1369 Effects of Low-temperature Plasma on Root Dentin Hardness and Elasticity

Saturday, March 24, 2012: 9:45 a.m. - 11 a.m.
Presentation Type: Poster Session
S.A. DAKHIL1, P.G. COELHO1, M.N. JANAL2, V.P. THOMPSON1, and N.R. SILVA3, 1Department Biomaterials and Biomimetics, College of Dentistry, New York University, New York, NY, 2Department of Epidemiology and Health Promotion, College of Dentistry, New York University, New York, NY, 3Department of Prosthodontics, College of Dentistry, New York University, New York, NY
Objective: To evaluate the influences of low-temperature plasma (LTP) on root dentin hardness and reduced modulus using sodium hypochlorite (NaOCl) as a positive control.

Methods: Five extracted single-rooted human teeth were sectioned to provide thirty root dentin specimens. The samples were categorized into six groups (n=5 per group) based upon cutting directions (n=15 transverse discs and n=15 longitudinal segments) and three surface treatments: untreated (negative control), treated with 5.25% NaOCl for 10 minutes (positive control), and LTP treated for 10 seconds using a kINPen device and pure Argon (Ar) as the operating gas to deliver LTP jet at a flow rate of 5 l/min. On each sample, twenty-five nano-indentations were performed to the inter-tubular dentin following a trapezoidal loading function to a maximum load of 5000 µN and using a TriboIndenter equipped with a Berkovich tip. Hardness and reduced modulus were derived according to the Oliver-Pharr method; additionally, Young’s modulus was calculated and ANOVA was applied (α= 0.05).

Results: Compared to the untreated groups and regardless of the direction of tooth sectioning, hardness and reduced modulus of radicular inter-tubular dentin were decreased in LTP treated samples, and increased in NaOCl treated groups (ANOVA main effect, p< .05). These changes were more pronounced in horizontal than vertical sectioned specimens (interaction effect, p< .05).

Conclusion: The application of low-thermal plasma (LTP) and sodium hypochlorite (NaOCl) to root dentin resulted in significant, yet opposite, effects on root dentin hardness and reduced modulus compared to the untreated samples.

Keywords: Dentin, Elasticity, Hardness, Low-temperature Plasma(LTP) and Root