title: Effect of acid etching on bond strength of nanoionomer as an orthodontic bonding adhesive.
abstract: OBJECTIVE
  A new Resin Modified Glass Ionomer Cement known as nanoionomer containing nanofillers of fluoroaluminosilicate glass and nanofiller 'clusters' has been introduced. An in-vitro study aimed at evaluating shear bond strength (SBS) and adhesive remnant index (ARI) of nanoionomer under etching/unetched condition for use as an orthodontic bonding agent.
  
  
  METHODS
  A total of 75 extracted premolars were used, which were divided into three equal groups of 25 each: 1-Conventional adhesive (Enlight Light Cure, SDS, Ormco, CA, USA) was used after and etching with 37% phosphoric acid for 30 s, followed by Ortho Solo application 2-nanoionomer (Ketac(™) N100, 3M, ESPE, St. Paul, MN, USA) was used after etching with 37% phosphoric acid for 30 s 3-nanoionomer was used without etching. The SBS testing was performed using a digital universal testing machine (UTM-G-410B, Shanta Engineering). Evaluation of ARI was done using scanning electron microscopy. The SBS were compared using ANOVA with post-hoc Tukey test for intergroup comparisons and ARI scores were compared with Chi-square test.
  
  
  RESULTS
  ANOVA (SBS, F = 104.75) and Chi-square (ARI, Chi-square = 30.71) tests revealed significant differences between groups (P < 0.01). The mean (SD) SBS achieved with conventional light cure adhesive was significantly higher (P < 0.05) (10.59 ± 2.03 Mpa, 95% CI, 9.74-11.41) than the nanoionomer groups (unetched 4.13 ± 0.88 Mpa, 95% CI, 3.79-4.47 and etched 9.32 ± 1.87 Mpa, 95% CI, 8.58-10.06). However, nanoionomer with etching, registered SBS in the clinically acceptable range of 5.9-7.8 MPa, as suggested by Reynolds (1975). The nanoionomer groups gave significantly lower ARI values than the conventional adhesive group.
  
  
  CONCLUSIONS
  Based on this in-vitro study, nanoionomer with etching can be successfully used as an orthodontic bonding agent leaving less adhesive remnant on enamel surface, making cleaning easier. However, in-vivo studies are needed to confirm the validity of present findings.
authors.affiliation: Department of Orthodontics, Dr. Z. A. Dental College, Aligarh Muslim University, Aligarh, Uttar Pradesh, India.
authors.forename: Saba
authors.initials: S
authors.lastname: Khan
authors.affiliation: Department of Orthodontics, Dr. Z. A. Dental College, Aligarh Muslim University, Aligarh, Uttar Pradesh, India.
authors.forename: Sanjeev K
authors.initials: SK
authors.lastname: Verma
authors.affiliation: Department of Orthodontics, Dr. Z. A. Dental College, Aligarh Muslim University, Aligarh, Uttar Pradesh, India.
authors.forename: Sandhya
authors.initials: S
authors.lastname: Maheshwari
keywords: Adhesive remnant index; etching; nanoionomer; orthodontics; shear bond strength