Student Theses, Dissertations and Capstones

Document Type


Degree Name

Master of Science (M.S.) in Dentistry

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All rights reserved. This publication is intended for use solely by faculty, students, and staff of Nova Southeastern University. No part of this publication may be reproduced, distributed, or transmitted in any form or by any means, now known or later developed, including but not limited to photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the author or the publisher.


College of Dental Medicine

First Advisor

Jeffrey Thompson

Publication Date / Copyright Date



Nova Southeastern University


Objective. This study was conducted to test the impact of exposure to artificial gastric acid combined with toothbrush abrasion on the properties of dental ceramics. Earlier research has indicated that immersion in artificial gastric acid increased surface roughness of dental ceramics. However, the combined effect of acid immersion and toothbrush abrasion and the impact of increased surface roughness on mechanical strength and optical properties has not been studied. Methods. Three commercially available ceramics were chosen for this study: feldspathic porcelain, lithium disilicate glass ceramic, monolithic zirconium oxide. The specimens (10×1 mm discs) were cut, thermally treated as required and polished. Each material was divided into four groups (n=8): Control (no exposure), Acid only, Brush only, Acid + Brush. The specimens were immersed in artificial gastric acid (50 ml of 0.2% (w/v) Sodium chloride in 0.7% (v/v) Hydrochloric acid mixed with 0.16g of pepsin powder, (pH=2) for 2 minutes and rinsed with deionized water for 2 minutes. The procedure was repeated 6 times/day x 9 days and specimens were stored in deionized water at 37ºC. Toothbrush abrasion was performed using an ISO/ADA design brushing machine for 100 cycles/day x 9 days. The Acid + Brush group received both treatments. Specimens were examined under SEM and an optical microscope for morphological changes. Color and translucency were measured using spectrophotometer CIELAB coordinates (L*, a* and b*); surface gloss was measured using a gloss meter. Surface roughness was measured using a stylus profilometer; biaxial strength was measured using an Instron mechanical testing machine. The data was analyzed by one-way ANOVA followed by Tukey's HSD post hoc test (p





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