title: A comparative effect of various surface chemical treatments on the resin composite-composite repair bond strength.
abstract: OBJECTIVE
  The aim of this in vitro study was an attempt to investigate the effect of different surface treatments on the bond strength between pre-existing composite and repair composite resin.
  
  
  METHODS
  Forty acrylic blocks were prepared in a cuboidal mould. In each block, a well of 5 mm diameter and 5 mm depth was prepared to retain the composite resin (Filtek™ Z350, 3M/ESPE). Aging of the composite discs was achieved by storing them in water at 37°C for 1 week, and after that were divided into 5 groups (n = 8) according to surface treatment: Group I- 37% phosphoric acid, Group II-10% hydrofluoric acid, Group III-30% citric acid, Group IV-7% maleic acid and Group V- Adhesive (no etchant). The etched surfaces were rinsed and dried followed by application of bonding agent (Adper™ Single Bond 2. 3M/ESPE). The repair composite was placed on aged composite, light-cured for 40 seconds and stored in water at 37°C for 1 week. Shear bond strength between the aged and the new composite resin was determined with a universal testing machine (crosshead speed of 0.5 mm/min).
  
  
  METHODS
  The compressive shear strengths were compared for differences using ANOVA test followed by Tamhane's T2 post hoc analysis.
  
  
  RESULTS
  The surface treatment with 10% hydrofluoric acid showed the maximum bond strength followed by 30% citric acid, 7% maleic acid and 37% phosphoric acid in decreasing order.
  
  
  CONCLUSIONS
  The use of 10% hydrofluoric acid can be a good alternative for surface treatment in repair of composite resin restoration as compared to commonly used 37% orthophosphoric acid.
authors.forename: Shaloo
authors.initials: S
authors.lastname: Gupta
authors.affiliation: Division of Restorative Dentistry, School of Dentistry, International Medical University, Kuala Lumpur, Malaysia.
authors.forename: Abhishek
authors.initials: A
authors.lastname: Parolia
authors.forename: Ashish
authors.initials: A
authors.lastname: Jain
authors.forename: M
authors.initials: M
authors.lastname: Kundabala
authors.forename: Mandakini
authors.initials: M
authors.lastname: Mohan
authors.forename: Isabel Cristina Celerino
authors.initials: IC
authors.lastname: de Moraes Porto
mesh_terms: D019343:Citric Acid / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry*; D001840:Dental Bonding / Q000379:methods*; D006858:Hydrofluoric Acid / Q000737:chemistry*; D008298:Maleates / Q000737:chemistry; D008422:Materials Testing; D010756:Phosphoric Acids / Q000737:chemistry; D033081:Shear Strength; D013499:Surface Properties
chemical_list: D003188:Composite Resins; D008298:Maleates; D010756:Phosphoric Acids; D019343:Citric Acid; C030272:maleic acid; C030242:phosphoric acid; D006858:Hydrofluoric Acid