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After tooth extraction, bone levels in the alveoli decrease. Using a bone substitute can help minimize this bone loss. The substitute can be sourced from a human or animal donor or synthetically prepared. In this study, we aimed to address the following PICOS question: In patients needing dental alveolar preservation for implant placement, how does alveolar preservation using a bovine hydroxyapatite bone xenograft with collagen compare to a xenograft without collagen in terms of changes in alveolar height and width, bone density, and the characteristics of the bone tissue observed in biopsies taken at 6 months? We evaluated two xenograft-type bone substitutes for preserving post-extraction dental sockets using tomography and microscopy to answer that question. A total of 18 dental alveoli were studied: 11 preserved with a xenograft composed of apatite (InterOss) and 7 with a xenograft composed of apatite–collagen (InterOss Collagen). Tomographic controls were performed at 1 and 6 months, and microscopic studies were performed on 13 samples. The biopsies were examined with scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). A Multivariate Analysis of Variance (MANOVA) was conducted in the statistical analysis, revealing a significant increase in bone density over time (p = 0.04). Specifically, bone density increased from an average of 526.14 HU at 30 days to 721.96 HU at 60 days in collagen-free samples. However, no statistically significant differences in height or width were found between groups. The MANOVA results indicated that the overall model had a low predictive ability for height, width, and density variables (R-squared values were low), likely due to sample size limitations and the complexity of bone tissue dynamics. On the other hand, FTIR analysis revealed the presence of phosphate groups, carbonates, and amides I, II, and III, indicative of inorganic (hydroxyapatite) and organic (type I collagen) materials in the xenografts. TGA and DSC showed high thermal stability, with minimal mass loss below 150 °C. Finally, both xenografts were influential in alveolar bone regeneration after extraction without significant differences. The trend of increasing collagen density suggests an effect that requires further investigation. However, it is recommended that the sample size be increased to enhance the validity of the results. [ABSTRACT FROM AUTHOR]

Introduction- The pyrolysis of agro-industrial waste is an alternative to produce second generation liquid fuels. Objective-Determine the kinetics in the pyrolysis process of cassava industrial waste as well as of evolved product formation. Methodology- Pyrolysis of waste from cassava starch processing was studied via thermogravimetric analysis coupled to mass spectrometry. Thermogravimetric data were adjusted to the distributed activation energy model with one pseudocomponent. Results- Pyrolysis of samples heated at ramps below 30 K/min showed kinetics parameters with different values from the ones obtained for the samples heated at ramps above 50 K/min. This suggests a change in the pyrolysis reaction mechanism linked to heating rate. The kinetics parameters obtained in this work are in agreement with values reported for other biomass in literature. From the evolved gases, 23 m/z signals were identified with enough signal/noise ratio. Mass spectrometry signals were also adjusted with the distributed activation energy model using the kinetics parameters obtained from thermogravimetric data. Conclusions- Satisfactory results were achieved with the DAEM model with one pseudocomponent for most of m/z ratio. The lack of adjustment in some m/z ratio can be attributed to secondary reactions in the gas phase. [ABSTRACT FROM AUTHOR]