163 Flowable vs restorative composites: flexural strength and fracture toughness

Thursday, March 22, 2012: 10:45 a.m. - 12:15 p.m.
Presentation Type: Oral Session
N.D. RUSE, University of British Columbia, Vancouver, BC, Canada

Objectives: To assess and compare flexural strength (sf), flexural modulus (Ef), and fracture toughness (KIC) of flowable and restorative composites.

Materials and Methods: Three flowable [G-aenial Universal Flo (GC) code GC; Grandio SO Heavy Flow (VOCO) GSOHF; Filtek Supreme Ultra Flow (3M ESPE) FSUF] and two restorative [Filtek Supreme Ultra (3M-ESPE) FSU; Herculite Ultra (Kerr) HU] composites were used to prepare (2x2x25) bars for three point bend (3pb) test and (6x6x6x12) mm triangular prisms for notchless triangular prism (NTP) specimen KIC test. Tests were conducted after 1h (clinically relevant) and 7d (full maturation, equilibration with water) immersion in distilled water at 37C. For each determination, eight samples were tested. Data was analyzed using ANOVA and Scheffe multiple means comparisons. SEM fractographic analysis was performed on one representative KIC sample per group.

Results: Table summarizes the results. GC had the highest KIC at both 1h and 7d; FSU showed a significant increase in KIC between 1h and 7d while the other materials did not; restorative composites did not have higher KIC than flowable materials; Ef increased from 1h to 7d; FSU had the highest 1h sf and the highest Ef at both 1h and 7d; GC, FSUF, and GSOHF had the highest 7d sf; With the exemption of FSU, which exhibited a decrease in sf between 1h and 7d, all materials showed an increase between 1h and 7d. SEM revealed significant built-in porosity in each material along with macroscopic voids introduced inadvertently during sample preparation. Crack propagation occurred through resin and resin-filler interface.

Conclusions: An overlap between the properties determined was identified for the materials tested.

Material/Test

Ef (in GPa)

Mean SD

sf (in MPa)

Mean SD

KIC (in MPam1/2)

Mean SD

1 hour

7 days

1 hour

7 days

1 hour

7 days

GC

5.28 0.80c

8.42 0.65* b

100.17 14.42 b

135.70 22.59* a

1.11 0.19 a

1.31 0.18 a

GSOHF

6.67 0.62b

11.40 1.52* a

95.84 15.58 b

140.08 16.80* a

0.75 0.14 b

0.87 0.14 b

FSUF

4.17 0.25d

7.03 0.66* b

91.42 8.94b

133.31 19.16* a

1.03 0.16 a

1.07 0.11 b

FSU

8.33 0.47a

12.61 0.93*a

125.07 8.19 a

116.09 9.66 a

0.88 0.09 ab

1.03 0.09* b

HU

6.29 0.52b

8.70 1.12* b

95.60 9.24 b

116.07 12.08* a

0.88 0.06 ab

0.86 0.07 b

 

This abstract is based on research that was funded entirely or partially by an outside source: GC Corporation

Keywords: Composites, Dental materials, Loading, Stress and fracture mechanics
Presenting author's disclosure statement: Although the study was sponsored by GC Corporation, the author has no financial interest and no affiliation with the company. The results presented are original and non-biased.