title: Fracture resistance of Class II approximal slot restorations.
abstract: BACKGROUND
  Determination of the fracture resistance of various restorative materials in Class II approximal slot restorations has not been studied.
  
  
  OBJECTIVE
  This study evaluated the effects of retention grooves and different restorative materials in Class II approximal slot restorations. To explore the possibilities for further research, the probable effects of preparation size and loading angle were investigated in a limited manner.
  
  
  METHODS
  Ninety sound, caries-free human maxillary premolars were divided into 9 groups. The cavities were prepared either by hand or in a computer-controlled CNC machine with or without retention grooves. Four were restored with adhesive amalgam, another 4 with composite, and a single group with Compomer resin. The gingival floor depth was 1.5 mm. The specimens were loaded at an angle of 13. 5 degrees to their longitudinal axes by using a computer-controlled material testing machine until failure occurred. For one specific preparation of adhesive amalgam, loading was applied at 0 and 30 degrees to determine the probable effects of the loading angle. For a specific composite, resin application, the effects of the change in gingival floor depth were analyzed by assigning the depth to 2.0 mm.
  
  
  RESULTS
  Composite and Compomer resin and composite exhibited better performance than amalgam. The existence of the retention grooves proved to be effective for adhesive amalgam restorations but did not have any advantageous effect in composite and Compomer restoration.
  
  
  CONCLUSIONS
  For improved fracture resistance in small approximal restorations, the use of composite was the appropriate choice. Compomer also gave satisfactory results. Use of amalgam restoration should be accompanied with retention grooves and an adhesive system to improve its performance.
authors.affiliation: Gazi University, and Middle East Technical University, Ankara, Turkey.
authors.forename: S D
authors.initials: SD
authors.lastname: Yaman
authors.forename: M
authors.initials: M
authors.lastname: Yetmez
authors.forename: E
authors.initials: E
authors.lastname: Türköz
authors.forename: N
authors.initials: N
authors.lastname: Akkas
mesh_terms: D001641:Bicuspid; D020770:Compomers; D003188:Composite Resins; D003723:Dental Amalgam; D003737:Dental Cavity Preparation / Q000379:methods*; D019232:Dental Restoration Failure; D003793:Dental Restoration, Permanent / Q000379:methods*; D003799:Dental Stress Analysis; D006801:Humans; D008422:Materials Testing; D018709:Statistics, Nonparametric
chemical_list: D020770:Compomers; D003188:Composite Resins; D003723:Dental Amalgam