Shear modulus of 5 flowable composites to the EverStick Ortho fiber-reinforced composite retainer: an in-vitro study.
BACKGROUND
Although fiber-reinforced composites (FRC) are now available for use as orthodontic retainers, little is known about their bonding properties. Our aim in this study was to investigate the adhesive properties of various composites to a commercially available FRC retainer.


METHODS
Five flowable composites (Grandio Flow [Voco GmbH, Cuxhaven, Germany], Synergy Flow [Coltène/Whaledent AG, Genf, Switzerland], Tetric Flow [Ivoclar Vivadent AG, Schaan Fürstentum, Liechtenstein], Tetric Flow Chroma [Ivoclar Vivadent AG], and Transbond LR [3M Unitek, Monrovia, Calif) were tested for their shear bond strengths to the EverStick Ortho (Stick Tech Ltd Oy, Turku, Finland) FRC retainer stick. Each group contained 15 samples and underwent 1000 aging cycles between 5 degrees C and 55 degrees C. A testing machine was used to measure the shear bond strengths at the composite-FRC interface. All specimens were visually controlled for the location of the fracture line.


RESULTS
Typical shear bond strengths were measured at 40 N or 8 MPa. No significant difference was found between the 5 composites (ANOVA, P < or = 0.05). The fracture line was consistently in the FRC retainer.


CONCLUSIONS
All composites had similar bonding characteristics, and visual inspection consistently showed fractures in the FRC retainer. Because the point of least resistance was in the retainer, we concluded that all tested composites were equally effective.
Brauchli
Lorenz
L
Clinic of Orthodontics and Pedodontics, University of Basel, Basel, Switzerland. Lorenz.Brauchli@unibas.ch
Pintus
Stefano
S
Steineck
Markus
M
Lüthy
Heinz
H
Wichelhaus
Andrea
A
D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D005898:Glass / Q000737:chemistry; D006801:Humans; D055115:Light-Curing of Dental Adhesives; D008422:Materials Testing; D008854:Microscopy, Electron; D016382:Orthodontic Appliance Design; D018704:Orthodontic Retainers; D019904:Polymethyl Methacrylate / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D033081:Shear Strength; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors
D003188:Composite Resins; D003764:Dental Materials; C509998:Grandio; D019279:Resin Cements; C452441:Synergy composite resin; C481385:Transbond LR; C496140:everStick; C009753:fiberglass; C111840:flowable hybrid composite; C452226:tetric flow composite resin; D017438:Bisphenol A-Glycidyl Methacrylate; D019904:Polymethyl Methacrylate