Evaluation of the Flexural Strength of Interim Restorative Materials in Fixed Prosthodontics.
BACKGROUND
Mechanical properties of interim restorations are considered as important factors specially when selecting materials for long-term application or for patients with para-functional habits. Flexural strength is one of the most important components of these restorations.


OBJECTIVE
The purpose of this study was to compare the flexural strength of five interim restorative materials.


METHODS
Fifty identical samples sized 25×2×2-mm were made from five interim materials (TempSpan; Protemp 4, Unifast III, Trim, and Revotek LC) according to ADA specification #27. The specimens were stored in artificial saliva for 2 weeks and then thermocycled for 2500 cycles (5-55˚C). A standard three-point bending test was conducted on the specimens with a universal testing machine at a crosshead speed of 0.75mm/min. Data were analyzed by using one-way ANOVA and Tamhane's post-hoc tests to measure the flexural strength of temporary materials.


RESULTS
One of the bis-acryl resins (TempSpan) showed the highest, and the light polymerized resin (Revotek LC) showed the lowest flexural strength. The mean values of flexural strength (MPa) for the examined materials were as follow: TempSpan=120.00, Protemp 4=113.00, Unifast III=64.20, Trim= 63.73 and Revotek LC=47.16. There were significant differences between all materials except Trim and Unifast III which did not show any statistical significant difference.


CONCLUSIONS
Bis-acryl resins were statistically superior to traditional methacrylate and light-cured resins. Therefore, application of bis-acryl resins should be deliberated in patients with heavy occlusion and in cases that need long-term use of interim restorations.
Biomaterials Research Center, Postgraduate Dept. of Prosthodontic Dentistry, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran.
Hanieh
H
Mehrpour
Dept. of Prosthodontics, School of Dentistry, Hormozgan University of Medical Sciences, Bandarabbas, Iran.
Ehsan
E
Farjood
Biomaterials Research Center, Postgraduate Dept. of Prosthodontic Dentistry, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran.
Rashin
R
Giti
Biomaterials Research Center, Postgraduate Dept. of Prosthodontic Dentistry, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran.
Alireza
A
Barfi Ghasrdashti
Biomaterials Research Center, Postgraduate Dept. of Prosthodontic Dentistry, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran.
Hossein
H
Heidari
Fixed Prosthesis; Flexural Strength; Interim