PURPOSE:To introduce a novel digital technique for analyzing the inclination of the tooth emergence profile and the distance between the bone crest (BC) and the cementoenamel junction (CEJ). MATERIALS AND METHODS:The study used CBCT scans from 24 patients, analyzing 57 teeth for emergence profile inclination and 206 teeth for the BC-CEJ distance. Digital measures were taken using an implant planning software. RESULTS:The emergence profile angle varies according to the tooth anatomy. Results indicated an increase in emergence profile angle from an average value of 13 to 19 degrees when simulating prosthetic chamfer preparation, highlighting the importance of maintaining the natural tooth anatomy in restorative procedures. The average distances between BC and CEJ were 2.43 ± 1.08 mm on the buccal side, 1.96 ± 0.88 mm on the palatal side, 1.88 ± 1.05 mm on the mesial side, and 1.97 ± 0.92 mm on the distal side. Discrepancies in BC heights, particularly at the vestibular reference point, were found, which could affect periodontal health. CONCLUSIONS:The research provides a foundation for future studies to refine soft tissue management techniques in dental practice. These findings underscore the need for a deeper understanding of supracrestal tissues in prosthetic rehabilitation, aiming to enhance the design of anatomical implant abutments and improve patient outcomes.

OBJECTIVES:This in vitro pilot study evaluated the effects of two professional cleansing protocols on surface roughness and color stability of various resins for complete dentures. METHODS:50 resin specimens were prepared and divided into five groups (n = 10): Probase Hot (PH, Ivoclar AG), IvoBase CAD (IBC, Ivoclar AG), Ivotion Dent (ID, Ivoclar AG), Dima Print Denture Base (DPDB, Kulzer), and Dima Print Denture Teeth (DPDT, Kulzer). After a 7-day immersion in coffee solution, two cleansing protocols were applied: a chemical one using an alkaline solution, and a combined mechanical+chemical one involving an acid-based cleaning agent with a rotating needle device followed by the same chemical protocol. Surface roughness was measured before and after cleaning using a structured light profilometer (Confovis) connected to a microscope (Eclipse LV150N, Nikon). Color stability was assessed with a colorimeter (Easy_Color, SmartVision). One specimen per group underwent SEM analysis at baseline and after both protocols. The data analysis was performed by using Kruskal-Wallis test and post-hoc Dunn test for comparison. RESULTS:Surface roughness was not significantly affected by either protocol (p>0.05). All ΔE values were below the perceptibility threshold (ΔE<1.2), except for ID after both the chemical (ΔE = 2.28) and the mechanical+chemical protocol (ΔE = 2.39) and DPDB after both the chemical (ΔE = 2.06) and the mechanical+chemical protocol (ΔE = 2.33). CONCLUSIONS:Surface roughness and color stability of PMMA resins were not affected by the tested cleansing protocols, so they could be used by clinician during the periodically control visit. CLINICAL SIGNIFICANCE:The proposed cleansing protocols help preserve the long-term aesthetic and functional integrity of dentures, enhancing patient satisfaction and oral health.

PURPOSE:To evaluate the effect of a staining solution on the color stability of resins for complete dentures produced with conventional and digital technologies. MATERIALS AND METHODS:A total of 60 resin specimens were prepared and divided into six groups of 10 specimens each: Probase Hot (PH; Ivoclar), IvoBase CAD (IBC; Ivoclar), Ivotion Dent (ID; Ivoclar), Ivotion Dent Multi (IDM; Ivoclar), Dima Print Denture Base (DPDB; Kulzer), and Dima Print Denture Teeth (DPDT; Kulzer). One surface of each specimen was polished following the manufacturer's instructions. The CIELab color differences were evaluated before and after 28 days of immersion in a coffee solution and measured as ∆E using two dental spectrophotometers. One specimen for each group was selected for scanning electron microscopy (SEM) analysis at baseline and at 28 days. RESULTS:Data analysis was performed with Kruskal-Wallis test and post-hoc Dunn test for comparison. Regarding specimens analyzed with VITA Easyshade, IDM white zone (polished and unpolished) scored higher (∆E = 0.87 and ∆E = 1.15, respectively). All milled samples (IBC, ID, IDM pink zone), scored significantly higher compared to PH and DPDT. Regarding SpectroShade, IDM pink zone performed better for both polished and unpolished specimens (∆E = 1.57 and ∆E = 2.07, respectively). ID demonstrated a statistically higher color stability compared to PH and DPDT. Regarding SEM analysis, any difference in surface morphology was observed between baseline and 28-day immersion analyses. CONCLUSIONS:Color stability was significantly higher in resin specimens obtained with digital technologies compared to conventional resin specimens afterimmersion in a staining solution.

Purpose: To evaluate the influence of different Co-Cr framework manufacturing techniques on the bond strength between metal and two types of veneering ceramics with and without a metal primer. Materials and Methods: A total of 72 metal specimens were fabricated using the same Co-Cr alloy (Keramit NP, Nobil Metal) with three different techniques: ingots for casting (Keramit NP); disks for CAD/CAM milling (sinergia disk Keramit NP); and powder for selective laser melting (SLM, Keramit NP-S). Each of the 24-specimen groups was divided into two subgroups, according to the application, or lack thereof, of Nobil Metal Bonding (NMB). Two different veneering ceramic systems were used: Ceramco iC (Dentsply Sirona) and Noritake Super Porcelain EX-3 (Noritake). The bond strength of the metal-ceramic system was evaluated using the three-point bending test and the modality of failure with SEM analysis. Three-way ANOVA with interactions was used to evaluate the influence of the metal production process, the presence or absence of the bonding agent, and the type of veneering ceramic on ceramic-metal adhesion. Results: All specimens exceeded the minimum bond strength of 25 MPa required by ISO Standard 9693-1:2012. The highest values of adhesion were registered for specimens manufactured with casted metal/Noritake veneering ceramic (40.59 +/- 7.30 MPa). The lowest values were registered for specimens manufactured with CAD/CAM metal/NMB/ Ceramco iC veneering ceramic (29.47 +/- 3.38 MPa). Conclusions: The fabrication method and the type of veneering ceramic had a significant influence on the mean bond strength. The application of the NMB did not show an influence on bond strength.

Objective: To determine the effect of grit-blasting before and after sintering on the surface roughness of zirconia and the micro-tensile bond strength of a pressable veneering ceramic to zirconia. Methods: Pre-sintered zirconia blocks (IPS e.max ZirCAD, Ivoclar) were divided into four test groups of three specimens each and a control group (‘CTR’; no surface treatment). Pre-S-30, Pre-S-50, and Pre-S-110 were grit-blasted with 30-µm SiO2-coated Al2O3, 50-µm Al2O3 and 110-µm Al2O3 particles, respectively, before sintering. Post-S-30 was grit-blasted with 30-µm SiO2-coated Al2O3 after sintering. For each treatment, the surface roughness was measured (Ra, Perthometer M4P, Mahr Perthen). After sintering the zirconia blocks, a liner was applied and a pressable ceramic (IPS e.max ZirPress, Ivoclar) was heat-pressed. Sixteen microbars were obtained from each block and submitted to micro-tensile bond-strength (µTBS) testing. Data were analyzed with one-way ANOVA. Any correlation between Ra and µTBS was evaluated (Sperman test). Results: Grit-blasting before sintering with 110-µm Al2O3 (RaPre-S-110 = 3.4 ± 0.4 µm), 50-µm Al2O3 (RaPre-S-50 = 2.3 ± 0.5 µm), and 30-µm SiO2-coated Al2O3 (RaPre-S-30 = 1.2 ± 0.2 µm) resulted in significantly higher roughness than grit-blasting after sintering with 30-µm SiO2-coated Al2O3 (RaPost-S-30 = 0.5 ± 0.1 µm). The highest µTBS was measured when the sintered zirconia was grit-blasted with 30-μm SiO2-coated Al2O3 (µTBSPost-S-30 = 28.5 ± 12.6 MPa), which was significantly different from that of specimens that were grit-blasted before sintering (µTBSPre-S-30 = 21.8 ± 10.4; µTBSPre-S-50 = 24.1 ± 12.6; µTBSPre-S-110 = 26.4 ± 14.1) or were not grit-blasted (µTBSCTR = 20.2 ± 11.2). Conclusions: Grit-blasting zirconia before sintering enhanced the surface roughness proportionally to the particle size of the sand used. Grit-blasting with 30-µm SiO2-coated Al2O3 after sintering improved bonding of the veneering ceramic to zirconia. Clinical Significance: As grit-blasting with 30-µm SiO2-coated Al2O3 after sintering improved bonding of the veneering ceramic to zirconia, it may reduce veneering ceramic fractures/chipping.

Objectives. To explore the feasibility of a 3D-microleakage protocol for the evaluation of various configurations of adhesive-tooth interfaces.Methods. Three different kinds of specimens were prepared: (1) a Class-I composite restoration placed without any bonding to maximize gap formation at the interface; (2) a glass-fiber post cemented with a self-adhesive composite cement into a prepared root canal; and (3) inlay MOD composite restorations placed with either a 1-step self-adhesive or a 2-step etch-and-rinse composite cement. After silver-nitrate (AgNO3) infiltration, the specimens were scanned using a Skyscan 1172 X-ray microtomograph (mu CT; Skyscan Bruker) at 100 kV, 100 mu A and 7.8-9.5 mu m resolution. Projection images were reconstructed, after which maximum-intensity projections (MIPs) and 3D-volumetric renderings were produced. For the inlays, an additional conventional stereomicroscopic (SM) microleakage evaluation was accomplished after specimen sectioning.Results. MIPs and 3D-renderings from specimens (1) and (2) revealed strongly varying microleakage patterns along the marginal gap/interface. For the specimens of setup (3), the high radiopacity of the 2-step composite cement hindered evaluation of the MIPs. MIP-microleakage patterns along the enamel margin of the restoration cemented with the 1-step composite cement corresponded well to the stereomicroscopic images.Significance. The reported mu CT-protocol revealed good sensitivity to detect AgNO3 infiltration at the adhesive-tooth interface when considerable microleakage was present. When microleakage was less apparent and spread in a more diffuse pattern, evaluation with mu CT was less sensitive compared to stereomicroscopic evaluation. (C) 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Objectives: To evaluate the influence of the ferrule effect (1) and the fibre-post placement (2) on the fracture resistance of endodontically treated teeth subjected to cyclic fatigue loading.Methods: 40 extracted single-rooted upper pre-molars were sectioned at the CEJ (groups a and b) or 2 mm above the CEJ (groups c and d), and subsequently endodontically treated. After 24-h water storage at 37 degrees C, specimens were restored according to four build-up approaches (n = 10 per group): (a) NF-NP (no ferrule, no post), (b) NF-P (no ferrule, fibre-post), (c) F-NP (ferrule, no post) and (d) F-P (ferrule, fibre post). RelyX Posts (3M-ESPE) were used in groups NF-P and F-P, and were cemented with Panavia F 2.0 (Kuraray). A standardized composite core was built, after which specimens were restored with an all-ceramic crown (IPS Empress CAD, Ivoclar-Vivadent) Specimens were fatigued by exposure to 1,200,000 cycles using a chewing simulator (Willytech). All specimens that survived fatigue loading were fractured using a universal loading device (Micro-Tester, Instron). A two-way analysis of variance was used to determine the statistical significance of the factors ferrule and post on fracture resistance.Results: Only one NF-NP specimen failed under fatigue. The ferrule effect significantly enhanced the fracture resistance of the restored teeth, regardless the use of a post (p = 0.003). F-NP obtained the highest fracture resistance (758.52 +/- 121.89 N), which was not significantly different from F-P (647.58 +/- 132.95 N); NF-NP presented the lowest fracture resistance (361.52 +/- 151.69 N). For all groups, only 'repairable' failures were recorded.Conclusions: Avoiding extra-removal of sound tooth structure, rather than placing a fibre post, can protect endodontically treated teeth against catastrophic failure. However, when any ferrule can be preserved, a fibre-post may improve the retention and fatigue resistance of the restoration. (C) 2012 Elsevier Ltd. All rights reserved.

Objectives. To evaluate flexural properties of different fiber posts systems and to morphologically characterize their micro-structure.Methods. Six types of translucent fiber posts were selected: RelyX Post (3M ESPE), Para-Post Taper Lux (Colthene-Whaledent), GC Fiber Post (GC), LuxaPost (DMG), FRC Postec Plus (Ivoclar-Vivadent), D. T. Light-Post (RTD). For each post system and size, ten specimens were subjected to a three-points bending test. Maximum fracture load, flexural strength and flexural modulus were determined using a universal loading device (5848 MicroTester (R), Instron). Besides, for each system, three intact posts of similar dimensions were processed for scanning electron microscopy to morphologically characterize the micro-structure. The following structural characteristics were analyzed: fibers/matrix ratio, density of fibers, diameter of fibers and distribution of fibers. Data were statistically analyzed with ANOVA.Results. Type and diameter of posts were found to significantly affect the fracture load, flexural strength and flexural modulus (p < 0.05). Regarding maximum fracture load, it was found to increase with post diameter, in each post system (p < 0.001). Regarding flexural strength and flexural modulus, the highest values were recorded for posts with the smallest diameter (p < 0.001). Finally, structural characteristics significantly varied among the post systems tested. However, any correlation has been found between flexural strength and structural characteristics.Significance. Flexural strength appeared not to be correlated to structural characteristics of fiber posts, but it may rather be affected by mechanical properties of the resin matrix and the interfacial adhesion between fibers and resin matrix. (C) 2013 Published by Elsevier Ltd on behalf of Academy of Dental Materials. All rights reserved.

Objectives: To evaluate the effect of the length of fibre-posts(1) and type of adhesive cement(2) on the fracture resistance of endodontically treated teeth, after fatigue loading.Methods: Eighty extracted upper pre-molars were sectioned at the CEJ and endodontically treated. After 24 h of water storage at 37 degrees C, RelyX Posts (3M-ESPE) were cemented with Panavia F 2.0 (Kuraray) or RelyX Unicem (3M-ESPE). A standardized composite core was built. Specimens were divided into four groups depending on the post-core ratio: (A) 2/1 (control); (B) 3/2; (C) 1/1 (small diameter); (D) 1/1(large diameter) and submitted to 1,200,000 cycles using a chewing simulator (Willytech). Immediately afterwards, all specimens that survived fatigue loading were fractured using a universal loading device (Micro-tester, Instron). Data were analysed with ANOVA.Results: Four percent of the specimens failed during fatigue loading. The length of the post into the root affected the fracture resistance. The statistical outcome varied according to the inclusion of specimens failed during fatigue loading. However, the control group always had the lowest fracture resistance. The type of adhesive cement did not affect the fracture resistance. A prevalence of not-repairable failures was observed in specimens restored with the longest posts, whilst shorter posts led to more repairable failures.Conclusions: Shortening the post length and the ensuing preservation of more tooth structure, offer the potential for reparability through an in-built fail safe mechanism and may thus reduce the occurrence of catastrophic failures. (C) 2012 Elsevier Ltd. All rights reserved.

Objetivo: El objetivo de este ensayo clinico controlado fue comparar los resultados a los 3 anos obtenidos con pernos de fibra de vidrio y munones de composite con los obtenidos con pernos y munones colados de oro para la restauracion de dientes tratados endodonticamente. Materiales y metodos: Se seleccionaron 144 pacientes que precisaban 205 restauraciones en dientes tratados mediante endodoncia, sometiendolos a un seguimiento de 7 a 37 meses (media: 21 +- 9 meses). Los dientes se clasificaron inicialmente segun el tejido residual disponible para restaurar el munon dental con o sin un perno. A continuacion, se adjudicaron aleatoriamente los dientes al grupo de estudio 1 (pernos de fibra de vidrio prefabricados), al grupo de estudio 2 (pernos de fibra de vidrio hechos a medida) o al grupo de estudio 3 (munones de composite sin pernos). El grupo de control consistio en pernos y munones de una aleacion de oro. Todos los pernos/munones fueron recubiertos con coronas unitarias totalmente ceramicas. Los fracasos se consideraron absolutos, en caso de fracturas radiculares o fracturas irreparables de los pernos/munones, o relativos, en caso de perdida de retencion del perno o fracturas reparables del munon. Para todo el conjunto de datos, se elaboraron las curvas de curso de vida de exito y de probabilidad de supervivencia, corregidas por grupos. Resultados: La tasa de visitas de seguimiento a los 3 anos fue del 97,1%. Los fracasos absolutos consistieron en dos fracturas radiculares y un fracaso endodoncico, mientras que los fracasos relativos incluyeron tres casos de perdida de la retencion de perno/munon y una fractura del perno. Debido al escaso numero de acontecimientos, no se realizaron test estadisticos. Las probabilidades de exito y supervivencia del conjunto de todos los grupos a los 3 anos ascendieron al 91,7% y el 97,2%, respectivamente. Conclusiones: Despues de un seguimiento de hasta 3 anos, tanto los sistemas de perno y munon de oro colado como de fibra composite se comportaron bien clinicamente. Se precisan periodos de seguimiento mas prolongados para detectar posibles diferencias significativas. Protesis Estomatologica 2012;2:115-124.

PURPOSE:This controlled clinical trial aimed to compare the 3-year outcomes of glass fiber posts and composite cores with gold alloy-based posts and cores for the restoration of endodontically treated teeth.MATERIALS AND METHODS:One hundred forty-four patients in need of 205 restorations on endodontically treated teeth were selected and followed for 7 to 37 months (mean: 21 ± 9 months). The teeth were primarily stratified based on the remaining tissue available to restore the tooth core with or without a post. Then, randomization allocated the teeth to either test group 1 (prefabricated glass fiber posts), test group 2 (custom-made glass fiber posts), or test group 3 (composite cores without posts). The control group consisted of gold alloy-based posts and cores. All posts/cores were covered with all-ceramic single crowns. Failures were either absolute, such as root fractures or irreparable fractures of the post/core, or relative, such as loss of post retention or reparable fractures of the core. Success and survival probability lifetime curves, corrected for clustering, were drawn for the entire data set.RESULTS:The recall rate at 3 years was 97.1%. Absolute failures consisted of two root fractures and one endodontic failure, while relative failures included three instances of retention loss of the post/core and one post fracture. Because of the low number of events, no statistical tests were performed. The success and survival probabilities over all groups together at 3 years amounted to 91.7% and 97.2%, respectively.CONCLUSIONS:After being followed for up to 3 years, both cast gold and composite post and core systems performed well clinically. Longer follow-up times are needed to detect possible significant differences. Int J Prosthodont 2011;24:363-372.

The relatively low elastic modulus of fiber posts reduces the risk of root fracture, but it also decreases composite core stabilization. To compensate for the lack of rigidity, larger post sizes can be necessary when restoring crownless teeth that have significant internal destruction of the root canal. This study evaluated the effectiveness of fiber posts with different emerging diameters and shapes on composite core stabilization as measured by fracture strength testing. Fracture strengths ranged from 262.6 ± 81 N to 422.8 ± 56 N. A one-way ANOVA test showed that fracture strength was affected by type of post (p<0.0001); single-tapered posts were weaker than double-tapered posts. Pearson's linear correlation test showed that the fracture strength results appear to have a direct correlation to the emerging diameter of the post (p<0.0001; r(2)=0.6191). The emerging diameter of fiber posts is important to stabilize the core. When restoring crownless teeth, it is advisable to use fiber posts with large emerging diameters; no additional preparation of the internal root dentin is necessary to enlarge the post diameter.

Objectives. To evaluate the effect of different factors on the push-out bond strength of glass fiber posts luted in simulated (standard) root canals using different composite cements.Methods. Three types of glass-fiber root-canal posts with a different matrix, namely an epoxy resin (RelyX post, 3M ESPE), a proprietary composite resin (FRC-Plus post, Ivoclar-Vivadent), and a methacrylate resin (GC post, GC), and three types of composite cements, namely an etch-and-rinse Bis-GMA-based (Variolink II, Ivoclar-Vivadent), a self-etch 10-MDP-based (Clearfil Esthetic Cement, Kuraray) and a self-adhesive (RelyX Unicem, 3M ESPE) cement, were tested. Posts were either left untreated (control), were treated with silane, or coated with silicated alumina particles (Cojet system, 3M ESPE). Posts were inserted up to 9-mm depth into composite CAD-CAM blocks (Paradigm, 3M ESPE) in order to solely test the strength of the cement-post interface, while excluding interference of the cement-dentin interface. After 1-week storage at 37 degrees C, three sections (coronal, middle, apical) of 2-mm thickness were subjected to a push-out bond-strength test.Results. All three variables, namely the type of post, the composite cement and the post-surface pre-treatment, were found to significantly affect the push-out bond strength (p < 0.001). Regarding the type of post, a significantly lower push-out bond strength was recorded for the FRC-Plus post (Ivoclar-Vivadent); regarding the composite cement, a significantly higher push-out bond strength was recorded for the self-adhesive cement Unicem (3M ESPE); and regarding the post-surface treatment, a significantly higher push-out bond strength was recorded when the post-surface was beforehand subjected to a Cojet (3M ESPE) combined sandblasting/silicatization surface pre-treatment. Many interactions between these three variables were found to be significant as well (p < 0.001). Finally, the push-out bond strength was found to significantly reduce with depth from coronal to apical.Significance. Laboratory testing revealed that different variables like the type of post, the composite cement and the post-surface pre-treatment may influence the cement-post interface, making clear guidelines for routine clinical practice hard to define. Further long-term durability testing may help to clarify, and should therefore be encouraged. (C) 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.