Influência das superfícies de apoio na distribuição da pressão de interface corporal durante o posicionamento cirúrgico

Objetivo: valiar a pressão de interface (PI) das superfícies de apoio (SAs) em proeminências ósseas. Método: um estudo quase experimental com medidas repetidas em diferentes SAs. Vinte voluntários adultos saudáveis participaram do estudo. Os participantes foram colocados em decúbito dorsal em uma mesa cirúrgica para avaliação da PI nas proeminências ósseas das regiões occipital, subescapular, sacral e calcânea utilizando sensores. Sete avaliações foram realizadas para cada proeminência óssea: uma avaliação em uma mesa de operação padrão e as outras avaliações em mesas contendo SAs à base de polímero viscoelástico, espuma macia, ou espuma selada. Estatística descritiva e análise de variância foram utilizadas para analisar os dados. Resultados: a PI média foi maior na SA feita de polímero viscoelástico em comparação com as outras SAs (p<0,001). A PI média foi relativamente menor na espuma selada de densidade 33 e na espuma macia de densidade 18. Além disso, essa variável foi comparativamente maior na região sacral (42,90 mmHg) e na região calcânea (15,35 mmHg). Conclusão: a PI foi menor em SAs à base de espuma, especialmente espuma macia de densidade 18 e espuma selada de densidade 33. No entanto, a PI não foi reduzida na SA à base de polímero viscoelástico comparado com a SA controle.Objective: to evaluate the interface pressure (IP) of support surfaces (SSs) on bony prominences. Method: a quasi-experimental study with repeated measures on each SS. Twenty healthy adult volunteers participated in the study. The participants were placed in the supine position on a standard operating table for evaluation of IP on the bony prominences of the occipital, subscapular, sacral, and calcaneal regions using sensors. Seven evaluations were performed for each bony prominence: one on a standard operating table, and the others on tables containing SSs made of viscoelastic polymer, soft foam, or sealed foam. Descriptive statistics and analysis of variance were used to analyze the data. Results: the mean IP was higher on the viscoelastic polymer-based SS compared to the other SSs (p<0.001). The mean IP was relatively lower on the density-33 sealed foam and density-18 soft foam. In addition, this variable was comparatively higher in the sacral region (42.90 mmHg) and the calcaneal region (15.35 mmHg). Conclusion: IP was relatively lower on foam-based SSs, especially on density-18 soft foam and density-33 sealed foam. Nonetheless, IP was not reduced on the viscoelastic polymer SS compared to the control SS.Objetivo: evaluar la presión de interfaz (PI) de las superficies de apoyo (SAs) en prominencias óseas. Método: un estudio casi experimental con medidas repetidas en diferentes SAs. Veinte voluntarios adultos saludables participaron del estudio. Los participantes fueron colocados en decúbito dorsal en una mesa quirúrgica para evaluación de la PI en las prominencias óseas de las regiones occipital, subescapular, sacra y calcánea utilizando sensores. Siete evaluaciones fueron realizadas para cada prominencia ósea: una evaluación en una mesa de operación estándar y otras evaluaciones en mesas que contenían SAs a base de polímero viscoelástico, espuma blanda, o espuma sellada. Fueron utilizadas la estadística descriptiva y el análisis de la varianza para analizar los datos. Resultados: la PI media fue mayor en la SA hecha de polímero viscoelástico en comparación con las otras SAs (p<0,001). La PI media fue relativamente menor en la espuma sellada de densidad 33 y en la espuma blanda de densidad 18. Además, esa variable fue comparativamente mayor en la región sacra (42,90 mmHg) y en la región calcánea (15,35 mmHg). Conclusión: la PI fue menor en SAs a base de espuma, especialmente espuma blanda de densidad 18 y espuma sellada de densidad 33. Sin embargo, la PI no fue reducida en la SA a base de polímero viscoelástico comparado con la SA control

In vitro integrity of implant external hexagon after application of surgical placement torque simulating implant locking

The aim of this study was to evaluate the integrity of the external hexagon of an implant system with internal and external hexagons but with prosthetic connection through the external hexagon (Internal Torque, IT) in comparison with that of an implant system with external hexagon with mount (External Hexagon, EH). A device was made to measure the rotational freedom angles between implant and abutment hexagons in 10 implants from each group after the application of surgical placement torques of 45, 60 and 80 Ncm simulating implant locking. The distances between the vertices of the external hexagon were also obtained. Rotational freedom data were subjected to ANOVA and Tukey's test (P < .05) showing no significant difference between the angles of the intact implants (EH - 3.31 ± 0.41° and IT - 3.30 ± 0.17°) and after application of a 45 Ncm torque (EH - 3.27 ± 0.38° and IT - 3.31 ± 0.22°). However, after application of a 60 Ncm torque there were significant differences (IT - 3.40 ± 0.20° and EH - 4.03 ± 0.54°). After application of a 80 Ncm torque, the IT implant presented values of 3.39 ± 0.21° whereas the EH did not support the torque, suffering deformation of its external hexagon. Within the limits of this study, it can be concluded that the IT implant system may be preferable in clinical situations where implant placement within a certain bone density could generate torques higher than 60 Ncm

Stress Distribution In Co-cr Implant Frameworks After Laser Or Tig Welding.

Lack of passivity has been associated with biomechanical problems in implant-supported prosthesis. The aim of this study was to evaluate the passivity of three techniques to fabricate an implant framework from a Co-Cr alloy by photoelasticity. The model was obtained from a steel die simulating an edentulous mandible with 4 external hexagon analog implants with a standard platform. On this model, five frameworks were fabricated for each group: a monoblock framework (control), laser and TIG welding frameworks. The photoelastic model was made from a flexible epoxy resin. On the photoelastic analysis, the frameworks were bolted onto the model for the verification of maximum shear stress at 34 selected points around the implants and 5 points in the middle of the model. The stresses were compared all over the photoelastic model, between the right, left, and center regions and between the cervical and apical regions. The values were subjected to two-way ANOVA, and Tukey's test (α=0.05). There was no significant difference among the groups and studied areas (p>0.05). It was concluded that the stresses generated around the implants were similar for all techniques.24147-5

Mechanical Study of the Properties of Sutures used in Orthopedics Surgeries

Abstract Objective To evaluate the mechanical properties of sutures commonly used in orthopedic surgeries, characterizing their behavior through tensile tests and determining which one has greater mechanical strength. Method Tensile tests of different sutures were performed in a mechanical testing machine BME 10 kN, using a 50 kgf maximum capacity loading cell. Seven samples from each suture material were tested. Both ends of the sample material were fixed in the proper metal claw, maintaining an initial length of 5 cm. Tests were performed at a speed of 20 mm/minute and at room temperature, recording data for maximum displacement and maximum force at the rupture point. Results FiberWire® #2 (Artrhex, Naples, FL, USA) presented the highest mean strength of rupture (240.17 N), followed by HiFi® #2 (Conmed, Utica, NY, USA) (213.39N) and Ethibond® #5 (Ethicon Inc., Somerville, NJ, USA) (207.38 N). Ethibond® #2 (Ethicon Inc., Somerville, NJ, USA) had the lowestmean strength of rupture (97.8 N). Conclusion Non-absorbable braided polyblend sutures, more recently introduced, are superior to conventional, braided polyester sutures, and FiberWire® #2 is the most resistant suture evaluated in the present study

Influence of support surfaces on the distribution of body interface pressure in surgical positioning

Abstract Objective: to evaluate the interface pressure (IP) of support surfaces (SSs) on bony prominences. Method: a quasi-experimental study with repeated measures on each SS. Twenty healthy adult volunteers participated in the study. The participants were placed in the supine position on a standard operating table for evaluation of IP on the bony prominences of the occipital, subscapular, sacral, and calcaneal regions using sensors. Seven evaluations were performed for each bony prominence: one on a standard operating table, and the others on tables containing SSs made of viscoelastic polymer, soft foam, or sealed foam. Descriptive statistics and analysis of variance were used to analyze the data. Results: the mean IP was higher on the viscoelastic polymer-based SS compared to the other SSs (p<0.001). The mean IP was relatively lower on the density-33 sealed foam and density-18 soft foam. In addition, this variable was comparatively higher in the sacral region (42.90 mmHg) and the calcaneal region (15.35 mmHg). Conclusion: IP was relatively lower on foam-based SSs, especially on density-18 soft foam and density-33 sealed foam. Nonetheless, IP was not reduced on the viscoelastic polymer SS compared to the control SS