title: Comparison of shear bond strength of orthodontic brackets bonded using two different hydrophilic primers: an in vitro study.
abstract: BACKGROUND
  Salivary control and maintenance of a dry operating field is a prime requisite of orthodontic bonding. Moisture insensitive primer (MIP) with a clinical significant bond strength values have a better edge over the conventional hydrophobic bonding systems.
  
  
  OBJECTIVE
  The aim of this study is to investigate the effectiveness of two hydrophilic primers with respect to conventional hydrophobic primer by comparing their shear bond strength (SBS) and adhesive-failure locations after contamination with saliva and saliva substitute.
  
  
  METHODS
  A total of 150 extracted human premolars were randomly divided into five groups; Group A (Transbond MIP/saliva substitute), Group B (Opal Primo/saliva substitute), Group C (Transbond MIP/natural saliva), Group D (Opal Primo/natural saliva), control group - Group E (Transbond XT/dry), adhesive-Transbond XT used for all five groups and bonded using stainless steel brackets. Shear forces were applied to the samples with a universal testing machine. SBSs was measured in megapascals. The mode of bond failure was determined using the adhesive remnant index (ARI).
  
  
  RESULTS
  The mean SBS produced by Transbond MIP was higher than Opal Primo, which was statistically significant according to one-way analysis of variance. Both the tested groups showed lesser bond strength values than Transbond XT (the control). ARI scores revealed that there was no statistically significant difference in the site of bond failure between study groups. ARI scores were found to be lower for study groups suggesting adhesive failure, compared to higher ARI scores for the control group suggesting cohesive failure.
  
  
  CONCLUSIONS
  Transbond XT adhesive with Transbond MIP or Opal Primo have clinically acceptable bond strength in wet fields. Opal Primo is a viable option to use as a hydrophilic primer clinically.
authors.affiliation: Department of Orthodontics and Dentofacial Orthopedics, Ragas Dental College and Hospital, The Tamil Nadu Dr. M.G.R. Medical University, Chennai, Tamil Nadu, India.
authors.forename: M Kumaraswamy
authors.initials: MK
authors.lastname: Anand
authors.forename: Kaberi
authors.initials: K
authors.lastname: Majumder
authors.forename: Sundaram
authors.initials: S
authors.lastname: Venkateswaran
authors.forename: N Rengarajan
authors.initials: NR
authors.lastname: Krishnaswamy
mesh_terms: D000293:Adolescent; D001641:Bicuspid; D001840:Dental Bonding; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D066298:In Vitro Techniques; D016910:Orthodontic Brackets; D033081:Shear Strength