Date of Award

2016

Document Type

Thesis

Degree Name

Master of Science in Dentistry

Department

Pediatric Dentistry and Orthodontics

College

College of Dental Medicine

First Advisor

Jing Zhou

Second Advisor

Jompobe Vuthiganon

Third Advisor

Robert Gardner

Abstract

Objective: This study aims to determine the shear bond strength of orthodontic brackets using Trans bond Plus Self Etching Primer with varying time intervals between activation and application. The scheduled bonding times include 0, 2, 8, and 24 hours after self-etching primer mixing and activation. Specifically, this research hopes to elucidate the following: compare the shear bond strength of self­-etching primer to conventional etch, assess bond strengths of self-etching primer at varying times after activation, and determine whether the shear bond strength (SBS) of self-etching primer (SEP) is clinically acceptable when applied hours after activation. A secondary objective is to evaluate the interface at which bond failure occurs. Materials and Methods: Extracted human teeth (SO premolars, 50 incisors) were divided into 5 groups of 10 specimens per tooth type, as follows: Group 1-conventional 37% phosphoric acid etch (CM), Group 2-SEP at time of activation, Group 3- SEP 2 hours after activation, Group 4- SEP 8 hours after activation, Group 5- SEP 24 hours after activation. The self-etching primer for groups requiring activation at a time prior to bonding application was mixed according to manufacturer's guidelines, sealed in Ziploc bags, then stored in a dark, dry drawer at room temperature until ready for bonding. Teeth were bonded in accordance with manufacturer's instructions, differing only in the time at which the bonding procedure takes place after the self-etching primer is opened and activated. Shear bond strengths of each specimen were recorded using the Ultra Tester Machine. To assess the efficacy of the product with a more accurate representation of the procedure that would occur to correct an emergency loose bracket, the incisors were rebonded. The brackets were sand-blasted, and the excess adhesive was removed from enamel. The same bonding procedures were followed for each of the 5 groups above, and the bond strengths were once again recorded. Brackets were analyzed under a stereomicroscope with 15x magnification to determine ARI values. Results: Shear bond strengths were not affected with increasing time between activation and application. No statistically significant differences existed between time intervals within a tooth type nor between tooth types within any single time group. Statistically significant differences were found within the data were ARI values between the following: group 1 and group 2 (p=0.0045), group 1 and group 5 (p=0.0016), group 3 and group 5 (p=0.0261), and combined incisors and premolars (p=0.0302). Conclusions: It is clinically viable, cost-effective, and time-efficient for orthodontists to maintain a single package of Trans bond Plus Self Etching Primer for any brackets requiring bonding or re bonding within a 24-hour period without compromising bond strengths.

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