title: Comparison of shear bond strength to clinically simulated debonding of orthodontic brackets: An in vitro study.
abstract: OBJECTIVE
  To assess in vitro the quantitative and qualitative debonding behavior of the AEZ debonding plier, compared to shear debonding force, in debonding orthodontic metal brackets.
  
  
  METHODS
  Thirty-two extracted premolars bonded with metal brackets were randomly divided into two equal groups according to the type of simulated debonding method; compressive bond strength (CBS) group using AEZ debonding plier (Ormco Corporation, USA) attached to the Instron machine, and shear bond strength (SBS) group using regular Instron attachments. All teeth were subjected to debonding forces, and debonding strength was assessed. The buccal surfaces were then examined, under a stereomicroscope, and adhesive remnants were scored using adhesive remnant index (ARI). Debonding strengths comparison was performed using the independent sample t-test. ARI score comparison was performed using the Mann-Whitney U-test. Correlation between debonding strength and ARI scores was performed using the Spearman correlation.
  
  
  RESULTS
  There was no significant difference in mean debonding strength between the SBS (M = 6.17 ± 0.77 MPa) and CBS (M = 6.68 ± 1.67 MPa) groups (P > 0.05). The CBS group showed significantly less adhesive remnants than the SBS group (P < 0.05); 62.5% of CBS group had ARI score 1, whereas 68.8% of SBS group had ARI score 3. No significant correlation between ARI and debonding strength was found (P < 0.05).
  
  
  CONCLUSIONS
  SBS was found to produce similar debonding strength to the AEZ debonding plier in vitro. However, the AEZ debonding plier resulted in less adhesive remnant which is of great advantage for reducing chair-time during cleanup after debonding brackets.
authors.affiliation: Department of Orthodontics, Faculty of Dentistry, King Abdulaziz University, Jeddah 21381, Saudi Arabia.
authors.forename: Amal Ibrahim
authors.initials: AI
authors.lastname: Linjawi
authors.affiliation: Department of Orthodontics, Faculty of Dentistry, King Abdulaziz University, Jeddah 21381, Saudi Arabia; Alexandria University, Alexandria, Egypt.
authors.forename: Mona A
authors.initials: MA
authors.lastname: Abbassy
keywords: Adhesive remnants; compressive strength; debonding plier; orthodontic brackets; shear strength