40 research outputs found
Evolución de la cerámica dental en la última década
Se estudian y presentan las modernas cerámicas dentales, así como la evolución que han sufrido en los últimos diez años las técnicas y materiales empleados en restauraciones tanto completamente de cerámica como las ceramo- metálicas. Se refieren sus indicaciones clínicas, ventajas e inconvenientes de las principales técnicas y materiales
Ion release from dental casting alloys as assessed by a continuous flow system: Nutritional and toxicological implications
Objectives: The aims of this study were to quantify the metallic ions released by various dental alloys subjected to a continuous flow of saliva and to estimate the nutritional and toxicological implications of such a release. Methods: Four pieces of three nickel-based, one noble, one high-noble and two copper-aluminum alloys were cast and then immersed in a continuous flow of artificial saliva for 15 days. To simulate three meals a day, casts were subjected to thrice-daily episodes, lasting 30 min each and consisting of pH decreases and salinity increases. After 15 days, the metallic ions in the artificial saliva were analyzed. Data were expressed as averaged release rate: microg/cm2/day of ion released for each alloy. The highest value of 95% Cl of each ion was adapted to a hypothetical worst scenario of a subject with 100 cm2 of exposed metal surface. The results were compared with the tolerable upper daily intake level of each ion. Results: The copper-aluminum alloys released copper, aluminum, nickel, manganese and iron. The nickel-based alloys essentially released nickel and chromium, while the beryllium-containing alloy released beryllium and significantly more nickel. The noble and high-noble alloys were very resistant to corrosion. The amount of ions released remained far below the upper tolerable intake level, with the exception of nickel, released by beryllium-containing nickel-based alloy, whose levels approach 50% of this threshold. Significance: The daily amount of ions released seems to be far below the tolerable upper intake levels for each ion
Topes en prótesis parcial removible. Realización y diseño actual
El concepto de soporte fue introducido en relación con los retenedores directos por BONWILL, a finales del siglo XIX, cuando estableció los primeros principios fundamentales de los retenedores directos, indicando la absoluta necesidad de la confección del tope oclusal de los mismos para evitar el enclavamiento en la encía de los elementos retenedor y recíproco (3), así como de toda la prótesis en general(9)..
Marginal Bone Loss in Implants with External Connection versus Internal Conical Connection Prior to Prosthetic Loading. A Randomized Clinical Study
Introduction: The prosthetic connection of implants has been related to the loss of marginal bone. The aim of this study was to evaluate bone loss around external connection (EC) and internal conical connection (ICC) implants prior to prosthetic loading. Material and methods: A randomized clinical trial (RCT) was carried out, with a sample size of 93 implants (31 EC and 62 ICC) placed in 27 patients. Radiological controls were performed and stability was measured by resonance frequency analysis (RFA) on the day of placement, at 1 month and at 4 months after the placement. Results: Bone loss in EC implants was not statistically different than in ICC implants between the time of placement (T0) and the subsequent month (T1): (EC = 0.18 mm and ICC = 0.17 mm). Between one month (T1) and four months (T2): (EC = 0.39 mm and ICC = 0.19 mm) this difference was highly significant (p = 0.00). Bone loss between T0 and T2 was significantly lower in the ICC (EC = 0.57 mm and ICC = 0.36 mm), (p = 0.01). The overall success rate of the implants was 97.8%. The stability of the implants increased from 70.69 (T0) to 73.91 (T1) and 75.32 (T2). Conclusions: ICC showed less bone loss up to the time of prosthesis placement. Such bone loss did not have a significant impact on bone stability. Long term RCTs are needed to demonstrate whether this bone loss, which is more pronounced at the beginning in EC, tends to stabilize and equate to ICC
Estudio clínico de puentes en extensión
Se han estudiado clínica y radio lógicamente un total de 20 puentes en extensión, de pacientes que han acudido a la Clínica Odontológica de la Universidad de Barcelona. Por estos y otros motivos los resultados clínicos son de un buen número de años de servicios y, aunque muy discutidos, siguen utilizándose en la práctica odontológica
Reproducibility of lateral excursive tooth contact in a semi-adjustable articulator depending on the type of lateral guidance
The purposes of this study were (i) to compare the reproducibility of lateral tooth contacts of casts mounted in a semi-adjustable articulator when condylar guidance was set by different methods and (ii) to assess the margin of error of the variations of condylar guidance without changing lateral tooth contacts, depending on the type of lateral guidance. In subjects with different types of lateral guidance, intraoral lateral tooth contacts identified with occlusal registration strips were compared with those identified by use of a semi-adjustable articulator, setting the condylar guidance in four different ways: using protrusive wax wafers, by axiography and by adding and subtracting 5 degrees from the value of condylar guidance obtained by protrusive wax wafers. Tolerance to variations of condylar guidance without changing lateral tooth contacts was determined by increasing and decreasing the value of condylar guidance until lateral tooth contacts changed. Different ways of setting condylar guidance on a semi-adjustable articulator give rise to different values of condylar guidance in the same subject. The occlusal repercussions of these variations of condylar guidance values depend on the type of lateral guidance. Canine protection had the greatest tolerance to variations in the setting of condylar guidance without changing lateral occlusal contacts
Estudio preliminar de la liberación de iones metálicos de aleaciones usadas en prótesis fija
En los últimos años estamos asistiendo a un marcado aumento de la utilización de aleaciones metálicas no nobles, como alternativa a las aleaciones de alto contenido en oro. Estas aleaciones son básicamente de dos tipos: base cobre y base níquel. Su coste es más asequible y, además, las aleaciones de base cobre poseen una apariencia que recuerda al oro
Marginal Bone Loss in Internal Conical Connection Implants Placed at the Crestal and Subcrestal Levels before Prosthetic Loading: A Randomized Clinical Study
The vertical position concerning the bone in which the implants are placed has been related as one of the factors causing marginal bone loss. The objective of this study was to evaluate the bone loss that occurs before prosthetic loading around tapered internal connection (CIC) implants placed at the crestal (C) and subcrestal (S) levels. Method: A randomized clinical trial (RCT) was carried out, with a sample size of 62 implants placed in 27 patients who underwent radiological controls on the day of placement, at one month, and at 4 months, and stability was measured by resonance frequency analysis (RFA) on three occasions. Results: Bone loss in implants C and S from the time of placement (T0) and the month after (T1) was not significant (p = 0.54) (C = 0.19 mm and S = 0.15 mm). The difference between one month (T1) and four months (T2) (C = 0.17 mm and S = 0.22 mm) was not significant either (p = 0.26). The difference between the day of placement (T0) and the third and last measurement (T2) was almost null (p = 0.94) (C = 0.35 mm and S = 0.36). The overall success rate of the implants was 97.8%. The stability of the implants measured with RFA went from 70.60 (T0) to 73.16 (T1) and 74.52 (T2). Conclusions: No significant differences were found in the bone loss for implants placed at the C and S levels. The millimeters of bone loss detected in both vertical positions did not have a significant impact on the stability of the implants
Análisis perfilométrico de algunas cerámicas de uso dental bajo diversos tratamientos de su superficie
Se estudian las diferentes superficies de dos cerámicas dentales usadas en restauraciones ceramo-metálicas. Para ello se emplearon Vita VMK-68® e IPS classic. Se estudió la perfilometría de las superficies en bizcocho, glaseado intrínseco, extrínseco y pulido. Se observa que la superficie glaseada por método extrínseco es la que ofrece la superficie más suave
Factores que alteran la exactitud y precisión en la determinación del ángulo de la guía condilea mediante registros de cera con un articulador semiajustable
El objetivo del estudio fue valorar la il')fluencia del operador, del tipo de articulador y de la programación previa del ángulo de Bennett, en la precisión y exactitud de la determinación del ángulo de guía condílea en un articulador semiajustable mediante registros de cera. Siete odontoestomatólogos programaron la guía condílea de un articulador arcón y uno no arcón, antes y después de situar el ángulo de Bennett, de un voluntario. Un octavo participante realizó una axiografía del voluntario. El valor de guía condílea obtenido con un articulador semiajustable y con registros intraorales plásticos depende en gran medida del operador. El articulador no arcón fue más exacto pero menos preciso que el arcón. La colocación del ángulo de Bennett antes de programar la guía condílea no afectó la exactitud pero si aumentó la precisión