Are there any posterior composites that you can recommend that do not have the Bis-GMA formula?

One option is Filtek LS Low Shrink Posterior Restorative System (3M ESPE). This composite is based on silorane chemistry and does not contain Bis-GMA. Note that Filtek LS requires a unique bonding agent (LS System Adhesive Self-Etch Primer and Bond). The composite did well at one-year recall with a 96% clinical rating. Other options are composites that contain urethane dimethacrylate instead of Bis-GMA.