title: Fracture strength of weakened human premolars restored with amalgam with and without cusp coverage.
abstract: OBJECTIVE
  To determine the effect of cusp coverage with amalgam restorations on the fracture strength of weakened human maxillary premolars.
  
  
  METHODS
  30 extracted human maxillary premolars were divided into three groups; Group A (control): uncut teeth, Group B: wide MOD cavities prepared and the pulp chamber's roof removed. The teeth were restored with amalgam without cusp coverage, Group C: same as Group B plus cusp reduction and restored with amalgam. The teeth were included in metal rings with self-curing polystyrene resin and stored in water for 24 hrs. The restorations were refined with rubber points, polished and further stored in water for 24 hrs before being subjected to a compressive axial load in a Universal testing machine at 0.5 mm/min.
  
  
  RESULTS
  The mean fracture strength obtained was: Group A: 173.3 Kgf, Group B: 47.3 Kgf and Group C: 127.7 Kgf. All values were statistically significantly different (P < 0.05). The amalgam restoration of weakened human premolars with cusp coverage amalgam significantly increased the fracture strength of the teeth (63%) as compared to teeth restored without cusp coverage. The results showed that cusp coverage with amalgam might be an option for restoring weakened endodontically-treated teeth.
authors.affiliation: Depto. de Dentística, FOB USP, Bauru, SP, Brazil.
authors.forename: R F
authors.initials: RF
authors.lastname: Mondelli
authors.forename: W F
authors.initials: WF
authors.lastname: Barbosa
authors.forename: J
authors.initials: J
authors.lastname: Mondelli
authors.forename: E B
authors.initials: EB
authors.lastname: Franco
authors.forename: R M
authors.initials: RM
authors.lastname: Carvalho
mesh_terms: D000704:Analysis of Variance; D001641:Bicuspid; D003723:Dental Amalgam; D003737:Dental Cavity Preparation / Q000379:methods*; D003799:Dental Stress Analysis; D006801:Humans; D014082:Tooth Fractures / Q000517:prevention & control*
chemical_list: D003723:Dental Amalgam