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Fracture strength of weakened human premolars restored with amalgam with and without cusp coverage
R F Mondelli1, W F Barbosa, J Mondelli
1Depto. de Dentística, FOB USP, Bauru, SP, Brazil.
Purpose:
To determine the effect of cusp coverage with amalgam restorations on the fracture strength of weakened human maxillary premolars.
Materials And 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.
