IN VITRO STUDY OF THE EFFECT OF ER:YAG LASER IRRADIATION ON THE APICAL SEALING OF DIFFERENT ROOT CANAL SEALERS

Objectives:

The aim of this study was to determine the effect of Er:YAG laser irradiation used to clean dentinal walls on the apical sealing of root canals filled with different types of sealers.

Background Data:

Laser application to the dentinal walls removed debris, rendering the root canals free of smear layers and leaving the dentinal canaliculi open.

Methods:

Sixty-four maxillary canines obtained from laboratory files were instrumented with K-files (Dentsply, Maillefer, Ballaigues, Switzerland) using the crown-down technique, and irrigated with a 0.5% sodium hypochlorite solution. The specimens were divided into two groups of 32 teeth each. In group I, the teeth were instrumented and irrigated with sodium hypochlorite solution, and divided into four subgroups to be sealed with the different materials (Endofill, N-Rickert, Sealapex and Sealer 26). In group II, the root canals were subjected to Er:YAG laser irradiation (200 mJ, 7 Hz and 60 J total energy), followed by root canal sealing as in group I.

Results:

The data showed lower levels of apical microleakage in the teeth filled with N-Rickert, Sealapex and Sealer 26 cements than in those sealed with Endofill (p < 0.01). No significant difference in microleakage was observed between teeth irrigated only with 0.5% sodium hypochlorite and those submitted to Er:YAG laser application (p > 0.05).

Conclusions:

The Er:YAG laser irradiation applied to the root canal walls was not able to prevent apical microleakage.     

Clinical management and subsequent healing of teeth with horizontal root fractures.

Horizontal root fractures are uncommon, mainly occurring on the cervical and middle third of the root of permanent upper incisors. The diagnosis is essentially radiographic and requires different healing patterns, depending on some pre- and postinjury factors. The aim of this article was to report the clinical management and different healing types in three cases of horizontal root fractures on permanent dentition. In case 1, the pulp tissue was vital and no treatment was necessary. In case 2, a root canal treatment of the cervical fragment was necessary and in case 3, pulpal necrosis was verified and an apical surgery was performed.     

Development of a new instrument for the evaluation of the desire for information and decision making in patients with asthma

The aim of this study was to design a new instrument for determining the asthmatic's desire for information as well as his or her active search for it and ability to make decisions about his or her disease. A questionnaire titled Information and Decisions in Asthma (IDEA) was compiled by writing a list of preliminary questions related to each of the three aforementioned aspects. The list was revised and the length reduced vased on the responses and signs of comprehension from a first group of patients. The draft under study then consisted of 36 items in the following subscales: desire for information (DI), active search for information (AS) and decision making (DM) in three scenarios describing stable asthma, mild exacerbation and severe exacerbation. The questionnaire was then administered to 120 adult asthmatic of both sexes whose disease was stable and at different levels of severity. Cronbach alpha coefficients were satisfactory for DI and AS (0.86 and 0.77, respectively) and did not improve with the elimination of any items. Factorial analysis overall for DI and AS (total explained variance = 44.16%) detected two correlated factors (r = 0.34, p < 0.01). The DM subscale contained problems of internal consistency which were solved by removing five items. Factorial analysis for DM then revealed a tri-factorial structure in which each factor adjusted well to each of the scenarios. Analysis of these results indicates that the final version of the IDEA shows very acceptable internal consistency and validity, suggesting that it could be used to assess the aspects it is intended to measure.     

Estudio computarizado de la influencia de la proliferación y de la variación de la radiosensibilidad en un programa de radioterapia fraccionada. Efecto del tiempo total de tratamiento sobre el control tumoral

Propósito

Estudiar, para la radioterapia fraccionada, la influencia que tienen las variaciones de radiosensibilidad y cinética de proliferación a lo largo del tratamiento, así como el efecto del tiempo total de tratamiento, sobre la probabilidad de control tumoral.

Métodos

Partiendo de los datos de la cinética de crecimiento y de la radiosensibilidad de los esferoides multicelulares (MTS) de la línea celular MCF-7 de cáncer de marna, se efectÚa la simulación computarizada de un tratamiento fraccionado de radiosterapia.

Resultados

Cuando se progresa en la terapia, aumenta la tasa de proliferación, lo que explica el fenómeno de repoblación acelerada. Sólo si aumenta la radiosensibilidad a lo largo del tratamiento, un agregado celular con las características proliferativas de los MTS puede ser esterilizado. Una demora en el inicio del tratamiento o una interrupción del mismo producen un empeoramiento de la probabilidad de control tumoral, que es más acusado en el caso de una interrupción y cuanto más tarde se produce ésta. El aumento de la dosis para el control del 50% de los tumores cuando se prolonga el tiempo total de tratamiento alcanza valores de 0,5–1,14 Gy por día de aumento en el tiempo total.

Conclusiones

En otros trabajos, cuando se analizan datos clínicos mediante modelos de probabilidad de control, los valores obtenidos para los parámetros puede que ajusten los datos, pero quizás no muestren las verdaderas características histológicas de los tumores correspondientes. En la situación aquí presentada, al igual que para otros tipos de tumores como los de cabeza y cuello, el aumento del tiempo total de tratamiento hace necesario corregir la dosis total para mantener los nivelés de control previstos.