Influence of surface treatment on the fluorescence of composite resins subjected to in situ bleaching.

OBJECTIVE: Use fluorescence analysis to evaluate the effect of polishing and surface sealant on the color of composite resin bleached with carbamide peroxide and subjected to staining. MATERIALS AND METHODS: Forty-eight composite resin specimens (Z250/Z350XT) were fabricated. After 24 hours stored in distilled water, all specimens were submitted to in situ bleaching with 16% home peroxide for 8 hours daily for a period of 14 days. Subsequently specimens were separated in three groups according to surface treatment proposed (group 1-polishing Sof-Lex; group 2-BisCover; group 3-control). After this, all the specimens were stained with red wine. A spectrofluorometer was used to evaluate the fluorescence in two readouts (L0-after surface treatment and L1-after staining).Data were analyzed by applying ANOVA using a statistical software program. RESULTS: No differences were shown for the factor treatment and other interactions. The lowest mean fluorescence value was found for Z350XT resin (1759.18 ± 0.13) when compared with Z250 (6863.92 ± 0.13). There was significant difference in the mean fluorescence values for all surface treatments between the two different readouts L0 (4820.93 ± 0.05) and L1 (3802.17 ± 0.05). CONCLUSION: The results suggested that all surface treatments proposed did not influenced the results of wine staining of bleached resins when compared with the control evaluated by the fluorescence method. CLINICAL SIGNIFICANCE: The purposes of this research was to find solutions, by means of surfaces treatment, to achieve restorations with a satisfactory and similar final aspect in relation to the teeth, and avoid discrepancies related to the esthetics and longevity of the restoration.

Retrospective review of efficacy of radiofrequency ablation for treatment of colorectal cancer liver metastases from a Canadian perspective.

PURPOSE: A retrospective single-center review of ultrasound-guided radiofrequency ablation (RFA) treatment of colorectal cancer liver metastases was performed. This study reviews the primary and secondary technical effectiveness, overall survival of patients, recurrence-free survival, tumour-free survival, rates of local recurrence, and postprocedural RFA complications. Technical effectiveness and rates of complication with respect to tumour location and size were evaluated. Our results were compared with similar studies from Europe and North America. METHODS: A total of 63 patients (109 tumours) treated with RFA between February 2004 and December 2009 were reviewed. Average and median follow-up time was 19.4 and 16.5 months, respectively (range, 1-54 months). Data from patient charts, pathology, and Picture Archiving and Communication System was integrated into an Excel database. Statistical Analysis Software was used for statistical analysis. RESULTS: Primary and secondary technical effectiveness of percutaneous and intraoperative RFA were 90.8% and 92.7%, respectively. Average (SE) tumour-free survival was 14.4 ± 1.4 months (range, 1-43 months), and average (SE) recurrence-free survival was 33.5 ± 2.3 months (range, 2-50 months). Local recurrence was seen in 31.2% of treated tumours (range, 2-50 months) (34/109). Overall survival was 89.4% at 1 year, 70.0% at 2 years, and 38.1% at 3 years, with an average (SE) overall survival of 37.0 ± 2.8 months. There were 14 postprocedural complications. There was no statistically significant difference in technical effectiveness for small tumours (1-2 cm) vs intermediate ones (3-5 cm). There was no difference in technical effectiveness for peripheral vs parenchymal tumours. CONCLUSIONS: This study demonstrated good-quality outcomes for RFA treatment of colorectal cancer liver metastases from a Canadian perspective and compared favorably with published studies.

Junctioning longitudinally adjacent PTVs with Helical TomoTherapy.

Irradiation of longitudinally adjacent PTVs with Helical TomoTherapy (HT) may be clinically necessary, for example in treating a recurrent PTV adjacent to a previously-treated volume. In this work, the parameters which influence the cumulative dose distribution resulting from treating longitudinally adjacent PTVs are examined, including field width, pitch, and PTV location. In-phantom dose distributions were calculated for various on- and off-axis cylindrical PTVs and were verified by ion chamber and film measurement. Dose distributions were calculated to cover 95% of the PTV by the prescribed dose (DP) using 25 and 50 mm long HT fields with pitches of either 0.3 or 0.45. These dose distributions where then used to calculate the 3D dose distribution in the junction region between two PTVs. The best junction uniformity was obtained for fields of equal width, with larger fields providing better intra-PTV dose homogeneity than smaller fields. Junctioning fields of different widths resulted in a much larger dose inhomogeneity, but this could be improved significantly by dividing the junction end of the PTV treated with the smaller field into multiple (up to 4) sub-PTVs, with the prescribed dose in each sub-PTV decreasing with proximity to the junction region. This provided a PTV matching with dose homogeneity similar to that achieved when junctioning two PTVs, both irradiated by the 50 mm field, and provided a distribution where 95% of the PTV received at least the prescribed dose, with maximum excursions from prescribed dose varying from -19% to +13%. We conclude that junctioning adjacent PTVs is possible. Treating longitudinally adjacent PTVs with different widths is a challenge, but dose uniformity is improved by breaking PTVs into multiple contiguous sub-PTVs modified to feather (broaden) the effective junctioning region.

Alpha/beta ratio: A dose range dependence study.

PURPOSE: To investigate the dependence of the alpha/beta ratio determined from in vitro survival curves on the dose ranges. METHODS: Detailed clonogenic cell survival experiments were used to determine the least squares estimators for the linear quadratic model for different dose ranges. The cell lines used were CHO AA8, a Chinese hamster fibroblast cell line; U-373 MG, a human glioblastoma cell line; and CP3 and DU-145, two human prostate carcinoma cell lines. The alpha, beta, and alpha/beta ratio behaviors, combined with a goodness-of-fit analysis and Monte Carlo simulation of the experiments, were assessed within different dose regions. RESULTS: Including data from the low-dose region has a significant influence on the determination of the alpha, beta, and alpha/beta ratio from in vitro survival curve data. In this region, the values are poorly determined and have significant variability. The mid-dose region is characterized by more precise and stable values and is in agreement with the linear quadratic model. The high-dose region shows relatively small statistical error in the fitted parameters but the goodness-of-fit and Monte Carlo analyses showed poor quality fits. CONCLUSION: The dependence of the fitted alpha and beta on the dose range has an impact on the alpha/beta ratio determined from the survival data. The low-dose region had a significant influence that could be a result of a strong linear, rather than quadratic, component, hypersensitivity, and adaptive responses. This dose dependence should be interpreted as a caution against using inadequate in vitro cell survival data for alpha/beta ratio determination.

Colobomatous microphthalmia and orbital neuroglial cyst: case report.

We present the case of a boy with a congenital right orbital cyst with bilateral colobomatous microphthalmia. Neuroimaging studies excluded communication between the cyst and the eye and between the cyst and the central nervous system. Analysis of cyst fluid obtained by aspiration detected beta 2-transferrin by high resolution immunofixation (IFE). The cyst recurred two months following aspiration. It was then completely excised and histopathologic studies demonstrated a cyst containing neuroglial tissue. No recurrence was observed for 12 months following excision.