Endocrown: una alternativa rehabilitadora a las restauraciones rígidas totales clásicas / Endocrown: a rehabilitative alternative to

La restauración ideal en los dientes tratados endodónticamente (DTE) ha sido un tema controversial y ampliamente discutido en la literatura odontológica. El alto índice de fracasos en los dientes endodónticos se asocia principalmente a la falta de un adecuado sellado coronario, motivo por el cual la restauración post endodóntica cumple un papel fundamental. Los propios tejidos del DTE constituyen el refuerzo más importante de la pieza dentaria. La odontología considerada hoy en día como ideal es la mínimamente invasiva. A su vez la restauración de elección deberá ser aquella que respete mayor cantidad de tejido remanente a la hora de seleccionar la restauración coronaria. Se deberá considerar la cantidad y la calidad del remanente dentario sano, como los requisitos funcionales de cada pieza en particular. Si bien existen diversos tipos de restauraciones que podrían rehabilitar un DTE, en este trabajo sólo nos referiremos a las de inserción rígida, específicamente a las endo-onlays, también denominadas endocrowns (AU)

Novas perspectivas para reabilitação de dentes tratados endodonticamente / Novel perspectives for the rehabilitation of endodontically treated teeth

Vários fatores podem influenciar o desempenho clínico de dentes com tratamento endodôntico (DTE). Além disso diversas são as opções restauradoras indicadas em respeito a este cenário, em especial com o notório avanço de novas técnicas e tecnologias para uso clínico. Dentre estas corriqueiramente envolvem-se o uso de restaurações diretas (confeccionadas com resina composta), pinos metálicos ou de fibra de vidro, pinos pré-fabricados ou fresados, assim como restaurações indiretas compostas de coroas cerâmicas, inlays, onlays ou endocrowns; sempre com o foco na reabilitação funcional e estética do caso em tela. Neste trabalho, através de uma revisão narrativa, foram expostos conceitos relativos às modalidades restauradores que se advêm do uso de novas tecnologias na reabilitação de dentes tratados endodonticamente(AU)

Several factors may influence the clinical performance of endodontically treated teeth (ETT). In addition, there are several restorative options indicated regarding this scenario, especially with the notable advance of new techniques and technologies for clinical use. These routinely involve the use of direct restorations (made of composite resin), metal or fiberglass posts, prefabricated or milled posts, as also indirect restorations composed of ceramic crowns, inlays, onlays or endocrown; always focusing on functional and aesthetic rehabilitation of the case in hand. In this study, through a narrative review, concepts related to the restorative modalities that were introduced with the use of new technologies in the rehabilitation of endodontically treated teeth were discussed(AU)

Pathologic root migration secondary to vertical root fracture and full-coverage crowns: a report of 3 cases.

Occasionally, tooth fractures may demonstrate exaggerated pathologic root migration (PRM), often resulting in tooth loss. The early propagation of the root fracture may not be readily identifiable through clinical inspection and conventional radiographic imaging. Ultimately, increased root separation, isolated deep periodontal probing depth, and characteristic radiolucent changes may facilitate the diagnosis. This article describes 3 patients with unusual presentations of PRM in endodontically treated teeth restored with full-coverage crowns. One case illustrates the use of cone beam computed tomography for restorative assessment following root separation. Although it is efficacious to place crowns on most posterior endodontically treated teeth to maintain structural integrity, patients may remain at risk for catastrophic PRM and tooth loss. Timely extraction of teeth with hopeless PRM may minimize underlying bone resorption and the need for osseous regenerative procedures, ultimately improving the dental implant recipient site.

Metal endocrown approach for a maxillary second molar: a novel technique.

Nonvital teeth with repeated restoration failures are particularly challenging to dental practitioners. This case report describes the fabrication of a novel cast metal endocrown following the failure of 2 different types of restorations (post and core-retained crown and ceramic endocrown). This approach was used to preserve the tooth and avoid extraction.

Evaluation of fiber posts vs metal posts for restoring severely damaged endodontically treated teeth: a systematic review and meta-analysis.

OBJECTIVES: This review was undertaken to answer a controversial clinical question with high-quality evidence: When severely damaged teeth are restored, which type of post (metal or fiber) demonstrates superior clinical performance? DATA SOURCES: The meta-analysis was conducted according to the guidelines in the Cochrane handbook. Electronic databases (MEDLINE, EMBASE, CENTRAL) and gray literatures were screened up to January 2018. Only randomized controlled trials (RCTs) with follow-up of at least 3 years were included. The quality of included studies was assessed by the Cochrane Collaboration's tool. Meta-analysis compared survival, success, post debonding, and root fracture incidence of teeth restored with fiber and metal posts. The GRADE system (Grading of Recommendations, Assessment, Development and Evaluations) was used to assess the strength of the evidence. Of 1,511 records, 14 full texts were obtained. Only four RCTs with follow-up times of 3 to 7 years met the selection criteria. The methodologic quality of included RCTs was low risk of bias. Fiber posts presented significantly higher survival rates than did metal posts (RR 0.57, 95% CI: 0.33 to 0.97, P = .04), while no difference was observed in success rates, post debonding rates, or root fracture rates. The GRADE assessment indicated a high quality of evidence for survival rates and a moderate quality for success rates. CONCLUSION: It was concluded that fiber posts displayed higher medium-term (3 to 7 years) overall survival rates than did metal posts when used in the restoration of endodontically treated teeth with no more than two coronal walls remaining.

[Advantages and disadvantages of endocrown restorations of endodontically treated teeth with large coronal destruction].

The strength of endodontically treated teeth were reduced apparently because of structural damage, therefore further reduction of healthy tissue should be avoided as much as possible in restoration. Endocrown made by chair-side CAD/CAM is some kind of minimal invasive restoration, and the retention of restoration is achieved by reliable bonding and macromechanial retention forces. Without post preparation, the root structure could be resevered. Following the indications and use of biomechanical dentin-like CAD/CAM materials could reduce the adverse effect of tensile stress on cervical part.

Survival of extensively damaged endodontically treated incisors restored with different types of posts-and-core foundation restoration material.

STATEMENT OF PROBLEM: Which post-and-core combination will best improve the performance of extensively damaged endodontically treated incisors without a ferrule is still unclear. PURPOSE: The purpose of this in vitro study was to investigate the restoration of extensively damaged endodontically treated incisors without a ferrule using glass-ceramic crowns bonded to various composite resin foundation restorations and 2 types of posts. MATERIAL AND METHODS: Sixty decoronated endodontically treated bovine incisors without a ferrule were divided into 4 groups and restored with various post-and-core foundation restorations. NfPfB=no-ferrule (Nf) with glass-fiber post (Pf) and bulk-fill resin foundation restoration (B); NfPfP=no-ferrule (Nf) with glass-fiber post (Pf) and dual-polymerized composite resin core foundation restoration (P); NfPt=no-ferrule (Nf) with titanium post (Pt) and resin core foundation restoration; and NfPtB=no-ferrule (Nf) with titanium post (Pt) and bulk-fill resin core foundation restoration (B). Two additional groups from previously published data from the same authors (FPf=2mm of ferrule (F) and glass-fiber post (Pf) and composite resin core foundation restoration; and NfPf=no-ferrule (Nf) with glass-fiber post (Pf) and composite resin core foundation restoration), which were tested concomitantly and using the same experimental arrangement, were included for comparison. All teeth were prepared to receive bonded glass-ceramic crowns luted with dual-polymerized resin cement and were subjected to accelerated fatigue testing under submerged conditions at room temperature. Cyclic isometric loading was applied to the incisal edge at an angle of 30 degrees with a frequency of 5 Hz, beginning with a load of 100 N (5000 cycles). A 100-N load increase was applied every 15000 cycles. The specimens were loaded until failure or to a maximum of 1000 N (140000 cycles). The 6 groups (4 groups from the present study and 2 groups from the previously published study) were compared using the Kaplan-Meier survival analysis (log-rank post hoc test at α=.05 for pairwise comparisons). RESULTS: None of the tested specimen withstood all 140 000 cycles. All specimens without a ferrule were affected by an initial failure phenomenon (wide gap at the lingual margin between the core foundation restoration/crown assembly and the root). NfPfP, NfPt, and NfPtB had similar survival (29649 to 30987 mean cycles until initial failure). NfPfB outperformed NfPt and NfPtB. None of the post-and-core foundation restoration materials were able to match the performance of the ferrule group FPf (72667 cycles). In all groups, 100% of failures were catastrophic. CONCLUSIONS: The survival of extensively damaged endodontically treated incisors without a ferrule was slightly improved by the use of a fiber post with a bulk-fill composite resin core foundation restoration. However, none of the post-and-core techniques was able to compensate for the absence of a ferrule. The presence of the posts always adversely affected the failure mode.

Prefabricated Laser Sintered Composite Veneers and Occlusal Vertical Dimensions: Case Reports.

AIM: To highlight the concept of prefabricated veneers and occlusal vertical dimension (OVD) and series of case report using edelweiss prefabricated veneer system. BACKGROUND: Edelweiss prefabricated veneer system presents a concept of biofunctional esthetics using laser sintered composite resins. The system's biofunctionality and versatile area of application combined with its time and cost saving procedure make the Edelweiss veneer and occlusion system a sound investment for the future. CASE DESCRIPTION: A series of case reports treated using prefabricated laser sintered composite veneer system has been presented. CONCLUSION: Prefabricated veneer is a milestone in operative dentistry, as it contributes tremendously to direct composite application, helping a larger number of our patients to receive esthetic restorations that are more conservative and affordable. CLINICAL SIGNIFICANCE: The prefabricated composite veneering technique provides a minimally invasive, chair-side technique for esthetic and full mouth rehabilitation.

Post-Retained Single Crowns versus Fixed Dental Prostheses: A 7-Year Prospective Clinical Study.

Biomechanical integrity of endodontically treated teeth (ETT) is often compromised. Degree of hard tissue loss and type of final prosthetic restoration should be carefully considered when making a treatment plan. The objective of this prospective clinical trial was to assess the influence of the type of prosthetic restoration as well as the degree of hard tissue loss on 7-y clinical performance of ETT restored with fiber posts. Two groups ( n = 60) were defined depending on the type of prosthetic restoration needed: 1) single unit porcelain-fused-to-metal (PFM) crowns (SCs) and 2) 3- to 4-unit PFM fixed dental prostheses (FDPs), with 1 healthy and 1 endodontically treated and fiber post-restored abutment. Within each group, samples were divided into 2 subgroups ( n = 30) according to the amount of residual coronal tissues after abutment buildup and final preparation: A) >50% of coronal residual structure or B) equal to or <50% of coronal residual structure. The clinical outcome was assessed based on clinical and intraoral radiographic examinations at the recalls after 6, 12, 24, 36, 48, and 84 mo. Data were analyzed by Kaplan-Meier log-rank test and Cox regression analysis ( P < 0.05). The overall 7-y survival rate of ETT restored with fiber post and either SCs or FDPs was 69.2%. The highest 84-mo survival rate was recorded in group 1A (90%), whereas teeth in group 2B exhibited the lowest performance (56.7% survival rate). The log-rank test detected statistically significant differences in survival rates among the groups ( P = 0.048). Cox regression analysis revealed that the amount of residual coronal structure ( P = 0.041; hazard ratio [HR], 2.026; 95% confidence interval [CI] for HR, 1.031-3.982) and the interaction between the type of prosthetic restoration and the amount of residual coronal structure ( P = 0.024; HR, 1.372; 95% CI for HR, 1.042-1.806) were statistically significant factors for survival ( ClinicalTrials.gov NCT01532947).

Different Patterns of Restoration Provision Between Initial Endodontic Treatment and Retreatment: A Retrospective Clinical Study.

PURPOSE: The aim of this study was to investigate the relationship between type of endodontic treatment and choice of definitive restoration and to show the prevalence of endodontic treatment options according to patient age and type of tooth. MATERIALS AND METHODS: Data were collected from the archive system of the School of Dentistry, National and Kapodistrian University of Athens in Athens, Greece. The sample included endodontically treated teeth being restored definitively at the time of data collection. RESULTS: Statistically significant difference was found regarding the type of restoration between initial endodontic treatments and retreatments (P < .001). CONCLUSION: Endodontic retreatment seemed to have a significant effect on the choice of definitive restoration of the tooth.

Single crowns versus conventional fillings for the restoration of root-filled teeth.

BACKGROUND: Endodontic treatment involves removal of the dental pulp and its replacement by a root canal filling. Restoration of root filled teeth can be challenging due to structural differences between vital and non-vital root-filled teeth. Direct restoration involves placement of a restorative material e.g. amalgam or composite, directly into the tooth. Indirect restorations consist of cast metal or ceramic (porcelain) crowns. The choice of restoration depends on the amount of remaining tooth, and may influence durability and cost. The decision to use a post and core in addition to the crown is clinician driven. The comparative clinical performance of crowns or conventional fillings used to restore root-filled teeth is unknown. This review updates the original, which was published in 2012. OBJECTIVES: To assess the effects of restoration of endodontically treated teeth (with or without post and core) by crowns versus conventional filling materials. SEARCH METHODS: We searched the following databases: the Cochrane Oral Health Group's Trials Register, CENTRAL, MEDLINE via OVID, EMBASE via OVID, CINAHL via EBSCO, LILACS via BIREME. We also searched the reference lists of articles and ongoing trials registries.There were no restrictions regarding language or date of publication. The search is up-to-date as of 26 March 2015. SELECTION CRITERIA: Randomised controlled trials (RCTs) or quasi-randomised controlled trials in participants with permanent teeth that have undergone endodontic treatment. Single full coverage crowns compared with any type of filling materials for direct restoration or indirect partial restorations (e.g. inlays and onlays). Comparisons considered the type of post and core used (cast or prefabricated post), if any. DATA COLLECTION AND ANALYSIS: Two review authors independently extracted data from the included trial and assessed its risk of bias. We carried out data analysis using the 'treatment as allocated' patient population, expressing estimates of intervention effect for dichotomous data as risk ratios, with 95% confidence intervals (CI). MAIN RESULTS: We included one trial, which was judged to be at high risk of performance, detection and attrition bias. The 117 participants with a root-filled, premolar tooth restored with a carbon fibre post, were randomised to either a full coverage metal-ceramic crown or direct adhesive composite restoration. None experienced a catastrophic failure (i.e. when the restoration cannot be repaired), although only 104 teeth were included in the final, three-year assessment. There was no clear difference between the crown and composite group and the composite only group for non-catastrophic failures of the restoration (1/54 versus 3/53; RR 0.33; 95% CI 0.04 to 3.05) or failures of the post (2/54 versus 1/53; RR 1.96; 95% CI 0.18 to 21.01) at three years. The quality of the evidence for these outcomes is very low. There was no evidence available for any of our secondary outcomes: patient satisfaction and quality of life, incidence or recurrence of caries, periodontal health status, and costs. AUTHORS' CONCLUSIONS: There is insufficient evidence to assess the effects of crowns compared to conventional fillings for the restoration of root-filled teeth. Until more evidence becomes available, clinicians should continue to base decisions about how to restore root-filled teeth on their own clinical experience, whilst taking into consideration the individual circumstances and preferences of their patients.

Remaining coronal dentin and risk of fiber-reinforced composite post-core restoration failure: a meta-analysis.

PURPOSE: The amount of coronal residual structure has been recognized as critical to the survival probability of pulpless teeth. The aim of this study was to analyze whether and how coronal dentin loss would affect the failure rate of fiber-reinforced composite (FRC) post-core restorations. MATERIALS AND METHODS: Eligible studies were searched in PubMed, Cochrane Library, Embase, and China National Knowledge Infrastructure databases from their inception through April 2014. The risk ratio with 95% confidence interval (CI) was estimated using the Mantel and Haenszel method. RESULTS: Five studies were included in this meta-analysis. The risk ratio for coronal wall absence was 2.73 (95% CI: 1.48-5.03). The risk ratio for ferrule absence was 1.94 (95% CI: 0.57-6.54). CONCLUSIONS: This meta-analysis of the limited studies available suggested that coronal wall absence might increase the risk of FRC post-core restoration failure, while the role of ferrule effect is still not entirely understood.

Influencia de la calidad de restauración coronal en el pronóstico de dientes tratados endodónticamente / Influence of the quality of coronal restoration in the prognosis of endodontically treated teeth

Introducción: la restauración de dientes tratados endodónticamente es compleja y controversial y su pronóstico está directamente relacionado con la calidad del tratamiento endodóntico y la restauración definitiva, lo que debe asegurar un correcto sellado marginal para evitar la filtración coronaria y el posterior fracaso endodóntico. Se ha demostrado que la aplicación de un inadecuado protocolo en el tratamiento del conducto posendodoncia podría causar fracasos por el arrastre y filtración de microorganismos que se encuentran en la cavidad oral y sus productos derivados hacia la porción apical de la raíz. Muchos factores a lo largo de las fases del tratamiento endorrestaurador influyen directamente en su pronóstico: calidad del sellado apical, cantidad de gutapercha remanente, desobturación temprana o tardía, capacidad de sellado de la restauración temporal o definitiva, desinfección del conducto, entre otras. Objetivo: actualizar a profesionales acerca de los parámetros clínicos a tener en cuenta en la rehabilitación de dientes tratados endodónticamente, que implica realizar todos los procedimientos bajo un estricto protocolo y una adecuada cadena aséptica para evitar contaminación bacteriana. Métodos: la búsqueda bibliográfica se llevó a cabo utilizando los siguientes términos: restauración coronal, microfiltración, desobturación radicular, calidad y estado endondóntico; se seleccionaron los artículos que evaluaron el efecto de la calidad de la obturación radicular, la restauración coronal o ambas, en el éxito de una endodoncia. Cincuenta y tres artículos fueron identificados y revisados por dos investigadores. Los datos fueron obtenidos de bases de datos como: Hinari, Sciencedirect, Wiley interscience, SciELO y fuentes indexadas nacionales e internacionales con criterios predeterminados. Resultados: de acuerdo con los conceptos de control de infección, todos los instrumentos y el material colocado dentro del conducto radicular deben ser estériles. La prevención de la microfiltración es un aspecto importante en el éxito del diente tratado endodónticamente, que debe ser rehabilitado en un período corto entre la endodoncia y la restauración definitiva, para reducir de forma considerable la contaminación. Conclusiones: sobre la base de la evidencia disponible se puede afirmar que, independiente de la técnica o material de obturación endodóntica o tipo de restauración, es indispensable mantener la cadena aséptica a lo largo de todo el tratamiento, lo que sumado a una adecuada restauración definitiva favorece la conservación del sellado a nivel coronal y apical que minimice al máximo el riesgo de contaminación bacteriana(AU)

Introduction: the restoration of endodontically treated teeth is complex and controversial, and its prognosis is directly related to the quality of endodontic treatment and the final restoration, which should ensure a proper marginal seal to prevent coronary filtration and avoid subsequent endodontic failure. It has been shown that to handle badly a post-endodontic canal could cause failures for skiddingand microorganisms filtration which are found in the oral cavity and derived products to the apical portion of the root. Many factors during the endo-restorer treatment phase directly influence in its prognosis: apical sealant quality, residual amount of gutta-percha, early or late desobturation, sealing ability of the temporary or permanent restoration, disinfection canal among other. Objective: the purpose is to update professionals about clinical parameters to take into account in the rehabilitation of endodontically treated teeth, for this it is necessary to follow all the procedures under strict protocol and proper aseptic chain to prevent bacterial contamination. Methods: the literature search was conducted using the following terms coronal restoration, microfiltration, desobturation root, quality and endodontic status, articles that evaluated the effect of the quality of the root filling and coronal restoration or both in the success of a root canal were selected. Fifty-three articles were identified and reviewed by two investigators. Data were obtained from databases such as: Hinari, Science Direct, Wiley interscience, and indexed sources national and indexed sources national and international to predetermined criteria. Results: according to the concepts of infection control, all instruments and equipment placed inside the root canal must be sterile. Prevention of microfiltration is an important success endodontically treated tooth appearance, which must be rehabilitated in a short period of time between endodontics and final restoration to significantly reduce contamination. Conclusions: based on the available evidence, the results say that regardless of the technical or endodontic filling material or type of temporary or permanent restoration, is essential to maintain the aseptic chain along the whole treatment which added to an adequate final restoration promote the conservation sealed coronal y apical level to reduce the risk of bacterial(AU)

A technique to ensure the reproducibility of a cast post and core.

The post-and-core pattern duplication technique is a simple, cost-effective, and accurate method of ensuring the reproducibility of a cast post and core. An acrylic resin pattern is fabricated for an endodontically treated tooth. The post portion of the pattern is duplicated with a polyvinyl siloxane impression material in the lower compartment of a container. The core portion is then duplicated with a polyether impression material in the upper compartment. After the original pattern has been retrieved, the duplicate resin pattern is fabricated in the provided space. This technique will improve efficiency if damage or loss of the pattern or the actual cast post and core occurs.

Effect of dentin conditioning on bond strength of fiber posts and dentin morphology: a review.

PURPOSE: Post and core systems are commonly used to restore endodontically treated teeth. A durable bond between fiber posts and dentin contributes to the success of the restorative treatment. Different irrigants are used during post space preparation and various studies have investigated the effects of these chemical agents on bond strength and dentin morphology. METHODS: The MEDLINE-PubMed, Cochrane, and SCOPUS databases were searched for appropriate papers addressing the effects of irrigants on bonding of fiber posts to dentin and on dentin morphology. Databases were searched from 2002 through 2012. The search was performed using a variety of keywords including fiber posts, bond strength, post space preparation, post space irrigation, and smear layer removal. RESULTS: Using multiple key words and different strategies, 68 publications were initially screened. The abstracts of these 68 publications were scanned for relevance, and 50 full-text articles were selected and read in detail. Thirty publications which discussed the effect of various intracanal irrigants on bond strengths of fiber posts and dentin morphology were incorporated in this review. Following review of all relevant papers, it can be concluded that bond strengths of fiber posts to radicular dentin can be affected by the irrigants used and that various irrigants affect different types of resin cements differently.

Fabricating a fiber-reinforced post and zirconia core with CAD/CAM technology.

This article describes a technique for overcoming the limitations of dental scanners in imaging post spaces by using a single fiber-reinforced post and computer-aided design and computer-aided manufacturing (CAD/CAM) technology, thereby eliminating the need for a 'Scan Post' and the post and core module in the CAD. This technique produces an anatomically correct core and ensures the correct thickness of crown restorations.

Restauración postendodóntica en conductos radiculares amplios / Postendodontic restoration in wide root canals

Gracias al auge que tiene la implantología en la actualidad y al aumento del porcentaje de éxitos de la misma, los clínicos ahora, antes que intentar prolongar la vida del órgano dental afectado en la cavidad oral, prefieren realizar una extracción. Siguiendo los cánones de la odontología conservadora, ponemos a consideración una técnica que puede ayudar, como última opción, a mantener dientes tratados endodónticamente, antes de llevar a cabo su extracción. Esta técnica ya ha sido propuesta y debidamente investigada por algunos autores. Esta propuesta se aplica a dientes con conductos radiculares amplios, los cuales se han debilitado por restauraciones deficientes, desmineralización de la dentina, por filtraciones en la corona y poste radicular o simplemente conductos amplios en pacientes de corta edad. Tenemos la firme convicción que no podremos garantizar la permanencia de un órgano dental en la cavidad oral, pero sí podemos intentar alargarle su permanencia en el alvéolo. Por eso damos a conocer la técnica de rellenar previamente el conducto con ionómero de vidrio de alta densidad. Este material dental tiene un módulo de elasticidad similar a la dentina, lo que aumenta su integridad y mejora la técnica al colocar un poste con menor cantidad de cemento o al emplear un poste demasiado amplio.

With the boom in implantology in today’s dentistry and its undeniable success, many clinicians now prefer to perform an extraction rather than extend the life of the tooth. According to the standards of conservative dentistry, we propose a technique that could be useful as a final option before resorting to an extraction, for teeth on which a root canal has been performed in the past. This type of treatment has been described and properly researched by several authors. It can be applied in wide root canals that have been weakened by poor restorations or demin-eralization of the dentin caused by a filtration through the crown, or simply in young patients with wide canals. Whilst we cannot guarantee that a tooth be preserved indefinitely, we do believe we can make it last longer. For this reason, we describe the technique that involves first filling the root canal with high-density glass ionomer —a dental material that has a modulus of elasticity similar to that of dentin—, which increases its integrity. This makes for an improved technique when posts are inserted as less luting cement is used and eliminates the need to use a wider post.

Effect of the crown, post, and remaining coronal dentin on the biomechanical behavior of endodontically treated maxillary central incisors.

STATEMENT OF PROBLEM: It is unclear how the amount of remaining coronal dentin and the type of post and core rehabilitation affect the strain, stress distribution, and fracture resistance of endodontically treated teeth. PURPOSE: The purpose of this study was to evaluate the effects of the type of post, type of crown, and the amount of remaining coronal dentin on the biomechanical behavior of endodontically treated teeth. MATERIAL AND METHODS: The investigation was conducted by using 3-dimensional finite element analysis and laboratory tests. Three-dimensional models of a maxillary central incisor were generated: without remaining coronal dentin, with 1.0 mm of remaining coronal dentin, with 2.0 mm of remaining coronal dentin, and restored with a glass-fiber post or a cast post and core in combination with a metal crown or an alumina-reinforced ceramic crown. The results were evaluated by using the von Mises criterion and Maximum Principal Stress. One hundred twenty bovine incisors were selected and divided into 12 treatment groups (n=10). Specimens were loaded at a 135-degree angle to perform strain measurements and were then loaded until fracture. The strain and fracture resistance results were analyzed with 3-way analysis of variance and the Tukey honestly significant difference test (α=.05). RESULTS: The alumina-reinforced ceramic crowns and metal crowns associated with a glass-fiber post showed a homogeneous stress distribution within the root. The cast post and core concentrated higher stresses at the post-dentin interface. Significant differences were found among the mean fracture resistance values for all groups (P<.05). The presence of 2.0 mm of coronal remnants resulted in lower strains and higher fracture resistance for both the metal and ceramic crowns. Roots restored with glass-fiber posts exhibited more favorable fractures. CONCLUSIONS: The presence of 2 mm of remaining coronal dentin improved the mechanical behavior of the endodontically treated maxillary incisors. Teeth restored with glass-fiber posts and composite resin cores showed a homogeneous stress distribution within the root dentin.

Effect of post length and type of luting agent on the dislodging time of metallic prefabricated posts by using ultrasonic vibration.

INTRODUCTION: The purpose of this study was to determine and compare the times needed to dislodge prefabricated titanium posts of different luting lengths with various cements. METHODS: Eighty-one intact extracted, single-canal human teeth were selected and endodontically treated. Specimens were randomly divided into 9 groups, which were arranged according to the post space length (5, 7, and 9 mm) and cement type (zinc phosphate, glass ionomer, and resin cement). Titanium posts were cemented into the post spaces, and after 1 week of storage they were subjected to ultrasonic vibration. The dislodging times were recorded and analyzed by using the Kruskal-Wallis and Mann-Whitney tests (P < .05). RESULTS: A significant difference was observed between the dislodging times on the basis of post length and luting agent (P < .001). There were also significant differences between different cements luted with the same length posts (P < .001). Significant differences were observed between the 5-mm posts and both the 7- and 9-mm posts for each cement, but the differences between the 7-mm and 9-mm posts were not significant (P < .05). CONCLUSIONS: Changes in the cement type and post length alter the time required to dislodge a post with an ultrasonic device.