Dynamics and predictors of hematologic toxicity during cranio-spinal irradiation.

Background: Craniospinal irradiation (CSI) is a complex radiotherapy (RT) technique required for treating specific brain tumors and some hematologic malignancies. With large volumes of hematogenous bone marrow (BM) being irradiated, CSI could cause acute hematologic toxicity, leading to treatment interruptions or severe complications. We report on the dynamics and dose/volume predictors of hematologic toxicity during CSI. Materials and methods: Pediatric patients (≤ 18years) undergoing CSI in a tertiary cancer center were included. Medical records were retrospectively reviewed for clinical data and blood parameters were collected at baseline and weekly, until four weeks after the end of RT. The BM substructures were contoured, and dose-volume parameters were extracted. We used Wilcoxon rank-sum test to compare quantitative data, Chi square test for qualitative data and receiver operating characteristics (ROC) curves for dose/volume thresholds. Results: Fifty-one patients were included. Severe toxicities (grade 3-4) were recorded as follows: 2% anemia, 8% thrombocytopenia, 25% leukopenia, 24% neutropenia. Ninety-eight percent of patients had lymphopenia (grade 1-4) at some point. Twenty-nine percent required granulocyte-colony stimulating factor, 50% had an infection and 8% required a blood transfusion. Dmean > 3.6 Gy and V15 Gy > 10.6% for Pelvic Bones were associated with a higher risk of developing any ≥ G3 toxicities. Dmean > 30-35 Gy to the thoracic and lumbar spine was predictive for G3-4 anemia and thrombocytopenia, and Cervical Spine Dmean > 30 Gy was associated with ≥ G3 neutropenia. Conclusion: CSI was well tolerated, without life-threatening complications in our cohort, but hematologic toxicity was frequent, with severity increasing with higher mean doses delivered to the hematogenous BM and larger volumes of BM receiving 30-35 Gy.

Assessment of the Cyclic Fatigue Performance of the Novel Protaper Ultimate File System Used in Different Kinematics: An In Vitro Study.

This in vitro study aims to assess the cyclic fatigue resistance of the Protaper Ultimate (PTU) files compared to the Protaper Gold (PTG) and the M3 UDG (M3) files using various motion kinematics in simulated canals. As far as the authors are aware, no study has previously compared the three file systems before this current investigation. Therefore, closing this information gap is the goal of the current research. Methods: A total of (60 new endodontic files were randomly divided into 6 groups (10 files per group); groups 1, 3, and 5 used continuous rotation (CR), while groups 2, 4, and 6 used forward reciprocating motion (FRM). A manufactured stainless-steel artificial canal was used to perform the cyclic fatigue testing. The results were analyzed using Student's t-test and two-way ANOVA. All pairwise comparisons revealed statistically significant differences in the time to failure (TTF) for every study group (p < 0.001), with the exception of the PTG and M3 files, which performed similarly using both CR and FRM. Conclusions: The PTU files performed better than the PTG and M3 files in terms of the TTF and number of cycles to failure (NCF) using both CR and FRM.

A Finite Element Method Study on a Simulation of the Thermal Behaviour of Four Methods for the Restoration of Class II Cavities.

The possibility of dental pulp damage during dental procedures is well known. According to studies, during finishing and polishing without cooling, temperatures of up to 140 °C or more can be generated. There are many studies that have analysed the influence of the finishing and polishing of fillings on the mechanical parameters, but the analysis of thermal parameters has led to uncertain results due to the difficulty of performing this in vivo. Background: We set out to conduct a study, using the finite element method, to determine the extent to which the type of class II cavity and the volume of the composite filling influence the duration of heat transfer to the pulp during finishing and polishing without cooling. Materials and Methods: A virtual model of an upper primary molar was used, with a caries process located on the distal aspect, in which four types of cavities were digitally prepared: direct access, horizontal slot, vertical slot and occlusal-proximal. All four cavity types were filled using a Filtek Supreme XT nanocomposite. Results: The study showed that the filling volume almost inversely proportionally influences the time at which the dental pulp reaches the critical temperature of irreversible damage. The lowest duration occurred in occlusal-distal restorations and the highest in direct access restorations. Conclusions: based on the results of the study, a working protocol can be issued so that finishing and polishing restorations without cooling are safe for pulpal health.