Student Theses, Dissertations and Capstones

Document Type


Degree Name

Master of Science (M.S.) in Dentistry

Copyright Statement

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

Abraham Lifshitz

Publication Date / Copyright Date



Nova Southeastern University


Introduction: 3M Unitek (2724 Peck Rd, Monrovia, CA 91016) has recently released a new adhesive system labeled APCTM Flash-Free (APCTM FF) that pledges to eliminate flash removal from the orthodontic bracket bonding process. The company states that the bond strength of this new system is comparable to other adhesive systems such as APCTM PLUS. The purpose of this study was to evaluate the bond quality of APCTM FF by measuring excess adhesive, shear bond strength (SBS), microleakage penetration and adhesive remnant index (ARI) compared to APCTM PLUS. Methods: Eighty brackets were bonded on freshly extracted bovine permanent mandibular incisors as per manufacturer recommendations. 3M Unitek Smart Clip SL3 metal maxillary right central incisor brackets were used for this study. Group A contained forty brackets with APCTM PLUS and Group B contained forty brackets with APCTM FF. Following bonding, teeth were stored for twenty-four hours in water at 37°C +/- 2°C. Both groups then underwent thermocycling and subsequently were immersed in two percent methylene blue dye for an additional twenty-four hours. Stereomicroscopic measurements were then taken to evaluate excess adhesive for both groups at 25x magnification. Next, the samples were mounted in dental stone and subsequently debonded using a universal testing machine (Instron, Canton, MA) to obtain the SBS. Stereomicroscopy of 25x magnification was again utilized to record the ARI and microleakage. Microleakage was assessed by measuring the deepest dye penetration perpendicular to the bracket margin of the adhesive remaining on the tooth and adhesive remaining on the bracket. Results: Excess adhesive values were tested with a nested-mixed, general linear model did not show statistically significant differences due to Group (p = 0.150). There was a statistically significant difference due to excess adhesive location (p < 0.001). Excess adhesive was more commonly observed at the gingival and incisal locations than at the distal or mesial locations. A Welch t-test was used to evaluate the dye penetration on both the teeth and also on the brackets. There was no significant difference in dye penetration on the teeth between the two groups (P=0.373). However, there was a significant difference in dye penetration on the bracket between the two groups (p<0.001). A welch t-test was also used to compare bond strength between the two groups which showed no significant difference between the two groups (p=0.229). A chi-square test compared the difference of ARI scores between the two groups and found that there was a significant difference between the two groups. Group I APCTM PLUS had significantly more ARI scores of 3 then the other group. Conclusions: SBS and excess adhesive were not significantly different for APCTM PLUS and APCTM FF. There was a significant difference in excess adhesive in terms of location. There was a significant difference in ARI where APCTM PLUS had more scores of 3 than APCTM FF.




Bond quality, Flash, Flash-free, Novel



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