Effect of platform switching on the peri-implant bone: a finite element study

Background: There exists a relation between the presence and location of the micro-gap and the loss of peri-implant bone. Several authors have shown that the treatments based on the use of platform switching result in less peri-implant bone loss and an increased tissue stability. The purpose of this study was to analyse the effect of the platform switching on the distribution of stresses on the peri-implant bone using the finite element method. Material and Methods: A realistic 3D full-mandible finite element model representing cortical bone and trabecular bone was used to study the distribution of the stress on the bone induced by an implant of diameter 4.1 mm. Two abutments were modelled. The first one, of diameter 4.1 mm, was used in the reference model to represent a conventional implant. The second one, of diameter 3.2 mm, was used to represent the implant with platform switching. Both models were subjected to axial and oblique masticatory loads. Results: The analyses showed that, although no relevant differences can be found for the trabecular bone, the use of platform switching reduces the maximum stress level in the cortical bone by almost 36% with axial loads and by 40% with oblique loads. Conclusions: The full 3D Finite Element model, that can be used to investigate the influence of other parameters (implant diameter, connection, ...) on the biomechanical behaviour of the implant, showed that this stress reduction can be a biomechanical reasons to explain why the platform switching seems to reduce or eliminate crestal bone resorption after the prosthetic restoratio

Med Oral Patol Oral Cir Bucal

Abstract Objective: The purpose of this study was to determine whether the bond of veneering porcelain to a ceramic core in bilayered ceramics was similar to that of the metal ceramic control of well known behaviour. Study design: Six groups of nine specimens each were fabricated, whose dimensions were 15 mm long and 8 mm in diameter at the core, and 2 mm long and 8 mm in diameter for the veneer. The groups were GR. 1 (control group): CrNi alloy/d.SIGN (Ivoclar), GR. 2: IPS e.maxPress/IPS e.maxCeram (Ivoclar), GR. 3: IPS e.maxZirCad/ IPS e.maxZirPress (Ivoclar), GR. 4: IPS e.maxZirCad/IPS e.maxCeram (Ivoclar), GR. 5: Lava Frame (3M ESPE)/ Lava Ceram (3M ESPE) and GR. 6: Lava Frame (3M ESPE)/IPS e.maxCeram (Ivoclar). A shear strength test was used in all samples with a universal testing machine. The chosen crosshead speed was of 0.50 mm/min. The obtained results were analyzed using a one way analysis of variance test (ANOVA) to determine whether significant differences existed between the groups (p<0.05). A Student Newman-Keuls multiple comparisons test was used. Results: GR. 1: 13.45 MPa, GR. 2: 24.20 MPa, GR. 3: 12.70 MPa, GR. 4: 7.86 MPa, GR. 5: 10.20 Mpa and GR. 6: 4.62 Mpa. Conclusions: The bond strength of group 1 (control) was similar to groups 3 and 5. Group 2, whose core and veneer are both porcelains with a similar chemical composition, with silica as their main component, achieved the best adhesive results between both porcelains. The technique on zirconia cores that showed the higher results was the pressed technique. The lowest results were for the group using porcelains from different manufacturers

Análisis microscópico e investigación experimental in vitro de la interfase de unión entre la circonia y su cerámica de recubrimiento en restauraciones completas de cerámica

Tesis inédita presentada en la Universidad Europea de Madrid. Facultad de Ciencias Biomédicas. Programa de Doctorado en Odontología AvanzadaPuesto que el fracaso que predomina en las restauraciones de circona es la fractura de la porcelana de recubrimiento, nos planteamos hacer una investigación de la interfase entre el núcleo de circona y su porcelana de recubrimiento. Nos planteamos utilizar dos tipos diferentes de circona. Seleccionamos igualmente el Cromo-Niquel y el disilicato de litio como núcleos de nuestros grupos control, dado que son materiales con más tiempo de utilización y comportamiento clínico conocido. Como materiales de recubrimiento hemos optado por la técnica de capas y la técnica de inyección. Nos planteamos dirigir nuestra investigación en analizar la interfase de unión de los mismos mediante el estudio, tanto de la forma de relacionarse los distintos materiales entre sí mediante la observación a microscopía, como la resistencia a la cizalla entre núcleo y su recubrimiento. El estudio a microscopía se va a dividir en dos fases diferentes. En primer lugar vamos a estudiar a microscopía óptica, elctrónica y de fuerza atómica una muestra de cada grupo no sometida al ensayo de cizalla, para apreciar las características de la unión a nivel de la interfase. En segundo lugar procederemos a la observación de la superficie de fractura de las muestras sometidas al ensayo de cizalla, mediante el microscopio óptico y elctrónico de barrido. Pretendemos relacionar los resultados del ensayo de cizalla con los resultados del estudio fractográfico lo que nos permitirá obtener las conclusiones de nuestro estudio. [Resumen Teseo

Digital Tools for Translucence Evaluation of Prosthodontic Materials: Application of Kubelka-Munk Theory

Translucency is one of the most important parameters to be considered by digital systems when predicting the matching appearance and hence the quality of prosthodontic restoration work. Our objective has been to improve the effectiveness of the algorithmic decision systems employed by these devices by (a) determining whether Kubelka-Munk theory can be used as an algorithm for predicting restoration suitability, and (b) evaluating the correlation between the visual evaluation of prosthodontic materials and the predicted translucency based on the use of the ∆E*, OP, CR, and K/S algorithms. In this regard, three zirconia systems and one lithium disilicate have been spectrophotometrically and visually characterized. Based on the results of this study, it has been proven that zirconia systems and lithium disilicate systems exhibit different optical behaviors. The psychophysical experience suggests that none of the existing mathematical methods can adequately estimate translucency, spectrophotometric, and colorimetric techniques, and that which is perceived by an experienced observer. However, translucency evaluation through the K/S algorithmic decision system should not be disregarded. New methods to measure translucency should be developed to improve digital systems for prosthodontic applications.2019/UEM303.390 JCR (2020) Q1, 42/176 Public, Environmental & Occupational Health0.814 SJR (2021) Q1, 34/136 Health, Toxicology and MutagenesisNo data IDR 2020UE

Fractographic Study of the Interface Between Zirconia Y-TZP and Its Veneering Ceramic After Shear Strength Testing

This study analyzed the shear strength and fracture characteristics of the interface between zirconia samples and their veneering ceramic compared with a metalceramic and a lithium disilicate glass-ceramic control group together with an assessment of the possible relationship between the fracture characteristics and the recorded shear strength. The greatest shear strengths corresponded to the lithium disilicate glass-ceramic control group followed by the metal-ceramiccontrol group, with lesser strengths in the zirconia groups. Since the fractographic study showed cohesive-type failure to predominate in the zirconia samples, it is concluded that improvements are needed in the veneering ceramic and liner used in zirconia restorations.López-Mollá, MV.; Martínez-González, A.; Amigó Borrás, V.; Mañes-Ferrer, JF. (2015). Fractographic Study of the Interface Between Zirconia Y-TZP and Its Veneering Ceramic After Shear Strength Testing. International Journal of Prosthodontics. 28(4):432-434. doi:10.11607/ijp.3873S43243428

Effect of platform switching on the peri-implant bone: A finite element study

There exists a relation between the presence and location of the micro-gap and the loss of peri implant bone. Several authors have shown that the treatments based on the use of platform switching result in less peri-implant bone loss and an increased tissue stability. The purpose of this study was to analyse the effect of the platform switching on the distribution of stresses on the peri-implant bone using the finite element method. A realistic 3D full-mandible finite element model representing cortical bone and trabecular bone was used to study the distribution of the stress on the bone induced by an implant of diameter 4.1 mm. Two abutments were modelled. The first one, of diameter 4.1 mm, was used in the reference model to represent a conventional implant. The second one, of diameter 3.2 mm, was used to represent the implant with platform switching. Both models were subjected to axial and oblique masticatory loads. The analyses showed that, although no relevant differences can be found for the trabecular bone, the use of platform switching reduces the maximum stress level in the cortical bone by almost 36% with axial loads and by 40% with oblique loads. The full 3D Finite Element model, that can be used to investigate the influence of other parameters (implant diameter, connexion type, …) on the biomechanical behaviour of the implant, showed that this stress reduction can be a biomechanical reasons to explain why the platform switching seems to reduce or eliminate crestal bone resorption after the prosthetic restoration.Sin financiaciónNo data (2016)UE

Bond strength evaluation of the veneering-ceramics bonds

Objective: The purpose of this study was to determine whether the bond of veneering porcelain to a ceramic core in bilayered ceramics was similar to that of the metal ceramic control of well known behaviour. Study design: Six groups of nine specimens each were fabricated, whose dimensions were 15 mm long and 8 mm in diameter at the core, and 2 mm long and 8 mm in diameter for the veneer. The groups were GR. 1 (control group): CrNi alloy/d.SIGN (Ivoclar), GR. 2: IPS e.maxPress/IPS e.maxCeram (Ivoclar), GR. 3: IPS e.maxZirCad/ IPS e.maxZirPress (Ivoclar), GR. 4: IPS e.maxZirCad/IPS e.maxCeram (Ivoclar), GR. 5: Lava Frame (3M ESPE)/ Lava Ceram (3M ESPE) and GR. 6: Lava Frame (3M ESPE)/IPS e.maxCeram (Ivoclar). A shear strength test was used in all samples with a universal testing machine. The chosen crosshead speed was of 0.50 mm/min. The obtained results were analyzed using a one way analysis of variance test (ANOVA) to determine whether significant differences existed between the groups (p<0.05). A Student Newman-Keuls multiple comparisons test was used. Results: GR. 1: 13.45 MPa, GR. 2: 24.20 MPa, GR. 3: 12.70 MPa, GR. 4: 7.86 MPa, GR. 5: 10.20 Mpa and GR. 6: 4.62 Mpa. Conclusions: The bond strength of group 1 (control) was similar to groups 3 and 5. Group 2, whose core and veneer are both porcelains with a similar chemical composition, with silica as their main component, achieved the best adhesive results between both porcelains. The technique on zirconia cores that showed the higher results was the pressed technique. The lowest results were for the group using porcelains from different manufacturers