Date of Award
Spring 1990
Document Type
Thesis - Restricted
Degree Name
Master of Science (MS)
Department
Dentistry
First Advisor
Dhuru, Virendra B.
Second Advisor
Ferguson, Donald J.
Third Advisor
Meyer, Ralph A. Jr.
Abstract
Ceramic brackets were introduced in response to an increased demand for "esthetic braces". Along with their improved esthetics there were increased bond strengths leading to enamel fractures during debonding. A logical question to be explored would be: Is there a specific resin-bracket combination that will aid in bracket removal yet maintain adequate bond strength? This experiment was designed to evaluate the affect of changes in adhesive filler concentration on the shear, torsion, and tensile bond strength of a chemical, mechanical, and chemical/mechanical retained ceramic bracket. Two hundred and ten bovine mandibular incisors were assigned to one of 21 treatment groups. The teeth were etched for 20 seconds and bonded with a 30, 55, or 80 percent filled adhesive. The teeth were stored in 37°C distilled water for 48 hours prior to testing. Custom fabricated apparatuses, a torque meter, and an lnstron testing machine were utilized to apply a shear, torsion, or tensile force. The force needed to induce bond failure was recorded and the site of bond failure evaluated under a stereo microscope. The following conclusions were obtained: 1. No significant difference was found in the shear, torsion, or tensile bond strength of each ceramic bracket type to changes in the adhesive filler concentration. However, there was a trend toward increased bond strength with increasing filler concentration. 2. Pooling the data according to adhesive type revealed that the 80 percent filled adhesive displayed a significantly greater shear bond strength than the 55 or 30 percent filled adhesive and a greater torsional bond strength than the 30 percent filled adhesive. Therefore, an increase in adhesive filler concentration causes an increase in shear and torsional bond strength. 3. Transcend 2000 brackets exhibited a greater shear and torsional bond strength than Allure Ill or Starfire brackets. 4. The tensile bond strength of Transcend 2000 brackets was comparable to that of metal brackets. All the failure sites were at the bracket-adhesive Interface (BI-1). 5. A significant difference exists in the site of bond failures with different bracket base designs. Under shear and torsional forces Transcend 2000 and Allure Ill brackets predominately undergo combination (COMB) bond failures; whereas, Starfire brackets predominately undergo bracket-adhesive interface (81-1) bond failures. 6. No significant difference, exists in the site of bond failure to changes in the adhesive filler concentration.
Recommended Citation
Ostertag, Alan J., "In Vitro Shear, Torsional, and Tensile Bond Strengths of Ceramic Brackets Utilizing Three Adhesive Filler Concentrations" (1990). Master's Theses (1922-2009) Access restricted to Marquette Campus. 5323.
https://epublications.marquette.edu/theses/5323