Bisphenol-A in Wastewater After Grinding of Composites - Methods for Prevention

Objectives: The aim of the present study was to evaluate the elution of Bisphenol A (BPA) in wastewater after grinding of composite materials and to test possible methods to prevent it.
Methods:

Four composite materials were used: an Ormocer Ceram X^TM (Dentsply DeTrey), a nanohybrid: Filtek^TM Supreme XTE (3M ESPE), a microhybrid: FiltekTM Silorane (3M ESPE) and a core built-up: CoreX Flow (Dentsply DeTrey). From each composite, 10 samples (5x2x2mm) were prepared in a metal mold and polymerized according to the manufacturers’ instructions. Each composite sample was ground under standardized conditions (dental bur: 106µm grid, 90 sec, 200.000 U/min). The experiment was performed in an isolated dental unit and the wastewater after drilling of each sample was collected in separate bottles (500ml). As control, clean wastewater was collected under the same conditions. Both water and sediment of each sample were tested for BPA by using HPLC. Three different methods were tested concerning their ability to prohibit the release of BPA in wastewater: one filtration and two adsorption methods.
For statistical analysis, a linear regression model was fitted to evaluate material effects on response variables and the Scheffe's method was applied (adjustment of p-values).
Results: BPA was detected in the wastewater of all tested composite materials. The detected amount differed significantly among each other (p<0.05): Ceram X^TM=Filtek^TM Supreme XTE>Filtek^TM Silorane=CoreX flow. Ceram X^TM and Filtek^TM Supreme XTE released significantly higher amounts of BPA compared to the other groups (p<0.05). Among the methods tested for water cleaning only one of the adsorption methods achieved a significant reduction in BPA (99.4%).
Conclusions: BPA can be released in wastewater through drilling of composite materials. The released amount is material dependent. Adsorption methods seem to be very promising in prohibiting the BPA release in wastewater of dental clinics.