title: Fracture strength of restored premolars.
abstract: OBJECTIVE
  To evaluate the fracture resistance (axial compressive strength) of premolars restored with different dental materials under two axial loads.
  
  
  METHODS
  Fracture strength was performed using two metal spheres with 3 mm and 9 mm diameter. Five restorative techniques were chosen for MOD cavity preparations (n = 10): (1) direct resin composite restorations (Z-250); (2) indirect resin composite restorations (Z-250 and RelyX); (3) ceramic inlays (Vitadur Alpha); (4) conventional amalgam restorations (GS-80); (5) bonded amalgam restorations. The restored teeth were compared to human caries-free premolars (Group 6/control). Enforce resin cement was used for ceramic and amalgam adhesive restorative techniques, according to the manufacturers' instructions. Whenever required, the teeth were conditioned by the total etch technique.
  
  
  RESULTS
  The ANOVA analysis pointed out a significant difference among the groups (P < 0.01) and the "site" factor (P < 0.1). The ceramic restorations presented the highest values for fracture strength and were similar to the control group. The statistical results of direct and indirect resin composite restorations were similar but inferior to the control group. The amalgam restorations (conventional and bonded) presented the lowest values, with no difference between them. All amalgam groups displayed lower strengths when the load was applied on the central fossa (3 mm 0 sphere) compared to load applied on cusps (9 mm 0 sphere).
authors.affiliation: Department of Dental Prosthesis Unit III, Pelotas Federal University, Pelotas, Rio Grande do Sul, Brazil.
authors.forename: Guilherme Brião
authors.initials: GB
authors.lastname: Camacho
authors.forename: Mariane
authors.initials: M
authors.lastname: Gonçalves
authors.forename: Tomio
authors.initials: T
authors.lastname: Nonaka
authors.forename: Angela Brys
authors.initials: AB
authors.lastname: Osório
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D000704:Analysis of Variance; D001641:Bicuspid / Q000737:chemistry*; D001732:Bite Force; D003188:Composite Resins / Q000737:chemistry*; D019245:Compressive Strength; D003723:Dental Amalgam / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D003793:Dental Restoration, Permanent / Q000009:adverse effects*; D006801:Humans; D011140:Polyurethanes / Q000737:chemistry*; D014082:Tooth Fractures
chemical_list: D000180:Acrylic Resins; C029012:Composite Dental Resin; D003188:Composite Resins; D003764:Dental Materials; D011140:Polyurethanes; D003723:Dental Amalgam