, 18.40 +/- 2.88(b); MBT, 8.57 +/- 1.00(d); MCJ, 25.24 +/- 3.46(a); MSB, 16.26 +/- 3.09(bc); and MCJSB, 13.11 +/- 1.24(c). On porcelain, the mean shear bond strength values of each group were as follows: PCL, 16.91 +/- 2.22(b); PBT, 18.04 +/- 3.23(ab); PCJ, 19.54 +/- 3.77(ab); PSB, 21.05 +/- 3.22(a); and PCJSB, 16.18 +/- 1.71(b). Within each substrate, identical superscript letters denote no significant differences among groups., Conclusions: The bond strength for the metal substrate was significantly higher using the CJ system. For porcelain, SB, CJ, and BT systems showed the highest shear bond strength values, and only SB was significantly different compared to CL and CJSB (P<.05)., Clinical Implications: This study suggests that when fracture involves only feldspathic porcelain, any of the evaluated systems may be used, since the fracture occurred on the porcelain substrate and not on the bond interface of porcelain-restorative material. However, for the nickel-chromium alloy tested, the CoJet Sand system showed the best results for repair.

The purpose of this study was to evaluate the effect of heat treatments on the Vickers hardness of commercially pure titanium and Ti-6Al-4V cast alloys. Six-millimeter-diameter cylindrical specimens were cast in a Rematitan System. Commercially pure titanium and Ti-6Al-4V alloy specimens were randomly assigned to 3 groups (n=10) that received the following heat treatments: control (no heat treatment); treatment 1 (T1): heating at 750 degrees C for 2 h; and treatment 2 (T2): annealing at 955 degrees C for 1 h and aging at 620 degrees C for 2 h. After heat treatments, the specimens were embedded in acrylic resin and their surface was ground and polished and hardness was measured. Vickers hardness means (VHN) and standard deviations were analyzed statistically by Kruskal-Wallis test at 5% significance level. For commercially pure titanium, Vickers hardness means of group T2 (259.90 VHN) was significantly higher than those of the other groups (control--200.26 VHN and T1--202.23 VHN), which presented similar hardness means to each other (p>0.05). For Ti-6Al-4V alloy, statistically significant differences were observed among the three groups: T2 (369.08 VHN), T1 (351.94 VHN) and control (340.51 VHN) (p<0.05). The results demonstrated different hardness of CP Ti and Ti-6Al-4V when different heat treatments were used. For CP Ti, VHN means of T2 group was remarkably higher than those of control and T1 group, which showed similar VHN means to each other. For Ti-6Al-4V alloy, however, VHN means recorded for each group may be presented as follows: T2>T1>control.

The purpose of this study was to compare the compressive strengths and compressive fatigue limits of three posterior composite resins (Filtek P-60, Surefil and Prodigy Condensable) and a universal restorative composite (Z-100). Cylindrical specimens (8 mm in length x 4 mm in diameter) were used. The dynamic test was performed using the staircase method, and the ratio between compressive fatigue limit and compressive resistance was also calculated (n = 15). The compressive strength and compressive fatigue limit data were analyzed by Anova and Tukeys test. The Z-100 composite demonstrated higher compression strength (307.20 MPa) than Surefil (266.93 MPa) and Prodigy Condensable (222.08 MPa). The resistance of Filtek P-60 (270.44 MPa) was similar to the resistances of Z-100 and Surefil, while Prodigy Condensable presented the lowest compressive strength. In the compressive fatigue limit tests, Filtek P-60 demonstrated a higher value (184.20 MPa) than Prodigy Condensable (155.50 MPa). Surefil (165.74 MPa) and Z-100 (161.22 MPa) presented limits similar to those of Filtek P-60 and Prodigy Condensable. The compressive fatigue limit/compressive strength ratio was 70.01% for Prodigy Condensable, 68.11% for Filtek P-60, 62.09% for Surefil and 52.48% for Z-100. It was concluded that the Z-100 universal composite was more sensitive to the dynamic test than the high viscosity materials.

In metallic restorations, the polymerization of dual-curing resin cements depends exclusively on chemical activation. The effect of the lack of photoactivation on the strength of these cements has been rarely studied. This study evaluated the influence of activation modes on the diametral tensile strength (DTS) of dual-curing resin cements. Base and catalyst pastes of Panavia F, Variolink II, Scotchbond Resin Cement, Rely X and Enforce were mixed and inserted into cylindrical metal moulds (4 x 2 mm). Cements were either: 1) not exposed to light (chemical activation = self-cured groups) or 2) photoactivated through mylar strips (chemical and photo-activation = dual-cured groups) (n = 10). After a 24 h storage in 37 masculineC distilled water, specimens were subjected to compressive load in a testing machine. A self-curing resin cement (Cement-It) and a zinc phosphate cement served as controls. Comparative analyses were performed: 1) between the activation modes for each dual-curing resin cement, using Students t test; 2) among the self-cured groups of the dual-curing resin cements and the control groups, using one-way ANOVA and Tukeys test (alpha = 0.05). The dual-cured groups of Scotchbond Resin Cement (53.3 MPa), Variolink II (48.4 MPa) and Rely X (51.6 MPa) showed higher DTS than that of self-cured groups (44.6, 40.4 and 44.5 MPa respectively) (p < 0.05). For Enforce (48.5 and 47.8 MPa) and Panavia F (44.0 and 43.3 MPa), no significant difference was found between the activation modes (p > 0.05). The self-cured groups of all the dual-curing resin cements presented statistically the same DTS as that of Cement-It (44.1 MPa) (p > 0.05), and higher DTS than that of zinc phosphate (4.2 MPa). Scotchbond Resin Cement, Variolink II and Rely X depended on photoactivation to achieve maximum DTS. In the absence of light, all the dual-curing resin cements presented higher DTS than that of zinc phosphate and statistically the same as that of Cement-It (p > 0.05).

Heating titanium structures is assumed to relieve tensions induced by the casting process as well as possibly optimizing some mechanical properties. The aim of this investigation was to evaluate the effect of thermal treatments on tensile strength of commercially pure titanium (CP Ti) and Ti-6Al-4V alloy. Thirty dumbbell rods, with diameters of 3.0 mm at the central segment and lengths of 42 mm, were cast for each metal using the Rematitan System. CP Ti and Ti-6Al-4V specimens were randomly divided into three groups of ten: a control group that received no thermal treatment and two test groups. One (T1) was heated at 750 degrees C for 2 h and the other (T2) was annealed at 955 degrees C for 1 h and aged at 620 degrees C for 2 h. Tensile strength was measured with a universal testing machine (MTS model 810). Tensile strength means and standard deviations were statistically compared using a Kruskal-Wallis test at a alpha=0.05 significance level. No statistically significant differences in tensile strength were observed among CP Ti groups. For the Ti-6Al-4V alloy, the control and T1 groups revealed statistically higher tensile strengths when compared to the T2 group, with no significant difference between the control and T1 groups.

Purpose: The objective of this study was to verify the effect of cyclic compressive loading on the shear bond strength of an adhesive system following collagen removal., Materials and Methods: Sixty bovine teeth were divided into 4 groups based on the adhesive procedure used: groups 1 and 2--etching with 35% phosphoric acid and application of the Single Bond adhesive system; groups 3 and 4--after etching, a 10% sodium hypochlorite solution was applied for 1 min before the application of the adhesive. In all the specimens, a Z100 resin cylinder was built up over the bond area. Groups 2 and 4 were submitted to 500,000 cycles with a load of 100 N., Results: The mean values for the shear bond test (MPa) were: group 1: 7.37 +/- 1.15; group 2: 5.72 +/- 1.66; group 3: 5.95 +/- 1.21; group 4: 3.66 +/- 1.12. There was no difference between groups 1 and 2 (p > 0.01). Between groups 1 and 3, 2 and 4, and 3 and 4 there was a significant difference (p < 0.01). The majority of the specimens demonstrated an adhesive failure., Conclusion: The application of sodium hypochlorite on dentin decreased the values of shear bond strength, as did the load cycling in the group treated with sodium hypochlorite.

The limitation of photoactivation of dual-polymerized resin cements along the margins of metal restorations may adversely affect the mechanical properties of these cements, thus impairing the retention of restorations. The aim of this study was to assess the bond strength of cast metal crowns cemented with three dual-polymerized resin cements, using a chemically-activated resin cement and zinc phosphate as controls. Fifty nickel-chromium alloy crowns were cast and randomly assigned to five groups of equal size. Castings were cemented on their corresponding metal dies with one of the tested luting agents: Scotchbond Resin Cement, Enforce and Panavia F (dual-polymerized resin cements), Cement-It (chemically-activated resin cement) and Zinc Phosphate Cement (zinc phosphate cement). Specimens were stored in distilled water at 37 degrees C for 24 h and then loaded in tension until failure. Panavia F and Zinc Phosphate Cement provided the highest and lowest bond strength means, respectively. Scotchbond Resin Cement, Enforce and Cement-It cements exhibited similar intermediate values, but with statistically significant difference compared to the other materials (P < 0.05). Even with the restriction or absence of light activation, all tested dual-polymerized resin cements produced significantly higher bond strength than did the zinc phosphate cement and yielded similar or better results than the chemically activated cement. It should be pointed out that the findings of this study relate to a test scenario which does not mimic clinical circumstances and that further work is required to identify the clinical significance of the reported tensile bond strength differences between the different luting materials.

During the cementation of metallic restorations, the polymerization of dual-curing resin cements depends exclusively on chemical activation. This study evaluated the influence of chemical activation compared with dual-curing (chemical and light activation), on the hardness of four dual-curing resin cements. In a darkened environment, equal weight proportions of base and catalyst pastes of the cements Scotchbond Resin Cement, Variolink II, Enforce and Panavia F were mixed and inserted into moulds with cavities of 4 mm in diameter and 2 mm in height. Subsequently, the cements were: 1) not exposed to light (chemical activation = self-cured groups) or 2) photoactivated (dual-curing = dual-cured groups). The Vickers hardness number was measured at 1 hour, 24 hours and 7 days after the start time of cements' spatulation. For all the cements, the hardness values of self-cured groups were lower than those of the respective dual-cured groups at 1 hour and 24 hours. At 7 days, this behavior continued for Variolink II and Panavia F, whilst for Scotchbond Resin Cement and Enforce there was no statistical difference between the two activation modes. All cements showed a significant increase in their hardness values from 1 hour to 7 days for both activation modes. Of the self-cured groups, Scotchbond Resin Cement and Variolink II presented the highest and the lowest hardness values, respectively, for all three times tested. Within the limitations of this study, up to the time of 24 h, chemical activation alone was unable to promote similar hardness as to that obtained with dual-curing.

Objective: To evaluate the content of inorganic particles and the flexural strength of new condensable composites for posterior teeth in comparison to hybrid conventional composites., Method: The determination of the content of inorganic particles was performed by mass weighing of a polymerized composite before and after the elimination of the organic phase. The volumetric particle content was determined by a practical method based on Archimedes' principle, which calculates the volume of the composite and their particles by differential mass measured in the air and in water. The flexural strength of three points was evaluated according to the norm ISO 4049:1988., Results: The results showed the following filler content: Alert, 67.26%; Z-100, 65.27%; Filtek P 60, 62.34%; Ariston pHc, 64.07%; Tetric Ceram, 57.22%; Definite, 54.42%; Solitaire, 47.76%. In the flexural strength test, the materials presented the following decreasing order of resistance: Filtek P 60 (170.02 MPa)>Z-100 (151.34 MPa)>Tetric Ceram (126.14 MPa)=Alert (124.89 MPa)>Ariston pHc (102.00 MPa)=Definite (93.63 MPa)>Solitaire (56.71 MPa)., Conclusion: New condensable composites for posterior teeth present a concentration of inorganic particles similar to those of hybrid composites but do not necessarily present higher flexural strength.

Statement of Problem: Difficulties in sterilizing impressions by traditional methods have led to chemical disinfection as an alternative, and some studies have shown that disinfectants may adversely affect impressions., Purpose: This study investigated the effect of disinfection methods on the dimensional stability of 6 elastomeric materials., Material and Methods: Impression materials were submitted to the following treatments: immersion in 5.25% sodium hypochlorite solution for 10 minutes, immersion in 2% glutaraldehyde solution for 30 minutes, and no immersion (control). After treatments, impressions were poured, and respective stone casts were measured with a Nikon Profile projector and compared with the master model., Results: The elastomeric materials had different reproduction capacities, and the disinfecting treatments did not differ from the control.

They were casted pieces using three kinds of alloy (Ni-Cr, Ag-Sn and Cu-Al) with circular and smooth surface. They were cemented to human teeth, on occlusal surface, grounded at dentin level, through three different materials kind (zinc polycarboxylate cement, glassionomer cement and composite). After 24 hours storing, the samples were subjected to the tensile test. The results showed that the samples cemented with composite and the casts made with Ag-Sn alloy had higher bond strength.

It was verified the penetration of phosphoric acid into 3 commercial calcium hydroxide-based cements (Life, Renew and Prisma VLC Dycal). The colorimetric method employed permitted the identidication of phosphorus amount in representative samples of 6 successive layers 0.1 mm thick of each material. The acid etching used were the commercial products Scotchbond Etching Gel--3M at 36.114% by weight and Solução Condicionadora--Johnson & Johnson at 36.054% by weight. The contact time was 60 seconds. The result showed that layers 0.1 mm tick for Life and Prisma VLC Dycal and 0.2 mm thick for Renew were able to block the penetration of phosphoric acid solution whereas layers 0.1 mm thick for the 3 cements were able to block the penetration of phosphoric acid gel.