The strongest Philips Zoom whitening gel is the Zoom WhiteSpeed gel, which offers a high concentration of hydrogen peroxide for professional-grade whitening results. This gel is used in-office and can lighten teeth by up to eight shades in just one session. Its powerful formula, combined with advanced LED light technology, effectively targets and removes deep stains. For at-home use, what is the strongest Philips zoom whitening gel effect with varying concentrations, though not as intense as the in-office WhiteSpeed gel? If seeking the most potent option, consult with a dental professional to explore the WhiteSpeed treatment.