Search

The purpose of this study is to verify whether the spectrophotometer makes similar color readings when subjected to the use of biosafety barriers. Eighty specimens were made in four colors of the Llis composite resin (EA1, DA1, EA3, DA3) and four of the Filtek Z350 XT (A1E, A1D, A3E e A3D) (n = 10). The specimens were subjected to color analysis with a VITA Easyshade device according to the groups regarding the physical barrier: the protector supplied with the VITA device, polyvinyl chloride plastic film, high-density polyethylene bag, and without protection as a control. The color difference (Delta E-00) between control and groups was evaluated and compared with the perceptibility and acceptability thresholds. In the Filtek Z350 XT, there was a significant Delta E-00 in color A3E, in the polyethylene bag (P < .001), and in color A1D, in the supplied protector (P = .01) in relation to the other groups. For Llis, in color EA1 for all protective barriers (P = .014), and in color DA1 only for polyethylene bag in relation to the other barriers (P = .02). Delta E-00 was higher than the perceptible threshold for all groups, colors, and brands. The results below the threshold of acceptability in relation to the Delta E-00 did not demonstrate consistency between barriers, colors, and resins. It was not possible to identify a statistically significant pattern of Delta E-00 between the barriers. The Delta E-00 were above the perceptibility threshold, and few were below the acceptability threshold. It was not possible to suggest that one biosafety barrier was superior to another or could be indicated.

Reasons for failures of bilayer yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) restorations include the core-veneer interface bond strength. The influence of the veneering method on the bond strength of veneered Y-TZP is unclear.The purpose of this systematic review and meta-analysis was to evaluate the effect of the veneering method on the bond strength of bilayer Y-TZP.This review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Searches were performed on PubMed/MEDLINE, Web of Science (Core Collection), and Scopus for in vitro studies evaluating the effect of the veneering technique on the bond strength of bilayer Y-TZP. Statistical analyses were performed with random-effect models (α=.05).From 619 identified studies, 140 were selected for full-text analysis and 16 were included. Manual searching yielded no additional articles. The meta-analyses comprised 15 studies, and 1 study was included only in the descriptive analysis. Meta-analyses compared the hand-layered method (control) with pressed, fused, and cemented veneering methods. The fused and cemented techniques were analyzed by using subgroups assessing the veneering ceramic type (predominantly glass-ceramics and particle-filled glass-ceramics). Similar bond strength results (P=.540) were found for pressed and hand-layered veneered Y-TZP specimens. Fused veneers achieved higher bond strength values (P.001) than the hand-layered veneers on Y-TZP frameworks, irrespective of the veneering ceramic type (predominantly glass-ceramics: P=.002; particle-filled glass-ceramics: P.001). Global and subgroup analyses indicated that lower core-veneer bond strength values (P.001) were found for cemented in relation to hand-layered veneers.Core-veneer interfacial adhesion was equivalent for pressed and hand-layered veneering techniques. Improved bond strength, regardless of the veneer ceramic material type, was achieved by the fused veneering method, which seems to be a promising choice for the veneering of Y-TZP. In contrast, the cemented method may be unsuitable for veneering Y-TZP structures because of its lower bond strength than the hand-layered veneering technique.

SUMMARY Purpose: To investigate the influence of ferrule thickness on fracture resistance after mechanical cycling of teeth restored with different intracanal posts. Methods and Materials: One hundred twenty bovine incisor teeth were randomized into six study groups, based on the intracanal post used (fiber post or cast post and core) and the presence and thickness of a ferrule (without ferrule, presence of 0.5-mm or 1-mm-thick ferrule, retaining unaltered 2-mm ferrule height). The root posts and the metal crowns were cemented using an adhesive cement. The samples were subjected to mechanical cycling (at 37°C, 45°, 130 N, 2.2 Hz, and 2 × 106 pulses). Afterward, they were subjected to a fracture load test at a speed of 0.5 mm/min and on a 45° slope until failure occurred. The failures were classified as favorable or unfavorable. The fracture resistance data were analyzed with two-way analysis of variance and Tukey test. The chi-square test was used to analyze the pattern of failure. Results: When considering the cast post and core, the 1-mm ferrule thickness group presented a higher resistance to fracture than did the group in which a ferrule was not used (p=0.001). When using a glass fiber post, the groups showed no differences in fracture resistance. Overall, 96.7% of the specimens survived the mechanical cycling. Of the fractures, 58.6% of the fractures were unfavorable, while 41.6% were favorable. Conclusions: A thicker ferrule statistically increased the fracture resistance only for cast post and core when it was at least 1 mm thick, despite causing more unfavorable failures. Thus, ferrule thickness should be considered when choosing different intracanal posts, to reduce the occurrence of unfavorable failures. In the absence of a ferrule, the use of a cast post and core presents more favorable failures, and in the presence of a 1-mm-thick ferrule, the use of a glass fiber post seems to be the best clinical decision.

Aim: To evaluate the retention of an endodontic titanium post with a spherical head for removable partial denture or overdenture attachment according to surface treatment type. Methods: Sixty healthy single-rooted teeth, sectioned at the enamel/cementum junction, were treated endodontically and steadily fixed in the embedding acrylic resin. The titanium posts were subdivided into four groups: control, no surface treatment (Ctrl); posts with macro-retentive grooves (MR); air abrasion of the post surface (AB); and posts with macro-retentive grooves and air abrasion of the post surface (MR+AB). The posts were luted in the root canal using self-adhesive dual resin cement. Pull-out testing was performed using a universal testing machine until complete detachment was achieved. After pull-out testing, the metallic posts were examined under an optical microscope and the failures were classified based on the cement distribution pattern on the extracted posts: 0, no cement left on the post (cement/post failure); 1, post surface partially covered by adhered cement (post/cement and dentin/cement mixed failure); 2, post surface completely covered by cement (dentin/cement failure). The retention data were analyzed by one-way ANOVA, Bonferroni–Dunn test (p

Temporomandibular myofascial pain presents a major challenge in the diagnosis of temporomandibular disorders (TMD). Due to the characteristics of this condition, intramuscular injection procedures are often needed for adequate control of symptoms and treatment. Thus, the aim of this systematic review was to evaluate the effectiveness of dry needling and injection with different substances in temporomandibular myofascial pain. Electronic databases PubMed, EMBASE, CENTRAL/Cochrane, Lilacs, Scopus, Web of Science and CAPES Catalog of Dissertations and Theses were searched for randomized clinical trials until January 2018. Manual search was performed in relevant journals and in the references/citations of the included studies. The selection of studies was carried out by two independent reviewers according to eligibility criteria. From 7128 eligible studies, 137 were selected for full-text analysis and 18 were included. Due to the heterogeneity of the primary studies it was not possible to perform a meta-analysis. The narrative analysis of the results showed that most of the studies had methodological limitations and biases that compromised the quality of the findings. Dry needling and local anaesthesic injections seem promising, but there is a need to conduct further randomized clinical trials, with larger samples and longer follow-up times, to evaluate the real effectiveness of the technique and evaluated substances.

Objective: To evaluate the bond strength of different repair treatments for composite resin to aged Y-TZP ceramics. Material and Methods: Zirconia blocks were cut into smaller specimens, sintered according to manufacturer’s recommendations (final dimensions of 4×4×3 mm), and randomly allocated into nine groups (n=15) according to the surface treatment and presence/absence of aging of the substrate (subjected to low-temperature degradation - LTD), as follows: without LTD (Control: without treatment; TBS: tribochemical silica coating + silane + adhesive); with LTD (Control-LTD: without treatment; TBS-LTD: TBS with hydrothermal degradation; MoS-LTD: Monobond S + adhesive; MoP-LTD: Monobond Plus + adhesive; MZP-LTD: Metal/Zirconia Primer + adhesive; USB-LTD: Single Bond Universal; AP-LTD: Alloy primer + adhesive). LTD was simulated in an autoclave (134 °C, 2 bar, 5 h). The ceramic blocks were embedded in PVC cylinders with a self-curing acrylic resin; each surface treatment protocol was performed; a composite resin cylinder (Æ: 3.25 mm and height: 3 mm) was then build-up using split metallic matrices. All the specimens were aged (thermocycling + storage in water for 90 days) and subjected to the shear bond strength test using a universal testing machine (1 mm/min). The failure mode was classified into four types: adhesive, composite resin cohesive fracture, ceramic cohesive fracture, and mixed. The bond strength values were subjected to Mann–Whitney test. Results: Only air-abraded samples (TBS and TBS–LTD) survived thermocycling. More than 80% of the samples of the other groups presented pre-test failures. TBS groups presented higher values of bond strength (3.94) compared to TBS-LTD (0.96). The predominant type of failure for the surviving samples were adhesive. Conclusion: Air particle abrasion is mandatory to improve the bond strength of the Y-TZP substrate; an aged substrate presents an even more unfavorable scenario for adhesion.Keywords Dental prosthesis repair; Hydrothermal degradation; Zirconia; Shear bond strength; Sandblasting.

Purpose To evaluate the influence of specimen configuration, bonding area and zirconia surface treatment on the push out bond strength to Y-TZP and on the stress distribution using finite element analysis (FEA). Materials and methods 240 Y-TZP blocks with a central perforation were assigned to 8 groups (n=30) according to the adhesive area (macro-test: 5 × 5.5 × 4 mm and micro-test: 5 × 5.5 × 1 mm), material inserted in the perforation (resin cement or composite resin) and surface treatment (silanization or tribochemical silica coating+silanization). Push-out bond strength test, failure modes evaluation and FEA were performed. Results Three-way ANOVA showed that bond strength was statistically higher for composite resin (p=0.00) and for macro specimens (p=0.00). Surface treatment significantly increased the adhesion, except for ‘resin cement macro-test’ (p=0.00). Finite element analysis showed that the stresses were more homogeneously distributed at the interface of micro-specimens. Conclusion Macro-push out with composite resin or cement does not appear to be promising when evaluating adhesion to zirconia ceramics; micro-push out with composite resin filler is an adequate method; the tribochemical silica coating surface treatment can be evaluated by all tested methods in the current study, except for the macro-test with resin cement condition.

Made available in DSpace on 2020-12-12T01:28:39Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-10-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul This study evaluated the influence of occlusal resin cement space on the fatigue performance of bonded-leucite crowns to a dentin-analogue material. Leucite anatomical crowns were adhesively cemented to dentin-like preparations having distinct occlusal cement space (50, 100 and 300 μm) (n = 18), and subjected to step-stress fatigue testing (150 N – 350 N; step-size: 25 N; 20,000 cycles/step; 20 Hz). Fatigue data (load and number of cycles for failure) were analyzed using Kaplan–Meier and Mantel–Cox (log-rank) tests (p

Aim: This study evaluated the fracture load and pattern failure of different prefabricated glass fiber posts (GFPs) of the same diameter. Methods: Seventy-eight (n=13 for six groups) GFPs of 1.6 mm coronal diameter of different brands were evaluated— Exacto (Angelus), Power Post (BM4), White Post DC (FGM), HiRem (Overfibers), MAQ (Maquira), and SD (Supordont). The posts were subjected to fracture load testing (45° of inclination and 1 mm/min until fracture). Each factor (load (N) and shear stress (MPa)) was analyzed separately using one-way ANOVA followed by the Tukey test (α=0.05). Results: The type of failure was evaluated on a stereomicroscope (×10). The Power Post samples presented higher values of fracture load (p

The present study analyzed the fatigue performance of prefabricated fiber reinforced composite posts (FRC post) with different diameters by means of two different fatigue testing methods. A total of 69 FRC double-tapered posts, presenting 20 mm in length associated with different coronal diameters (1.4, 1.6, 2.0 mm) were embedded with acrylic resin in PVC cylinders, maintaining 6 mm free from the coronal part of the post. The posts of each diameter were submitted to step stress testing (inclination: 45°; initial load: 20 N; step-size: 10 N; cycles per step: 18,000; frequency: 5 Hz) (n = 5) or staircase testing (inclination: 45°; initial load: 60% of the monotonic load-to-fracture reported on existing literature; increment: 10% of the monotonic load-to-fracture reported on existing literature; cycles: 18,000; frequency: 5 Hz) (n = 18). The statistical differences were determined for Kaplan-Meier and Mantel-Cox (Log-Rank) tests for step stress testing and based on confidence interval overlapping for staircase testing. All the failures were analyzed in a stereomicroscope (10 × magnification) after the tests, and representative samples were analyzed by scanning electron microscope (500 × and 1000 × magnification). The FRC post with the wider diameter had greater fatigue failure load in step stress testing (DT1.4–56 N

The aim of this study was to evaluate if acid etching prior to application of different universal adhesives influences the bond strength of the glass fiber post to root dentin. One hundred and twenty (120) bovine-tooth roots were prepared to receive glass fiber posts #3 (White Post, FGM) and then divided into 12 groups (n = 10) according to two factors: the adhesive system (Single Bond Universal, Ambar Universal, Prime & Bond Universal, Gluma Bond Universal, YBond Universal or Ambar Universal APS); and acid etching prior to application of the adhesive (presence or absence). After cementation, the specimens were stored in a humid environment at 37 °C for 24 h. Each sample was sectioned into 5 slices with 1.5 ± 0.2 mm thickness and subjected to a pushout test with an increasing load of 1 mm/min in a universal testing machine until failure and the data were analyzed using two-way ANOVA and post-hoc Tukey's tests. There was no statistical difference in the bond strength values for the acid etching factor. There were only differences for the adhesive system factor. Higher bond strength values were found for the Universal Single Bond adhesive (3 M) regardless of acid etching or not, and for Gluma Bond Universal adhesive without acid etching. It was possible to conclude that acid etching prior to applying the universal adhesives used in this study does not influence the bond strength of glass fiber posts to root dentin.

It evaluated the effects of different zirconia surface treatments on the bond strength of a resin cement to Y-TZP (yttria-stabilized tetragonal zirconia) ceramics, as well as their phase-transformations. 75 blocks (5 mm × 5 mm × 4 mm) of Y-TZP were assigned into five groups (n = 15): (tribochemical silica coating - TBS) zirconia surface was abraded by silica coated alumina particles followed by silanization; (GLZ1) zirconia surface received the application of a thin layer of low-fusing porcelain glaze, followed by hydrofluoric acid (HF) etching for 1 min; (GLZ5) glaze application + HF etching by 5 min; (GLZ10) glaze application + HF etching by 10 min; (GLZ15) glaze application + HF etching by 15 min. After etching, all the specimens were washed, dried and silanized. Cylinders of composites (diameter: 3.25 mm; height: 3 mm) were cemented to the Y-TZP blocks using a resin cement. All the specimens were subjected to aging (10,000 thermal cycles and 90 days storage), tested under shear conditions, and...

Made available in DSpace on 2019-10-06T15:56:59Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-02-01 Statement of problem: Studies that evaluate the survival rate and load to fracture of premolars restored with inlays produced using different methods are lacking. Purpose: The purpose of this in vitro study was to compare the survival rate and fracture load of premolars restored with inlays fabricated using different methods. Material and methods: Thirty maxillary premolars were selected, embedded, and prepared to receive inlays fabricated using different methods (n=10): LaCom-digital scanning with Lava C.O.S. scanner (3M ESPE), followed by milling of composite resin block (Lava Ultimate; 3M ESPE) in a milling unit; CeCom-digital scanning with Cerec 3D Bluecam scanner (Dentsply Sirona), followed by milling of a Lava Ultimate block in Cerec (Dentsply Sirona); PresDis-impression with polyvinyl siloxane, inlay made using the lost wax technique, and IPS e.max Press (Ivoclar Vivadent AG) pressed ceramic (lithium disilicate). A dual-polymerizing resin cement system was used to lute the inlays. Inlays were mechanically cycled (2 Hz, 106 mechanical pulses, 80 N) after 24 hours, and the specimens were stored in distilled water at 37°C for 11 months. Then, a fatigue test was conducted using a 10-Hz frequency and 400-N load on the inner inclines of the cusps. The test was complete when the specimen fractured or when the specimen reached 1.5×106 cycles. The specimens that survived fatigue testing were submitted to a single-load fracture test in a universal testing machine and analyzed using a stereoscope for failure classification. Survival rates were estimated using the Kaplan-Meier method and log-rank test (Mantel-Cox). Fracture load data were analyzed using 1-way ANOVA (α=.05). Results: No significant differences were detected among the groups for the survival rate (P=.87) or for the load to fracture (P=.78). Most failures were longitudinal, catastrophic fractures. Conclusions: Premolars restored with inlays fabricated using the tested methods had similar survival rates and loads to fracture. Adjunct Professor Prosthodontics Unit Faculty of Odontology Federal University of Santa Maria (UFSM) Assistant Professor and Researcher Department of Biomedical Sciences and Neuromotor Division of Prosthodontics Alma Mater Studiorum University of Bologna Graduate student Prosthodontics Unit Faculty of Odontology Federal University of Santa Maria (UFSM) Adjunct Professor Prosthodontics Unit Faculty of Odontology Franciscan University Center Master student Department of Biomedical Sciences and Neuromotor Division of Prosthodontics Alma Mater Studiorum University of Bologna Professor Department of Biomedical Sciences and Neuromotor Division of Prosthodontics Alma Mater Studiorum University of Bologna Professor Dental Materials and Prosthodontics Unit São Paulo State University (UNESP) São José dos Campos Associate Professor Prosthodontics Unit Faculty of Odontology Federal University of Santa Maria (UFSM) Professor Dental Materials and Prosthodontics Unit São Paulo State University (UNESP) São José dos Campos

To compare the effect of different surface treatments (pre-treatments and bonding agents) on the bond strength between glass-fiber post and composite resin, and the topographic alterations of the treated post surface.Thirty-six glass-fiber blocks (12mm×10mm×8mm) were specifically manufactured for this study and randomly assigned into 12 groups considering two factors: 'pre-treatments' (-cleaning with 70% alcohol; air-abrasion with silica-coated aluminum oxide particles; 35% hydrogen peroxide) and type of 'bonding agent' (no bonding agent; application of Monobond Plus; RelyX Ceramic Primer; Single Bond Universal). After that, 6 cylindrical templates (1mm high×1mm Ø) were fixed on each block, filled with composite resin (n=18) and light-cured. Specimens were stored under 37°C for 24h and microshear tests (wire loop Ø=0.2mm) were performed. Topographic, roughness and failure analyses were also performed.Different surface pre-treatments led to different topographic and roughness alterations; a higher surface alteration was noted after silica particles air-abrasion, while a slight surface alteration in the hydrogen peroxide group and a smooth pattern were observed in the cleaning group. The factors 'pre-treatments' (p0.05), 'bonding agent' (p0.05) and their interaction (p0.05) influenced the bond strength. Silica coating, apart from bonding agent application, or Single Bond Universal application without pre-treatment promoted the highest bond values. The main failure type was adhesive at the resin-post interface.In terms of pre-treatments, silica coating promotes the best bonding performance, but pre-treatments can be dispensable when applying Single Bond Universal.

Aim: To evaluate the retention of Y-TZP crowns cemented in aged composite cores ground with burs of different grit sizes. Methods: Sixty composite resin simplified full-crown preparations were scanned, while 60 Y-TZP crowns with occlusal retentions were milled. The composite preparations were stored for 120 days (wet environment-37°C) and randomly distributed into three groups (n=20) according to the type of composite core surface treatment. The groups were defined as: CTRL (control: No treatment), EFB (extra-fine diamond bur [25μm]), and CB (coarse diamond bur [107μm]). The grinding was performed with an adapted surveyor standardizing the speed and pressure of the grinding. The intaglio surfaces on the crowns were air-abraded with silica-coated alumina particles (30 μm) and then a silane was applied. The crowns were cemented with self-adhesive resin cement, thermocycled (12,000 cycles; 5/55°C), stored (120 days) and submitted to aretention test (0.5mm/min). The retentive strength data (MPa) were analyzed using one-way analysis of variance and Tukey test, as well as Weibull analysis. Failures were classified as 50C (above 50% of cement in the crown), 50S (above 50% of cement in the substrate) and COE (composite core cohesive failure). Results: No statistical difference was observed among the retention values (p=0.975). However, a higher Weibull modulus was observed in the CTRL group. The predominant type of failure was 50S (above 50% of cement in the substrate composite). Conclusion: The retention of zirconia crowns was not affected by grinding using diamond burs with different grit sizes (coarse/extra-fine) or when no grinding was performed.

Objective To evaluate the effect of restorative strategy (fiber post vs cast post and core), coronal height (0 mm vs 2 mm) and thickness (higher than 1 mm vs lower than 1 mm) on survival rate, fracture resistance and stress distribution. Material and Methods Seventy-two bovine teeth were cleaned and allocated in six groups (n = 12). Twenty-four teeth were sectioned at 13 mm length (no remaining coronal structure) and forty-eight were sectioned at 15 mm (2 mm remaining coronal structure). Half of the forty-eight had remaining coronal thickness lower than 1 mm and the other half had thickness higher than 1 mm. All root canals were prepared at 10 mm (luting length), fiber posts were cemented in thirty-six specimens and cast post and core in other thirty-six. All teeth were restored with metallic crowns. Specimens were submitted to 1.5 million cycles (100 N, 45°, 10 Hz at 2 mm below incisal edge) and evaluated at each 500,000 cycles to detect failures. Specimens that survived were submitted to load to fracture test. Bidimensional (Rhinoceros® 4.0) models were obteined survival data submitted to Kaplan-Meier (α=0.05) analysis and load to fracture values submitted to ANOVA and Tukey tests (α=0.05). Results Groups without remaining coronal structure showed survival rates lower than other groups (p=0.001). ANOVA showed higher values of load to fracture for groups with coronal thickness higher than 1 mm (p=0.0043). Finite element analysis showed better stress distribution in groups with remaining coronal structure and restored with fiber post. Conclusion Specimens without remaining coronal structure have lower survival rates. Specimens with remaining structure lower than 1 mm and without coronal structure support the same load to fracture value independently of the restorative strategy.

Objective To compare file-splitting multilayer (fused and cemented) with monolithic Y-TZP on the fatigue flexural strength and finite element analysis (FEA) stresses. Additionally, to verify the effect of the material under tension in multilayer Y-TZP. Methods Disc-shaped (diameter: 14.4 mm; thickness: 1.4 mm) monolithic Y-TZP (IPS e.max ZirCAD — Ivoclar Vivadent) and trilayer specimens with Y-TZP framework (IPS e.max ZirCAD), intermediate layer of fusion ceramic (IPS e.max CAD Crystall./Connect) or resin cement (Multilink Automix) and lithium disilicate veneer (IPS e.max CAD) were divided into five groups (n = 20): monolithic Y-TZP (M), fused file-splitting with framework under tension (F-FT), cemented file-splitting with framework under tension (C-FT), fused file-splitting with veneer under tension (F-VT) and cemented file-splitting with veneer under tension (C-VT). Fatigue flexural strength was determined (piston-on-three ball) by the staircase approach (750,000 cycles; 20 Hz). Mean and confidence intervals (CI) were calculated. FEA was evaluated under the application of the experimental mean fatigue load. Results The fatigue strength was statistically different for all groups. Means and CI (MPa) were: M — 405.92 (CI 397.58–414.26), F-FT — 377.73 (CI 374.59–380.88), C-FT — 346.54 (CI 340.62–352.46), F-VT — 154.79 (CI 151.86–157.72) and C-VT — 100.34 (CI 97.42–103.26). FEA tensile stresses were similar to the mean experimental values (up to ≅10 MPa of variation), with the most discrepant calculated stresses for C-FT (≅20 MPa higher than experimental result). Significance Monolithic specimens showed the highest flexural fatigue strength and fused file-splitting resulted in higher fatigue strength than cemented file-splitting. Groups with the framework under tension exhibited higher flexural fatigue strength.

SUMMARY Objectives: The aim of this prospective randomized multicenter clinical trial was to evaluate the survival rate of glass fiber–reinforced posts cemented with self-adhesive or regular resin cements. Methods: The sample was comprised of 152 teeth randomized within two centers and in accordance with the adhesive strategies for RelyX U100/U200 (3M ESPE) or Single Bond and RelyX ARC (3M ESPE). The cementation procedures were standardized and performed by previously trained operators. The primary outcome evaluated was post debonding. A trained evaluator, one for each center, assessed all subjects at intervals of 12 months for up to 6 years. Statistical analysis was performed using the Kaplan-Meier method. Results: There was no statistically significant difference in survival rates between the two strategies assessed (p=0.991), with a 92.7% survival rate for the self-adhesive cement and 93.8% for the regular cement. Conclusion: Both the self-adhesive and the regular resin cements are good alternatives for glass fiber post cementation.

This study evaluated the effect of different protocols of low-temperature degradation simulation on the mechanical behavior (structural reliability and flexural strength), the surface topography (roughness), and phase transformation of a Y-TZP ceramic. Disc-shaped specimens (1.2 mm×12 mm, Lava Frame, 3M ESPE, Seefeld, Germany) were manufactured according to ISO:6872-2008 and divided (n=30) according to the aging protocol executed: “Ctrl” – as-sintered – without any treatment; “Dist Water” – stored at distilled water at 37 °C for 365 days; “MC” mechanical cycling into two steps: First – 200 N, 2.2 Hz for 2.000.000 cycles, Second – 450 N, 10 Hz for 1.000.000 cycles; “Aut” – steam autoclave at 134 °C, 2 bar (200 kPa) for 20 h; “Aut+MC”– Aut and MC methods. Roughness analysis (μm) showed, for Ra parameter, higher statistically significant values for Ctrl 0.68 (0.27), while for Rz parameter, the highest values were observed for Ctrl 4.43(1.53) and Aut 2.24 (0.62). Surface topography analysis showed that none aging method promoted surface alterations when compared to control group. Phase transformation analysis showed that all aging methods promoted an increase in m-phase content (Ctrl: 0.94%, Dist Water: 20.73%, MC: 9.47%, Aut: 53.33% and Aut+MC: 61.91%). Weibull Analysis showed higher statistical characteristic strength values for Aut (1033.36 MPa) and Dist Water (1053.76 MPa). No aging method promoted deleterious impact either on the biaxial flexural strengths or on the structural reliabilities (Weibull moduli). Also, none of the aging methods promoted reduction of Y-TZP mechanical properties; thus the development of new methodologies and the association between mechanical stimuli and hydrothermal degradation should be considered to better understand the mechanism of low-temperature degradation.

Statement of problem: Although several monolithic zirconia ceramics have recently been introduced, the need for improved optical properties remains. The newest cubic-zirconia has been claimed to have optimal translucency characteristics for esthetic restorations. Purpose: This in vitro study evaluated the optical properties of novel cubic ultratranslucent (UT) and supertranslucent (ST) zirconia by comparing them with lithium disilicate (L-DIS) glass-ceramic for the manufacture of monolithic computer-aided design and computer-aided manufacturing (CAD-CAM) molar crowns. Material and methods: The UT and ST multilayered zirconia and the low-translucency grade L-DIS were milled. Eighty monolithic crowns were made from 2 CAD files, corresponding to thicknesses of 1.0 and 1.5 mm, and subdivided (n=20) into 4 groups: UT1.0, UT1.5, ST1.0, and L-DIS1.5. All groups were shaded using A2 color standard. Translucency of the crowns was measured by total transmission, using a photoradiometer in a dark chamber; furthermore, the contrast ratio was analyzed using a dental spectrophotometer applied to the buccal surface of the crowns. Data were analyzed using the Kruskal-Wallis and post hoc multiple Mann-Whitney U tests with Bonferroni correction (α=.05 divided by the number of tests performed in each set). Results: When the ceramic types were analyzed, using total transmission and contrast methods, they showed significantly different translucency levels: UT1.0>ST1.0>UT1.5>L-DIS1.5 (total transmission P

The occurrence of canine impaction is not a rare phenomenon, but transmigration of the tooth across the midline is a less common event. The finding is normally asymptomatic and the etiologic factors involved in the transmigration process are still unclear. Objective: To present a clinical case of surgical treatment of a transmigrated mandibular canine. Case report: A 17-year-old male patient presented to the dental clinic to remove an unerupted canine. Clinical and radiological examinations led to the diagnosis of a transmigrated canine in the mental region. Surgical removal was the treatment of choice and further radiographs were needed to complement the clinical exam and to determine the location of the tooth precisely for the surgical procedure. Postoperative period was uneventful. Canine transmigration is a rare finding and symptoms are usually absent. Conclusion: An early detection is important to plan the treatment and mainly to avoid future complications.

SUMMARY Purpose To evaluate the fracture load and survival rate of weakened and non-weakened roots restored with different intracanal posts. Methods Eighty teeth (16 mm) were prepared to a length of 10 mm with a custom drill. Fifty roots were weakened with a tapered diamond drill, and 30 roots were not. The specimens were embedded with acrylic resin up to 3 mm from the coronal aspect, and the periodontal ligament was simulated. The 50 weakened roots were restored with (n=10) CPC-gold (cast post and core made of gold alloy), CPC-Ni (cast post and core made of Ni-Cr alloy), FP (glass fiber posts), FP-W (glass fiber posts with a wider coronal diameter), and FP-CR (fiber posts relined with composite resin). The 30 nonweakened roots were restored with (n=10) CPC-gold, CPC-Ni, and FP. All of the posts were adhesively cemented. All of the specimens were mechanically cycled (37°C, 45°, 130 N, 2.2 Hz, and 1.5 million pulses) and evaluated after every 5 × 104 cycles to evaluate the presence of cracks as a primary outcome (event). The specimens that survived cycling were subjected to a fracture load test (load application on the palatal aspect at a 45° inclination). Failure mode was classified as favorable (above the simulated bone level) and catastrophic (below the simulated bone level). Survival rates were estimated using the Kaplan-Meier method. Fracture load data were analyzed using the Kruskal-Wallis test (α=0.05) for weakened roots, one-way analysis of variance, and Tukey test (p Results For the preliminary survival results, FP-W showed a higher survival rate when compared with CPC (gold/Ni). For the fracture load (N), the statistical analysis (p FP (282.2) = FP-W (274.1) = FP-RC (216.6). No differences were observed for the groups that were nonweakened (majority of favorable failures): CPC-gold (459.3) = CPC-Ni (422.0) = FP (347.9). Weakened roots restored with CPC-gold promoted high values of load fracture and unfavorable failure rates. Conclusion Cast post and cores or fiber posts can be used for restoring nonweakened roots. However, for weakened roots, a fiber post with a wider cervical emerging diameter appears to be a better alternative when compared with cast post and cores.

To investigate the effects of a novel tribochemical silica coating technique with powders made from feldspathic ceramic and leucite-based ceramic on the bond strength of zirconia to resin cement before and after aging.Zirconia blocks were divided into 3 groups according to the material used for airborne-particle abrasion: 1) SP (control): silica-coated alumina particles; 2) FP: feldspathic ceramic powder; 3) LP: leucite glass-ceramic powder. After silanization, composite resin cylinders were cemented on the zirconia surface using a dual-curing resin cement. Prior to the shear bond strength (SBS) test, half of the samples (n = 15) were stored in distilled water for 24 h; the other half (n = 15) were submitted to aging (10,000 thermocycles of 5°C to 55°C; 150 days of water storage). The bond strength data were analyzed using two-way ANOVA and Tukey's test (α = 0.05). Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and x-ray diffraction analysis were performed.The initial bond strengths did not differ significantly between the groups (p = 0.053). However, after aging procedures, airborne-particle abrasion with feldspathic ceramic powder (FP) resulted in higher values of bond strength (p = 0.0001). SEM and EDS indicated that all the treatments promoted silica deposition on the Y-TZP surface ceramic. Airborne-particle abrasion with FP and LP induced a lower percentage of the monoclinic phase.Airborne abrasion with fine feldspathic ceramic particles is a novel tribochemical technique and appears to be suitable for improving the bond strength between zirconia and resin cements.

This study investigated the effects of different zirconia surface conditioning methods on the biaxial flexure strength, surface characteristics and fractographic analysis of a Y-TZP ceramic. Disc-shaped specimens were manufactured according to ISO 6872-2008 for biaxial flexure strength testing, and then randomly assigned into seven groups (n=30). Control (CTRL): without treatment; Tribochemical silica coating (TBS): specimens were sandblasted with silica-coated aluminum oxide particles (CoJet-Sand) for 10s; Silica nanofilm (SNF): specimens were silica coated with a 5nm SiO2 nanofilm; and four protocols of low-fusing porcelain glaze (GLZ): etching with 10% hydrofluoric acid gel (HF) for 1min (GLZ1), 5min (GLZ5), 10min (GLZ10) and 15min (GLZ15). Phase transformation, roughness, micro-morphological, flexural analysis tests, and fractographic analyses were performed. X-ray diffraction (XRD) analysis showed that the TBS promoted the highest m-phase content (20.35). However, for the GLZ groups, XRD analysis was not sensitive enough to obtain an accurate reading for phase transformation. The GLZ group had the highest roughness values. The TBS group had the highest characteristic strength (1291.38MPa), followed by SNF (999.26MPa). These results suggest that (TBS) and (SNF) treatments did not reduce the mechanical properties, while (GLZ) led to a degradation in the mechanical properties.

Made available in DSpace on 2022-04-29T08:03:52Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-11-01 Statement of problem The color stability of luting agents influences the esthetics of ceramic laminate veneers. Clinical studies that have evaluated the color changes of veneers cemented to enamel with light- and dual-polymerizing resin cement are lacking. Purpose The purpose of this split-mouth randomized clinical trial was to evaluate the color change and marginal discoloration of dual- and light-polymerizing cement used for cementation of ceramic laminate veneers. Material and methods In 10 participants, 0.3-mm-thick ceramic laminate veneers were cemented on the buccal surface of the second premolars without tooth preparation. A randomized application of light-polymerized cement was used on one side and a dual-polymerized cement on the contralateral side. The operator and participants were blinded to the activation mode. Color was evaluated by a blinded evaluator with a spectrophotometer at 24 hours and at 2, 6, 12, and 24 months after cementation. The CIELab (ΔE*ab) and CIEDE2000 (ΔE*00) formulas were used to quantify color alteration, and Δa* Δb* and ΔL* were calculated between the first and subsequent measurements. US Public Health Service guidelines were used to evaluate the marginal discoloration. Results Wilcoxon tests did not show a statistical difference in ΔE*ab and ΔE*00 between the groups (P>.05). At 24 months, the median ΔE*ab was 2.31 (interquartile ranges [IQR]: 3.34) for the light-polymerizing mode and 1.57 (IQR: 0.41) for the dual-polymerizing mode, while the median ΔE*00 was 1.65 for the light-polymerizing mode (IQR: 2.34) and 1.18 for the dual-polymerizing mode (IQR: 0.25). The thresholds for clinically acceptable color changes ΔE*ab>3.46 and ΔE*00>2.25 were found for both curing modes. Marginal discoloration was observed from the 2-year assessment. Conclusions The color stability of ceramic laminate veneers was similar for both of the polymerizing modes for all evaluated periods. Marginal discoloration increased over a 2-year period for both the light- and the dual-polymerizing modes. Doctoral student Department of Restorative Dentistry Faculty of Dentistry Federal University of Santa Maria, Rio Grande do Sul Staff dentist Department of Restorative Dentistry Faculty of Dentistry Federal University of Santa Maria, Rio Grande do Sul Titular Professor Department of Restorative Dentistry São José dos Campos Dental School São Paulo State University Adjunct Professor Department of Restorative Dentistry Faculty of Dentistry Federal University of Santa Maria, Rio Grande do Sul Titular Professor Department of Restorative Dentistry São José dos Campos Dental School São Paulo State University

Purpose/Aim: Fatigue resistance is a crucial factor for the clinical long-term survival of prosthetic restorations. High strength full-contour ceramics combined with CAD/CAM technology showed promising clinical outcomes and lower costs; however, their fatigue resistance was seldom compared to natural teeth. Aim of this study was to validate a fatigue testing machine concept comparing the fatigue survival and the wear patterns of monolithic ceramic crowns to those of sound human teeth. The null hypothesis was that the fatigue resistance and the wear pattern induced by the machine did not differ among the tested groups (alpha=.05) Materials and Methods: Five groups (n=20) of monolithic crowns of different thickness (1.0mm Y-TZP HT, 1.0mm cubic-zirconia UT, 1.5mm cubic-ziconia UT, 1.0mm cubic-zirconia ST, all from Kuraray-Noritake, and 1.5mm lithium-disilicate, L-DIS, from Ivoclar Vivadent) and 20 human sound third molars have been collected and mounted in epoxy-resin cylinders, then subjected to impact fatigue cycles (Ball-Mill). The specimens were analyzed after 10, 20, 30 and 60min cycling, then analyzed every hour until a total time of 480min cycling. Wear and damage analysis was carried out using a stereomicroscope. The material losses (mm3) were calculated (Rhinoceros software) by comparing the digital impressions (Carestream CS3500 scanner) of each specimen at the different time intervals. Gehan-Breslow-Wilcoxon test and Kruskal-Wallis with post-hoc Dunn's test were applied to survival and volume loss data (alpha=.05). Results: After 480min 1.0mm Y-TZP HT showed the highest fatigue resistance, similar (p>0.05) to 1.5mm UT cubic-zirconia and 1.5mm L-DIS. 1.0mm UT cubic-zirconia showed the highest failure rate (p

SUMMARY Objective: This article aims to present a fractographic analysis of an anterior tooth restored with a glass fiber post with parallel fiber arrangement, taking into account force vectors, finite element analysis, and scanning electron microscopy (SEM). Methods: A patient presented at the Faculty of Dentistry (Federal University of Santa Maria, Brazil) with an endodontically treated tooth (ETT), a lateral incisor that had a restorable fracture. The treatment was performed, and the fractured piece was analyzed using stereomicroscopy, SEM, and finite element analysis. Results: The absence of remaining coronal tooth structure might have been the main factor for the clinical failure. We observed different stresses actuating in an ETT restored with a fiber post as well as their relationship with the ultimate fracture. Tensile, compression, and shear stresses presented at different levels inside the restored tooth. Tensile and compressive stresses acted together and were at a maximum in the outer portions and a minimum in the inner portions. In contrast, shear stresses acted concomitantly with tensile and compressive stresses. Shear was higher in the inner portions (center of the post), and lower in the outer portions. This was confirmed by finite element analysis. The SEM analysis showed tensile and compression areas in the fiber post (exposed fibers=tensile areas=lingual surface; nonexposed fibers=compression areas=buccal surface) and shear areas inside the post (scallops and hackle lines). Stereomicroscopic analysis showed brown stains in the crown/root interface, indicating the presence of microleakage (tensile area=lingual surface). Conclusion: We concluded that glass fiber posts with parallel fibers (0°), when restoring anterior teeth, present a greater fracture potential by shear stress because parallel fibers are not mechanically resistant to support oblique occlusal loads. Factors such as the presence of remaining coronal tooth structure and occlusal stability assist in the biomechanical equilibrium of stresses that act upon anterior teeth.

The aim of this study was to evaluate the influence of the frequency of mechanical pulses during mechanical fatigue aging on bond strength between glass fiber posts and root dentin. Fiber posts were adhesively cemented in 30 bovine roots and the core was built up with composite. All specimens were subjected to mechanical cycling (45° angle; 37 °C; 50 N; 2×106 pulses) at different frequencies: 2, 4, and 8 Hz. After the fatigue, each specimen was submitted to push out test. The bond strength was calculated for data analysis (one-way ANOVA, p = 0.05). The frequency did not affect the push-out (p = 0.7). The main failure mode was between dentin and cement in all groups. The mechanical pulses were not influenced by the bond strength between root dentin and fiber posts. Thus, it is possible to decrease the time-consuming in vitro tests involving posts without damaging the reliability of the test.

Several rotary instruments have been daily employed on clinic to promote cut aiming to adjust the length of fiber posts to the radicular conduct, but there is no information on the literature about the effects of the different rotary instruments and its impact on the micromorphology of surface and mechanical properties of the glass fiber post. This study aimed the impact of rotary instruments upon fiber-matrix integrity, micromorphology and flexural-strength of glass-fiber posts (GFP). GFP (N=110) were divided into 5 groups: Ctrl: as-received posts, DBc: coarse diamond-bur, DBff: extra-fine diamond-bur, CB: carbide-bur, DD: diamond-disc. Cutting procedures were performed under abundant irrigation. Posts exposed to rotary instruments were then subjected to 2-point inclined loading test (compression 45°) (n=10/group) and 3-point flexural-strength test (n=10/group). Fiber-matrix integrity and micromorphology at the cut surface were analyzed using a SEM (n=2/group). Cutting procedures did not significantly affect the 2-point (51.7±4.3-56.7±5.1 MPa) (p=0.0233) and 3-point flexural-strength (671.5±35.3-709.1±33.1 MPa) (p=0.0968) of the posts (One-way ANOVA and Tukey׳s test). Fiber detachment was observed only at the end point of the cut at the margins of the post. Cut surfaces of the CB group were smoother than those of the other groups. After 3-point flexural strength test, fiber-matrix separation was evident at the tensile side of the post. Rotary instruments tested with simultaneous water-cooling did not affect the resistance of the tested fiber posts but caused disintegration of the fibers from the matrix at the end of the cut, located at the margins.

Made available in DSpace on 2015-10-22T06:26:00Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-03-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) This study evaluated the shear stress presented in glass fiber posts with parallel fiber (0) and different coronal diameters under fatigue, fracture resistance and PEA. 160 glass-fiber posts (N=160) with eight different coronal diameters were used (DT = double tapered, number of the post = coronal diameter and W=Wider - fiber post with coronal diameter wider than the conventional): DT1.4; DT1.8 W; DT1.6; DT2W; DT1.8; DT2.2 W; DT2; DT2.2. Eighty posts were submitted to mechanical cycling (3 x 10(6) cycles; inclination: 45 degrees; load: 50 N; frequency: 4 Hz; temperature: 37 degrees C) to assess the surviving under intermittent loading and other eighty posts were submitted to fracture resistance testing (resistance [N] and shear-stress [MPa] values were obtained). The eight posts types were 3D modeled (Rhinoceros 4.0) and the shear-stress (MPa) evaluated using FEA (Ansys 13.0). One-way ANOVA showed statistically differences to fracture resistance (DT2.2 W and DT2.2 showed higher values) and shear stress values (DT1.4 showed lower values). Only the DT1.4 fiber posts failed after mechanical cycling. FEA showed similar values of shear stress between the groups and these values were similar to those obtained by shear stress testing. The failure analysis showed that 95% of specimens failed by shear. Posts with parallel fiber (0 degrees) may suffer fractures when an oblique shear load is applied on the structure; except the thinner group, greater coronal diameters promoted the same shear stresses. (C) 2014 Elsevier Ltd. All rights reserved. Univ Fed Santa Maria, Fac Odontol, Prosthodont Unit, Grad Program Oral Sci, BR-97119900 Santa Maria, RS, Brazil Univ Fed Pelotas, Dept Restorat Dent, Div Prosthodont, Capao Do Leao, RS, Brazil Univ Fed Santa Maria, Fac Odontol, BR-97119900 Santa Maria, RS, Brazil Univ Est Paulista Julio de Mesquita Filho, Inst Sci &Technol, Sao Jose Dos Campos, SP, Brazil Univ Fed Santa Maria, Fac Mech Engn, BR-97119900 Santa Maria, RS, Brazil Univ Est Paulista Julio de Mesquita Filho, Inst Sci &Technol, Sao Jose Dos Campos, SP, Brazil CEPID/CDMF-FAPESP: 2013/07296-2

O objetivo deste estudo foi comparar diferentes tratamentos de superfície na resistência de união entre pino de fibra de vidro e resina composta. Trinta e seis blocos de fibra de vidro foram divididos em 12 grupos. Cada grupo consistiu de 3 blocos de fibra de vidro, onde foram avaliados dois fatores: pré-tratamento (sem tratamento, jateamento e peróxido de hidrogênio) e tratamento químico (sem tratamento, Monobond Plus, Relyx Ceramic Primer e Single Bond Universal (SBU)). Após, foram colados 6 “tubes” de amido preenchidos com resina composta em cada bloco (n18). Após 24 horas de armazenamento em estufa a 37°C com água destilada o teste de microcisalhamento foi realizado. Análise de falha foi observada com estereomicroscópio. Os dados obtidos foram submetidos ao teste ANOVA dois fatores e teste Tukey (p0.05). A análise estatística revelou que o tipo de pré tratamento (p

Este estudo objetivou avaliar a resistência à fadiga de estruturas cerâmicas compostas por Y-TZP e dissilicato de lítio, confeccionadas pelas técnicas CAD-on e cimentação em comparação com Y-TZP monolítica. Foram fabricados discos (diâmetro: 14,4 mm espessura: 1,4 mm) trilayer (infraestrutura de Y-TZP, cerâmica de fusão ou cimento resinoso e cobertura de dissilicato de lítio) e monolayer de Y-TZP. A resistência flexural à fadiga foi determinada pelo método da escada com configuração piston-on-three-ball em água (750000 ciclos, 20 Hz). A tensão inicial (o1) foi de 60% do valor obtido com ensaio monotônico (n3) e os incrementos foram de 10% de o1. Os seguintes grupos foram testados (n20): Y-TZP (zircônia monolítica), CAD-ZT (técnica CAD-on com zircônia sob tração), CAD-DT (CAD-on com dissilicato sob tração), CIM-ZT (técnica de cimentação com zircônia sob tração), CIM-DT (cimentação com dissilicato sob tração). Foram calculados média e intervalos de confiança (IC) e a diferença estatística foi determinada com base na não-sobreposição dos IC. Houve diferença estatística entre todos os grupos. As médias de resistência à fadiga (MPa) foram: Y-TZP 405,92 (IC 397,58-414,26) CAD-ZT 377,73 (IC 374,59-380,88) CAD-DT 154,79 (IC 151,86-157,72) CIM-ZT 346,54 (IC 340,62-352,46) e CIM-DT 100,34 (IC 97,42-103,26). Conclusões: Y-TZP monolítica apresentou a maior resistência à fadiga. O método CAD-on gerou resistência à fadiga superior à cimentação. Houve influência do material sob tração, sendo que a zircônia resultou em resistência à fadiga superior.Palavras-chave: Fadiga. Cerâmica. Resistência à Tração.

Este estudo avaliou a resistência ao microcisalhamento (μC) entre duas cerâmicas e cimento resinoso comparando o método de condicionamento tradicional e simplificado. Blocos de dissilicato de lítio (DL) e cerâmica feldspática (F) foram divididos (n10) de acordo com o tratamento de superfície (HF: ácido fluorídrico 5% + silano EP: Etch & Prime) e ausência (24h de armazenagem) ou presença (termociclagem por 12x103 ciclos com 5-55°C + armazenagem por 70 dias em ambiente úmido a 37°C) de envelhecimento. Após o tratamento de superfície, um cimento resinoso foi aplicado no interior de matrizes circulares (área: 0,72 mm2) sobre as superfícies cerâmicas (fotoativação: 20s). O teste de μC foi realizado (0,5 mm/min) e o padrão de falha foi analisado em estereomicroscópio (25x). Os valores de μC foram submetidos ao teste t (t0,05) e foi realizada análise do ângulo de contato. A média e desvio-padrão (MPa) foram: sem envelhecimento DL-EP 10,42±2,43 DL-HF 21,24±2,18 F-EP-EP 13,54±5,44 F-HF 19,57±4,29 e pós envelhecimento DL-EP 9,05±3,40 DL-HF 14,64±2,31 F-EP 11,09±3,26 F-HF 14,73±3,33. HF apresentou adesão estatisticamente superior em ambas as condições de envelhecimento e cerâmicas. Para EP não houve redução da resistência após o envelhecimento, para ambos os materiais cerâmicos. A maioria das falhas foi adesiva entre cerâmica e cimento resinoso. Os grupos tratados com HF apresentaram maior molhabilidade. Concluiu-se que HF apresentou maior resistência adesiva, porém EP apresentou maior estabilidade adesiva.Palavras-chave: Cerâmicas. Materiais Dentários. Resistência ao Cisalhamento.

Objective: Considering that periodontal ligament simulation may influence the stress distribution over teeth restored with intraradicular retainers, this study aimed to assess the combined effect of mechanical cycling and periodontal ligament simulation on both the bond strength between fiber posts and root dentin and the fracture resistance of teeth restored using glass fiber posts. Material and Methods: Ninety roots were randomly distributed into 3 groups (n=10) (C-MC: control; P-MC: polyether; AS-MC: addition silicone) to test bond strength and 6 groups (n=10) (C: control; P: polyether; AS: addition silicone, without mechanical cycling, and C-MC, P-MC and AS-MC with mechanical cycling) to test fracture strength, according to the material used to simulate the periodontal ligament. For the bond strength test, fiber posts were cemented, cores were built, mechanical cycling was applied (2×106 cycles, 88 N, 2.2 Hz, and 45º incline), and the teeth cut into 3 slices (2 mm), which were then subjected to the push-out test at 1 mm/min. For the fracture strength test, fiber posts were cemented, cores were built, and half of the groups received mechanical cycling, followed by the compressive strength (45° to the long axis and 1 mm/min) performed on all groups. Results: Periodontal ligament simulation did not affect the bond strength (p=0.244) between post and dentin. Simulation of periodontal ligament (p=0.153) and application of mechanical cycling (p=0.97) did not affect fracture resistance. Conclusions: The materials used to simulate the periodontal ligament did not affect fracture or bond strength, therefore periodontal ligament simulation using the tested materials could be considered optional in the conditions of the study.

To evaluate the effect of different strategies for post cementation on the pullout bond strength of a double-tapered glass fiber post cemented into a root canal.The root canals of 70 single-rooted bovine teeth (16 mm-length) were prepared to 9 mm using the preparation drill of a double-tapered glass fiber post system (White Post DC, FGM). Each specimen was embedded in a plastic cylinder using acrylic resin up to 3 mm of the most coronal portion of the specimen and allocated into one of seven groups (n=10) based on strategies for cementation: Gr1-ScotchBond Multi Purpose plus (SBMP) + Relyx ARC resin cement; Gr2-Single Bond + Relyx ARC; Gr3-ED Primer + Panavia F resin cement; Gr4-SBMP + AllCem resin cement; Gr5-Relyx ARC; Gr6-Relyx Unicem resin cement; Gr7-Relyx Luting 2 glass ionomer cement. After cementation, the specimens were stored for seven days (in a humid environment at 37 degrees C) and submitted to pullout bond strength testing (the inferior part of each specimen was fixed and the fiber post was pulled out). The data (Kgf) were submitted to statistical analysis (one-way ANOVA and post-hoc Tukey tests, alpha=.05). The tested specimens were analyzed under the microscope and SEM for fracture analysis.The strategy for post cementation affected the pullout retentive strength (Kgf) (p0.0001) significantly. Gr6 (37.7 +/- 8a), Gr1 (37.4 +/- 5.7a) and Gr4 (31.6 +/- 6.6ab) presented the highest pullout bond strengths. Gr2 (12.2 +/- 5.6c), Gr3 (6.5 +/- 5.2c) and Gr7 (5.1 +/- 2.8c) presented the lowest pullout bond strengths. Gr5 (24.2 +/- 7.4b) was similar to Gr4 and inferior to Gr6 and Gr1.The use of a three-step etch--rinse adhesive system appears to be effective. The application of other adhesive systems (single-bottle etch--rinse and self-etch adhesive systems) did not present high pullout strength values. The simplified self-adhesive resin cement (without adhesive application) presented good retentive performance. Further studies should be conducted.