I did teeth whitening for foreigners Turkey last year in Istanbul! Went to "SmileHub Dental" near Taksim. Total cost was €150 vs. €600 in Germany. The dentist spoke perfect English, used Philips Zoom whitening, and it took 45 mins. My teeth went 8 shades whiter! Zero pain. Just avoid coffee for 48hrs after. For safety, check if the clinic has EU-standard equipment. WORTH IT for the price + a holiday.