Date of Award

Spring 1993

Document Type

Thesis - Restricted

Degree Name

Master of Science (MS)



First Advisor

Dhuru, Virendra B.

Second Advisor

Ferguson, Donald J.

Third Advisor

Kittleson, Russell T.


Composite resins are the most popular orthodontic materials used for direct bonding brackets to teeth. Manufactures, researchers, and clinicians are continually looking for improved adhesion and enhanced biocompatibility of these types of materials. Unfortunately, composite resins have fallen short of the ideal with a lack of metal adhesion and poor biocompatibility. Recently, a 'hybrid' composite resin glass-ionomer cement has been developed and may show improvements to conventional composite resin adhesives. This experiment was designed to evaluate the tensile bond strength of three different types of orthodontic bonding adhesives: Phase II, a chemical cure composite resin adhesive, Light Bond, a visible light cure composite resin, and Band Lok, a dual cure, hybrid, resin-modified glass-ionomer cement. Ninety bovine incisors were assigned to three treatment groups. The teeth were etched for 60 seconds and stainless steel brackets of the same type were bonded to labial surfaces. The teeth were stored in water for 48 hours prior to testing. A custom fabricated alignment apparatus and an lnstron testing machine were utilized to apply a tensile load. The load needed to induce bond failure was recorded and the site of bond failure was evaluated under a stereo microscope. Diametral tensile strengths were determined for each material using the lnstron machine. Ten disc-shaped specimens were fabricated for each material and subjected to compression loading along the diameter. The following conclusions were obtained: 1. No significant difference exists in the tensile bond failure loads for the three orthodontic bracket adhesives. 2. A significant difference exists in the site of bond failure between the three orthodontic bracket adhesives. Phase II and Light Bond showed bond failures sites predominantly at the bracket-adhesive interface, where no adhesive remained on the bracket base. Band Lok presented mainly with 0% to 25% of the adhesive remaining on the bracket base. 3. A significant difference exists in the Diametral tensile strengths (DTS) of the three orthodontic bracket adhesives. Light Bond, the strongest, showed a mean DTS of 58.1 MPa, Phase II, 44.9 MPa and Band Lok, the weakest, a mean value of 36.9 MPa.



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