title: Influence of ceramic inlays and composite fillings on fracture resistance of premolars in vitro.
abstract: OBJECTIVE
  The aim of this study was to assess the resistance of fracture of mesio-occlusal-distal (MOD) ceramic inlays and composite fillings in premolars and to compare fracture modes between the groups.
  
  
  METHODS
  Twenty seven extracted intact human premolars were selected and divided into three groups: I - intact teeth (control group), II - MOD cavities restored with indirect ceramic inlays (Finesse, Dentsply Ceramco, USA), III - MOD cavities restored with direct composite fillings (Filtek P60, 3M ESPE, USA). The fracture resistance (N) was assessed under axial compressive loading with a metal cylinder 3.2 mm in diameter at a cross-head speed of 0.5 mm/min in a universal testing machine. The data were analyzed with ANOVA and t-test (pd< or =0.05). Fracture modes were recorded based on the degree of tooth structure and restoration damage.
  
  
  RESULTS
  The mean force applied to cause failure for group I was 1.218 kN +/-0.223, for group II - 1.407 kN +/-0.374 and for group III - 0.941 kN +/-0.258. T-test showed significant difference between groups I and III (p=0.027), and groups II and III (p=0.008). The fracture modes observed in all groups tended to involve restoration's and cusp's fracture.
  
  
  CONCLUSIONS
  It was observed that ceramic inlays in premolars have higher load to fracture value than composite fillings and similar to intact teeth. Both restorations, ceramic and composite in the premolars, tended to fracture together with palatal cusp of tooth.
authors.affiliation: Department of Prosthodontics, Faculty of Stomatology, Riga Stradins University, 20 Dzirciema Street, Riga, LV-1007, Latvia. antraragauska@inbox.lv
authors.forename: Antra
authors.initials: A
authors.lastname: Ragauska
authors.forename: Peteris
authors.initials: P
authors.lastname: Apse
authors.forename: Vladimirs
authors.initials: V
authors.lastname: Kasjanovs
authors.forename: Liga
authors.initials: L
authors.lastname: Berzina-Cimdina
mesh_terms: D001641:Bicuspid; D001732:Bite Force; D003188:Composite Resins / Q000009:adverse effects*; D019245:Compressive Strength; D003776:Dental Porcelain / Q000009:adverse effects; D019232:Dental Restoration Failure; D003793:Dental Restoration, Permanent / Q000009:adverse effects* / Q000379:methods; D003799:Dental Stress Analysis; D006801:Humans; D007284:Inlays / Q000009:adverse effects; D008422:Materials Testing; D014082:Tooth Fractures / Q000209:etiology*
chemical_list: D003188:Composite Resins; C438835:Filtek P60 Composite Resin; D003776:Dental Porcelain; C037884:finesse