Analysis of Vertical Marginal Adaptation of Zirconia Fixed Dental Prosthesis Frameworks Fabricated by the CAD/CAM System: A Randomized, Double-Blind Study.

PURPOSE: The purpose of this study was to evaluate the marginal adaptation of fixed dental prosthesis frameworks fabricated by computer-aided design/computer-assisted manufacture (CAD/CAM) with three different systems of data acquisition. MATERIALS AND METHODS: A total of 50 specimens were fabricated as follows: using the conventional method (Ni-Cr) (n=10); iTero/industrial milling (Group 1, n=10); Cerec Bluecam/industrial milling (Group 2, n=10); 3S/industrial milling (Group 3, n=10); and Cerec BlueCam/Sirona milling (Group 4, n=10). The specimens were numbered and randomized, and the vertical marginal discrepancy was analyzed. RESULTS: Intraobserver analysis indicated no statistically significant difference (paired t test, P=.822) between periods before and after analysis. The conventional method (321 µm) showed greater discrepancy when compared with the CAD/CAM system (89 µm) (P<.001). The intraoral system showed a lower rate of marginal discrepancy when compared with the extraoral system (3S) (P<.001). The closed system presented a higher marginal discrepancy (114 µm) than the open intraoral system (iTero) at P<.001. In addition, the intraoral system when open showed statistically significant differences in mean marginal discrepancy values compared with the same system in closed condition (P>.05). CONCLUSION: The CAD/CAM systems showed less marginal discrepancy than the conventional method for the fabrication of the frameworks.

Regeneração óssea guiada em implantodontia - relato de caso / The guided bone regeneration in implant dentistry - case report

Objetivo: a utilização de métodos de regeneração te-cidual tem sido amplamente empregada na Implanto-dontia em situações clínicas com deficiências ou limi-tações anatômicas que impossibilitam a instalação de implantes osseointegrados. A evolução no desenvolvi-mento de biomateriais revolucionou essa modalidade terapêutica facilitando a resolução clínica de casos com deficiências teciduais. Sendo assim, o intuito des-te trabalho foi realizar a descrição de um caso clíni-co, abordando os métodos, as técnicas e os materiais empregados em regeneração óssea guiada aplicada à implantodontia. Relato de Caso: um caso clínico de um paciente que recebeu implante dentário do tipo cone--morse (região: 15) é descrito. Houve necessidade de utilização de biomaterial e membrana na parede vesti-bular do alvéolo. Após o período de osseointegração, realizou-se a cirurgia de reabertura e, confeccionou--se um provisório imediato. Decorridos 2 meses de acompanhamento, realizou-se a confecção da prótese definitiva, envolvendo outros elementos adjacentes. Considerações finais: A técnica de regeneração óssea guiada empregada apresentou desempenho satisfató-rio. O paciente demonstrou-se favorável no quesito de estética e função. Entretanto, mais estudos controlados e com maior período de acompanhamento são neces-sários para análises de previsibilidade.

Influence of the connector and implant design on the implant-tooth-connected prostheses.

PURPOSE: The purpose of this study was to evaluate stress transfer patterns between implant-tooth-connected prostheses comparing rigid and semirigid connectors and internal and external hexagon implants. MATERIALS AND METHODS: Two models were made of photoelastic resin PL-2, with an internal hexagon implant of 4.00 x 13 mm and another with an external hexagon implant of 4.00 x 13 mm. Three denture designs were fabricated for each implant model, incorporating one type of connection in each one to connect implants and teeth: 1) welded rigid connection; 2) semirigid connection; and 3) rigid connection with occlusal screw. The models were placed in the polariscope, and 100-N axial forces were applied on fixed points on the occlusal surface of the dentures. RESULTS: There was a trend toward less intensity in the stresses on the semirigid connection and solid rigid connection in the model with the external hexagon; among the three types of connections in the model with the internal hexagon implant, the semirigid connection was the most unfavorable one; in the tooth-implant association, it is preferable to use the external hexagon implant. CONCLUSIONS: The internal hexagon implant establishes a greater depth of hexagon retention and an increase in the level of denture stability in comparison with the implant with the external hexagon. However, this greater stability of the internal hexagon generated greater stresses in the abutment structures. Therefore, when this association is necessary, it is preferable to use the external hexagon implant.

Utilización de una guía para el posicionamiento de prótesis fija cementada sobre implantes: relato de un caso clínico / Use of guide to positioning of cement-retained implant protheses: case report

Actualmente el uso de prótesis sobre implantes se incrementó gradualmente desde el descubrimiento de la oseointegración. La indicación inicial de los implantes fue para pacientes edéntulos totales extendiéndose después para pacientes parcialmente edéntulos. Las alternativas de retención de las piezas protésicas van desde las prótesis atornilladas hasta las prótesis cementadas o por preparación de los pilares de la forma convencional. Las prótesis cementadas sobre implantes se utilizan frecuentemente en los casos donde la inclinación de los implantes imposibilita la confección de prótesis atornilladas, debido a la salida de los tornillos de fijación por vestibular o entre los espacios interdentales comprometiendo la estética, y la resistencia cuando están localizados en las cúspides oclusales de los dientes posteriores. En ese sentido, la confección de "copings" en los pilares preparados, puede tornar el tratamiento en un proceso más rápido y seguro. No obstante, pueden surgir problemas en el momento de la instalación, debido a que el intermediario puede asumir diversas posiciones en relación a la posición del implante dificultando la colocación de la prótesis definitiva, principalmente en situaciones clínicas con más de dos implantes. De este modo, el objetivo de este trabajo fue mostrar una técnica del uso de una guía para posicionamiento de los pilares protésicos en prótesis fija cementada sobre implantes, por medio de la descripción de un caso clínico

Nowadays, the use of implant-retained prostheses has been increasing progressively since the advent of the osseointegration. The basic indication was in total edentulous patients and it was also enlarged for partially edentulous patients. Alternatives of retention could be from screw-retained implant prostheses, cement-retained implant prostheses or conventional preparations. Cement-retained implant prostheses are used frequently when the implant inclination don't allow the use of screw-retained prostheses because the screw emerge in vestibular surface or the interdental space resulting in an unaesthetic appearance and when the screw emerge on the top of the posterior cuspid teeth, diminishing the resistance. The confection of the copings on the abutments, turn the treatment faster and secure. Although, some complications can appear in the placement, because the abutment can take different positions in relation to the implant modifying the set of the prosthesis, mainly in clinical situations with more than two implants support. Thus, the aim of this study was demonstrated the use of guide to positioning of cement-retained implant prostheses, by means of a clinical case

Influencia en los modelos del alisamiento de las impresiones de alginato con el dedo humedecido / Influence of finger-smoothed moistening of irreversible hidrocolloid on dimension and surface changes of molds

El objetivo del estudio fue evaluar la presencia de burbujas superficiales y la alteración dimensional en los modelos obtenidos de impresiones de alginato, con y sin alisamiento con el dedo humedecido en agua. Se hizo una matriz en resina acrílica del maxilar desdentado cuyo paladar se modificó para que presentara una superficie llana y lisa y se insertaron 5 pernos metálicos en la cresta del reborde en lugares predeterminados. El estudio se dividió en 6 grupos de acuerdo con la técnica de impresión y del material usado (Jeltrate, Jeltrate plus e Hidrogum), con un total de 10 modelos para cada grupo. El paladar de los modelos se valoró con lupa (50 aumentos) lo que permitió la estimación de las burbujas. La lectura de los modelos se hizo por digitalización de los modelos, midiendo la distancia entre los pernos con el software AutoCAD 2000. Los datos según el análisis de la varianza (ANOVA) y el test de Tukey (5%) indicaron una reducción significativa en el porcentaje de burbujas cuando se hacia el alisamiento. Los modelos donde se hizo el alisamiento presentaran alteraciones sin diferencias estadísticamente significativas respecto a los grupos donde no se hizo el alisamiento. El análisis de los resultados permitió concluir que el alisamiento del alginato con el dedo humedecido no afectó la precisión de los modelos del yeso en ningunos de los alginatos probados. El alisado dio lugar a una reducción significativa en el número de burbujas superficiales (AU)

The purpose of this study was to evaluate the presence of superficial bubbles and dimensional changes of three types of irreversible hydrocolloids smoothened with a moist finger and not smoothened. A master die was made with acrylic resin, representing an edentulous maxillary palate that was modified in order to provide a flat surface. Five pins were inserted in the alveolar crest at predetermined areas. The study was divided in 6 groups in agreement with the molding technique and the hydrocolloid material (Jeltrate, Jeltrate Plus and Hidrogum). These consisted of 10 impressions for each group. The palate region of the molds was assessed with a microscope (50x) to allow bubble scoring. The mold was immediately poured with type IV dental stone. The casts were scanned and digitalized. The distances between pins were measured employing AutoCAD 2000. The data was submitted to ANOVA and Tukey´s test with significance level of 5%. There were no significant differences between cast accuracy obtained from either impression technique regardless of the alginate tested. From the results obtained it was concluded that the presence of bubbles was significantly higher (p < 0.05) in the groups that water rinsing with was not performed; the alginate «Jeltrate» showed a larger discrepancy between both techniques (with and without moist finger smoothening) (AU)