Estudio microtomográfico de la porosidad en la cementación de postes de fibra / Microtomographic study of the porosity in the cementation of fiber posts

El objetivo de este estudio fue evaluar con microto-mografía los poros existentes entre el cemento de resina, poste de fibra y paredes del conducto en los distintos tercios radiculares en premolares inferio-res. Se utilizaron 15 premolares inferiores unirra-diculares humanos recientemente extraídos. Se les realizó el tratamiento endodóntico, y se obturó con conos de gutapercha y cemento endodóntico a base de resina. Una vez desobturados se procedió a la ce-mentación de los postes. Cada muestra se posicionó en un accesorio personalizado y se escaneó utilizan-do un Microtomógrafo. Con el software CTAn v.1.12 (Bruker-microCT) se analizaron las microtomografías para obtener el volumen de interés (VOI) que permi-tió calcular el área de superficie (mm2) y volumen de cada poro (mm3) entre la dentina y el poste a nivel co-ronal, medio y apical. Los datos fueron analizados me-diante las pruebas estadísticas de Friedman o ANOVA de medidas repetidas. El volumen de los poros entre los tres tercios radiculares mediante la prueba de Friedman, encontró una diferencia global significativa (F = 30,00; p < 0,05). El tercio en donde los poros presentaron un mayor volumen (mm3) fue el tercio coronal (mediana: 0,29250), seguido por los tercios medio (mediana: 0,03200), y apical (mediana: 0,00140). La comparación de la superficie de los poros entre los 3 tercios brindó un resultado análogo al de la comparación del volumen. La mayor superficie (mm2) correspondió al tercio coronal (media ± DE = 1,66377 ± 0,27175), seguido por los tercios medio (media ± DE = 1,16210 ± 0,20343) y apical (media ± DE = 0,41074 ± 0,12641). La microtomografía permitió realizar un análisis cuantitativo y cualitativo de los poros en toda la muestra, sin deterioro de la misma. Se puede concluir que el tercio coronal presenta más poros que el tercio apical con la técnica de cementación utilizada. En cuanto a la superficie y volumen de los poros, los resultados encontrados son similares a los reporta-dos por diversos autores (AU)

The aim of this study was to evaluate with microtomography the existing pores between the resin cement, fiber post and canal walls in the different in thirds of the canal, in single-root lower premolars. Fifteen recently extracted human single root lower premolars were used, endodontically treated, and filled with gutta-percha cones and resin-based endodontic cement. Once unfilled, the posts were cemented. Each sample was positioned on a custom fixture and scanned using a Microtomograph. Each sample was evaluated using CTAn v.1.12 software (Bruker-microCT) to obtain the surface area (mm2), volume of interest (mm3) of each pore between dentin and post at the coronal, middle and apical levels. Data were analyzed using Friedman's tests or repeated measures ANOVA. The volume of the pores between the three root thirds using the Friedman test, a significant global difference was found (F = 30.00; p < 0.05). The third in which the pores presented a greater volume (mm3) was the coronal third (means: 0.29250), followed by the middle (means: 0.03200) and apical (means: 0.00140) thirds. The comparison of the pore surface between the 3 thirds gave an analogous result to that of the volume comparison. The largest surface area (mm2) corresponded to the coronal third (mean ± SD 1.66377 ± 0.27175), followed by the middle (mean ± 1.16210 ± 0.20343) and apical (mean ± 0.41074 ± 0.12641) thirds.Microtomography allowed a quantitative and qualitative analysis of the pores in the entire sample without deterioration. It can be concluded that the coronal third has more pores than the apical third with the cementation technique used. Regarding the surface and volume of the pores, the results found are similar to those reported by various authors (AU)

Intermediate to Long-Term Follow-up of Cementing Liners into Well-Fixed Acetabular Components.

BACKGROUND: The cementation of a new liner into a well-fixed acetabular component is common during revision total hip arthroplasty (THA) for many indications, but most commonly for lack of a modern, compatible, highly cross-linked polyethylene (HXLPE) liner. However, little is known about the intermediate-term to long-term durability of this strategy. The purpose of this study was to evaluate the implant survivorship, risk of complications, clinical outcomes, and radiographic results of cementing a new HXLPE liner into a well-fixed acetabular component. METHODS: We retrospectively identified 323 revision THAs in which a nonconstrained HXLPE liner was cemented into a well-fixed acetabular component. The mean age at the time of the revision THA was 63 years, and 50% of patients were female. The most common indications for revision THA were polyethylene wear and osteolysis (48%), aseptic femoral loosening (35%), and hip instability (8%). The mean follow-up was 9 years. RESULTS: Polyethylene liner failure occurred in 11 cases (3%). In all cases, the cemented liner dissociated from the acetabular component. At 10 years, the survivorship free from any revision was 80% (95% confidence interval [CI], 75% to 84%) and the survivorship free from any reoperation was 77% (95% CI, 72% to 82%). The most common reason for re-revision was dislocation (45% of reoperations). A dislocation occurred in 17% of cases. Hips that underwent revision for instability were significantly more likely to dislocate compared with hips that underwent revision for liner wear (hazard ratio [HR], 2.3 [95% CI, 1.2 to 4.5]; p = 0.02). Elevated rim or face-changing liners were significantly more likely to dissociate than flat liners (HR, 9.0 [95% CI, 1.2 to 70.6]; p = 0.04). CONCLUSIONS: Cementation of a nonconstrained HXLPE liner into a well-fixed acetabular component during revision THA provided durable fixation with only a small number of failures at the cement interface (3%). Instability after this procedure remains a concern, but this is multifactorial in nature. These data support the continued use of this technique, when necessary, during revision THA. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Cementation: for better or worse? Interim results of a multi-centre cohort study using a fenestrated spiral blade cephalomedullary device for pertrochanteric fractures in the elderly.

INTRODUCTION: Cephallomedullary nail fixation is currently the most popular treatment for pertrochanteric fractures. Despite continuous improvement in implant design, fixation failures still occur in a concerning number of cases. This study aims to evaluate the effect of cement augmentation of the new-generation Trochanteric Femoral Nail Advanced (TFNA) perforated spiral blade on complications including fixation failure in the elderly population. MATERIALS AND METHODS: We retrospectively evaluated 107 patients aged 65 + treated for pertrochanteric fractures via TFNA between 2015 and 2019 based on whether cementation was used. Baseline demographics, fracture classifications, and reduction quality were compared. Patients with a follow-up of at least 6 months were analyzed for the primary outcome of fixation failure. All patients, regardless of loss to follow-up within 6 months, were analyzed for other complications including mortality. RESULTS: Seventy-six patients (47 cemented, 29 non-cemented) had a minimum follow-up of 6 months (mean 13 months). There were no statistically significant differences between the two treatment groups in terms of patient demographics, ASA or AO/OTA fracture classification, reduction quality, or length of follow-up. There was a lower rate of fixation failure in the cement-augmented (CA) group versus the non-cement-augmented (NCA) group (2.1% vs 13.8%; p = 0.047). No cut-out or cut-through was observed in the CA group. Seven patients had adverse intraoperative events, with a significantly higher rate of fixation failure in these patients (40% vs 2.8%; p = 0.00). There were no statistically significant differences in 30-day mortality (6.3% CA vs 4.3% NCA; p = 0.632) or 3-month mortality (9.5% CA vs 12.8% NCA; p = 0.589). CONCLUSIONS: Cementation of TFNA blades may decrease risk of fixation failure, however, the surgeon must be aware of potential complications such as cement leakage into the hip joint and be able to manage them as they arise.

Prótesis sobre implantes: ¿atornillada o cementada? / Implant supported prosthesis: screw retained or bonded?

El objetivo de este artículo es revisar la evidencia científica existente acerca de los tipos de retención protética fija sobre implantes: atornillada, cementada y cemento-atornillada. Fueron evaluadas sus ventajas y desventajas a fin de facilitar al clínico la elección del sistema de retención en el tratamiento rehabilitador con implantes. Si bien la evidencia científica no es concluyente, la prótesis atornillada presentaría más complicaciones técnicas, y las cementadas, más complicaciones biológicas. Por ello, las prótesis cemento-atornilladas podrían ser en la actualidad una opción de elección, por su versatilidad en la rehabilitación implanto-soportada, combinando las ventajas de cada tipo de retención (AU)

The objective of this article is to review the existing scientific evidence about the different types of retention of fixed prosthetic on implants: screwed, cemented and cement-screwed. The advantages and disadvantages of them were evaluated in order to facilitate the clinician's choice of the retention system in the rehabilitation treatment with implants. Although the scientific evidence is inconclusive, the screwed prosthesis would present more technical complications, while the cemented, more biological complications. Therefore, cement-screwed prostheses could be an option of choice, due to their versatility when rehabilitating an implant, combining the advantages of each type of retention (AU)

Microscopic evaluation of luting techniques for a fiber-reinforced post system.

This study assessed application techniques for cementation of fiber-reinforced posts (FRPs). The treatment groups were defined by FRP luting application techniques and included 5 groups of 10 simulated teeth each: 1, application of the cement on the post using a syringe; 2, application of the cement in the canal using a syringe; 3, application of the cement in the canal and on the post using a syringe; 4, application of the cement in the canal using a syringe/Lentulo spiral instrument; and 5, application of the cement in the canal using a syringe/Lentulo spiral and on the post using a syringe. A dual-curing, automixing cement was utilized as the luting agent. For each group, the canals were endodontically prepared using tapered hand and rotary files and obturated, and then the FRPs were cemented in place. All specimens were encased in acrylic and sectioned at 2 locations, creating 4 viewing surfaces: coronal (C), middle coronal (MC), middle apical (MA), and apical (A). The surfaces were examined using a stereomicroscope and digitized computer software. The efficacy of each FRP application technique was determined in terms of percentages of cement void area by group and by surface. Group 1 exhibited a significantly (P < 0.05) greater overall percentage of cement void area than all other groups. Group 2 exhibited the smallest overall percentage of void area, although the difference was not always statistically significant. There were no statistically significant differences among the surfaces in cement void area (P > 0.05) when the areas of the different groups were combined. The most efficacious cementation method was the injection of cement into the canal space with a syringe, while the use of a Lentulo spiral instrument was found to be an unnecessary step.

A technique to facilitate ceramic veneer cementation.

This report describes a technique to facilitate ceramic veneer cementation. By stabilizing a ceramic veneer in its fully seated position with miniature wooden spring clips before resin polymerization, excess luting resin cement can be removed from ceramic veneer margins without the risk of veneer dislodgement or fracture.

Profundidad de curado e interfaces en medios cementantes para incrustaciones de resina / Curing depth and interphases in luting agents for resin inlays

Los medios de fijación a base de resinas compuestas para cementado, no son más que una resina compuesta fluida, que contiene un menor porcentaje de relleno inorgánico. Es por esto que en la actualidad, algunos autores plantean el uso de resina compuesta de restauración como medio de fijación de restauraciones indirectas (inlay fabricado en cerómero). Dicha resina debe ser fluidificada con calor (50ºC), para posteriormente ser fotoactivada por un tiempo adecuado. Asimismo, como se trata de un material cuya reacción de polimerización sólo es activada por luz, surge la pregunta de si será capaz de ser fotoactivada eficazmente como para polimerizar correctamente, en especial en las zonas más profundas de la preparación cavitaria. El presente estudio busca analizar si existen diferencias en el grado de sellado marginal y en la profundidad de curado de restauraciones cementadas con un medio de fijación a base de resina, previa técnica de grabado y colocación de adhesivo y con una resina compuesta a través de la técnica fluidificada.

The fixing means based on composite resins for cementing, are nothing more than a fluid composite resin, which contains a lower percentage of inorganic filler. This is why, at present, some authors propose the use of composite resin restoration as a means of fixing indirect restorations (inlay made of ceramics). Said resin must be fluidized with heat (50 ° C), to be photoactivated for a suitable time. Also, since it is a material whose polymerization reaction is only activated by light, the question arises whether it will be able to be effectively photoactivated to properly polymerize, especially in the deeper areas of the cavity preparation. The present study aims to analyze if there are differences in the degree of marginal sealing and in the depth of cure of cemented restorations with a resin-based fixing medium, prior to etching and adhesive placement and with a composite resin through the fluidized technique.

Extraoral Cementation Technique to Minimize Cement-Associated Peri-implant Marginal Bone Loss: Can a Thin Layer of Zinc Oxide Cement Provide Sufficient Retention?

This report describes the use of laboratory-fabricated crown intaglio replicas for extraorally prepared cementation of fixed restorations to implants. This technique minimizes excess cement and may therefore reduce the risk of cement-related marginal peri-implant bone loss. It is unclear whether the remaining thin layer of luting agent provides sufficient retention if low-adhesive zinc oxide (ZnO) cement is used. In 85 consecutive patients, 113 single crowns were cemented to implants using extraoral cementation technique (ECT) and ZnO cement. All patients were followed for 6 months and investigated for decementation. Seven events of decementation (incidence: 6.19%) were found in 7 patients (8.24%). ECT may represent a viable cementation technique for implant-supported single crowns, even using low-adhesion cements.

Comparación en la resistencia de unión en la fijación de postes de base orgánica con la utilización de cementos resinosos vs. ionómeros modificados con resina / A comparison of bond strength in cementing organic base posts by using resin cements vs. resin-modified glass ionomer cements

Los postes de base orgánica reforzados con fibras constituyen un recurso terapéutico de gran relevancia para la rehabilitación de dientes tratados endodónticamente. Sin embargo, la metodología para obtener una adecuada fijación a las paredes radiculares todavía es objeto de estudio y discusión. El objetivo de este trabajo fue evaluar la resistencia de unión en la cementación de postes de base orgánica reforzadoscon fibra de vidrio, empleando un cemento resinoso, y compararla con la resistencia de unión de dichos postes utilizando un cemento de ionómero vítreo modificado con resinas como medio de fijación. Se utilizaron 24 premolares inferiores humanos unirradiculares recientemente extraídos. Se realizó el tratamiento endodóntico a todas las piezas dentarias empleando instrumentación mecanizada con un sistema rotatorio y técnica híbrida para la obturación. Posteriormente, se realizaron las maniobras de desobturación y preparación del lecho radicular, y la cementación del poste en cada pieza dentaria. Los especímenes obtenidos se dividieron en 2 grupos según los materiales utilizados para la cementación: 1) Cemento resinoso (Rebilda DC; VOCO Germany) con sistema adhesivo; 2) Cemento de ionómero vítreo modificado con resina (Meron Plus; VOCO Germany). Resultados: La resistencia de unión en la cementación de postes de fibra de vidrio fue significativamente mayor con la utilización de cementos resinosos en comparación con el uso de cemento de ionómero vítreo reforzado con resina (p <0,0001). Conclusión: la utilización de cementos de resina duales como medio de fijación es más recomendable que el uso de cementos de ionômero.

Organic base posts reinforced with fibers constitute a therapeutic resource of great relevance for the rehabilitation of endodontically treatedteeth. However, the methodology for proper attachment to the root walls is still under study and discussion. The aim of this study was toevaluate the bond strength in cementing organic base posts reinforced with fiberglass, using resin cement, and compare it with the bondstrength of these posts using glass ionomer cement modified with resins as fixing means. 24 single-rooted human premolars recentlyextracted were used. Endodontic treatment was performed to all teeth using a mechanized rotary instrumentation and hybrid technique forsealing. Subsequently, we proceeded to unsealing all the teeth, preparing root beds and cementing the posts. The obtained specimens weredivided into 2 groups according to the materials used for cementation: 1) Resin cement (Rebilda DC, VOCO Germany) with adhesivesystem; 2) Glass ionomer cement modified with resin (Meron Plus, VOCO Germany). Results: The bond strength of fiberglass postscementation was significantly higher with the use of resin cements compared with using glass ionomer cement reinforced with resin (p<0.0001). Conclusion: The use of dual resin cements is more recommendable as fixing means than ionomer cements.

Minimizing excess cement in implant-supported fixed restorations using an extraoral replica technique: a prospective 1-year study.

PURPOSE: Cementation of implant-supported restorations poses two major challenges: (1) minimizing excess cement (reducing the risk of peri-implantitis), and (2) establishing sufficient retention (reducing the risk of decementation). This study presents the first data on a clinical cementation technique that might address both problems. MATERIALS AND METHODS: Between 2011 and 2013, 39 patients were provided with 52 implants supporting 52 single crowns (SCs). All restorations were cemented extraorally using replicas made of pattern resin and zinc oxide cement. All decementation events and the peri-implant soft tissue status were assessed and compared with those from a group of 29 patients with 40 conventionally cemented SCs (control). RESULTS: In the experimental group, after 12 months, decementation was recorded in three individuals (7.69%) with 3 SCs (5.77%). In the control group, after 12 months, no case of decementation was recorded. No cases of peri-implantitis were detected in either group. CONCLUSION: Within the limitations of this study, the authors conclude that the use of zinc oxide cement initially establishes sufficient retention of implant-supported fixed restorations independent of conventional or replica cementation techniques.

An in vitro study comparing limited to full cementation of polyethylene glenoid components.

BACKGROUND: Glenoid component survival is critical to good long-term outcomes in total shoulder arthroplasty. Optimizing the fixation environment is paramount. The purpose of this study was to compare two glenoid cementing techniques for fixation in total shoulder arthroplasty. METHODS: Sixteen cadaveric specimens were randomized to receive peg-only cementation (CPEG) or full back-side cementation (CBACK). Physiological cyclic loading was performed and implant displacement was recorded using an optical tracking system. The cement mantle was examined with micro-computed tomography before and after cyclic loading. RESULTS: Significantly greater implant displacement away from the inferior portion of the glenoid was observed in the peg cementation group when compared to the fully cemented group during the physiological loading. The displacement was greatest at the beginning of the loading protocol and persisted at a diminished rate during the remainder of the loading protocol. Micro-CT scanning demonstrated that the cement mantle remained intact in both groups and that three specimens in the CBACK group demonstrated microfracturing in one area only. DISCUSSION: Displacement of the CPEG implants away from the inferior subchondral bone may represent a suboptimal condition for long-term implant survival. Cement around the back of the implant is suggested to improve initial stability of all polyethylene glenoid implants. CLINICAL RELEVANCE: Full cementation provides greater implant stability when compared to limited cementation techniques for insertion of glenoid implants. Loading characteristics are more favorable when cement is placed along the entire back of the implant contacting the subchondral bone.

Cemented implant restoration: A technique for minimizing adverse biologic consequences.

The purpose of this technique was to eliminate excess cement from the implant restoration by using a 2-step cementation process. A custom acrylic resin abutment, a duplicate of the titanium abutment, is fabricated before the restoration is cemented. At cementation, cement is placed inside the restoration, which is placed onto the acrylic resin abutment outside the mouth. The majority of the excess cement from inside the restoration is expressed onto the acrylic resin abutment. The restoration is then placed on the titanium abutment inside the mouth. The result is a minimum amount of excess cement expressed intraorally. This technique minimizes the adverse biological consequences of leaving excess cement beneath implant-supported restorations.

Recambio de polietileno mediante la cementación de un nuevo componente sobre el metal-back osteointegrado / Polyethylene replacement by cementing a new component over the osseointegrated metal-back

Objetivo. Ante una cirugía de revisión de artroplastia total de cadera no cementada por desgaste de polietileno está indicado mantener el cotilo metálico cuando se compruebe intraoperatoriamente su estabilidad, sustituyendo únicamente el polietileno que se cementa si el anclaje no es posible. El objetivo del presente estudio fue evaluar los resultados clínicos y radiográficos a medio plazo de la cementación de polietileno dentro de un componente acetabular metálico osteointegrado. Material y método. Se analizaron retrospectivamente 15 pacientes cuya indicación para la cirugía fue el desgaste de polietileno, con un periodo de seguimiento medio de 6,1 años (rango 3,5-9,7 años). El Harris Hip Score se utilizó para valorar los resultados clínicos antes de la intervención y al final del seguimiento. Se realizaron radiografías anteroposteriores y axiales de cadera para descartar complicaciones. Resultados. La puntuación media en el Harris Hip Score mejoró, pasando de los 64,7 puntos en el preoperatorio a los 80,3 al final del seguimiento. Las lesiones osteolíticas desaparecieron, o al menos no aumentaron de tamaño, en los controles radiográficos. Una paciente (6,7%) sufrió 2 episodios de luxación, que se trataron sin necesidad de cirugía. Otro paciente presentó aflojamiento aséptico del vástago femoral, que requirió el recambio. Conclusiones. La cementación del polietileno, cuando no sea posible su anclaje, en un cotilo metálico no cementado osteointegrado es una técnica que ofrece buenos resultados a medio plazo, y que minimiza las complicaciones que conlleva el recambio del componente acetabular, sin comprometer su estabilidad (AU)

Objective. In uncemented revision total hip replacement due to polyethylene wear, the metal cup needs to be maintained when its stability is checked during surgery, only replacing the polyethylene that is cemented if anchoring is not possible. The aim of the present study was to evaluate the medium-term clinical and radiological results of a polyethylene liner cemented into an osseointegrated acetabular shell component. Material and method. A retrospective analysis was performed on 15 patients in whom the surgical indication was polyethylene wear, with a mean follow-up of 6.1 years (range 3.5-9.7 years). The Harris Hip Score was used to assess the clinical results before surgery and at the end of follow-up. Anteroposterior and axial X-rays of the hip were taken to rule out complications. Results. The mean Harris Hip Score improved, increasing from 64.7points before the surgery to 80.3 at the end of follow-up. The osteolytic lesions disappeared, or at least the size did not increase, in the follow-up X-rays. One patient (6.7%) suffered 2 dislocation episodes that were treated without the need for surgery. Another patient presented with aseptic loosening of the femoral stem that required a replacement. Conclusions. Cementing the polyethylene liner, when anchoring is not possible, in an uncemented osseointegrated metal shell is a technique that offers good results in the medium term, and which may minimise the complications that may occur with the replacement of the shell component, without compromising its stability (AU)

The effect of using a cement gun with a narrow nozzle on cement penetration for total elbow arthroplasty: a cadaveric study.

PURPOSE: To compare the cement mantle characteristics associated with use of a narrow nozzle cement gun versus the use of a 60-mL catheter tip syringe. METHODS: Twelve cadaveric distal humeri were cemented with either a cement gun or a syringe without canal occlusion. The humeri were sectioned and photographed. The corticocancellous junction and the outer margin of the cement mantle were analyzed digitally. The corticocancellous junction defined the available area for cement penetration. The outline of the cement mantle defined the actual area of penetration. The ratio of penetration to the available area was recorded for each slice. The mean ratio for each humerus was multiplied by the number of slices in that sample containing cement to calculate a cement index. RESULTS: The cement penetration ratios observed in cross-sections at the same level and the cement index were significantly greater with the use of the cement gun than with the use of the syringe. There was no difference in the number of slices that contained cement. CONCLUSIONS: The use of a cement gun with a narrow nozzle improved cement mantle characteristics compared with the use of a syringe when measured in a cadaveric model in the absence of canal occlusion. CLINICAL RELEVANCE: Improving cement mantle characteristics may decrease the incidence of aseptic loosening after total elbow arythroplasty.

Capacidad de sellado de tres agentes cementantes para restauraciones coronarias indirectas / Sealing ability of three luting agents used for cementation of indirect coronal restorations

Objetivo: comparar ex vivo, por medio de un modelo de filtración bacteriana, la capacidad de sellado de un ionómero vítreo modificado con resinas, de un ionómero vítreo convencional y de un cemento de fosfato de cinc, utilizados para la cementación de coronas coladas (AU). Materiales y métodos: un total de 30 premolares humanos sanos, extraídos, fueron preparados de forma estandarizada para recibir una corona metálica con terminación en chamfer sobre dentina. Se realizaron impresiones, se vaciaron en densita tipo IV, se enceraron y se colaron en aleación de oro tipo III. Luego fueron separadas al azar en tres grupos de 10 (n=10) especímenes cada uno. Las coronas del grupo 1 fueron cementadas con Rely-X Luting Plus (3M/ESPE); y las del grupo 2, con Ketac-Cem (3m/ESPE); y las del grupo 3 (control), con el cemento de fosfato de cinc Harvard Cement (Harvard Debtal International GmbH, Hoppengarten, Alemania). Todos los especímenes fueron termociclados. Posteriormente, la superficie metálica oclusal fue reducida 1 mm hasta exponer la dentina, y las muestras se esterilizaron en autoclave. El proceso de filtración se realizó por medio de un sistema de doble cámara con medio de cultivo. El medio de la cámara superior se inoculó con E. faecalis y el sistema fue incubado durante 60 días. En la cámara inferior, la filtración bacteriana se controló diariamente. Los datos registrados fueron analizados por medio de las pruebas de Kaplan-Meyer y de Fischer, con un nivel de significación de P<0,05. Resultados: el tiempo de supervivencia para Rely-X Luting Plus no pudo ser estimado, ya que fue superior a los 60 días, tiempo máximo de duración de la experiencia. Para Ketac-Cem fue de 60 días, con un intervalo de confianza (95 por ciento) de 29,6-90,4. Y para Harvard Cement fue de 40 días, con un intervalo de confianza de 32,6-47,4. Las diferencias entre los grupos fueron estadísticamente significativas. Conclusión: Rely-X Plus demostró una capacidad de sellado superior.

Comparison of two pressurisers for cementation of the proximal femur.

PURPOSE: To compare pressures generated by 2 different cement pressurisers at various locations in the proximal femur. METHODS: Two groups of 5 synthetic femurs were used, and 6 pressure sensors were placed in the femur at 20-mm intervals proximally to distally. Cement was filled into the femoral canal retrogradely using a cement gun with either the half-moon pressuriser or the femoral canal pressuriser. Maximum pressures and pressure time integrals (cumulative pressure over time) of the 2 pressurisers were compared. RESULTS: At all sensors, the half-moon pressuriser produced higher maximum pressures and pressure time integrals than the femoral canal pressuriser, but the difference was significant only at sensor 1 (proximal femur). This may result in reduced cement interdigitation in the proximal femur. CONCLUSION: The half-moon pressuriser produced higher maximum cementation pressures and pressure time integrals than the femoral canal pressuriser in the proximal femur region, which is critical for rotational stability of the implant and prevention of implant fracture.

Resistencia de unión en la fijación de postes de base orgánica con la utilización de cementos resinosos con y sin sistema adhesivo / Bond strength of organic base posts cementation by using resin cements with and without an adhesive system

En la actualidad, los postes de fibra de vidrio son ampliamente utilizados para la reconstrucción de piezas tratadas enodónticamente con indicación de anclaje intrarradicular. Por lo tanto, el objetivo de este trabajo fue evaluar la resistencia de unión en la cementación de postes de fibra de vidrio con la utilización de cementos resinosos con y sin sistema adhesivo. Se utilizaron 24 premolares inferiores humanosunirradiculares recientemente extraídos. Luego, se procedió a realizar los tratamientos endodónticos a todas las piezas dentarias con el sistema Protaper y a su obturación con técnica híbrida. A continuación, se procedió a la desobturación de todas las piezas y a lacementación de los postes. Las muestras se dividieron en 4 grupos según los materiales utilizados para la cementación: 1) Cemento Rebildacon sistema adhesivo; 2) Cemento Rebilda sin sistema adhesivo; 3) Cemento Paracore con sistema adhesivo; 4) Cemento Paracore sinsistema adhesivo. Resultados: no se observaron diferencias significativas de resistencia entre los tratamientos con y sin sistema adhesivo; ni entre los tratamientos con los cementos Rebilda y Paracore. Tampoco se evidenció interacción entre la utilización o no del sistema adhesivo y el tipo de cemento. Conclusión: todas las combinaciones estudiadas otorgan la misma resistencia de unión de los postes a los tejidosintrarradiculares...

Irradiation conditions for fiber laser bonding of HAp-glass ceramics with bovine cortical bone.

Orthopedic implants are widely used to repair bones and to replace articulating joint surfaces. It is important to develop an instantaneous technique for the direct bonding of bone and implant materials. The aim of this study was to develop a technique for the laser bonding of bone with an implant material like ceramics. Ceramic specimens (10 mm diameter and 1 mm thickness) were sintered with hydroxyapatite and MgO-Al2O3-SiO2 glass powders mixed in 40:60 wt% proportions. A small hole was bored at the center of a ceramic specimen. The ceramic specimen was positioned onto a bovine bone specimen and a 5 mm diameter area of the ceramic specimen was irradiated using a fiber laser beam (1070-1080 nm wavelength). As a result, the bone and the ceramic specimens bonded strongly under the irradiation conditions of a 400 W laser power and a 1.0 s exposure time. The maximum shear strength was 5.3 ± 2.3 N. A bonding substance that penetrated deeply into the bone specimen was generated around the hole in the ceramic specimen. On using the fiber laser, the ceramic specimen instantaneously bonded to the bone specimen. Further, the irradiation conditions required for the bonding were investigated.

A new design of cemented stem using functionally graded materials (FGM).

One of the most frequent complications of total hip replacement (THR) is aseptic loosening of femoral component which is primarily due to changes of post-operative stress distribution pattern with respect to intact femur. Stress shielding of the femur is known to be a principal factor in aseptic loosening of hip replacements. Many designers show that a stiff stem shields the surrounding bone from mechanical loading causing stress shielding. Others show that reducing stem stiffness promotes higher proximal interface shear stress which increases the risk of proximal interface failure. Therefore, the task of this investigation is to solve these conflicting problems appeared in the cemented total hip replacement. The finite element method and optimization technique are used in order to find the optimal stem material which gives the optimal available stress distribution between the proximal medial femoral bone and the cement mantle interfaces. The stem is designed using the concept of functionally graded material (FGM) instead of using the conventional most common used stem material. The results showed that there are four feasible solutions from the optimization runs. The best of these designs is to use a cemented stem graded from titanium at the upper stem layer to collagen at the lower stem layer. This new cemented stem design completely eliminates the stress shielding problem at the proximal medial femoral region. The stress shielding using the cemented functionally graded stem is reduced by 98% compared to titanium stem.

Restoration of pull-out strength of the failed pedicle screw: biomechanical comparison of calcium sulfate vs polymethylmethacrylate augmentation.

OBJECTIVE: The aim of the present study was to compare calcium sulfate (CAS) and polymethylmethacrylate (PMMA) bone cements used for the augmentation of a failed pedicle screw with biomechanical pull-out strength (POS) testing. METHODS: Thirty lumbar vertebrae were harvested from 6 calves and bone mineral densities (BMD) were measured. Primary polyaxial pedicle screws were randomly inserted and pulled out and the POSs of the specimen were recorded. For revision, specimens were randomly assigned to the CAS-augmented pedicle screws group (Group 1) or PMMA-augmented pedicle screw group (Group 2). Pull-out tests were repeated to compare both groups. RESULTS: Mean BMD of the specimens was 1.006 ± 0.116 g/cm(2). There were no statistically significant differences between BMD results of the two groups (p=0.116). For Group 1, mean POS of primary screws was 2,441.3 ± 936.4 N and was 2,499.5 ± 1,425.1 N after CAS augmentation, demonstrating no statistically significant difference (p=0.865). In Group 2, mean POS of the primary screws was 2,876.6 ± 926.6 N and significantly increased to 3,745.5 ± 1,299.2 N after PMMA augmentation (p=0.047). There was also a significant difference in mean POS between the CAS and PMMA groups (p=0.026). CONCLUSION: Although CAS augmentation facilitates a revision screw POS as strong as that of primary screws, it is not as strong as PMMA augmentation.