title: Fracture toughness of pin-retained class 4 restorations.
abstract: Standardized class 4 cavities were prepared in bovine incisors and restored with a microfilled composite resin. The composite restorations were retained either by acid etching technique (AET) alone or by acid etching technique in combination with a self-threading retentive pin. Pins covered with a bonding/opaquer coating (PCR pin) and uncovered pins (FO pin) were used. After having been aged for 3 days, the fracture resistance of the restorations was determined with a Universal Testing Machine. The restorations were loaded at an angle of 45 degrees. The restorations retained by AET and a PCR pin showed the highest failure load. The restorations accomplished with AET and a FO pin yielded the lowest fracture load. The fracture toughness of the restorations retained by AET and a PCR pin was slightly but statistically significant, higher compared to the restorations exclusively attached by acid etching technique. It was concluded that there was only a small increase of fracture toughness of large class 4 composite restorations if the acid etching technique was combined with the application of bonding/opaquer-covered retentive pins.
authors.affiliation: University Clinic of Dentistry, Department of Operative Dentistry, Freiburg, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Attin
authors.forename: E
authors.initials: E
authors.lastname: Hellwig
authors.forename: R D
authors.initials: RD
authors.lastname: Hilgers
authors.forename: U
authors.initials: U
authors.lastname: Zimmermann
mesh_terms: D000134:Acid Etching, Dental; D000704:Analysis of Variance; D000818:Animals; D002417:Cattle; D003188:Composite Resins; D003772:Dental Pins; D003793:Dental Restoration, Permanent / Q000379:methods*; D004867:Equipment Design; D005069:Evaluation Studies as Topic; D008855:Microscopy, Electron, Scanning; D012821:Silanes; D014082:Tooth Fractures / Q000517:prevention & control
chemical_list: D003188:Composite Resins; D012821:Silanes