Date of Award

Spring 2017

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Dentistry

First Advisor

Berzins, David

Second Advisor

Stover, Sheila

Third Advisor

Hashimoto, Lance

Abstract

Introduction: The aim of this study was to document and identify precipitate formation and exothermic reaction caused when mixing NaOCl and QMiX. Methods: Photography captured time-dependent changes when mixing NaOCl and QMiX at; 0 seconds, 30 seconds, 1 minute, 30 minutes, 1 hour, and 24 hours. A differential scanning calorimeter (DSC) was utilized in determination of heat flow while analyzing temperature change (°C), enthalpy (mJ), and time (seconds) for NaOCl with QMiX and NaOCl with 2% chlorhexidine (CHX). 1H Nuclear Magnetic Resonance (NMR) and 2D NMR (DOSY) spectroscopy analyzed precipitation formed from NaOCl and QMiX. Results: Digital photography documented immediate, intense color change (blue-green to orange-brown) with colorless, pungent gas production. 1-30 minutes - color change gradually lightened to a brownish-yellow and gas production lessened until cessation. 30 minutes - precipitation was noted throughout solution. 24 hours - precipitate coalesced from suspension to the bottom of the test tube. DSC analysis revealed endothermic reactions for both control groups (QMiX and QMiX, CHX and CHX). NaOCl and QMiX resulted in an exothermic reaction with an average temperature change of 4.60 +/- 0.20°C, enthalpy of 6266 +/- 608 mJ, and time to maximum peak of 3 +/- 1 seconds. NaOCl and CHX resulted in an exothermic reaction with an average temperature change of 0.40 +/- 0.20°C, enthalpy of 3045 +/- 384 mJ, and time to maximum peak of 52 +/- 7 seconds. All t-tests revealed a p value of p<0.01.1H NMR revealed trace amounts of aromatic ring compounds (CHX, PCU). 2D spectra indicated unidentified inorganic salt with a molecular weight of 500 g/mol. Conclusions: Mixing 5.25% NaOCl and QMiX causes an immediate, intense reaction leading to color change, gas production, and a time-dependent precipitate formation (unidentified inorganic salt). Mixing creates an exothermic reaction and heat increase of 4.60°C +/- 0.20°C within 3 +/- 1 seconds. Intermediate irrigation protocols and drying techniques must be utilized to lessen precipitate and gas formation, helping to prevent occluded dentinal tubules before endodontic obturation. Further research is needed to identify the molecular structure of formed precipitate and evaluate potential in vivo effects.

Available for download on Thursday, November 09, 2017

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