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Objective: The aim of this in vitro study was to compare the shear bond strength (SBS) and the adhesive remnant index (ARI) of the metal APC™ Flash-Free adhesive system, the APC™ pre-coated adhesive system and a conventional uncoated system., Materials and Methods: One hundred eighty-six freshly extracted human premolars were randomly divided into 3 groups and bonded by a single operator. Group A/Control Group (60 teeth): the manual bonding group treated with Transbond™ XT Light Cure Adhesive Paste (3M™ Unitek). Group B (60 teeth): treated with APC™II metal maxillary premolar precoated brackets. Group C (66 teeth): treated with metal maxillary premolar APC Flash-Free brackets. The teeth were then stored in distilled water at 37̊C for 24hours, and five hundred cycles of thermocycling were performed. The Shear Bond Strength (SBS) test was performed using an Instron Universal Testing Machine, and the adhesive remnant index (ARI) was determined using a dental optical microscope at ×25 magnification., Results: The mean shear bond strength values showed differences between the three types of brackets (P=0.016; Anova). It was significantly higher with APC™II and lower with APC Flash-Free brackets; however, no significant differences were found between conventional and APC Flash-Free brackets (P-value=0.574). The distribution of the dichotomized ARI score was significantly different between the three brackets (P-value=0.049). The ARI score for APC Flash-Free brackets was higher with no significant difference between the conventional system and APC brackets (P-value=0.361)., Conclusions: The mean SBS values were not significantly different between APC Flash-Free metal brackets and uncoated metal brackets. The APC Flash-Free metal system's bond failure occurred at the bracket-adhesive interface, with the highest percentage of teeth having more than 50% of the residual composite on the enamel after debonding., (Copyright © 2022 Elsevier Masson SAS. All rights reserved.)

Introduction: The aim of this in vitro study was to determine if there is a significant difference in the excess adhesive flash between the metallic APC™ Flash-Free adhesive system, the APC™ pre-coated adhesive system and a conventional uncoated system., Materials and Methods: One hundred eighty-six freshly extracted human premolars were randomly and blindly divided into three groups according to the type of brackets. Group A (control group n=60): The conventional uncoated metallic bracket (Victory, 3M Unitek®) with a Transbond XT™ Light Cure Adhesive Paste was used. Group B (n=60): The APC™ II metallic maxillary precoated premolar brackets was used. Group C (n=66) : The metallic APC™ Flash-Free adhesive system without flash clean up was used. Images were taken at 40 magnifications in a dental microscope (Leica M320 for dental, Wetzlar, Germany) then analyzed with the ImageJ software and the area of excess adhesive flash was measured., Results: The mean percentage was significantly different between the three groups (p<0.001; ANOVA). It was significantly smaller for brackets in the APC Flash-Free group (p<0.001), and the difference was not significant between conventional brackets and APC (p=0.224)., Discussion: The new technique seems to reduce the amount of excessive adhesive around orthodontic brackets.

Objective: The aim of this in vitro study was to evaluate the effects of enamel deproteinization on the shear bond strength of a self-etching primer Transbond Plus™(TBP), with different application times of sodium hypochlorite (NaOCl 5.25%), primarily and secondarily on the adhesive remnant index score., Materials and Methods: One hundred twenty-five freshly extracted human premolars were randomly and blindly divided into five groups according to the enamel surface preparation, as follows (n=25): group 1(control): Etching with 37% phosphoric acid for 15seconds+Bonding; group 2 (control): TBP™ without NaOCl, group 3: 60seconds NaOCl+TBP™, group 4: 30seconds NaOCl+TBP™, group 5: 15seconds NaOCl+TBP™. The same composite resin was used (Transbond XT™) to bond the orthodontic metal brackets. After the immersion of the teeth in distilled water at 37°C for 24hours the shear bond strength was measured using the universal testing machine and the adhesive remnant index score (ARI) was evaluated under an optical microscope (25×)., Results: The mean SBS values (inMPa) of the groups were respectively: group 1: 13.03±5.36; group 2: 12.28±3.06; group 3: 12.38±4.55; group 4: 12.98±5.76; and group 5: 11.73±5.67. Enamel deproteinization increased the SBS for groups 3 and 4, but no statistically significant difference was found between the five groups (P=0.883). Group 1 showed the highest ARI scores, with 52% of the teeth retaining all the adhesive (score 3). However, for all the other groups, scores 0 and 1 were predominant, with less than half of the adhesive or no adhesive at all remaining on the teeth., Conclusions: Enamel deproteinization with sodium hypochlorite (5.25%) and the variation of its application time has no effect on the SBS of the self-etching primer Transbond Plus ™., (Copyright © 2021. Published by Elsevier Masson SAS.)