Mechanical Properties of Novel Experimental BPA-Free Composites

Objective:

Trace amount of bisphenol-A (BPA) can potentially be found in dental products which utilize bisphenol-A glycidyl dimethacrylate (bis-GMA) or its derivative (such as ethoxylated bis-GMA).  Development of alternative resin matrices has been challenging due to good performance of bis-GMA type systems. This study investigated key mechanical properties of recently developed novel experimental BPA-free composites.

Method:

Materials evaluated include: two DENTSPLY/Caulk experimental BPA-free composites (BFC-1 and BFC-2), commercially available BPA-free composite Venus Diamond™ (Heraeus Kulzer) and Kalore™ (GC). Specimens for flexural strength (25X2X2 mm, n=6) were prepared, light-cured, and tested according to ISO 4049. Specimens for compressive strength (4X6mm, n=6) and barcol hardness (30X1mm, n=3) were prepared, light-cured, and tested according to DENTSPLY/Caulk’s internal test methods. Specimens for flexural and compressive testing were stored in DI-water at 37°C for 24-hour before final testing on Instron 3366 at crosshead speed of 0.75 mm/min for flexural testing and 5.0 mm/min for compressive testing.

Result: Evaluation results are shown in the table:  

BPA-Free Composite	BFC-1	BFC-2	Venus Diamond	Kalore
Filler Loading (wt%)	80.0	81.5	81.2	82.0
Flexural Strength (MPa)	170 (4)	157 (3)	169 (15)	112 (3)
Flexural Modulus (MPa)	12872 (345)	13198 (379)	12088 (475)	6941 (115)
Compressive Strength (MPa)	314 (14)	317 (4)	406 (28)	262 (15)
Compressive Modulus (MPa)	6365 (515)	6227 (381)	5973 (180)	4973 (164)
Barcol Hardness (Hard )	82	84	84	77

Conclusion: The newly developed experimental BPA-free composites exhibited overall similar mechanical properties as compared to Venus Diamond, whereas Kalore showed substantially lower mechanical properties.