ABSTRACT
OBJECTIVE: This study analyzes the biomineralization potential of calcium silicate-based sealers Ceraseal (Meta Biomed Co., Cheongju, Korea) and AH Plus Bioceramic (Dentsply Sirona, United States), focusing on evaluating apatite deposition in root canal dentin and pH increases. MATERIALS AND METHODS: Calcium silicate-based sealers Ceraseal (Meta Biomed Co.) and AH Plus Bioceramic (Dentsply Sirona) were applied to the root canal dentin of premolars that had undergone root canal preparation procedures. This was followed by a 14-day immersion in phosphate-buffered saline (PBS). Biomineralization analysis was performed by analyzing the formation of the apatite layer after the 14-day immersion. The thickness of the apatite layer deposits was observed using a scanning electron microscope (SEM). Additionally, the sealers were placed in molds and submerged in PBS solution with pH measurements taken on days 0, 7, and 14 using a digital pH meter. STATISTICAL ANALYSIS: The average thickness of apatite deposition in the interfacial layer was analyzed using the Mann-Whitney's test. The pH value differences among the groups were analyzed using a one-way analysis of variance test, followed by a post hoc least significant difference. RESULTS: There were differences in the apatite deposition in the interfacial layer between Ceraseal and AH Plus Bioceramic within 14 days of observation. There was a significant difference (p < 0.05) between the pH values of Ceraseal and AH Plus Bioceramic at 7 and 14 days of observation. Ceraseal showed greater alkalizing activity compared with AH Plus Bioceramic. CONCLUSION: Calcium silicate-based sealer Ceraseal showed better biomineralization potential than AH Plus Bioceramic.
ABSTRACT
Photorespiration recovers carbon that would be otherwise lost following the oxygenation reaction of rubisco and production of glycolate. Photorespiration is essential in plants and recycles glycolate into usable metabolic products through reactions spanning the chloroplast, mitochondrion, and peroxisome. Catalase in peroxisomes plays an important role in this process by disproportionating H2O2 resulting from glycolate oxidation into O2 and water. We hypothesize that catalase in the peroxisome also protects against nonenzymatic decarboxylations between hydrogen peroxide and photorespiratory intermediates (glyoxylate and/or hydroxypyruvate). We test this hypothesis by detailed gas exchange and biochemical analysis of Arabidopsis thaliana mutants lacking peroxisomal catalase. Our results strongly support this hypothesis, with catalase mutants showing gas exchange evidence for an increased stoichiometry of CO2 release from photorespiration, specifically an increase in the CO2 compensation point, a photorespiratory-dependent decrease in the quantum efficiency of CO2 assimilation, increase in the 12CO2 released in a 13CO2 background, and an increase in the postillumination CO2 burst. Further metabolic evidence suggests this excess CO2 release occurred via the nonenzymatic decarboxylation of hydroxypyruvate. Specifically, the catalase mutant showed an accumulation of photorespiratory intermediates during a transient increase in rubisco oxygenation consistent with this hypothesis. Additionally, end products of alternative hypotheses explaining this excess release were similar between wild type and catalase mutants. Furthermore, the calculated rate of hydroxypyruvate decarboxylation in catalase mutant is much higher than that of glyoxylate decarboxylation. This work provides evidence that these nonenzymatic decarboxylation reactions, predominately hydroxypyruvate decarboxylation, can occur in vivo when photorespiratory metabolism is genetically disrupted.