Prevalencia de dos conductos radiculares en incisivos inferiores: una experiencia con alumnos de grado / Prevalence of two root canals in mandibular incisors: an experience with undergraduate students

Objetivo. El propósito de este estudio fue evaluar, ex vivo, en incisivos inferiores tratados por alumnos de grado en el área preclínica de la USAL/AOA, el porcentaje de dientes que presentaban dos conductos y comparar la frecuencia de conductos no tratados según la cantidad de conductos presentes. Material y métodos. Setenta y seis incisivos mandibulares humanos extraídos fueron tratados endodónticamente por alumnos de grado y luego radiografiados en sentido vestibulolingual y mesiodistal. Las raíces de las piezas dentarias fueron seccionadas transversalmente a diferentes niveles obteniendo tres cortes transversales: coronario, medio y apical. A continuación se examinaron los cortes y las radiografías, y se evaluaron la cantidad de conductos radiculares presentes y los instrumentados y obturados de cada especimen. Los resultados obtenidos a partir del porcentaje de conductos encontrados fueron evaluados con un intervalo de confianza del 95% (IC) a partir de la distribución binomial. Para comparar la frecuencia de conductos no tratados según la cantidad de conductos presentes se empleó la prueba de probabilidad exacta de Fisher. Resultados. De los 76 incisivos inferiores, 18 (23,7%) (IC 14,7%-34,8%) presentaban dos conductos radiculares, de los cuales solo en 1 (5,6%) ambos conductos fueron instrumentados y obturados. En los 17 (94,4%) (IC 72,7%-99,9%) incisivos restantes uno de los conductos fue ignorado. La evaluación comparativa entre la frecuencia de conductos no tratados y la cantidad de conductos presentes mostró diferencias estadísticas significativas (p< 0,001). Conclusiones. En consideración de la experiencia expuesta, se destaca la necesidad de insistir en la docencia de grado, en la importancia de la complejidad anatómica de los incisivos inferiores y resaltar los procedimientos clínicos apropiados para su tratamiento (AU)

Objective. The purpose of this ex vivo study was to evaluate, in mandibular incisors treated by undergraduate students of the pre-clinic area of USAL/AOA, the percentage of teeth with two canals and the comparison between the frequency of untreated root canals and the amount of root canals present. Material and methods. 76 human extracted mandibular incisors, endodontically treated by students, were radiographed in buccolingual and mesiodistal directions. Afterward, the teeth were transversally sectioned at different levels of the roots obtaining three sections: coronal, middle and apical. Then, the sections and the radiographs obtained were evaluated taking into consideration the number of root canals and those who were instrumented and filled in each specimen. The results of the percentage of root canals found were evaluated with a 95% confidence intervals (CI) calculated with the binomial distribution. In order to compare the frequency of untreated root canals and the amount of root canals present the Fisher exact probability test was used. Results. From the 76 mandibular incisors, 18 (23.7%) (CI 14.7%-34.8%) showed two canals, only in 1 (5.6%) of them both root canals were instrumented and filled. In the other 17 (94.4%) (CI 72.7%-99.9%) one of the canals was missed. Statistical significant differences were observed between the frequency of untreated root canals and the amount of root canals present (P<0.001). Conclusions. In consideration with this experience, it was pointed out that it is necessary to insist, in the undergraduate training, on the importance of the anatomical complexity of the mandibular incisors and that the proper clinical procedures for its treatment are to be enhanced (AU)

Diagnostics design for steady-state operation of the Wendelstein 7-X stellarator.

The status of the diagnostic developments for the quasistationary operable stellarator Wendelstein 7-X (maximum pulse length of 30 min at 10 MW ECRH heating at 140 GHz) will be reported on. Significant emphasis is being given to the issue of ECRH stray radiation shielding of in-vessel diagnostic components, which will be critical at high density operation requiring O2 and OXB heating.

Diagnostic developments for quasicontinuous operation of the Wendelstein 7-X stellarator.

The stellarator Wendelstein 7-X will allow for quasicontinuous operation with the duration only being limited to two 30 min discharges per day, at a continuous heating power of 10 MW electron cyclotron resonance heating (ECRH) at 140 GHz, by the capacity of the cooling water reservoir. This will result in high thermal loads on all plasma facing components of 50-100 kW/m(2) from radiation alone and of up to about 500 kW/m(2) on components additionally exposed to convective loads. In high density scenarios toroidally varying ECRH stray radiation levels of 50-200 kW/m(2) need to be coped with, requiring careful material selection and different shielding and hardening techniques. Furthermore, a gradual buildup of coatings on plasma facing optical components, which without any measures being taken, would lead to high transmission losses already within a few days of long pulse operation (equivalent to about 1 year of operation in pulsed devices like JET or ASDEX-upgrade) and therefore needs to be prevented as much as possible. In addition in situ cleaning as well as absolute calibration techniques need to be developed for all plasma facing optical systems. Here we report about some of our efforts to find, for various types of diagnostics, ways to cope with these adverse effects. Moreover, we give a few examples for individual diagnostic specific issues with respect to quasicontinuous operation, such as the development of a special integrator for the magnetic diagnostics as well as special interferometer types which can cope with unavoidable vibrations and slow path length changes due to, e.g., thermal expansion of the plasma vessel.

Optical design study of an infrared visible viewing system for Wendelstein 7-X divertor observation and control.

For the Wendelstein 7-X stellarator, which will allow quasicontinuous operation (tau < or = 30 min) with 10 MW of electron cyclotron radiation heating power, a conceptual design study for an IR/visible viewing system (IVVS) has been elaborated. Ten such systems, as part of the machine protection system, will be required for real time monitoring of all ten discrete, water cooled divertor modules with high spatial (< 10 mm) resolution, in order to prevent local overheating of the target tiles, which could easily lead to their destruction. On the physics side, the systems will be used for divertor symmetry investigations by studying the power load distribution on all targets modules and by observing the island divertor plasmas in the light of H alpha, C II, and C III using the visible imaging section of the systems. The optics of the system can be divided into three parts: a mirror based optical head, creating an intermediate image, a Cassegrain telescope system, and individual lens based imaging optics adapted to the various detectors for IR (3-5 microm and 8-14 microm) and visible observations, with their optical light paths being separated by in-vacuum dichroic beam splitters.