Microleakage Beneath Orthodontic Metal Brackets Bonded After Thermocycling with Two Different Adhesive Systems of Different Temperatures: an in-vitro Study

Document Type : Original Article

Authors

1 Suez Canal University Hospitals

2 Associate professor Suez Canal University

3 Orthodontics, dentistry, Suez Canal University, Egypt

Abstract

Introduction: The possibility of using traditional composite restoratives has been
raised to bond orthodontic brackets. The higher viscosity observed with restorative
composites compromised their ability to adhere to the bracket base. Pre-heating the
restorative composites puts the monomers into a state of thermal agitation that increases
molecular motion which enhances flowability. The first null hypothesis was that
microleakage underneath brackets using bulk fill composite was comparable to that of
conventional orthodontic adhesives. Additionally, a second null hypothesis was set up,
that preheating bulk fill composite before polymerization decreased the polymerization
shrinkage hence the microleakage scores. Materials and methods: A sample of 56
upper first premolars was collected and divided across 4 groups; I: Transbond XT at
room temperature; II: Transbond XT preheated to 60ºC; III: X-tra fil at room temp; and
IV: X-tra fil preheated to 60ºC. After thermocycling, roots were coated with wax while
crowns with nail varnish then submerged into a solution of 2% methylene blue. After
roots were cut off, the remaining crowns in every group were divided into 2 subgroups,
those of one subgroup were longitudinally split into mesial and distal halves, while those
of the other subgroup were transversely split into gingival and occlusal halves. Depth of
dye penetration at the adhesive-enamel interface was measured under stereomicroscope
at x45 magnification. Results: photopolymerization of x-tra fil after preheating has
exhibited lesser microleakage when compared to Transbond XT, however the results
rendered statistically insignificant. Conclusion: The X-tra fil proved to be a reliable
adhesive for orthodontic brackets.

Keywords

Main Subjects

Dental Science Updates
Volume 6, Issue 2
September 2025
Pages 253-261

Files

Share

How to cite

Statistics