Date of Award

Spring 1992

Document Type

Thesis - Restricted

Degree Name

Master of Science (MS)



First Advisor

Dhuru, Virendra B.

Second Advisor

Ferguson, Donald J.

Third Advisor

Schuckit, William I.


Metal orthodontic brackets systems are popular appliances in orthodontic treatment. Manufacturers and researchers are continually looking for improved methods of bracket retention. Recently, several manufactures have modified the retentive characteristics in their bracket bases. It is not known if these modifications have improved retention nor is it known which bracket base is most retentive. This experiment was designed to evaluate the tensile bond strength of six current bracket base types: an 80 gauge mesh base type, two different 100 gauge mesh base types, a double-layer of mesh (200/100 gauge) base type, a grooved base type, and base type with sintered projections. Ninety bovine incisors were assigned to six treatment groups. The teeth were etched for 60 seconds and then a bracket was bonded to each tooth. After bonding, the teeth were stored in water 48 hours prior to testing. A custom fabricated alignment apparatus and an lnstron testing machine were utilized to apply a tensile force. The force needed to induce bond failure was recorded and the site of bond failure was evaluated under a stereo microscope. The following conclusions were obtained: 1. There was no significant difference between the two 100 gauge mesh base types, which had the lowest bond failure load. 2. There was no significant difference between one of the 100 gauge base types and the 80 gauge base type. 3. There was no significant difference between the 80 gauge base type and the sintered projection. base type. 4. There was no significant difference between the double-layer mesh base type, which had the highest bond failure load, the grooved base type. 5. There was a significant difference between the sintered projection base type and the 100 gauge mesh base type. 6. The grooved and double-mesh base types had significantly higher bond failure loads. 7. The majority of bond failures occurred at the bracket-adhesive interface. No failures occurred at the enamel-adhesive interface.



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