Shear bond strength of a bracket-bonding system cured with a light-emitting diode or halogen-based light-curing unit at various polymerization times

Abstract

PurposeTo determine and compare the shear bond strength (SBS) of bracket-bonding system cured with light-emitting diode (LED) and halogen-based light-curing unit at various polymerization times.Materials and methodsNinety six human maxillary premolar teeth extracted for orthodontic purpose were divided into four groups, according to the light-curing unit and exposure times used. In the halogen group, the specimens were light cured for 20 and 40 seconds. In the LED group, the specimens were light cured for 5 and 10 seconds. Stainless steel brackets were bonded with Enlight bonding system, stored in distilled water at 37°C for 24 hours and then submitted to SBS testing in a universal testing machine at a crosshead speed of 0.5 mm/minute. Adhesive remnant index (ARI) was used to evaluate the amount of adhesive remaining on the teeth determined by stereomicroscope at 10× magnification.ResultsThe highest mean SBS was obtained with the halogen 40 seconds (18.27 MPa) followed by halogen 20 seconds (15.36 MPa), LED 10 seconds (14.60 MPa) and least with LED 5 seconds (12.49 MPa) group. According to analysis of variance (ANOVA) and Tukey’s multiple-comparison test, SBS of halogen 20 seconds group was not significantly different from halogen 40 seconds group, LED 5 seconds group and LED 10 seconds group, whereas halogen 40 seconds group was significantly different from LED 5 seconds and LED 10 seconds group. The method of light curing did not influence the ARI, with score 2 being predominant.ConclusionPolymerization with both halogen and LED resulted in SBS values that were clinically acceptable for orthodontic treatment in all groups. Hence, for bonding orthodontic brackets, photoactivation with halogen for 20 seconds and LED for 5 seconds is suggested.

A Comparative Study on the Effect of Different Methods of Recycling Orthodontic Brackets on Shear Bond Strength

“…Ltd, Delhi, India), and the teeth thus collected were mounted on an acrylic block such that the roots were completely embedded into the acrylic up to the cementoenamel junction leaving the crown exposed. The labial surfaces of the teeth were kept perpendicular to the bottom surface of the mould [ 15 ]. Each sample was assigned number 1 to 120 and randomly divided into 4 groups.…”

A comparative study on effect of different methods of recycling orthodontic brackets on shear bond strength

“…Ltd.) and the teeth thus collected were mounted on an acrylic block such that the roots were completely embedded into the acrylic up to the cemento-enamel junction leaving the crown exposed. The labial surfaces of the teeth were kept perpendicular to the bottom surface of the mould [17]. Each sample was assigned number 1 to 120 and randomly divided into 4 groups ( Fig.…”

“…Each tooth was then rinsed with a distilled water spray for 5 seconds and dried with oil free air till the etched tooth will appear chalky white. [13,16,17,21] A thin coat of light cured adhesive primer Orthosol (Enlight, Ormco corp. USA) was applied to acid-etched enamel. Enlight light cure adhesive resin was applied on the 0.022" slot MBT stainless steel double mesh premolar bracket base (Standard, Leone co, Sesto, Florentine, Florence, Italy) having a surface area of 11.6 mm 2 , which was then placed on the teeth with a reverse tweezers near the centre of the buccal surfaces.…”

“…All samples were stored in distilled water until nal debonding was done. Final debonding was done immediately after 24 hours of bonding to standardize shear bond strength in a universal testing machine (AG-IC/100 KN, Shimadzu, Japan) ( After bond strength testing, all specimens were collected and visually examined with a stereomicroscope (Olympus SZX12, Olympus corp., Japan) at 10X magni cation to assess the adhesive remnant index [17,24] available at Nepal Agricultural Research Council (NARC), Khumaltar. The adhesive remnant index was used to evaluate the amount of resin remaining on the tooth after debonding.…”

“…available at the Nepal Bureau of Standards and Metrology, Balaju at a crosshead speed of 0.5 mm/min[17]. The force required to dislodge the brackets was measured in Newton, and the shear bond strength (MPa) was calculated by dividing the force values with the bracket base area of 11.6 mm 2…”