Influencia de la presencia de barrillo en la profundidad de penetración dentinaria del agente fotosensible empleado en la terapia fotodinámica / Influence of the presence of semar layer in the depth of dentinal penetration of the phosotensitizing agent used in photodynamic therapy

La efectividad antimicrobiana de la terapia fotodinámica (TFD), como complemento a la preparación biomecánica, depende del íntimo contacto entre un agente fotosensible, una fuente de energía (LED) y los microorganismos presentes en el conducto. Objetivo. Evaluar si la eliminación del barrillo dentinario influye en la penetración del agente fotosensibilizante dentro de los túbulos dentinarios en la TFD. Metodología. 20 premolares con conductos tipo I fueron decoronados a 12 mm del ápicy preparados biomecánicamente con MTwo y NaOCL al 5,25%. La muestra se dividió aleatoriamente en dos grupos (ni = 10): I, se irrigó con EDTA 17% seguido de suero fisiológico; II, se irrigó sólo con suero fisiológico. Tras la aplicación de la TFD, los especímenes fueron seccionados, obteniéndose discos correspondientes a los tercios coronal, medio y apical. Las muestras fueron visualizadas con un microscopio óptico de reflexión y el software Canvas X16. Se evaluaron el porcentaje de área teñida (PAT) y la penetración intratubular media (PIM). Análisis estadístico: Tests U de Mann-Whitney y Wilcoxon con un nivel de significación de p<0,05. Resultados. Los resultados de PAT y PIM fueron mayores en el grupo I (11,1 ± 5,1/0,45 ± 0,18) que en el II (4,93 ± 4,1/0,26 ± 0,16). No hubo diferencias significativas de PIM en los tercios coronales de I vs. II. Ambos grupos presentaron diferencias de PAT y PIM entre sus tercios. Conclusión. La remoción del barrillo dentinario previa a la aplicación de la TFD mejora significativamente la penetración del agente fotosensible en los tres tercios de la raíz

Antimicrobial efectiveness of the photodynamic therapy (PDT), in addition to chemicomechanical preparation, depends on the contact between a photosensitizer, a light source (LED) and root canal microorganisms. Aim. To evaluate if the removal of smear layer influences the penetration of the photosensitizer into dentinal tubules in the PDT. Methodology. 20 premolars with Type I canals were sectioned at 12 mm from apex and conformed with MTwo and 5.25% NaOCl. Were randomized divided in two groups (ni = 10): group I was irrigated with 17% EDTA and 0.9% NaCl; group II was irrigated with 0.9% NaOCl. For the PDT 0.01% of TBO (Fotosan® ,CMS) as photosensitizer was applied into the canal and activated for 30 sec with a LED red light source (Foto-san630®, CMS). After this, all specimens were sectioned in order to obtain dentin discs of coronal, medium and apical third. Samples were evaluated with an optical microscope at 20x and the software Canvas X16, measuring the percentage of stained area (PAT) and Intratubular media penetration (PIM). Statistical analysis: Test U de Mann-Whitney y Wilcoxon with a significance level of p < 0.05. Results. The results of PAT and PIM were higher in Group I (11,1 ± 5,1/0,45 ± 0,18) than Group II (4,93 ± 4,1/0,26 ± 0,16). No significant differences of PIM were founded between coronal thirds of I vs II. Both groups presented differences of PAT and PIM between their thirds. Conclusion. The removal of smear layer before the TFD application improves the penetration of the photosensitizer in the three root thirds

A comparison of a T1 weighted 3D gradient-echo sequence with three different parallel imaging reduction factors, breath hold and free breathing, using a 32 channel coil at 1.5 T. A preliminary study.

PURPOSE: To investigate whether increasing temporal resolution with higher parallel imaging (PI) reduction factors (RF) in both breath-hold and free breathing approaches, using a non-contrast T1-weighted 3D gradient echo (GRE) sequence and a 32-channel phased array coil, permits diagnostic image quality, with potential application in patients unable to cooperate with breath-hold requirements. MATERIALS AND METHODS: The 9 healthy subjects (5 females and 4 males; age range was 20-49, mean 36 yrs) were recruited. A 3D GRE MR imaging of the abdomen was performed on 1.5 T MR system using a 32-element phased-array torso coil with PI RFs of 2, 4 and 6, breath hold and free breathing. Two reviewers retrospectively qualitatively evaluated all sequences for image quality, extent of artifacts, including motion, truncation, aliasing, pixel graininess and signal heterogeneity. The results were compared using Wilcoxon signed rank and a Bonferroni adjustment was applied for multiple comparisons. RESULTS: Image quality and extent of artifacts were better with breath hold than with free breathing acquisitions. The rate of artifacts increased with higher RF. The best quality was acquired with breath hold sequence using RF=2. RF=4 had lower but diagnostic rates (P=.004). The severity of artifacts, mainly pixel graininess (P=.004), rendered sequences with RF=6 non-diagnostic. All sequences were non-diagnostic in free breathing acquisitions. CONCLUSION: Breath hold sequences with RF=2 had excellent quality and RF=4 had good quality and may be potentially used in partially cooperative patients. None of the sequences was considered diagnostic in free breathing acquisitions.

[In-phase and out-of-phase single-shot magnetization-prepared gradient recalled echo: description and optimization of technique at 1.5 T]. / Secuencia de disparo único eco de gradiente en fase y fase opuesta con preparación de la magnetización: descripción y optimización de la técnica con equipo de 1,5 T.

PURPOSE: To implement in-phase and out-of-phase (IP/OP) techniques with Magnetization-Prepared Gradient Recalled Echo (MP-GRE) and to evaluate the feasibility and diagnostic image quality among pre and post-optimized MP-GRE sequences, including patients unable to cooperate with breath-hold requirements. MATERIALS AND METHODS: Institutional review board approval with waiver of informed consent was obtained for this HIPAA-compliant retrospective study. Two groups of patients were included in the study, before and after optimization of MP-GRE parameters, with seventy-three (24 noncooperative/49 cooperative) and sixty-four (22 noncooperative/42 cooperative) consecutive patients, respectively. The motion-insensitive sequence used in this study was a single-shot 2D MP-GRE. Two radiologists qualitatively evaluated the sequences to identify the presence of phase cancellation artifact in OP images and to determine image quality, extent of artifacts (respiratory ghosting, bounce-point artifact, spatial misregistration and pixel graininess) and lesion conspicuity on the various sequences. The ability to visually detect liver steatosis and fatty adrenal adenomas was evaluated. Qualitative analyses were compared using the Wilcoxon and Mann-Whitney tests. RESULTS: There were statistically significant differences between all MP-GRE sequences concerning phase cancellation artifact (P<.0001) which was present in MP-GRE OP sequences and negligible to absent in the pre (IP1) and post-optimized (IP2) MP-GRE IP sequences, respectively, in all patients. Bounce point artifacts were significantly more pronounced in MP-GRE IP1 (P<.0001). Spatial misregistration was slightly more prominent in noncooperative patients with MP-GRE IP2 (P=.0027). MP-GRE OP and MP-GRE IP2 showed significantly higher overall image quality (P<.0001). MP-GRE sequences subjectively identified hepatic steatosis (n=20) and adrenal adenomas (n=5) based on signal loss from IP to OP sequence. CONCLUSION: Single shot IP/OP MP-GRE is feasible and allows motion resistant imaging with adequate diagnostic image quality. This technique is able to provide IP and OP information in patients unable to suspend respiration.