Sum Chee Peng
Email Address
denscp@nus.edu.sg
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Publication Characterizing bacteria adhesion to substrate and early biofilm formation using atomic force microscopy: A review(2013-01) Sum, C.-P.; Shrestha, A.; Kishen, A.; RESTORATIVE DENTISTRYBacterial adherence has received continued interest, as it is the most important and crucial step in the development of a biofilm. Bacterial interactions with various surfaces are characterized by examining their morphology and physico-chemical parameters. Atomic force microscopy (AFM) is an attractive tool that not only provides high-resolution images at nanometric range but also provides information on the interaction forces. AFM with functionalized probes can be used to measure interaction forces as small as a few picoNewtons. This review describes the aspects of initial biofilm formation i.e., bacterial adhesion and how AFM can be used to study the interaction forces. © Indian Intitute of Science.Publication Effects of concentrations and exposure times of sodium hypochlorite on dentin deproteination: Attenuated total reflection fourier transform infrared spectroscopy study(2010-12) Hu, X.; Peng, Y.; Sum, C.-P.; Ling, J.; RESTORATIVE DENTISTRYIntroduction: The purpose of this study was to quantitatively analyze the effects of different concentrations and exposure times of sodium hypochlorite (NaOCl) on dentin deproteination and to determine the suitable concentrations and exposure times to minimize the effects of deproteination on dentin. Methods: Intact human dentin slabs were treated with 0.5%, 1%, or 2.25% NaOCl for 1, 5, or 10 minutes. A 0.9% NaCl solution served as the control. To investigate the effect of NaOCl on the surface chemical changes to human dentin, the attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy technique was used to analyze the amide:phosphate ratio and carbonate:phosphate ratio. Results: The amide:phosphate ratio decreased significantly after NaOCl treatment as compared with the control group (p < 0.05). In the 0.5% NaOCl treatment group, the amide:phosphate ratio was significantly higher than that in the 1% and the 2.25% NaOCl treatment groups (p < 0.05). The different exposure times (1, 5, or 10 minutes) of NaOCl within the same concentration did not influence the amide:phosphate ratio (p > 0.05). NaOCl treatment did not affect the carbonate:phosphate ratio (p > 0.05). Conclusions: NaOCl, 0.5%, is recommended as the predominant concentration for routine use during root canal therapy to minimize any NaOCl-induced dentin deproteination. It is suggested that a prolonged exposure to low concentrations of NaOCl is less damaging to dentin in attempting to achieve antisepsis during instrumentation of root canal therapy. © 2010 American Association of Endodontists.