title: In vitro fracture resistance of molar teeth restored with a short fibre-reinforced composite material.
abstract: OBJECTIVE
  The purpose of this in vitro study was to evaluate the efficiency of a short fibre-reinforced composite (SFRC) material compared to conventional composites when restoring class II. MOD cavities in molar teeth with different layering techniques.
  
  
  METHODS
  One hundred and thirty mandibular third molars were divided into 5 groups (n=26). Except for the control group (intact teeth), in all other groups MOD cavities were prepared. The cavities were restored by either conventional composite with horizontal and oblique layering or by SFRC with horizontal and oblique layering. The specimens were submitted to static fracture toughness test. Fracture thresholds and fracture patterns were evaluated.
  
  
  RESULTS
  In general, no statistically significant difference was found in fracture toughness between the study groups, except for horizontally layered conventional composite restorations, which turned out to be significantly weaker than controls. However, SFRC yielded noticeably higher fracture thresholds and only obliquely applied SFRC restorations exhibited favourable fracture patterns above chance level.
  
  
  CONCLUSIONS
  The application of SFRC did not lead to a statistically significant improvement of the fracture toughness of molar teeth with MOD cavities. Still, SFRC applied in oblique increments measurably reduces the chance of unrestorable fractures of molar teeth with class II MOD cavities.
  
  
  CONCLUSIONS
  The restoration of severely weakened molar teeth with the use of SFRC combined with composite might have advantages over conventional composites alone. It was observed from the statistical data, that the application of SFRC with an oblique layering technique yielded not significantly but better fracture thresholds and more favourable fracture patterns than any other studied material/technique combination. Thus further investigations need to be carried out, to investigate the possible positive mechanical effects of SFRC. The application of the horizontal layering technique with conventional composite materials is inferior to the oblique technique and SFRC materials.
authors.affiliation: Department of Operative and Esthetic Dentistry, Faculty of Dentistry, University of Szeged, Szeged, Hungary. Electronic address: meddentist.fm@gmail.com.
authors.forename: Márk
authors.initials: M
authors.lastname: Fráter
authors.affiliation: Department of Operative and Esthetic Dentistry, Faculty of Dentistry, University of Szeged, Szeged, Hungary.
authors.forename: András
authors.initials: A
authors.lastname: Forster
authors.affiliation: Department of Operative and Esthetic Dentistry, Faculty of Dentistry, University of Szeged, Szeged, Hungary.
authors.forename: Márk
authors.initials: M
authors.lastname: Keresztúri
authors.affiliation: Department of Oral Surgery, Faculty of Dentistry, University of Szeged, Szeged, Hungary.
authors.forename: Gábor
authors.initials: G
authors.lastname: Braunitzer
authors.affiliation: Department of Oral Surgery, Faculty of Dentistry, University of Szeged, Szeged, Hungary.
authors.forename: Katalin
authors.initials: K
authors.lastname: Nagy
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods; D003188:Composite Resins / Q000737:chemistry*; D003737:Dental Cavity Preparation / Q000145:classification; D003764:Dental Materials / Q000737:chemistry*; D003775:Dental Polishing / Q000379:methods; D019232:Dental Restoration Failure; D003793:Dental Restoration, Permanent / Q000145:classification / Q000379:methods*; D003799:Dental Stress Analysis / Q000295:instrumentation; D005898:Glass / Q000737:chemistry*; D006801:Humans; D055115:Light-Curing of Dental Adhesives / Q000379:methods; D008422:Materials Testing; D008963:Molar / Q000503:physiopathology*; D011108:Polymers / Q000737:chemistry; D019233:Retreatment; D013314:Stress, Mechanical; D013499:Surface Properties; D014082:Tooth Fractures / Q000503:physiopathology*
chemical_list: D003188:Composite Resins; D003764:Dental Materials; D011108:Polymers; C009753:fiberglass; C509952:fiberglass reinforced polymers
keywords: Biomechanical stability; Conventional composite; Fracture resistance; Short fibre reinforced composite