Brown, Alexander2017-11-272017-11-272017-08https://hdl.handle.net/11299/191193University of Minnesota M.S. thesis. August 2017. Major: Dentistry. Advisors: Scott McClanahan, Samantha Roach. 1 computer file (PDF); v, 48 pages.Introduction The aims of the study were to determine if restoration with glass ionomer over unset MTA affects the amount of silver nitrate penetration in a furcation perforation repair and to evaluate micro-computed tomography as a technique by which to quantitatively measure marginal integrity in endodontic research. Methods Twenty-two previously extracted human mandibular molars were sectioned to isolate a furcation region section. Each sample had a furcation perforation induced using a bur. Samples were randomly divided into two experimental groups. Group 1 was restored with grey MTA followed immediately by a resin-modified glass ionomer, while group 2 had the placement of resin-modified glass ionomer delayed for approximately 72 hours. 2 samples were used as negative controls that would not be exposed to silver nitrate. Experimental group samples were submerged in a radiopaque silver nitrate solution (25% w/w) for six hours. All samples were then scanned using a micro-computed tomography machine. The volume of radiopacity above a threshold level was then used to determine the volume of silver nitrate penetration. Results Samples that were immediately covered with resin-modified glass ionomer (group 1) demonstrated less silver nitrate penetration than those that had been covered after full setting of the MTA. The mean volumes above the radiographic threshold for group 1 and group 2 were 0.24 ± 0.27 and 0.54 ± 0.25 mm3, respectively. The difference between the two groups was statistically significant (p < 0.05). Conclusions In a furcation perforation repair model, silver nitrate solution penetration is lower in grey MTA restorations that are immediately covered by glass ionomer on the pulp chamber floor side than those that were covered after 72 hours. Silver nitrate penetration and micro-computed tomography is a feasible option for the study of interface integrity in endodontics.enbioceramicfurcationmicro-CTMTAperforationsilver nitrateThesis or Dissertation