Determination of Fracture Toughness of Provisional Dental Materials

Objectives: � To determine and compare the fracture toughness of five provisional dental materials.�

Methods: � Five groups of ten samples each of provisional materials were tested in this study. The samples were made using a stainless steel mold 2 mm in height, 4.95 mm in width, and 25 mm in length.� After 24 hours of polymerization, �a notch (2.6 � .05 mm) was inserted into the middle of each sample using a separating disc (thickness 320 �m) attached to an immobilized low speed handpiece . �Microscope examination was used to observe any defects. �The three-point bending test was performed using a universal testing machine (Instron, 5566A) at a cross-head speed of 1mm/min (load cell 500 N). ��The notch was positioned centrally beneath the contact and the distance between the two supports was 20 mm. The radius of each support was 1 mm.

The fracture toughness (K_1C) was calculated according to ISO 13586.� The Kolmogorov-Smirnov test was used to determine normal distribution and the homogeneity of the samples was checked using the Levene test.� A one-way ANOVA was used to test the mean fracture toughness between groups. �Statistical significance was predetermined at level p<0.05.

 

Results: �

Group (n=10)	Material	Mean Fracture Toughness (MPa ∙ m0.5)
1	Structur Premium (Voco)	1.36 � .14b
2	Protemp Plus (3M)	1.66 � .22c,d
3	Luxatemp (DMG)	1.05 � .11a
4	Luxatemp Ultra (DMG.)	1.54 � .17b,d
5	Experimental (Dentsply Caulk)	1.35 � .17b

 

Conclusions: � Group 3 exhibited a statistically lower resistance to crack propagation than all other groups, whereas Group 2 exhibited a statistically higher resistance than Group 1, Group 3, and Group 5.� No statistical difference is evident between Groups 1, 3, and 5.