Use of measuring gauges for in vivo accuracy analysis of intraoral scanners: a pilot study

PURPOSE: The purpose of this study is to present a methodology to evaluate the accuracy of intraoral scanners (IOS) used in vivo. MATERIALS AND METHODS: A specific feature-based gauge was designed, manufactured, and measured in a coordinate measuring machine (CMM), obtaining reference distances and angles. Then, 10 scans were taken by an IOS with the gauge in the patient's mouth and from the obtained stereolithography (STL) files, a total of 40 distances and 150 angles were measured and compared with the gauge's reference values. In order to provide a comparison, there were defined distance and angle groups in accordance with the increasing scanning area: from a short span area to a complete-arch scanning extension. Data was analyzed using software for statistical analysis. RESULTS: Deviations in measured distances showed that accuracy worsened as the scanning area increased: trueness varied from 0.018 ± 0.021 mm in a distance equivalent to the space spanning a four-unit bridge to 0.106 ± 0.08 mm in a space equivalent to a complete arch. Precision ranged from 0.015 ± 0.03 mm to 0.077 ± 0.073 mm in the same two areas. When analyzing angles, deviations did not show such a worsening pattern. In addition, deviations in angle measurement values were low and there were no calculated significant differences among angle groups. CONCLUSION: Currently, there is no standardized procedure to assess the accuracy of IOS in vivo, and the results show that the proposed methodology can contribute to this purpose. The deviations measured in the study show a worsening accuracy when increasing the length of the scanning area

Evaluación de un Articulador Virtual para la identificación de interferencias en movimientos mandibulares excéntricos

El objetivo del estudio fue determinar la concordancia del articulador virtual Whip-Mix Denar Mark 330 soportado por 3 Shape Dental System™, para la identificación de interferencias oclusales en los movimientos excéntricos. Se utilizó una muestra probabilística de 50 pacientes adultos, mayores de 20 años, Clase-Angle-I o II, con soporte dental anterior y posterior, sin patologías articulares. Como método estándar se utilizó el análisis oclusal (presencia y ubicación de interferencias oclusales durante los diferentes movimientos mandibulares) realizado por dos examinadores cualificados -tanto en los pacientes como en los montajes en el articulador semiajustable Whip Mix serie 2240. Para determinar la exactitud se compararon las mediciones realizados por el método estándar y por el articulador virtual sobre 50 montajes de los 50 pacientes, y para evaluar la precisión se compararon tres mediciones realizadas a intervalos de 7 días por el articulador virtual sobre 35 montajes codificados a ciego para cada medición. En el análisis estadístico se calculó el coeficiente correlación intraclase. La exactitud del articulador virtual reportó fuerza de concordancia moderada para la localización de interferencias en lateralidad izquierda/balanza y protrusión derecha. Y la fuerza de concordancia regular en lateralidad derecha/trabajo, lateralidad izquierda trabajo y balanza, y protrusión izquierda. Se obtuvo una precisión muy buena en todos los casos. Concluyendo que el articulador virtual evaluado no es una prueba confiable para identificar interferencias oclusales en movimientos excéntricos.Los autores agradecen la financiación del estudio a la Vicerrectoría de Investigaciones de la Universidad El Bosque (PCI: 2013-395) y la cooperación prestada por las Clínica Odontológicas de la Universidad El Bosque

Nola aurre egin itsas garraioak eragindako klima-aldaketari? Estrategia berriak

Currently maritime transport is growing due to globalization and economic growth, and it transports approximately the 90% of the world’s goods. World maritime transport fleet is increasing in amount and in size of vessels and, accordingly, marine fuel oil consumption is also increasing. The marine fuel oil consumption represents the 50% of the operational costs of a vessel and it has a huge environmental impact (ocean acidification, pollution, greenhouse effect, climate change…). Consequently, IMO (International Maritime Organization) created a specific environmental regulation and divided the ocean in different ECA zones (Emission Control Areas). The present work analyses the best strategy, a shipowner should adopt, to comply with ECA regulations, in three different panoramas: i) using an active vessel, placing a scrubber or consuming low sulphur marine fuel oil; ii) constructing a new vessel, choosing between marine dual engine or marine diesel mengine in both cases with or without scrubber; and iii) in case new ECA zones are created, which affects directly the vessel’s operational area.; Gaur egun, itsas garraioak munduko ondasunen % 90 mugitzen du. Ekonomiaren hazkundea eta globalizazioa direla-eta, garraio mota hori goraka doa. Munduko garraioontzi flotaren kopurua haziz doan neurrian, fuel-olioaren kontsumoa ere hazten ari da. Fuel-olioaren kostua garraio-ontzi baten kostu operazionalen % 50 baino gehiago da, eta erregai horren erabilerak eragin nabarmena du ingurumenean (azidifikazioa, kutsadura, berotegi-efektua…); hori kontuan izanik, ECA direlako guneetan (Emission Control Areas) banatu ditu munduko itsasoak IMOk (International Maritime Organization), ingurumen-legedi berezi baten pean. Artikulu honetan, aztergai da zer estrategia jarraitu behar duen armadore batek (itsasontzi baten ustiatzaileak) lege sorta horietara egokitzeko, honako hiru aldagai hauek kontutan izanda: i) eraikita dagoen itsasontzi bat ustiatzen badu, sufre gutxiagoko fuelak erabiltzea edo itsasontziaren motorra egokitzea; ii) itsasontzi berri bat eraikitzera badoa, motor duala edo diesel-motorra jartzea; eta iii) zer aukera dagoen IMOk ECA gune berriak sortzeko

Aerosol Delivery by Inhalation Catheter and Trachea Digitalization

Neonatal respiratory distress syndrome (RDS) is related with high mortality and morbidity in preterm infants and the best approach to treat it is an open research field. The use of perfluorocarbons (PFC) together with non-invasive respiratory support techniques, such as nasal continuous positive airway pressure (CPAP), has confirmed its effectiveness to achieve a more homogeneous surfactant distribution. The goal of the current study was to evaluate the main features of the aerosol generated by an intracorporeal inhalation catheter, which consists of one central lumen delivering the liquid and six peripheral lumens delivering compressed air. Firstly, experiments were made through an Aerodynamic Particle Sizer (APS) with sterile water and perfluorocarbon FC75 with a driving pressure of 4 bar to analyze properties linked with lung deposition such as the aerodynamic diameter (Da), mass median aerodynamic diameter (MMAD) and geometric standard deviation (GSD). Subsequently, a numerical model was developed with CFD techniques. The experimental validation of the numerical model provides an accurate prediction of the air flow axial velocity.This work has been supported by Consolidated Groups from the Basque Government. Technical and human support provided by IZO-SGI, SGIker is gratefully acknowledged

Aerosol Delivery by Inhalation Catheter and Trachea Digitalization

Neonatal respiratory distress syndrome (RDS) is related with high mortality and morbidity in preterm infants and the best approach to treat it is an open research field. The use of perfluorocarbons (PFC) together with non-invasive respiratory support techniques, such as nasal continuous positive airway pressure (CPAP), has confirmed its effectiveness to achieve a more homogeneous surfactant distribution. The goal of the current study was to evaluate the main features of the aerosol generated by an intracorporeal inhalation catheter, which consists of one central lumen delivering the liquid and six peripheral lumens delivering compressed air. Firstly, experiments were made through an Aerodynamic Particle Sizer (APS) with sterile water and perfluorocarbon FC75 with a driving pressure of 4 bar to analyze properties linked with lung deposition such as the aerodynamic diameter (Da), mass median aerodynamic diameter (MMAD) and geometric standard deviation (GSD). Subsequently, a numerical model was developed with CFD techniques. The experimental validation of the numerical model provides an accurate prediction of the air flow axial velocity.This work has been supported by Consolidated Groups from the Basque Government. Technical and human support provided by IZO-SGI, SGIker is gratefully acknowledged

Biomechanical Consequences of the Elastic Properties of Dental Implant Alloys on the Supporting Bone: Finite Element Analysis

The objective of the present study is to evaluate how the elastic properties of the fabrication material of dental implants influence peri-implant bone load transfer in terms of the magnitude and distribution of stress and deformation. A three-dimensional (3D) finite element analysis was performed; the model used was a section of mandibular bone with a single implant containing a cemented ceramic-metal crown on a titanium abutment. The following three alloys were compared: rigid (Y-TZP), conventional (Ti-6Al-4V), and hyperelastic (Ti-Nb-Zr). A 150-N static load was tested on the central fossa at 6° relative to the axial axis of the implant. The results showed no differences in the distribution of stress and deformation of the bone for any of the three types of alloys studied, mainly being concentrated at the peri-implant cortical layer. However, there were differences found in the magnitude of the stress transferred to the supporting bone, with the most rigid alloy (Y-TZP) transferring the least stress and deformation to cortical bone. We conclude that there is an effect of the fabrication material of dental implants on the magnitude of the stress and deformation transferred to peri-implant bone

Biomechanical Consequences of the Elastic Properties of Dental Implant Alloys on the Supporting Bone: Finite Element Analysis

The objective of the present study is to evaluate how the elastic properties of the fabrication material of dental implants influence peri-implant bone load transfer in terms of the magnitude and distribution of stress and deformation. A three-dimensional (3D) finite element analysis was performed; the model used was a section of mandibular bone with a single implant containing a cemented ceramic-metal crown on a titanium abutment. The following three alloys were compared: rigid (Y-TZP), conventional (Ti-6Al-4V), and hyperelastic (Ti-Nb-Zr). A 150-N static load was tested on the central fossa at 6° relative to the axial axis of the implant. The results showed no differences in the distribution of stress and deformation of the bone for any of the three types of alloys studied, mainly being concentrated at the peri-implant cortical layer. However, there were differences found in the magnitude of the stress transferred to the supporting bone, with the most rigid alloy (Y-TZP) transferring the least stress and deformation to cortical bone. We conclude that there is an effect of the fabrication material of dental implants on the magnitude of the stress and deformation transferred to peri-implant bone

A new method to measure the accuracy of intraoral scanners along the complete dental arch: A pilot study

PURPOSE. The purpose of this study is to assess the accuracy of three intraoral scanners along the complete dental arch and evaluate the feasibility of the assessment methodology for further in vivo analysis. MATERIALS AND METHODS. A specific measurement pattern was fabricated and measured using a coordinate measuring machine for the assessment of control distances and angles. Afterwards, the pattern was placed and fixed in replica of an upper jaw for their subsequent scans (10 times) using 3 intraoral scanners, namely iTero Element1, Trios 3, and True Definition. 4 reference distances and 5 angles were measured and compared with the controls. Trueness and precision were assessed for each IOS: trueness, as the deviation of the measures from the control ones, while precision, as the dispersion of measurements in each reference parameter. These measurements were carried out using software for analyzing 3-dimensional data. Data analysis software was used for statistical and measurements analysis (alpha=.05). RESULTS. Significant differences (P<.05) were found depending on the intraoral scanner used. Best trueness values were achieved with Hero Element1 (mean from 10 +/- 7 mu m to 91 +/- 63 mu m) while the worst values were obtained with Trios3 (mean from 42 +/- 23 mu m to 174 +/- 77 mu m). Trueness analysis in angle measurements, as well as precision analysis, did not show conclusive results. CONCLUSION. iTero Elementl was more accurate than the current versions of Trios3 and True Definition. Importantly, the proposed methodology is considered reliable for analyzing accuracy in any dental arch length and valid for assessing both trueness and precision in an in vivo study.The work was partially supported by the Country Council of Gipuzkoa (Grant number 70/19)

Cooperando : mayor satisfacción. Experiencias de dinámicas cooperativas en 1er curso de Ingeniería en el área de expresión gráfica

Resumen basado en el de los autoresUniversidad del País Vasco. Escuela Técnica Superior de IngenieríaSe muestra el beneficio de la enseñanza activa en un entorno de enseñanza tradicional. Es una muestra: de la importancia de la discusión entre pares frente a la explicación del profesor; del cambio metodológico sin modificar el curriculum (contenido); y de la satisfacción generalizada del alumnado con igual o mejor rendimiento académico. En la Escuela de Ingeniería de Bilbao UPV/EHU, la asignatura de Gráficos de Ingeniería está colegiada y tiene un examen final como prueba de evaluación. Durante tres cursos se han realizado intervenciones didácticas introduciendo metodologías activas en el grupo experimental, manteniendo el mismo temario y evaluación que el grupo de control. La metodología elegida es una dinámica cooperativa (jigsaw) en la que su característica más importante es que el conocimiento es desarrollado por estudiantes en grupo (discusión entre pares) y que el profesor no explica ni la teoría ni la práctica ligada al conocimiento en cuestión, el profesor asesora a los estudiantes en su proceso de aprendizaje. El análisis cuantitativo y cualitativo de los datos recogidos muestra que el empleo de dinámicas cooperativas es beneficioso para la docencia, teniendo en cuenta además que la asignatura de Gráficos de Ingeniería se imparte en grupos grandes y con estudiantes de 1er curso.ES