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Aim: To evaluate the retention of an endodontic titanium postwith a spherical head for removable partial denture or overdentureattachment according to surface treatment type. Methods: Sixtyhealthy single-rooted teeth, sectioned at the enamel/cementumjunction, were treated endodontically and steadily fixed in theembedding acrylic resin. The titanium posts were subdivided intofour groups: control, no surface treatment (Ctrl); posts with macroretentivegrooves (MR); air abrasion of the post surface (AB); andposts with macro-retentive grooves and air abrasion of the postsurface (MR+AB). The posts were luted in the root canal usingself-adhesive dual resin cement. Pull-out testing was performedusing a universal testing machine until complete detachment wasachieved. After pull-out testing, the metallic posts were examinedunder an optical microscope and the failures were classifiedbased on the cement distribution pattern on the extracted posts:0, no cement left on the post (cement/post failure); 1, postsurface partially covered by adhered cement (post/cement anddentin/cement mixed failure); 2, post surface completely coveredby cement (dentin/cement failure). The retention data wereanalyzed by one-way ANOVA, Bonferroni–Dunn test (p

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 a retention 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.

Prendendo le mosse da un’ampia riflessione storiografica, l’autore propone una rilettura circa complessiva del dossier e mette in luce come la frantumazione territoriale e la debolezza della Repubblica sociale siano alla base della radicalizzazione della violenza e del fallimento amministrativo, da un lato, e, dall’altro, del recupero di spazi di gestione dell’emergenza bellica e di canali di continuità sul piano locale.

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

Objective: To evaluate the impact of the type of root canal preparation, intraradicular post and mechanical cycling on the fracture strength of roots. Material and Methods: eighty human single rooted teeth were divided into 8 groups according to the instruments used for root canal preparation (manual or rotary instruments), the type of intraradicular post (fiber posts- FRC and cast post and core- CPC) and the use of mechanical cycling (MC) as follows: Manual and FRC; Manual, FRC and MC; Manual and CPC; Manual, CPC and MC; Rotary and FRC; Rotary, FRC and MC; Rotary and CPC; Rotary, CPC and MC. The filling was performed by lateral compactation. All root canals were prepared for a post with a 10 mm length, using the custom #2 bur of the glass fiber post system. For mechanical cycling, the protocol was applied as follows: an angle of incidence of 45°, 37°C, 88 N, 4 Hz, 2 million pulses. All groups were submitted to fracture strength test in a 45° device with 1 mm/ min cross-head speed until failure occurred. Results: The 3-way ANOVA showed that the root canal preparation strategy (p

This study evaluated the effect of mechanical cycling on the bond strength of zirconia posts to root dentin. Thirty single-rooted human teeth were transversally sectioned to a length of 16 mm. The canal preparation was performed with zirconia post system drills (CosmoPost, Ivoclar) to a depth of 12 mm. For post cementation, the canals were treated with total-etch, 3-steps All-Bond 2 (Bisco), and the posts were cemented with Duolink dual resin cement (Bisco). Three groups were formed (n = 10): G1 - control, no mechanical cycling; G2 - 20,000 mechanical cycles; G3 - 2,000,000 mechanical cycles. A 1.6-mm-thick punch induced loads of 50 N, at a 45° angle to the long axis of the specimens and at a frequency of 8 Hz directly on the posts. To evaluate the bond strengths, the specimens were sectioned perpendicular to the long axis of the teeth, generating 2-mm-thick slices, approximately (5 sections per teeth), which were subjected to the push-out test in a universal testing machine at a 1 mm/min crosshead speed. The push-out bond strength was affected by the mechanical cycling (1-way ANOVA, p = .0001). The results of the control group (7.7 ± 1.3 MPa) were statistically higher than those of G2 (3.9 ± 2.2 MPa) and G3 (3.3 ± 2.3 MPa). It was concluded that the mechanical cycling damaged the bond strength of zirconia posts to root dentin.

New polyvinyl siloxane (PVS) materials with enhanced properties have been developed to improve and facilitate implant impression techniques. However, studies on their accuracy are lacking. The purpose of this in vitro study was to determine the accuracy and precision of implant impressions made with some recently introduced materials on a simulated patient requiring an all-on-4 implant-supported prosthesis. Well-established polyether materials were also evaluated as a comparison. The variables considered were material type, consistency, splinting or not splinting techniques, and implant angulation. A reference master model was made by inserting 4 implants at angles of 0, 5, and 10 degrees. Eighty impressions were made at 37 °C in wet conditions by using a standardized technique. Eight groups (n=10) were created using monophasic, single-viscosity materials (Hydrorise Implant Medium, HIM-ns; Hydrorise Implant Medium, HIM; Honigum Mono, HM; Impregum, IMP), and 2-viscosity materials (Hydrorise Implant Heavy+Light-ns, HIH+L-ns; Hydrorise Implant Heavy+Light, HIH+L; Honigum Heavy+Light, HH+L; and Permadyne and Garant [Heavy+Light, PeH+L]). Hydrorise materials were used with splinting and not splinting (ns) techniques. The reference points located on the connecting platforms of the transfer copings (TCP) were compared with the same points on the implant connecting platforms (ICP) located in the reference model. The accuracy and precision of the impressions were determined as linear 3D errors and standard deviation between each TCP-ICP couple by using an optical coordinate measuring machine (OCMM). PVS materials were generally better than polyether materials, with Hydrorise materials (HIM and HIH+L) showing significantly better accuracy and precision (30.9 ±14.4 μm and 28.7 ±15.5 μm, respectively) than IMP and PeH+L polyethers (44.2 ±16 μm and 43.8 ±17.6 μm, respectively; P <.001). Honigum materials were statistically similar to Hydrorise materials (P =.765). The values shown by Hydrorise nonsplinted groups (HIH+L-ns and HIM-ns) were not statistically different from those of the splinted polyether impressions (P =.386). The viscosities (monophasic or heavy+light) had no effect on accuracy, but monophasic material positively influenced precision (HIM and HIH+L, P =.001). No correlation was found between implant angulation and accuracy (multilevel analysis and Kendall rank correlation coefficient=-0.065; P =.133). Recently introduced materials designed for implant impressions showed significantly higher accuracy and precision; even with the unfavorable nonsplinting technique, the new materials performed similarly to, or better than, polyether materials. Although the transfer coping splinting technique generally improved the accuracy and precision of Hydrorise materials, the effect was significant only within HIH+L groups. [ABSTRACT FROM AUTHOR]

Purpose: Under thin, partial coverage restoration the proper cement thickness to be clinically employed still remains an issue. The aim of this study was to determine the failure and success rates of simplified lithium disilicate occlusal veneers as a function of cement thickness. The null hypothesis was that cement thickness has no effect on the fatigue resistance.Methods: Sound human molars were severed in a plane parallel to the occlusal surface to create a flat dentin surface surrounded by enamel edges. Forty-five occlusal veneers 1.0 mm thick (IPS e.max CAD LT) were luted to the teeth with Multilink Automix resin cement, creating 3 experimental groups (n=15) with cement thicknesses of 50, 100, and 200 µm. The restorations were fatigue-cycled using a ball mill machine containing zirconia and stainless steel spheres. Twelve 60 min cycles were performed. Survival statistics were applied to "failure" and "success" events, comparing the three groups using a log-rank Mantel--Cox test and a log-rank test for trends (alpha = 0.05).Results: The failure and success rates were not significantly influenced by cement thickness (P = 0.137 and P = 0.872, respectively); thus, the null hypothesis was accepted. However, when log-rank test for trends was applied to failure events, the tendency to have less failures with increasing thicknesses was found statistically significant (P = 0.047). Conclusions: The cement thickness within the range adopted here did not have a significant effect on the failure or success rate of lithium disilicate occlusal veneers when exposed to randomized impact stresses generating fatigue phenomena. [ABSTRACT FROM AUTHOR]

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 macroretentive 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<0.05) and Weibull analysis. Results: AB showed the highest retention value (485.37±68.36), followed by MR+AB (355.80±118.47), MR (224.63±42.54) and Ctrl (113.12 ± 51.32). AB and MR showed the highest Weibull moduli. Conclusions: The data indicated that air abrasion alone could significantly increase the retention of titanium posts/attachments for use with overdentures or removable partial denture. [ABSTRACT FROM AUTHOR]

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 a retention 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. [ABSTRACT FROM AUTHOR]

PURPOSE: This pilot clinical trial evaluated the clinical behavior of 3-unit inlay fixed partial dentures (IFPDs) made of the glass-fiber composite system SR Adoro/Vectris and luted with 2 different bonding systems over an observation period of 2 years. MATERIALS AND METHODS: Thirty-nine glass-fiber-reinforced composite IFPDs were made to replace 1 missing maxillary or mandibular tooth. Nineteen IFPDs were randomly assigned to group A and luted with a 2-step bonding system (Excite DSC), while the other 20 IFPDs of group B were cemented with a 3-step adhesive (Syntac). Events such as partial or total debonding of the IFPDs, fracture of the framework, or veneer and fiber exposures were considered failures. Color match, marginal discoloration, secondary caries, marginal adaptation, postoperative sensitivity, and surface texture were evaluated according to the United States Public Health Service modified criteria. RESULTS: Two debondings and 2 fiber exposures occurred during the observation period. All failures occurred in group A. Some fatigue microcracks in the pontic area of the 2 detached IFPDs were observed under scanning electron microscopy. The postoperative sensitivity of group A was much higher than that of group B, and the abutments luted with Excite DCS showed postoperative sensitivity during the first month in 42.2% of cases. The sensitivity disappeared completely after 6 months. Statistical analysis indicated significant differences in postoperative sensitivity (P < .05) between the 2 groups. CONCLUSION: The IFPDs bonded with a 3-step adhesive demonstrated good clinical service in the short observation period. The microfractures of the layering material observed on the debonded IFPDs may suggest excessive flexibility of the fiber structures, which occurs if the framework is fabricated without observing the recommended dimensions. [ABSTRACT FROM AUTHOR]

Objective: The purpose of this case report is to provide a simple forced eruption technique to recover a decayed canine that was a primary abutment for a fixed partial denture (FPD). After an analysis of casts on an articulator, a forced eruption technique was applied, using the old FPD as a bracket to apply the extrusion force on the root of the canine. After 6 weeks, the desired 5-mm extrusion was achieved, maintaining the old FPD in its original position. This simple procedure has many advantages compared with the traditional root extrusion techniques. The use of the old FPD allowed preservation of esthetics and function, better application of the eruption force, guided extrusion of the tooth, and reasonable stabilization time. [ABSTRACT FROM AUTHOR]

Abstract Objective This study aimed to evaluate the fracture load and displacement of roots restored with posts of different elastic modulus. Material and method Thirty-six replicas of epoxy resin mixed with glass microfibers were made from an endodontically-treated human premolar root prepared to a length of 12 mm with a custom drill, leaving the apical 4 mm unprepared. Replicas were randomly restored with (n = 12): FP-LM (fiber post with low elastic modulus– 50 GPa), FP-HM (fiber post with high elastic modulus – 67 GPa) and MP (metallic post – 208 GPa), using self-curing adhesive and dual resin cement. Cores were built up with composite resin and metallic crowns were cemented in all the roots with self-adhesive resin cement with self-curing mode. Specimens were subjected to a fracture load test (45° inclination/0.5 mm/min) and displacement was registered at 100 N. Result One-way ANOVA showed that elastic modulus of the post did not affect the fracture load means (p = 0.203) (FP-LM: 237.4 ± 65.11 N; FP-HM: 236.7 ± 92.85 N; MP: 295.8 ± 108.7 N) but was statistically significant for the displacement (p < 0.00): Tukey’s test showed that FP-LM displacement mean (0.81 ± 0.15 mm) was significantly higher than those for FP-HM (0.46 ± 0.26 mm; p = 0.00) and MP (0.62 ± 0.07 mm; p = 0.04). Conclusion Posts with different elastic modulus exhibit similar fracture loads, but a lower displacement is achieved when fiber posts with a high elastic modulus and metallic posts are used.

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 <.001). Contrast ratio evaluation yielded similar results ( P ≤.006); however, the differences between ST1.0 and UT1.5 were not significant. Conclusions Both the ST1.0 and UT1.0 crowns, even at the maximum thickness tested (UT1.5), showed significantly higher translucency than L-DIS. Zirconia translucency was improved by eliminating the tetragonal phase, which is responsible for the toughening effect; thus, further studies are advocated to investigate the mechanical resistance of cubic zirconia. [ABSTRACT FROM AUTHOR]

This in vitro study evaluated the marginal microleakage of composite inlays luted with 3 different cement systems. The null hypothesis was that the luting materials would not influence dye penetration, showing the same degree of microleakage. Thirty-six sound molars were selected, mesio-occlusodistal cavities were prepared, and the teeth were randomly divided into 3 groups (n = 12). Composite resin inlay restorations were made and cemented using a dual-curing resin cement (Calibra), a light-curing flowabie composite (Charisma Flow), or a self-adhesive resin cement (RelyX Unicem). The restored teeth were subjected to fatigue cycles and immersed in 0.5% basic fuchsin dye for 24 hours. Two orthogonal cuts were made to enable evaluation of dye penetration at the cervical and occlusal margins. The sections were evaluated with a 4-point scale ranging from 0 (no penetration) to 3 (penetration up to the cavity floor [occlusal margins] or axial wall [cervical margins]). The Calibra and Charisma Flow groups showed greater microleakage, notably at the cervical margins, whereas RelyX Unicem specimens showed the least dye penetration. Significant differences were found between the Calibra and Charisma Flow groups and between the Charisma Flow and RelyX Unicem groups (P < 0.05). No statistically significant differences were detected between the Calibra and RelyX Unicem groups. The microleakage associated with the flowabie composite was significantly greater than that associated with both resin cements, results that discourage its use for luting of Class II composite inlays. [ABSTRACT FROM AUTHOR]

This study evaluated the influence of the cementation length of glass fiber-reinforced composite (FRC) on the fatigue resistance of bovine teeth restored with an adhesively cemented FRC. Thirty roots of single-rooted bovine teeth were allocated to 3 groups (n = 10), according to the ratio of crown length/root length (post cementation length): group 1 = 2/3, group 2 = 1/2, and group 3 = 1/1. The roots were prepared, the fiber posts (FRC Postec Plus) were cemented, and the specimens were submitted to 2 million mechanical cycles. After fatigue testing, a score was given based on the number of fatigue cycles until fracture, and data were submitted to statistical analysis. All specimens were resistant to fatigue. Taking into account the methodology and results of this study, the evaluated fiber posts can be cemented based on the ratio of crown/root at 1/1. Further clinical studies must be conducted to verify this ratio. [ABSTRACT FROM AUTHOR]

PURPOSE: To evaluate the failure patterns of teeth restored with both cast metal and fiber posts after fatigue cycling. MATERIALS AND METHODS: Thirty-five crownless human teeth subdivided into 5 groups were subjected to 2 x 106 100-N fatigue cycles at 8 Hz under 37 degrees C water. RESULTS: No root fatigue fractures were recorded. High microleakage values were found in specimens that survived fatigue. No statistically significant relationships were found for fatigue (P > .4), fracture strength (P > .8), and microleakage (P > .1). CONCLUSIONS: Cast-metal and fiber posts undergo insidious microscopic adhesive failures at similar levels. Increasing the post diameter and/or post stiffness could improve the core stabilization. [ABSTRACT FROM AUTHOR]

PURPOSE: Fiber-reinforced composite (FRC) posts can be air-abraded to obtain good attachment to the resin cement. This study tested the effect of silica coating on the flexural strength of carbon, opaque, and translucent quartz FRC posts. MATERIALS AND METHODS: Six experimental groups of FRC posts (n=10 per group) were tested, either as received from the manufacturer or after chairside silica coating (30-microm CoJet-Sand). RESULTS: There was no significant difference in the flexural strength of nonconditioned (504 to 525 MPa) and silica-coated (514 to 565 MPa) specimens (P > .05) (analysis of variance). The type of post did have a significant effect on flexural strength (P < .05). CONCLUSION: Chairside silica coating did not affect the flexural strength of both carbon and quartz FRC posts. [ABSTRACT FROM AUTHOR]