Paper: Flowable vs restorative composites: flexural strength and fracture toughness (AADR Annual Meeting (March 21-24, 2012))

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 (s_f), flexural modulus (E_f), and fracture toughness (K_IC) 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 K_IC test. Tests were conducted after 1h (clinically relevant) and 7d (full maturation, equilibration with water) immersion in distilled water at 37°C. 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 K_IC sample per group.

Results: Table summarizes the results. GC had the highest K_IC at both 1h and 7d; FSU showed a significant increase in K_IC between 1h and 7d while the other materials did not; restorative composites did not have higher K_IC than flowable materials; E_f increased from 1h to 7d; FSU had the highest 1h s_f and the highest E_f at both 1h and 7d; GC, FSUF, and GSOHF had the highest 7d s_f; With the exemption of FSU, which exhibited a decrease in s_f 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

E_f (in GPa)
Mean ± SD

s_f (in MPa)
Mean ± SD

K_IC (in MPa·m^1/2)
Mean ± SD

1 hour

7 days

1 hour

7 days

1 hour

7 days

GC

5.28 ± 0.80^c

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 ± 0.62^b

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 ± 0.25^d

7.03 ± 0.66*^b

91.42 ± 8.94^b

133.31 ± 19.16*^a

1.03 ± 0.16^a

1.07 ± 0.11^b

FSU

8.33 ± 0.47^a

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 ± 0.52^b

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.

See more of: Physico-mechanical Properties of Flowables and Hybrid Resin-composites
See more of: Dental Materials 7: Polymer-based Materials-Physical Properties and Performance

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Material/Test	E_f (in GPa) Mean ± SD		s_f (in MPa) Mean ± SD		K_IC (in MPa·m^1/2) Mean ± SD
Material/Test	1 hour	7 days	1 hour	7 days	1 hour	7 days
GC	5.28 ± 0.80^c	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 ± 0.62^b	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 ± 0.25^d	7.03 ± 0.66*^b	91.42 ± 8.94^b	133.31 ± 19.16*^a	1.03 ± 0.16^a	1.07 ± 0.11^b
FSU	8.33 ± 0.47^a	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 ± 0.52^b	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

163 Flowable vs restorative composites: flexural strength and fracture toughness